-
Introduction to Physiology
Introduction
Physiology
is
the
study
of
the
functions
of
living
matter.
It
is
concerned
with
how
an
organism
performs
its
varied
activities:
how
it
feeds,
how
it
moves,
how
it
adapts
to
changing
circumstances,
how
it
spawns
new
generations.
The
subject
is
vast
and
embraces
the
whole
of
life.
The success of physiology in explaining how
organisms perform their
daily
tasks
is
based
on
the
notion
that
they
are
intricate
and
exquisite
machines
whose
operation
is
governed
by
the
laws
of
physics
and
生理学简介
介绍
生理学是研究生物体功能的科学
。
它研
究生物体如何进行各种活动,如何饮食,如
何运动,如何适应不断改变的环境,如何繁
殖后代。这门学科包罗万象,涵盖
了生物体
整个生命过程。
生理学成功地解释了生物体
如何进行日常活动,
基于的观点是生物体好
比是结
构复杂而灵巧的机器,
其操作受物理
chemistry.
Although
some
processes
are
similar
across
the
whole
spectrum
of
biology
—
the
replication
of
the
genetic
code
for
or
example
—
many
are
specific to particular
groups of organisms. For this reason it is
necessary to
divide
the
subject
into
various
parts
such
as
bacterial
physiology,
plant
physiology, and animal physiology.
To study how an animal works it is
first necessary to know how it is
built. A full appreciation of the
physiology of an organism must therefore
be based on a sound knowledge of its
anatomy. Experiments can then be
carried
out
to
establish
how
particular
parts
perform
their
functions.
Although there
have been many important physiological
investigations on
human
volunteers,
the
need
for
precise
control
over
the
experimental
conditions
has
meant
that
much
of
our
present
physiological
knowledge
has been derived
from studies on other animals such as frogs,
rabbits, cats,
and
dogs.
When
it
is
clear
that
a
specific
physiological
process
has
a
common
basis
in
a
wide
variety
of
animal
species,
it
is
reasonable
to
assume
that
the
same
principles
will
apply
to
humans.
The
knowledge
gained
from
this
approach
has
given
us
a
great
insight
into
human
physiology
and
endowed
us
with
a
solid
foundation
for
the
effective
treatment of many diseases.
The
building
blocks
of
the
body
are
the
cells,
which
are
grouped
together
to
form
tissues.
The
principal
types
of
tissue
are
epithelial,
connective,
nervous,
and
muscular,
each
with
its
own
characteristics.
Many
connective
tissues
have
relatively
few
cells
but
have
an
extensive
extracellular
matrix.
In
contrast,
smooth
muscle
consists
of
densely
packed
layers
of
muscle
cells
linked
together
via
specific
cell
junctions.
Organs such as
the brain, the heart, the lungs, the intestines,
and the liver
are formed by the
aggregation of different kinds of tissues. The
organs are
themselves
parts
of
distinct
physiological
systems.
The
heart
and
blood
vessels
form
the
cardiovascular
system;
the
lungs,
trachea,
and
bronchi
together with the
chest wall and diaphragm form the respiratory
system;
the
skeleton
and
skeletal
muscles
form
the
musculoskeletal
system;
the
brain, spinal cord,
autonomic nerves and ganglia, and peripheral
somatic
nerves form the nervous system,
and so on.
Cells
differ
widely
in
form
and
function
but
they
all
have
certain
common
characteristics.
Firstly,
they
are
bounded
by
a
limiting
membrane, the plasma membrane.
Secondly, they have the ability to break
down large molecules to smaller ones to
liberate energy for their activities.
和化学规律控制。
尽管从生物学整个
范畴看,
生物体某些
活动过程是相似的
——
如基因编码的复制
——
但许多过程
还是某些生物体群组特有
的。
鉴于此有必要将这门学科分成不同
部分
研究,如细菌生理学、植物生理学和动物生
理学。
要研究一种动物如何活动,
首先需要了
解它的构成。
要充分了解一个生物体的生理
学
活动就必须掌握全面的解剖学知识。
一个
生物体的各部分起着什
么作用可通过实验
观察得知。
尽管我们对志愿者进行了许多重<
/p>
要的生理调查,但是实验条件需要精确控
制,
所以我们当前大多生理知识还是源于对
其它动物如青蛙,兔子,猫和狗等的研究。<
/p>
当我们明确大多数动物物种的特定生理过
程存在共同之处时,
p>
相同的生理原理适用于
人类也是合理的。通过这种方法,我们获得<
/p>
了大量的知识,
从而让我们对人类生理学有
了更深入的了解,
为我们有效治疗许多疾病
提供了一个坚实的
基础。
机体的基本组成物质是细胞,
细胞结合
在一起形成组织。
组织的基本类型有上皮组
织,结缔组织,神经组织和肌组织,每类组
织都有各自的特征。
许多结缔组织中细胞量
相对较少,但是有大量的细胞外基质。相比
而言,
光滑的肌组织由大量密密麻麻的肌细
胞通
过特定的细胞连接组成。各种器官如
脑,心脏,肺,小肠和肝等由不同种类的组
织聚集而成。
这些器官是不同生理系统的组
成部
分。心脏和血管组成心血管系统;肺,
器官,支气管,胸壁和膈肌组成呼吸系统;
骨骼和骨骼肌组成骨骼肌系统;
大脑,
脊髓,
自主神经和神经中枢以及周围躯体神经组
成神经系统等等。
p>
细胞在形体和功能上差异很大,
但是它<
/p>
们有某些共同的特征。第一,它们由限制膜
包被,即细胞质膜;第
二,细胞有把大分子
Thirdly, at some point in
their life history, they possess a nucleus which
contains genetic information in the
form of deoxyribonucleic acid (DNA).
Living
cells
continually
transform
materials.
They
break
down
glucose and fats to provide energy for
other activities such as motility and
the
synthesis
of
proteins
for
growth
and
repair.
These
chemical
changes
are collectively called metabolism. The
breakdown of large molecules to
smaller
ones
is
called
catabolism
and
the
synthesis
of
large
molecules
from smaller ones anabolism.
In
the
course
of
evolution,
cells
began
to
differentiate
to
serve
different functions.
Some developed the ability to contract (muscle
cells),
others
to
conduct
electrical
signals
(nerve
cells).
A
further
group
developed the ability
to secrete different substances such as hormones
or
enzymes.
During
embryological
development,
this
process
of
differentiation
is
re-enacted
as
many
different
types
of
cell
are
formed
from
the fertilized egg.
Most
tissues
contain
a
mixture
of
cell
types.
For
example,
blood
consists of red cells, white cells, and
platelets. Red cells transport oxygen
around the body. The white cells play
an important role in defense against
infection
and
the
platelets
are
vital
components
in
the
process
of
blood
clotting. There are a number of
different types of connective tissue but all
are
characterized
by
having
cells
distributed
within
an
extensive
noncellular matrix. Nerve tissue
contains nerve cells and glial cells.
The Principal Organ Systems
The cardiovascular system
The cells of large multicellular
animals cannot derive the oxygen and
nutrients
they
need
directly
from
the
external
environment.
The
oxygen
and nutrients must be
transported to the cells. This is one of the
principal
functions of the blood, which
circulates within blood vessels by virtue of
the pumping action of the heart. The
heart, blood vessels, and associated
tissues form the cardiovascular system.
The
heart
consists
of
four
chambers,
two
atria
and
two
ventricles,
which
form
a
pair
of
pumps
arranged
side
by
side.
The
right
ventricle
pumps deoxygenated
blood to the lungs where it absorbs oxygen from
the
air,
while
the
left
ventricle
pumps
oxygenated
blood
returning
from
the
lungs to the rest of
body to supply the tissues. Physiologists are
concerned
with
establishing
the
factors
responsible
for
the
heartbeat,
howthe
heart
pumps
the
blood
around
the
circulation,
and
how
it
is
distributed
to
perfuse the tissues according to their
needs. Fluid exchanged between the
blood
plasma
and
the
tissues
passes
into
the
lymphatic
system,
which
eventually drains back
into the blood.
