Download 第五章信号1 序

• 第二节
细胞通讯与信号传递
• cell communication and
• signal transduction
CELL COMMUNICATION
Cells communicate with one
another using chemical signals.
These signals are essential to
regulation and coordination of cell
activities. For a receiving cell, the
three stages of signaling are
reception, transduction, and
response.
• Overview of cell signaling
Sex hormone
ectohormone
(5) 外激素
ectohormone
•信息素由外分
泌腺通过导管
离开身体刺激
另一个体的靶
细胞。
昆虫的信息素
警戒素
性息素或性外激素
雌蛾最大量的分泌可引来100万只雄蛾。
接受器如何？
触角是接受天线，能感受气味分子发射的红外光
谱。
卡达汉的故事
corruption
blankly
Cell signaling can affect virtually every aspect of
cell structure and function:
Activation of enzyme activity;
 Change in cytoskeletal organization;
 Change in ion permeability;
 Initiation of DNA synthesis;
 Activation or repression of gene expression.
Four features of signal-transducing systems
枪响-
交感
神经
肾上腺髓
质
肾上腺素
肌肉细胞
与G蛋白偶联的膜受体
肝细胞
糖原分解
肌肉细胞
环化腺苷酸增高
跨膜运输
最终活化磷酸
化酶
糖原分解
内质网
1磷酸 葡萄糖
6磷酸葡萄糖
放大阶式级联
葡萄糖
ATP
6磷酸葡萄糖
1磷酸 葡萄糖
内质网
线立体3羧酸循环
胞质糖酵解
葡萄糖
过线立体膜
丙酮酸
乳酸
Signaling pathways consist of a series of steps
signal magnification
1.
Recognition of the
stimulus by a specific
plasma membrane
receptor.
2.
Transfer of a signal across
the plasma membrane.
3.
Transmission of the signal
to effector molecules
within the cell, which
causes a change in cellular
activities.
4.
Cessation of the cellular
response due to
inactivation of the signal
molecule.
• The Nervous and Endocrine Systems
• The pituitary脑垂体 gland (often called
the master gland) is located in a small
bony cavity at the base of the brain. A
stalk links the pituitary to the
hypothalamus, which controls release of
pituitary hormones. The pituitary gland
has two lobes: the anterior and
posterior lobes. The anterior pituitary
is glandular.
•The endocrine system in females and males. Image from
Purves et al., Life: The Science of Biology, 4th Edition,
• The hypothalamus contains neurons
that control releases from the
anterior pituitary. Seven
hypothalamic hormones are released
into a portal system connecting the
hypothalamus and pituitary, and
cause targets in the pituitary to
release eight hormones.
•The location and roles of the hypothalamus and pituitary glands.
Images from Purves et al., Life: The Science of Biology, 4th
Edition,
• Growth hormone (GH) is a peptide anterior
pituitary hormone essential for growth. GHreleasing hormone stimulates release of GH.
GH-inhibiting hormone suppresses the
release of GH. The hypothalamus maintains
homeostatic levels of GH. Cells under the
action of GH increase in size (hypertrophy
肥大,过度生长, 过度增大) and number
(hyperplasia增生, 数量性肥大). GH also
causes
• increase in bone length and
thickness by deposition of
cartilage 软骨at the ends of bones.
During adolescence, sex hormones
cause replacement of cartilage by
bone, halting further bone growth
even though GH is still present.
Too little or too much GH can cause
dwarfism or gigantism, respectively.
• Hypothalamus receptors monitor
blood levels of thyroid hormones.
Low blood levels of Thyroidstimulating hormone (TSH)cause the
release of TSH-releasing hormone
from the hypothalamus, which in
turn causes the release of TSH from
the anterior pituitary.
• TSH travels to the thyroid where it
promotes production of thyroid
hormones, which in turn regulate
metabolic rates and body
temperatures.
• Hypothalamus release TSH (Thyroidstimulating hormone ) -releasing
hormone
• TSH-releasing hormone causes
anterior pituitary release TSH
(Thyroid-stimulating hormone ).
• TSH
thyroid
promotes
production of thyroid hormones
• thyroid hormones
metabolic rates
and body temperatures.
• Gonadotropins促性腺激素 and prolactin催
乳激素are also secreted by the anterior
pituitary. Gonadotropins (which include
follicle-stimulating hormone, FSH, and
luteinizing促黄体hormone, LH) affect the
gonads生殖腺by stimulating gamete
formation and production of sex hormones.