The respiratory system
分解为小分子来释放活动所需能量的能力;
第三,在生命过程中
某个阶段,细胞体内存
在一个以脱氧核糖核酸
(DNA)
形式包含基
因信息的细胞核。
活体细胞不断转化物质。
它们为其它活
动提供能量分
解葡萄糖和脂肪,
比如自身生
长和修复所需的蛋白质运动和合成
。
这些化
学变化统称为新陈代谢。
把大
分子分解为小
分子的过程称为分解代谢,
小分子合成大分
子的过程称为合成代谢。
细胞在进化过程中
不断分化进行不同
的功能活动。有些细胞具有收缩能力(如肌
细
胞)
,
有些可以传导电信号
(如神经细
胞)
。
进一步进化的细胞能够分泌不同物质如荷
尔蒙(如内分泌细胞)或酶。胚胎发育过程
中,
分化的
过程由于很多不同细胞来源于受
精卵而再次发生。
大多数组织包含有不同的细胞类型。
比
如,血液中
含红细胞,白细胞和血小板。红
细胞运输全身的氧气。
白细胞在
抵御感染时
起重要作用,
血小板是血液凝集过程中重要
的成分。结缔组织有多种不同类型,但有一
个共同特征,
即细胞分布在丰富的细胞外基
质中。神经组织含神经细胞和神经胶质细
胞。
主要的器官系统
心血管系统
大型多细胞动物体的细胞
不能从外界
环境中获取直接所需的氧气和营养物质。
这
些氧气和营养物质必须转运到细胞。
这是血
液的
主要功能之一,
血液凭借心脏的泵血作
用在血管内流动循环。心
脏、血管和结缔组
织组成了心血管系统。
心脏包括四个腔,
两个心房和两个心室
构成了一对并排存在
的泵。
右心室将脱氧的
血液泵至肺中,
肺中的血液吸收空气中的氧
气,
而左心室把从肺回流来的有氧血
液泵出
至身体其它部位,供应给各组织。生理学家
研究促使心脏
跳动的因素,
心脏如何泵送血
液使其循环,
心脏如何根据各组织所需分配
血液。
血浆和组织间的流动液
体交换流入淋
巴系统,最终回流到血液中。
The energy required for performing the
various activities of the body
呼吸系统
is
ultimately derived from respiration. This process
involves the oxidation
of
foodstuffs
to
release
the
energy
they
contain.
The
oxygen
needed
for
机体进行各项活动所需的能量最终来
this process
is absorbed from the air in the lungs and carried
to the tissues
源于呼吸。这一过程包括食物(主要是糖类
by the
blood. The carbon dioxide produced by the
respiratory activity of
和脂肪)的氧化,释放它们所含的能量。这
the
tissues
is
carried
to
the
lungs
by
the
blood
in
the
pulmonary
artery
where it is excreted in the expired
air. The basic questions to be answered
include the following: How is the air
moved in and out of the lungs? How
is
the
volume
of
air
breathed
adjusted
to
meet
the
requirements
of
the
body? What
limits the rate of oxygen uptake in the lungs?
The digestive system
The
nutrients needed by the body are derived from the
diet. Food is
taken
in
by
the
mouth
and
broken
down
into
its
component
parts
by
enzymes
in
the
gastrointestinal
tract.
The
digestive
products
are
then
absorbed
into
the
blood
across
the
wall
of
the
intestine
and
pass
to
the
liver via the portal
vein. The liver makes nutrients available to the
tissues
一过程中,氧气来自于肺中的空气,经由血
液
到达全身各组织。
组织呼吸活动中释放的
二氧化碳由肺动脉中的
血液运送至肺,
然后
呼气排出体外。需回答的基本问题如下:空
气是如何进出肺的?呼吸的空气量如何适
应机体所需?限制肺吸
收氧气频率的因素
是什么?
消化系统
机体所需营养物质来源于饮
食。
食物经
口腔进入体内,
在胃肠道内
经酶将其分解成
小分子物质。
这些消化物通过肠壁吸收入血
p>
both for their growth and repair and for
the production of energy. In the
case
of the digestive system, key physiological
questions are: How is food
ingested?
How
is
it
broken
down
and
digested?
How
are
the
individual
nutrients absorbed? How is the food
moved through the gut? How are the
indigestible remains eliminated from
the body?
The kidneys and urinary tract
The chief function of the kidneys is to
control the composition of the
extracellular
fluid.
In
the
course
of
this
process,
they
also
eliminate
non-volatile
waste
products
from
the
blood.
To
perform
these
functions,
the
kidneys
produce
urine
of
variable
composition
which
is
temporarily
stored
in
the
bladder
before
voiding.
The
key
physiological
questions
in
this case are: how do the
kidneys regulate the composition of the blood?
How do they eliminate toxic waste? How
do they respond to stresses such
as
dehydration?
What
mechanisms
allow
the
storage
and
elimination
of
the urine?
The
reproductive system
Reproduction
is
one
of
the
fundamental
characteristics
of
living
organisms.
The
gonads
produce
specialized
sex
cells
known
as gametes.
At the core of
sexual reproduction is the creation and fusion of
the male
and
female
gametes,
the
sperm
and
ova
(eggs),
with
the
result
that
the
genetic
characteristics
of
two
separate
individuals
are
mixed
to
produce
offspring that differ genetically from
their parents.
The musculoskeletal
system
This
consists
of
the
bones
of
the
skeleton,
skeletal
muscles,
joints,
and their associated
tissues. Its primary function is to provide a
means of
movement,
which
is
required
for
locomotion,
for
the
maintenance
of
posture,
and
for
breathing.
It
also
provides
physical
support
for
the
internal
organs.
Here
the
mechanism
of
muscle
contraction
is
a
central
issue. The endocrine and nervous
systems.
The endocrine and nervous
systems
The activities of the different
organ systems need to be coordinated
and regulated so that they act together
to meet the needs of the body. Two
coordinating systems have evolved: the
nervous system and the endocrine
液,通过门静
脉进入肝脏。经肝脏作用后,
这些营养物质能够满足组织生长修复及能
< br>量需求。在消化系统部分,重要的生理学问
题是:
食物是
如何消化的?食物如何被个体
分解消化?个体营养物质如何吸收?食物
< br>如何在肠内转运的?未消化的残留如何从
体内排出?
泌尿系统
肾脏主要功能是控制细胞外
液体的形
成。在这一过程中,肾脏也会把不可挥发的
废物排出去
。
为行使这一功能,
在排出之前,
肾脏
产生含有各种成分的尿液并将其暂时
储存在膀胱中。
这一部分主
要的生理学问题
是:
肾脏如何调节血液中的成分?如何排出
p>
有毒废物?如何应对像脱水这样的应激反
应?以及尿液可以存储和排
出体外的机制
是什么?
生殖系统
生殖是活生物体的一个基本
特征。
生殖
腺产生专门的性细胞,被称为配子。性生殖
的核心是雌雄配子即精子和卵子的产生和
融合,
因此两个独立个体的基因特征融合而
产生一个基因上与双亲不同的后代。
运动系统
这一系统由骨、
骨骼肌、关节和它们的
相关组织组成。其主要功能是提供运动需
要,维持姿势及呼吸运动。它也为内脏器官
提供物理支持。这一部分,肌肉收缩机制是<
/p>
主要问题。
内分泌系统和神经系统
不同器官系统
的活动需要协作和调节,
以便共同作用满足机体需要。
人体有两
大调
节系统:神经系统和内分泌系统。神经系统
system.
The nervous system uses electrical signals to
transmit information
very rapidly to
specific cells. Thus the nerves pass electrical
signals to the
skeletal muscles to
control their endocrine system secretes
chemical
agents,
hormones,
which
travel
in
the
bloodstream
to
the
cells
upon
which they exert a regulatory effect. Hormones
play a major role in
the regulation of
many different organs and are particularly
important in
the regulation of the
menstrual cycle and other aspects of reproduction.
The
immune
system
provides
the
body’s
defenses
against
infection
both
by
killing
invading
organisms
and
by
eliminating
diseased
or
damaged cells.
Although it is helpful to study how
each organ performs its functions,
it
is
essential
to
recognize
that
the
activity
of
the
body
as
a
whole
is
通过电信号迅速将信息传导给特定细胞。
这
样神经将
电信号传递给骨骼肌以控制收缩。
内分泌系统分泌化学物质
―<
/p>
激素。
激素通过
血流到达施与调节作用的
细胞。
激素在许多
不同器官中起着重要作用,
< br>在月经期调节和
其它生殖方面尤其重要。
免疫系统通过杀死入侵的有机体,
清除
致病或损伤细
胞为机体提供防御功能。
虽然研究各器官如何行使功能很有益
处,
但我们必须认识到机体作为一个整体所
做的活动依赖于各器官系统间错综复杂的
相互作用。如果一部分无法正常工作,全身
dependent on the intricate interactions
between the various organ systems.
If
one
part
fails,
the
consequences
are
found
in
other
organ
systems
throughout the whole
body. For example, if the kidneys begin to fail,
the
regulation of the internal
environment is impaired which in turn leads to
disorders of function elsewhere.
Homeostasis
Complex
mechanisms are at work to regulate the composition
of the
extracellular
fluid
and
individual
cells
have
their
own
mechanisms
for
regulating their
internal composition. The regulatory mechanisms
stabilize
the internal environment
despite variations in both the external world and
the
activity
of
the
animal.
The
process
of
stabilization
of
the
internal
environment is called homeostasis and
is essential if the cells of the body
are to function normally.
Taking
one
example,
the
beating
of
the
heart
depends
on
the
rhythmical contractions
of cardiac muscle cells. This activity depends on
electrical
signals
which,
in
turn,
depend
on
the
concentration
of
sodium
and potassium ions in
the extracellular and intracellular fluids. If
there is
an excess of potassium in the
extracellular fluid, the cardiac muscle cells
become too excitable and may contract
at inappropriate times rather than
in a
coordinated manner. Consequently, the
concentration of potassium in
the
extracellular fluid must be kept within a narrow
range if the heart is to
beat normally.
How Does The Body Regulate Its Own
Composition?
The concept of balance
In the course of a day, an adult
consumes approximately 1 kg of food
and
drinks 2~3 liters of fluid. In a month, this is
equivalent to around 30
kg of food and
60~90 liters of fluid. Yet, in general, body
weight remains
remarkably constant.
Such individuals are said to be in balance; the
intake
of food and drink matches the
amounts used to generate energy for normal
bodily activities plus the losses in
urine and feces. In some circumstances,
such as starvation, intake does not
match the needs of the body andmuscle
tissue
is
broken
down
to
provide
glucose
for
the
generation
of
energy.
Here,
the
intake
of
protein
is
less
than
the
rate
of
breakdown
and
the
individual is said to have a negative
nitrogen balance. Equally, if the body
其它器官系统也会受到影响。例如,如果肾
脏出现问题,内部环境的调节受损,结果导<
/p>
致其它器官系统功能紊乱。
稳态
各种复杂机制共同作用调节细胞
外液
的形成,
不同个体细胞有自身机制调节内在
组成成分。
尽管外界环境和动物活动不停变
化,调节机
制维持着体内环境的稳定。内部
环境的稳定被称为稳态,
它是机
体能够正常
发挥作用所必须的。
例如
,
心脏的跳动依赖于心肌细胞有节
律的收缩。这一活动依赖于电
信号,而电信
号反过来依赖存在于细胞外和细胞内液体
中钠和钾
离子的浓度。
如果细胞外液中钾离
子过多,心肌细胞兴奋性增强
,可能出现不
规律的收缩。因此,要维持心脏正常跳动,
细胞外
液中钾离子的浓度就必须控制在一
定范围内。
机体如何调节物质成分
平衡的概念
一天中,
一个成人需要消耗约
1
千克食
物,
2~3
升液体。以一个月计算,这相当于
< br>约
30
千克食物,
60~90<
/p>
升液体。
然而,
一般
来说,机体体重是基本不变的。这类个体可
以说处于平衡状态。
食物和液体的摄入量相
当于正常机体活动消耗的能量加上尿液和
粪便中丢失的能量。在一些情况下,如饥饿
状态,摄入量与机体所需量并不相当,肌
组
织断裂,提供葡萄糖产生能量。蛋白质的摄
入低于肌组织断裂
的速度,
机体处于负氮平
衡。同样地,如果机体组织正处于生长
期,
如生长期的儿童,
孕妇和早期训练阶段的运
动员,
那么蛋白质的日常摄入量比正常机体
所需要的多
。
相反,
此时个体处于
正氮
平衡。
tissues
are
being
built
up,
as
is
the
case
for
growing
children,
pregnant
women
and
athletes
in
the
early
stages
of
training,
the
daily
intake
of
protein is greater than the normal body
turnover and the individual is in
positive nitrogen
balance.
This
concept
of
balance
can
be
applied
to
any
of
the
body
constituents including water and salt
and is important in considering how
the
body regulates its own composition. Intake must
match requirements
and
any
excess
must
be
excreted
for
balance
to
be
maintained.
Additionally,
for each chemical constituent of the body there is
a desirable
concentration
range,
which
the
control
mechanisms
are
adapted
to
example, the concentration of glucose
in the plasma is about
4~5mmol/L
between
meals.
Shortly
after
a
meal,
plasma
glucose
rises
above this level and this stimulates
the secretion of the hormone insulin by
the
pancreas,
which
acts
to
bring
the
concentration
down.
As
the
concentration
of
glucose
falls,
so
does
the
secretion
of
insulin.
In
each
case,
the
changes
in
the
circulating
level
of
insulin
act
to
maintain
the
plasma glucose at an appropriate level.
This type of regulation is known as
negative
feedback. During
the
period
of
insulin
secretion,
the
glucose
is
being stored as either glycogen or fat.
A negative feedback loop is a control
system that acts to maintain the
level
of
some
variable
within
a
given
range
following
a
disturbance.
Although
the
example
given
above
refers
to
plasma
glucose,
the
basic
principle
can
be
applied
to
other
physiological
variables
such
as
body
temperature, blood pressure, and the
osmolality of the plasma. A negative
feedback loop requires a sensor of some
kind that responds to the variable
in
question but not to other physiological variables.
Thus an osmoreceptor
should
respond
to
changes
in
osmolality
of
the
body
fluids
but
not
to
changes in
body temperature or blood pressure. the
information from the
sensor
must
be
compared
in
some
way
with
the
desired
level
by
some
form of comparator. if the two do not
match ,an error signal is transmitted
to an effector, a system that can act
to restore the variable to its desired
level .these features of negative
feedback can be appreciated by examining
a
simple
heating
system
.the
controlled
variable
is
room
temperature,
which
is
sensed
by
a
thermostat.
the
effector
is
a
heater
of
some
kind .when the room temperature falls
below the set point,the temperature
difference is detected by the
thermostat which switches on the heater .this
heats the room until the temperature
reaches the per set level whereupon
the
heater is switched off.
To summarize,
the body is actually a social order of about 100
trillion
cells
organized
into
different
functional
structures,
some
of
which
are
called
organs.
each
functional
structures
its
share
to
the
maintenance
of
homeostatic
conditions
in
the
extracellular
fluid,
which
is
called
the
internal long as normal
conditions are maintained in this
internal environment ,the cells of the
body continue to live and function
properly.
Each
cell
benefits
from
homeostasis,
and
in
turn,
each
cell
contributes
its
share
toward
the
maintenance
of
homeostasis.
This
reciprocal interplay provides
continuous automaticity of the body until one
or
more
functional
systems
lose
their
ability
to
contribute
their
share
of
function.
When
this
happens,
all
the
cells
of
the
body
suffer.