Prolactin is secreted near the end of
pregnancy and prepares the breasts for milk
production.
• The Posterior Pituitary
• The posterior pituitary stores and
releases hormones into the blood.
Antidiuretic 抗利尿剂hormone
(ADH)and oxytocinare 催产素
produced in the hypothalamus and
transported by axons to the
posterior pituitary where they are
dumped into the blood.
• ADH controls water balance in the
body and blood pressure. Oxytocin
催产素is a small peptide hormone
that stimulates uterine
contractions during childbirth.
• Other Endocrine Organs
• The Adrenal Glands
• Each kidney has an adrenal gland located
above it. The adrenal gland is divided into
an inner medulla and an outer cortex. The
medulla synthesizes amine hormones, the
cortex secretes steroid hormones.
• The adrenal medulla consists of modified
neurons that secrete two hormones:
epinephrine and norepinephrine.
Stimulation of the cortex by the sympathetic
nervous system交感神经causes release of
hormones into the blood to initiate the "fight
or flight" response.
• The adrenal cortex produces several steroid
hormones in three classes:
mineralocorticoids盐皮质激素,
glucocorticoids糖皮质激素, and sex
hormones. Mineralocorticoids maintain
electrolyte balance.
• Glucocorticoids produce a long-term,
slow response to stress by raising
blood glucose levels through the
breakdown of fats and proteins;
they also suppress the immune
response and inhibit the
inflammatory炎性的response.
•The structure of the kidney as
relates to hormones. Image
from Purves et al., Life: The
Science of Biology, 4th
Edition,
• The thyroid gland is located in the
neck. Follicles 滤 泡 in the thyroid
secrete thyroglobulin甲状腺球蛋白 ,
a storage form of thyroid hormone.
• Thyroid stimulating hormone (TSH) from
the anterior pituitary causes conversion of
thyroglobulin into thyroid hormones T4 and
T3. Almost all body cells are targets of
thyroid hormones.
• Thyroid hormone increases the
overall metabolic rate, regulates
growth and development as well as
the onset of sexual maturity.
Calcitonin is also secreted by
large cells in the thyroid; it
plays a role in regulation of
calcium.
• The Pancreas
• The pancreas contains exocrine
cells that secrete digestive
enzymes into the small intestine
and clusters of endocrine cells
(the pancreatic islets). The islets
secrete the hormones insulin and
glucagon, 胰高血糖素 which regulate
blood glucose levels.
• After a meal, blood glucose levels rise,
prompting the release of insulin, which
causes cells to take up glucose, and liver
and skeletal muscle cells to form the
carbohydrate glycogen.
• As glucose levels in the blood fall,
further insulin production is
inhibited. Glucagon胰高血糖素
causes the breakdown of glycogen
into glucose, which in turn is
released into the blood to maintain
glucose levels within a homeostatic
range.
• Glucagon胰高血糖素 production is
stimulated when blood glucose
levels fall, and inhibited when
they rise.
• Diabetes results from inadequate levels of
insulin. Type I diabetes is characterized by
inadequate levels of insulin secretion, often
due to a genetic cause. Type II usually
develops in adults from both genetic and
environmental causes. Loss of response of
targets to insulin rather than lack of insulin
causes this type of diabetes.
• Diabetes causes impairment in the
functioning of the eyes,
circulatory system, nervous system,
and failure of the kidneys.
Diabetes is the second leading
cause of blindness in the US.
Treatments involve daily injections
of insulin, monitoring of blood
glucose levels and a controlled
diet.
• Other Chemical Messengers
• Interferons are proteins released
when a cell has been attacked by a
virus
. They cause neighboring cells to
produce antiviral proteins. Once
activated, these proteins destroy
the virus.
• Prostaglandins前列腺素 are fatty
acids that behave in many ways like
hormones. They are produced by most
cells in the body and act on
neighboring cells.
• Pheromones 信息素,外激素are
chemical signals that travel
between organisms rather than
between cells within an organism.
Pheromones are used to mark
territory, signal prospective mates,
and communicate. The presence of a
human sex attractant/pheromone has
not been established conclusively.
• Biological Cycles
• Biological cycles ranging from
minutes to years occur throughout
the animal kingdom. Cycles involve
hibernation冬眠
• , mating behavior, body temperature
and many other physiological
processes.