Extreme
平衡的概念可以应用到机体的任何构
成成分上,包括水和盐,而且平衡在机体调
节其自身成分上是非常重要的
。
摄入必须等
于所需,为维持机体平衡,任何多余的能量
都必须排出。此外,因为机体的每种化学成
分都有一个可取的浓度范围
,
控制机制维持
这个范围。例如,两餐间血糖浓度大约为
4~5mmol/L
。进食后不久,血糖含量超过这
< br>一范围,刺激胰腺分泌胰岛素,降低浓度。
随着葡萄糖浓度的下降,胰岛素分泌减
少。
在此情况下,
循环胰岛素水平的改变都是为
了使血浆中的葡萄糖维持在一个合适的范
围内。这种调节称为负反馈机制。在胰
岛素
分泌期间,
葡萄糖像肝糖原或脂肪一样被储
存。
负反馈调节是在机体出现紊乱时,
将一
些变量控制在限定范围内的一个控制系统。
虽然
上面的例子讲到血糖,
但这一基本原则
可以应用到其它生理变量
中如体温、
血压和
血浆的渗透浓度。
负
反馈调节需要一种能对
不确定的变量做出反应而对其它生理变量
不应答的传感器。因此,渗透压感受器应该
能对机体体液渗透的变化而不是体温和血
p>
压的变化产生应答。
感受器传递的信息必须
和理想水平(系统的调定点)以比较者的身
份,
以某种方式进行
比较。
如果两者不相符,
一个错误信号就会传递给效应器,
p>
效应器是
一种能使变量保持在理想水平的系统。
负反
馈的这些特点可以通过检测一种简单的加
热系统来理解
。被控制的变量是室温,它可
以由一个温度计检测到,
效应器是
一种加热
器。当室温降低到调定点以下时,温度计就
可以监测到
温度的变化而开启加热器,
对室
内进行加温,
< br>直到室温升高到先前调好的调
定点,加热器关闭。
p>
总而言之,
机体实际上是由
100
万亿细
胞有序组成了不同的功能结构,
其中一些
被
称为器官。
每个功能结构都在维持细胞外液
< br>稳态方面发挥其作用,这称之为内环境。只
要内部环境处于正常状态,
机体细胞继续生
存并正常运行。每个细胞都从稳态中获益,
反过来,每个细胞都为稳态做出贡献。这种
相互作用促使机体持续自主运行,<
/p>
直至一个
或多个功能系统不能正常运转。此时,机体
所有细胞都会受损。
功能极度异常会导致死
亡,轻微
的功能异常导致疾病的发生。
dysfunction
leads to death; moderate dysfunction leads to
sickness.
The Other Side of Antibiotics
Antibiotics
have
eliminated
or
controlled
so
many
infectious
diseases that virtually everyone has
benefited from their use at one time
or
another. Even without such personal experience,
however, one would
have
to
be
isolated
indeed
to
be
unaware
of
the
virtues,
real
and
speculative,
of
these
“miracle”
drugs.
The
Am
erican
press,
radio,
and
television have done a good job of
reporting the truly remarkable story
of
successes
in
the
chemical
war
on
germs.
What’s
more,
any shortcomings on
their part have been more than made up for by the
aggressive
public
relations
activity
of
the
pharmaceutical companies
抗生素的另一面
抗生素已经消除或控
制了很多传染
病,实际上每个人都从这种或那种使用中
受益。即
使没有这样的个人经验,人们也
不得不孤立地认识到这些
“
p>
奇迹
”
药物的优
点
,真实性和推测性。美国新闻界,广播
电台和电视台在报道有关细菌化学战争成
功的真实故事方面做得很好。更重要的是,
制造和销售抗生素的制药公司
的积极的公
共关系活动已经弥补了他们的缺点。
which manufacture and sell antibiotics.
In
comparison,
the
inadequacies
and
potential
dangers
of
these
remarkable
drugs
are
much
less
widely
known.
And
the
lack of
such
knowledge
can
be
bad,
especially
if
it
leads
patients
to
pressure
their
doctors
into
prescribing
antibiotics
when
such
medication
isn’t
really
needed, or leads them
to switch doctors until they find one who is, so
to
speak, antibiotics-minded.
Because
the
good
side
of
the
antibiotics
story
is
so
very
well-known,
there
seems
more
point
here
to
a
review
of
some
of the
immediate and
long-
range problems that can come from
today’s casual
use
of
these
drugs.
It
should
be
made
clear
in advance
that
calamities
from the use of antibiotics are rare in
relation to the enormous amounts
of the
drugs administered. But the potential hazards, so
little touched on
generally,
do
need
a
clear
statement.
The
antibiotics
are
not,
strictly
speaking, exclusively prescription drugs. A number
of them are
permitted
in
such
over-the-counter
products
as
nasal
sprays, lozenges,
troches,
creams, and ointments. Even if these products do
no harm, there
is
no
point
whatsoever
in
using
them.
If you
have
an
infection
serious
enough
to
warrant
the
launching
of
chemical
warfare,
you
need
much
bigger doses of the antibiotics than
any of the non-prescription products
are allowed to contain.
Over-the-counter
products,
however,
account
for
only
a
small
percentage of total
antibiotics production. It is
the
prescription dosages
that
give
people
trouble.
These
drugs
—
even
allowing
for
the
diverse
abilities
of
the
many
narrow-spectrum
ones
and
the
versatility
of
the
broad-
spectrum
ones
—
are
not
the
cure-
alls,
they
often
are
billed
as
being. There are wide gaps in their
ability to master contagious diseases.
Such important infections as mumps,
measles, common colds, influenza,
and
infectious hepatitis still await conquest. All are
virus infections and
despite
intense
efforts,
very
little progress
has
been
made
in
chemotherapy
against
viruses.
Only
small
progress
has
been
achieved
against fungi. Many
strains
of bacteria and fungi are
naturally resistant
to
all
currently
available
antibiotics
and
other
chemotherapeutic
drugs.
Some microorganisms
originally
sensitive
to
the
action
of
antibiotics,
especially
staphylococcus,
have
developed
resistant
strains.
This
acquired resistance
imposes on the long range value of the drugs a
very
important
limitation,
which
is
not
adequately met
by
the
frequent
introduction of new antimicrobial
agents to combat the problem.
相比之下,这些显着
的药物的不足之
处和潜在的危险是广为人知的。缺乏这样
的知识
可能是不好的,特别是如果它导致
病人迫使他们的医生处方抗生素,当这种
药物是不是真的需要,或导致他们切换到
医生,直到他们找到一个谁可以说,
抗生
素
-
头脑。
因为抗生素故事的好处是如此
众所周
知,在这里似乎更重要的是要回顾一下当
今随便使用这些
药物可能产生的一些近期
和远期问题。应该预先说明,使用抗生素
造成的灾难与所投入的大量药物有关。但
是一般来说很少涉及的潜在危害确实需要
p>
一个明确的说法。严格来说,抗生素不是
完全处方药。它们中的一些
允许用于鼻腔
喷雾剂,锭剂,锭剂,霜剂和软膏等非处
方产品。
即使这些产品没有坏处,使用它
们也没有任何意义。如果感染的严重程度
足以保证发动化学战争,则需要比任何非
处方产品所含的抗生素剂量大得多的抗
生
素。
然而,非处方药产品仅占抗生
素总产
量的很小比例。这是给人们麻烦的处方剂
量。这些药物,
即使考虑到许多窄谱药物
的多样性和广谱药物的多样性,也不是治
愈所有的药物,
他们往往被称为
“
药
物
”
。
掌
握传
染病的能力差距很大。像腮腺炎,麻
疹,感冒,流行性感冒和传染性肝炎等重
要感染仍在等待征服。所有这些都是病毒
感染,尽管付出了巨大的努力,但
在化学
疗法方面进展甚微。真菌只取得小的进展。
许多细菌和真
菌菌株对所有目前可用的抗
生素和其他化学治疗药物都具有天然的抗
性。一些原本对抗生素作用敏感的微生物,
特别是葡萄球菌,已经产生了耐药菌株。
这种获得的耐药性对药物的远距离价值提
出了一个非常重要的限
制,而这种限制并
不能通过频繁引入新的抗菌剂来解决这个
It
has
been
pretty
well
established
that
the
increase
in
strains
of
bacteria resistant to an antibiotic
correlates directly with the duration and
extent
of
use
of
that
antibiotic
in
a
given
location.
In
one
hospital
a
survey showed that, before
erythromycin had been widely used there, all
strains of staphylococci taken from
patients and personnel were sensitive
to
its
action.
When
the
hospital
started
extensive
use
of
erythromycin,
however,
resistant staphylococcus strains began to appear.
The
development
of
bacterial
resistance
can
be
minimized
by
a
more
discriminating
use
of
antibiotics,
and
the
person taking
the
drug
can help
here. When an antibiotic must be used, the best
way to prevent
the development of
resistance is to wipe out the infection as rapidly
and
thoroughly as possible.
Ideally, this
requires a
bactericidal drug, which
问题。
已经确定的是,对抗生素耐药的细菌
菌株的增加直接与在给定位
置使用抗生素
的持续时间和程度相关。在一家医院进行
的一项调
查显示,在红霉素被广泛使用之
前,所有从患者和人员中获得的葡萄球菌
菌株对其作用敏感。当医院开始广泛使用
红霉素时,耐药葡萄球菌菌株开始出现
。
细菌耐药性的发展可以通过更加区分
使用抗生素来最小化,服用这种药物的人
可以在这里帮助。当必须使用抗生素时,
p>
防止抗药性发展的最好方法是尽可能迅速
destroys,
rather than a bacteriostatic drug, which inhibits.
And the drug
must
be
taken
in
adequate
dosage
for
as
long
as
it
is necessary
to
eradicate
the
infection
completely.
The
doctor,
of
course,
must
choose
the
drug,
but
patients
can
help
by
being
sure
to
take
the
full
course
of
treatment recommended by
the
doctor, even though symptoms seem to
disappear before all the pills are
gone. In rare instances the emergence of
resistance
can
be
delayed
or
reduced
by
combinations
of
antibiotics.
Treatment
of
tuberculosis
with
streptomycin
alone
results
in
a
high
degree of
resistance, but if para-aminosalicylic acid or
isoniazid is used
with
streptomycin
the
possibility
that
this
complication
will
arise
is
greatly reduced.
In
hospital
treatment
of
severe
infections,
the
sensitivity
of
the
infecting
organism
to
appropriate
antibiotics
is determined
in
the
laboratory before
treatment
is started. This enables the
doctor to select
the most
effective drug or drugs; it determines whether the
antibiotic is
bactericidal
or
bacteriostatic
for
the
germs
at
hand; and
it
suggests
the
amount needed to destroy the growth of
the bacteria completely. In either
hospital or home, aseptic measures can
help to reduce the prevalence of
resistant strains of germs by
preventing cross infection and the resultant
spreading of organisms.
Every
one
of
the
antibiotics
is
potentially
dangerous
for
some
people.
Several
serious
reactions
may
result
from
their
use.
One
is
a
severe,
sometimes
fatal,
shock-like
anaphylactic
action,
which
may
strike
people
who
have
become
sensitized
to penicillin.
Anaphylactic
reaction happens less frequently and is
less severe when the antibiotic is
given
by
mouth.
It
is most
apt
to
occur
in
people
with
a
history
of
allergy,
or
a
record
of
sensitivity
to
penicillin.
Very
small
amounts
of
penicillin, even the traces which get into the
milk of cows for a few
days
after
they
are
treated
with
the
antibiotic
for mastitis,
may
be
sufficient
to
sensitize;
hence,
the
strong
campaign
by
food
and
drug
officials keeps such milk off the
market.
To
minimize
the
risk
of
anaphylactic
shock
in
illnesses
where
injections of
penicillin are the preferred treatment, a careful
doctor will
question the patient
carefully about allergies and previous reactions.
In
case
of
doubt
another antibiotic
will
be
substituted
if
feasible,
or
other
precautionary measures
will be taken before the injection is given.
Other
untoward
reactions
to
antibiotics
are
gastrointestinal
彻底地消灭感染。理想情
况下,这需要一
种杀菌药物,而不是一种抑制抑制药物的
杀菌药
物。只要有必要彻底根除感染,必
须服用足够的药物。当然,医生必须选择
药物,但即使在所有药丸消失之前症状似
乎消失,患者仍然可以通过确保服用
医生
推荐的整个治疗过程来提供帮助。在极少
数情况下,抵抗的
出现可以通过抗生素的
组合来延迟或减少。单独使用链霉素治疗
结核病会导致高度的耐药性,但是如果对
氨基水杨酸或异烟肼与链霉素一起使用,
则会出现这种并发症的可能性大大降低。
在
医院治疗严重感染时,在开始治疗
之前,在实验室中确定感染生物对适当抗
生素的敏感性。这使医生能够选择最有效
的药物或药物
;
它决定了抗生素是否对手边
的细菌具有杀菌或抑菌作用
p>
;
它提示了完全
消灭细菌生长所需的量。在
医院或家中,
无菌措施可以通过预防交叉感染和生物体
的扩散来
帮助减少耐药菌株的流行。
每一种抗生素都对某些人有潜在危
险。他们的使用可能会导致一些严重的反
应。一种是严重的,有
时是致命的,类似
休克的过敏反应,可能会引起对青霉素敏
感的
人。口服抗生素时,过敏反应发生频
率较低,严重程度较轻。最容易发生在有
过敏史或对青霉素有敏感记录的人群中。
非常少量的青霉素,甚至在用抗生
素治疗
乳腺炎之后进入母牛乳中几天的痕迹可能
足以致敏。因此
,食品和药物官员的强力
运动使这种牛奶不在市场上。
为了尽量减少注射青霉素是首选治疗
的疾病过敏性休克的风险,谨慎的
医生会
仔细询问病人有关过敏和以前的反应。如
果有疑问,如果
可行,另一种抗生素将被
替代,或在注射前采取其他预防措施。
对抗生素的其他不良反应是使用四环
disorders
—
such
as
sore
mouth,
cramps,
diarrhea,
or
anal
itch
—
which
occur
most frequently after
use of the
tetracycline group but have also
been
encountered
after
use
of
penicillin
and
streptomycin.
These
reactions
may
result
from
suppression
by
the
antibiotic
of
bacteria
normally
found
in
the
gastrointestinal
tract.
With
their
competition
removed,
antibiotic-
resistant
staphylococci
or
fungi,
which
are
also
normally present,
are
free
to
flourish
and
cause
what
is
called
a
super-
infection. Such infections can be extremely
difficult to cure.
A
few
antibiotics
have
such
toxic
effects
that
their
usefulness
is
strictly
limited.
They
include
streptomycin
and dihydrostreptomycin,
which
sometimes
cause
deafness,
and
chloramphenicol,
which
may
injure
the
bone
marrow.
Drugs
with
such
serious
potential
dangers
as
素组后最频繁出现的胃肠疾病
-
例如口
疮,痉挛,腹泻或肛门瘙痒
,但在使用青
霉素和链霉素后也遇到过。这些反应可能
是由抗生
素抑制胃肠道中正常发现的细菌
引起的。通过消除竞争,抗生素抗性葡萄
球菌或真菌(通常也存在)可以自由繁殖
并引起所谓的超感染。这种感染可能极
难
治愈。
一些抗生素有这样的毒性作
用,它们
的用途是严格限制的。它们包括有时引起
耳聋的链霉素
和二氢链霉素,以及可能伤
害骨髓的氯霉素。只有在生命受到威胁的
these should be used only if life is threatened and nothing else will work.
All the
possible troubles that can result from antibiotic
treatment should
not
keep
anyone
from
using
one
of
these
drugs
when
it
is
clearly indicated. Nor
should they discourage certain preventive uses of
antibiotics which have proved extremely
valuable.