• Rhythms or cycles that show cyclic
changes on a daily (or even a few
hours) basis are known as circadian
生理节奏的rhythms. Many hormones,
such as ACTH-cortisol, TSH, and GH
show circadianrhythms(二十四小时节
奏,生物钟. )
• The menstrual cycleis controlled by
a number of hormones secreted in a
cyclical fashion. Thyroid secretion
is usually higher in winter than in
summer. Childbirth is hormonally
controlled, and is highest between
2 and 7 AM.
• Internal cycles of hormone
production are controlled by the
hypothalamus, specifically the
suprachiasmic nucleus (SCN).
According to one model, the SCN is
signaled by messages from the
light-detecting retina of the
eyes.The SCN signals the pineal
gland in the brain to signal the
hypothalamus, etc.
Hypothalamus 下
丘脑
pituitary 垂体
thyroid甲状腺
•
•
一、细胞通讯与细胞识别
（一）细胞通讯
1 分泌化学信号
2 膜接触依赖性通讯
3 间隙连接
1 分泌化学信号
•
•
•
•
(1) 内分泌（endocrine）
(2) 旁分泌(paracrine)
(3) 自分泌(autocrine)
(4) neurotransmitters
• (5) 外激素ectohormone
• General schemes of intercellular signaling
•(1) 内分
泌
（endocri
ne）
•(2) 旁分泌
(paracrine)
如旁泌素
（FGF）
（TGF）
•(1) 内分泌（endocrine）
(2) 旁分泌(paracrine)
•(3) 自分泌(autocrine)
(4) neurotransmitters
(4) neurotransmitters
• 内分泌
信号激素
类物质
血管
靶细胞
• 旁分泌
引起胞
内一系
列生理
生化反
应
引起胞
内一系
列生理
生化反
应
信号类
• 自分泌
信号类
引起胞内一系列生
理生化反应
2 膜接触依赖性通讯
•3 间隙连接
(二)细胞识别与信号通路
signal transduction pathways
细胞识别的概念
Signal molecules bind to receptors on the
membrane or inside the cell. Receptors
activate various kinds of signal
transduction pathways, which regulate
activities in the cytoplasm and gene
transcription in the nucleus.
The cell targeted by a particular signal has a
receptor molecule complementary to the signal
molecule, or ligand. The ligand fits like a key in
a lock and triggers a change in the receptor
molecule.
Signal transduction converts the change in the
receptor to a form that can bring about a
cellular response. This might involve a series
of steps-- a signal-transduction pathway-- that
alters and amplifies the change.
In the third stage of cell signaling, the
transduction process brings about a
cellular response. This can be any of
many different cellular activities, such as
activation of a certain enzyme,
rearrangement of the cytoskeleton, or
activation of specific genes.
•A 细胞和细胞的识别
•1 同种同类
• 血小板
•2 同种异类
• 精卵
•3 异种异类
• 细菌 真菌感染
•4 异种同类
• 器官移植
B 细胞和大分子之间的识别
（三）细胞的信号分子与受体
Signal Molecules and Receptors
1、细胞的信号分子
•（1）.亲脂
•甾类激素和甲状腺素
•（2）.亲水
•神经递质 生长因子 大多数激素
（3）气体分子
Signal molecules:
Odorant
Pheromones
tastants
2、受体
Receptors that are plasma-membrane
proteins usually affect the cell through
multistep signal-transduction pathways.
These pathways allow for amplification
of signals and signal coordination and
regulation.
Most signal molecules act on target
cells by binding to receptors in the
cell membrane. There are several
kinds of membrane receptors. Some
signal molecules enter target cells
and bind to intracellular receptors in
the cytoplasm.
Receptors include two classes:
ligand和 receptor不是简单的一对一的关系
不同靶细胞的不同 receptor可以应答相同的ligand，
但靶细胞的反应不同
同种信号会引起不同细胞的不同响应。
乙酰胆碱引起
骨骼肌细胞收缩
心肌细胞舒张
分泌细胞分泌
同一靶细胞不同receptor应答不同ligand却有相同
的效应。
Different cells can respond differently to the same
extracellular signal molecule
Various responses induced by neurotramsmitter acetylcholine
Two-dimensional representation
of a “composite”transmembrane
receptor showing the approximate
sites of a number of mutations
responsible for causing human
disease