情况下才能使用这类具有如此严重潜在危
险的药物,否则就不能起作用
。在抗生素
治疗中可能产生的所有可能的麻烦都不应
该使任何人
在使用这些药物时明确指出。
他们也不应该阻止某些已被证明非常有价
< br>值的抗生素的预防性用途。
Discovery of
Insulin, and the Making of a
Medical
Miracle
Background
Insulin
is
a
hormone
that
regulates
the
amount
of
glucose
(sugar) in the blood
and is required for the body to function normally.
Insulin is produced by
β
-cells in the pancreas, also called
the islets of
Langerhans.
These
cells
continuously
release
a
small
amount
of
insulin into the body,
but release surges of the hormone in response to
胰岛素的发现和医学奇迹的建立
背景
胰岛素是一种调节血液中葡萄糖
(糖)
含
量的激素,
< br>是人体正常功能所必需的。
胰岛素
由胰腺中的
β
细胞产生,也称为朗格罕氏胰
岛。这些细胞不断
释放少量的胰岛素进入人
体,但随着血糖水平的升高而释放激素的激
增。
体内的某些细胞会将摄入的食物转化为
a rise in
the blood glucose level.
Certain cells
in the body change the food ingested into energy,
or
blood
glucose,
that
cells
can
use.
Every
time
a
person
eats,
the
blood
glucose
rises.
Raised
blood
glucose
triggers
the
cells
in
the
islets
of
Langerhans
to
release
the
necessary
amount
of
insulin.
Insulin allows the blood glucose to be
transported from the blood into
the
cells. Cells have an outer wall, called a
membrane, which controls
what enters
and exits the cell. Researchers do not yet know
exactly
how insulin works, but they do
know insulin binds to receptors on the
cell
membrane.
This
activates
a
set
of
transport
molecules
so
that
glucose
and
proteins
can
enter
the
cell.
The
cells
can
then
use
the
glucose as energy to carry out its
functions. Once transported into the
cell, the blood glucose level is
returned to normal within hours.
Without insulin, the blood glucose
builds up in the blood and the
cells
are starved of their energy source. Some of the
symptoms that
may
occur
include
fatigue,
constant
infections,
blurred
eye
sight,
numbness, tingling in
the hands or legs, increased thirst, and slowed
healing of bruises or cuts. The cells
will begin to use fat, the energy
source stored for emergencies. When
this lasts for too long a time the
body
produces ketones, chemicals produced by the liver.
Ketones can
poison
and
kill
cells
if
they
build
up
in
the
body
over
an
extended
period of time. This can lead to
serious illness and coma.
People
who
do
not
produce
the
necessary
amount
of
insulin
have
diabetes.
There
are
two
general
types
of
diabetes.
The
most
severe
type,
known
as
Type
or
juvenile-onset
diabetes,
is
when
the
body
does
not
produce
any
insulin,
Type
I
diabetics
usually
inject
themselves
with
different
types
of
insulin
three
to
four
times
daily.
Dosage is taken based on the person's
blood glucose reading, taken
from a
glucose meter. Type n diabetics produce some
insulin, but it is
either
not
enough
or
their
cells
do
not
respond
normally
to
insulin.
This usually occurs
in obese or middle aged and older people. Type II
diabetics do not necessarily need to
take insulin, but they may inject
insulin once or twice a day.
How Insulin Almost Wasn't Discovered
Before
the
discovery
of
insulin,
diabetes
was
a
feared
disease
that
most
certainly
led
to
death.
Patients
wasted
away,
grew
weak,
and
suffered
indescribably
before
their
inevitable
death.
They
had
细胞可以利用的能
量或血糖。
每人一吃,
血糖
就会升高。
升高的血糖引发朗格汉斯胰岛中的
细胞释放必要量的胰岛素。<
/p>
胰岛素允许血液从
血液运输到细胞。细胞有一个外壁,称为膜,<
/p>
它控制着什么进入和离开细胞。
研究人员尚不
清楚胰岛素是如何工作的,
但他们知道胰岛素
与细胞膜上的
受体结合。
这激活了一组转运分
子,
使
葡萄糖和蛋白质可以进入细胞。
然后细
胞可以使用葡萄糖作为能
量来执行其功能。
一
旦运送到细胞中,
血糖水平在数小时内恢复正
常。
如果
没有胰岛素,
血液中的血糖会积聚在
血液中,
< br>细胞就会缺乏能量来源。
可能发生的
一些症状包括疲劳,
感染持续,视力模糊,手
脚麻木,
手脚刺痛,
< br>口渴增加,
伤口愈合减慢。
细胞将开始使用脂肪,紧急情
况下储存的能
源。当这种持续时间太长时,身体会产生酮,
肝脏
产生的化学物质。
如果酮在体内长时间累
积,
< br>酮可以毒杀细胞。
这可能导致严重的疾病
和昏迷。
不产生必需量的胰岛素的人患有糖尿病。
有
两种一般类型的糖尿病。
最严重的类型,
即
类型或青少年型糖尿病,
是当身体不产生任何
胰岛素时,<
/p>
I
型糖尿病患者通常每天注射不同
类型的
胰岛素三至四次。
根据从葡萄糖计取得
的人的血糖读数来服用剂
量。
n
型糖尿病患者
会产生一些胰岛素,
但这或者是不够的,
或者
他们的细胞对胰岛素没有正常的反应。
这通常
发
生在肥胖或中年人和老年人。
II
型
糖尿病
患者不一定需要服用胰岛素,
但可以每天注射
一次或两次胰岛素。
胰岛素几乎没有被发现
在发现胰岛素
之前,
糖尿病是一种可怕的
疾病,最可能导致死亡。病人浪费了
,变得虚
弱,
在不可避免的死亡之前难以形容。
他们渴
望饥渴,
但饥饿只是让事情变得更糟,
继续减
肥。医生知道,糖会加重糖尿病患者的病情,
最有效的治疗方法是将病人的糖摄入量控制
insatiable
thirst
and
hunger,
but
trying
to
satisfy
their
hunger
only
made things worse, and they continued
to lose weight. Doctors knew
that
sugar
worsened
the
condition
of
diabetic
patients
and
that
the
most
effective
treatment
was
to
put
the
patients
on
very
strict
diets
where
sugar
intake
was
kept
to
a
minimum.
At
best,
this
treatment
could buy patients
a few extra years, but it never saved them. In
some
cases, the harsh diets even caused
patients to die of starvation.
During
the nineteenth century, observations of patients
who died
of diabetes often showed that
the pancreas was damaged. In 1869, a
German
medical
student,
Paul
Langerhans,
found
that
within
the
pancreatic tissue that produces
digestive juices there were clusters of
cells
whose
function
was
unknown.
Some
of
these
cells
were
eventually
shown
to
be
the
insulin-producing
beta
cells.
Later,
in
honor
of
the
person
who
discovered
them,
the
cell
clusters
were
named the islets of
Langerhans.
In
1889
in
Germany,
physiologist
Oskar
Minkowski
and
physician
Joseph
von
Mering,
showed
that
if
the
pancreas
was
removed from a dog, the animal got
diabetes. But if the duct through
which
the
pancreatic
juices
flow
to
the
intestine
was
ligated-surgically tied off so the
juices couldn't reach the intestine-the
dog
developed
minor
digestive
problems
but
no
diabetes.
So
it
seemed that the pancreas must have at
least two functions:
?
To produce
digestive juices
?
To produce a substance that regulates
the sugar glucose.
This
hypothetical internal secretion was the key.
If a substance
could
actually be isolated, the mystery of diabetes
would be solved.
Progress, however, was
slow.
In
1920,
an
unknown
Canadian
surgeon
named
Frederick
Banting
approached
Professor
John
Macleod,
the
head
of
the
University
of
Toronto's
physiology
department,
with
an
idea
about
finding
that
secret. He
theorized
that
the pancreatic
digestive
juices
could
be
harmful
to
the
secretion
of
the
Pancreas
produced
by
the
islets
of
Langerhans.
He
therefore
wanted
to
ligate
the
pancreatic
ducts in order to
stop the flow of nourishment to the pancreas. This
would cause the pancreas to degenerate,
making it shrink and lose its
ability
to secrete the digestive juices. The cells thought
to produce an
antidiabetic
secretion
could
then
be
extracted
from
the
pancreas
without
being
harmed.
Unfortunately,
Macleod,
a
leading
figure
in
the
study
of
diabetes
in
Canada,
didn't
think
much
of
Banting's
theories and
rebuffed his suggestion. Despite this, Banting
managed
to
convince
Macleod
that
his
idea
was
worth
trying.
Macleod
gave
Banting
a
laboratory
with
a
minimum
of
equipment
and
ten
dogs.
Banting
also
got
an
assistant,
a
medical
student
by
the
name
of
Charles Best. The
experiment was set to start in the summer of 1921.
Banting
and
Best
began
their
experiments
by
removing
the
pancreas from a dog. This resulted in
the following:
?
It's blood sugar rose.
?
It became
thirsty drank lots of water, and urinated more
often.
?
It
became
weaker
and
weaker
Experimenting
on
another
dog, <
/p>
在非常严格的水平。
充其量,
这种治疗可
以多
买几年的病人,
但从来没有挽救过。
在某些情
况下,严酷的饮食甚至导致病人死于饥饿。
在十九世纪期间,
死于糖尿病的病人的观
察结
果常常表明胰脏已经受损。
1869
年,一
位德国医学学生
Paul Langerhans
发现,
在产生
消化液的胰腺组织内,有功能未
知的细胞簇。
其中一些细胞最终被证明是产生胰岛素的
β
细胞。后来,为了纪念发现他们的人,细胞群
被命名为朗格汉斯岛。<
/p>
1889
年在德国,生理学家奥斯卡<
/p>
·
闵可夫
斯基(
Oskar Minkowski
)和医师约瑟夫
·
冯
·
梅
林(
Joseph von Mering
)发现,如果将胰脏从
狗身上取下,动物就会患上糖尿病。但是,如
果将胰液流入肠道的导管结扎在外
科手术中,
使得汁液不能到达肠道,
那么狗就会产生轻微
的消化问题,
但不会产生糖尿病。
所以胰腺似
乎至少有两个功能:
?
产生消化液
?
生产调节糖分的物质。
这个假设的内
分泌是关键。
如果一个物质
实际上可以孤立,
< br>糖尿病的奥秘将被解决。
但
进展缓慢。
< br>
1920
年
,
一
位
名
叫
弗
雷
德
里
克
·
班
廷
(<
/p>
Frederick Banting
)
的未知加拿大外科医生向
多伦多大学生理学系主任约翰
·
麦克劳德
(
John
Macleod
)教授提供了一个关于如何找到这个
秘密的想
法。
他推论胰腺消化液可能对朗格汉
斯胰岛产生的胰腺分泌有害
。
因此,
他想结扎
胰管,
以阻止营养物流向胰腺。
这会导致胰腺
退化,使其萎
缩,失去分泌消化液的能力。认
为产生抗糖尿病分泌物的细胞然后可以从胰
腺中提取而不受伤害。
不幸的是,
加拿大糖尿
病研究领域的领军人物麦克劳德(
Macleod
)
对班廷的理论并没有太多的想法,
并且拒绝了
他的建议。
尽管如此,
万津设法说服了麦克劳
p>
德,
他的想法值得尝试。
麦克劳德给班廷一
个
实验室,
配备了最少的设备和十只狗。
班廷还
找到了一位名叫查尔斯
·
贝斯
特的医学助理。
实验定于
1921
年夏
天开始。
万津和最好的开始他们的实验,
从狗取出
胰腺。这导致了以下结果:
?
血糖升高
?
口渴,多喝水,多喝水。
?
变得越来越弱对另一只狗进行试验
,
万津
和贝佳手术结扎胰腺,停止营养的流动,
使胰腺退化。
过了一段时间,
他们将胰脏
切除,
将其切片并冻结在水和盐的混合物
中。当冰块
半冻时,将其磨碎并过滤。分
Banting
and
Best
surgically
ligated
the
pancreas,
stopping
the
flow of nourishment,
so that the pancreas degenerated. After
a
while,
they
removed
the
pancreas,
sliced
it
up
and
froze
the
pieces
in a mixture of water and salts. When the pieces
were half
frozen, they were ground up
and filtered. The isolated substance
was named “isletin”.
The extract was injected into the
diabetic dog. Its blood glucose
level
dropped,
and
it
seemed
healthier
and
stronger.
By
giving
the
diabetic dog a few injections a day,
Banting and Best could keep it
healthy
and free of symptoms. Banting and Best showed
their result
to
Macleod,
who
was
impressed
but
he
wanted
more
tests
to
prove
that their pancreatic
extract really worked. For the increased testing,
离的物质被命名为“通报”。
将提取
物注射到糖尿病狗中。
其血糖水平
下降,
似乎更健康和更强。
通过给糖尿病狗每
天注射几次,
Banting
和
Best
可以保持健康和
没有症状。
Ba
nting
和
Best
向麦克劳德展示
了
他们的成果,
他对此印象深刻,
但他
想要进行
更多的测试来证明他们的胰脏提取物确实有
效。为了增
加测试,
Banting
和
Best<
/p>
认识到他
们需要比他们的狗能够提供更多的器官供应,
并且他们使用来自牛的胰脏来主演。
有了这个
新的
来源,
他们设法产生足够的提取物,
让几
只糖尿病的狗保持活着。
新的结果使麦克劳德
Banting
and Best realized that they required a larger
supply of organs
than their dogs could
provide, and they starred using pancreases from
cattle. with this new source, they
managed to produce enough extract
to
keep
several
diabetic
dogs
alive.
The
new
results
convinced
Macleod
that
they
were
onto
something
big.
He
gave
them
more
funds
and
moved
them
to
a
better
laboratory
with
proper
working
conditions.
He
also
suggested
that
they
should
call
their
extract
Now,
the
work
proceeded
rapidly.
In
late1921,
a
third
person biochemist
Bertram Collip, joined the team. Collip was given
the task of trying topuri4 the insulin
so that it would be clean enough
for
testing
on
humans.
During
the
intensified
testing,
the
team
also
realized
that
the
process
of
shrinking
the
pancreases
had
been
unnecessary.
Using
whole
fresh
pancreases
from
adult
animals
worked just as well.
In
1922
the
insulin
was
tested
on
Leonard
Thompson,
a
14-year-old
diabetes
patient
who
lay
dying
at
the
Toronto
General
Hospital.
He
was
given
an
insulin
injection.
At
first
he
suffered
a
severe,
allergic
reaction
and
further
injections
were
cancelled.
The
scientists
worked
hard
on
improving/
the
extract
and
then
a
second
dose of
injections were administered on Thompson. The
results were
spectacular.
The
scientists
went
to
the
other
wards
with
diabetic
children,
most
of
them
comatose
and
dying
from
diabetic
keto-acidosis.
They
reacted
just
as
positively
as
Leonard
to
the
insulin extract.
Banting and
Macleod were awarded the Nobel Prize in 1923 for
the practical extraction of insulin.
They were incensed that the other
members
of
their
team
were
not
included,
and
they
immediately
shared their prize money with Best and
Collip. They sold the original
patent
to the University of Toronto for one half dollar.
They were not
looking for fame or
fortune; they wanted to keep sick children from
dying.
They
did
eventually
benefit
financially,
but
that
was
the
last
thing on their minds.
Very
soon
after
the
discovery
of
insulin,
the
medical
firm
Eli
Lilly started large-scale production of
the extract. As early as in 1923,
the
firm
was
producing
enough
insulin
to
supply
the
entire
North
American continent. Although insulin
doesn't cure diabetes, it's one
of
the
biggest discoveries
in
medicine.
When
it
came,
it
was
like
a
相信他们正在做一些大事。
他给了他们更多的
资金,
把他们搬到了一个有适当工作条件的更
好的实验室。
他还建议,
他们应该叫他们的提
取物
“
胰岛素
”
。
现在,
工作进展迅速。
在
1
921
年底,第三人称生物化学家
Bertram
Collip
加
入了队伍。
Collip
被赋予尝试
topu
ri4
胰岛素
的任务,
以便它足够干净
,
可以在人体上进行
测试。
在加强检测
过程中,
团队也意识到缩小
胰腺的过程是不必要的。
使用来自成年动物的
全新鲜的胰腺也同样如此。
1922
年,在
14
< br>岁的多伦多综合医院死亡
的
糖
尿
病
患
者
伦
p>
纳
德
·
汤
普
森
(
Leonard
Thompson
)身上测试了胰岛素。他被给了胰
岛素注射。起初,他遭受了严重的过敏反应,
取消了进一步的注射。科学家
努力改善
/
提取
物,
< br>然后在汤普森进行第二次注射。
结果是壮
观的。科学家去
了另一个病房与糖尿病的孩
子,他们大多是昏迷和死于糖尿病酮酸中毒。
他们的反应和
Leonard
一样积极。
万津和麦克劳德在
1923
年被授予诺贝尔
奖,用于实际提取胰岛素。他们被激怒,其他
队员不包括在内,他们立即用
Best
和
Collip
分享他们的奖金。
他们把原来的专利卖给了多<
/p>
伦多大学半美元。
他们不是为了名利,
他
们想
让生病的孩子免于死亡。
他们最终在经济上受
益,但这是他们心中的最后一件事。
在发现胰岛素后不久,医药公司
Eli
Lilly
就开始大规模生产提取物。早在
1923
年,该
公司就生产出足够的胰岛素供应整个北美大
陆。
虽然胰岛素不能治愈糖尿病,
但这是医学
界最大的发现之一。
一旦到来,
就像是一个奇
迹。
患有严重糖尿病,
只剩下几天生活的人得<
/p>
救了。
只要不断得到胰岛素,
他们就能过
上几
乎正常的生活。
使用人胰岛素
1982
年,礼来公司生产了一种人胰岛素
miracle. People
with severe diabetes and only days left to live
were
(
Humulin?
),成
为首个获得批准的基因工
saved. And as long as they
kept getting their insulin, they could live
程药物产品。
这一重要成就是
20
< br>世纪
50
年代
an
almost normal life.
由沃森和克里克对
DNA
进行的经典结构研究
以及由桑格公司提供的胰岛素开始的
一个广
Working with human insulin
泛的基础和应用科学进展网络的结果。
研究人
In
1982,
the
Eli
Lilly
Corporation
produced
a
human
insulin
员不需要依赖动物,
就可以生产出无限制供应
(Humulin?)
that
became
the
first
approved
genetically
engineered
的基因工程胰岛素。
< br>它也没有包含任何动物污
pharmaceutical product.
This important achievement was the result of
染物。
使用人体胰岛素也消除了将任何潜在动
a
vast network of basic and applied scientific
advances that began in
物疾病转移到胰岛素中的担忧。尽管
从
20
世
the 1950s
with the classic structural studies on DNA by
Watson and
纪
80
年代开
始,公司仍然出售少量由动物产
Crick
and
on
insulin
by
Sanger.'
Without
needing
to
depend
on
生的胰岛素(主要是猪),但是胰岛素使用者
animals,
researchers could produce genetically engineered
insulin in
越来越多地转向通过重组
DNA
技术形成的人
unlimited
supplies.
It
also
did
not
contain
any
of
the
animal
contaminants.
Using
human
insulin
also
took
away
any
concerns
about
transferring
any
potential
animal
diseases
into
the
insulin.
While companies still sell a small
amount of insulin produced from
animals
—
mostly
porcine
—
from
the
1980s
onwards,
insulin
users
increasingly
moved
to
a
form
of
human
insulin
created
through
recombinant DNA
technology.
Insulin
is
a
protein
consisting
of
two
separate
chains
of
amino
acids,
an
A
above
a
B
chain,
that
are
held
together
with
disulfide
bonds.
The
insulin
A
chain
consists
of
21
amino
acids
and
the
B
chain
has
30.
Before
becoming
an
active
insulin
protein,
insulin
is
first produced as
preproinsulin. This is one single long protein
chain
with
the
A
and
B
chains
not
yet
separated,
a
section
in
the
middle
linking the chains
together and a signal sequence at one end telling
the
protein
when
to
start
secreting
outside
the
cell.
After
preproinsulin,
the
chain
evolves
into
proinsulin,
still
a
single
chain
but
without
the
signaling
sequence.
Then
comes
the
active
protein
insulin, the protein
without the section linking the A and B chains. At
each
step,
the
protein
needs
specific
enzymes
to
produce
the
next
form of insulin.
Lilly
has
prepared
human
insulin
by
two
different
means'
by
transforming
human
proinsulin
into
human
insulin.
In
the
first
method,
the
two
insulin
chains
are
produced
separately.
Manufacturers
need
the
two
mini-
genes:
one
that
produces
the
A
chain and one for the B chain. Since
the exact DNA sequence of each
chain
is
known,
they
synthesize
each
mini-gene's
DNA
and
insert
them
into
plasmids.
The
recombinant,
newly
formed,
plasmids
are
then
transformed into bacterial cells. During a
fermentation process,
the millions of
bacteria harboring the recombinant plasmid
replicate
roughly
every
20
minutes
through
cell
division,
and
each
expresses
the
insulin
gene.
After
multiplying,
the
cells
are
taken
out
of
the
fermentation tanks and
broken open to extract the protein chains. The
two
chains
are
then
mixed
together
and
joined
by
disulfide
bonds
through
the
reduction-reoxidation
reaction.
Although
the
chain
combination
procedure
worked
quite
well,
the
proinsulin
approach
required
fewer
processing
steps
and,
consequently,
superseded
the
胰岛素形式。
胰岛素是一种蛋白质,
由两条独立的氨基
酸链组成,一条
B<
/p>
链以上的
A
链与二硫键结
合在一起。胰岛素
A
链由
21
个氨基酸组成,
B
链有
30
个。
在成为活性胰岛素蛋白质之前,
胰岛素首先作为前胰岛素原产生。
这是一个单
链长的
蛋白质链,
A
链和
B
< br>链还没有分开,
中
间的一段链接在一起,
信号序列的一端告诉蛋
白质何时开始在细胞外分泌。前胰岛素原后,
链发展成胰岛素原,
仍然是单链,
但没有信号
p>
序列。然后是活性蛋白质胰岛素,不含连接
A
和
B
链的部分的蛋白质。
在每个步骤
中,
蛋白
质都需要特定的酶来产生下一种形式的胰岛
素。
礼来公司通过两种不同的方式来制备人
p>
胰岛素
-
最初
是通过链式结合的方法,自
1986
年以来,
< br>通过将人胰岛素原转化成人胰岛
素,
第一种方法是分别生
产两种胰岛素链,
基
因:一个产生
A<
/p>
链和一个
B
链,由于每条链
的确切的
DNA
序列是已知的,他们合成每个
小基因的
DNA
并将它们插入到质粒中,然后
转化新形成的重组质粒在发酵过程中,
携带重
< br>组质粒的数百万个细菌通过细胞分裂大约每
隔
20
分钟复制一次,每个细胞表达胰岛素基
因
;
倍增后,将细胞从发酵罐中取出,打开提
取蛋白质链,
然后将两条链混合在一起,
通过
还原
-
再氧化反应通过二硫键连接,尽管链
组合过程起作用胰岛素原方法需要较少的处
理步骤,因此在
1986
年取代了链式方法。将
编码胰岛素原的序
列插入到非致病性大肠杆
菌细菌中。
细菌经过发酵过程,
再生产胰岛素
原。然后用酶将
A
链和
B
链之间的连接顺序
剪
切掉,得到的胰岛素被纯化。
未来
胰岛素的未来有很多可能性。
由于胰岛素
首先被合成,
糖尿病患者需要定期用注射器将
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