Comparative Animal Physiology

introduction

1.Animal physiology: It is the science that studies the life activities and laws of animal

organisms.

Animal physiology research content:①To clarify the functional activities of various parts

of the bodyandthe rules of interaction betweenthe activities of various parts.

②To explain the changing laws of the activities of various organs and systems when the

organisminteracts with the environment.

Research levels of animal physiology:①Overall and environmental levels;②Organ and

system levels; Cell③and molecular levels.

Research methods of animal physiology:1.Acute experiments ( in vitro①

experiments;②in vivo experiments) 2.Chronicexperiments

2.Internal environment: Extracellular fluid is the direct living environment of the body's

cells and is called the body's internal environment.

Homeostasis:The changes of various physical and chemical factors that make up the

internal environment are kept within a small range,which is calledhomeostasis.

state.

Homeostasis of the internal environment is a necessary condition for cells to maintain

normal physiological functions, and is also a basic condition for the body to maintain

normal life activities.

3.Regulation methods of physiological functions: neural regulation, humoral regulation,

and self-regulation.

Neuroregulation:When the body is stimulated, the central nervous system participates in

regulating its physiological functions through reflex activities.

Mode.

Reflex:The adaptive response of the body to changes in the internal and external

environment with the participation of the central nervous system is called reflex.

The basic mode of neural regulation is reflex. Types:1.Unconditioned

reflex;2.Conditionedreflex

Thestructuralbasis of the reflexis the reflex arc, which includes receptors, afferent

nerves, nerve centers, efferent nerves and effectors.

Features:rapid, accurate, short time, limited site of action

Humoral regulation:special chemicalsubstancesproduced by endocrine glands and

tissue cells with endocrine functionsreach distantor nearbyspecific organs, tissues or

cellsthroughbody fluids, regulating their physiological functions.

Modes ofhumoral regulation: endocrine, paracrine, autocrine, neurocrine

Features: widerange, slow, long duration

4.Control systems of animal physiological functions: non-automatic control system

(open-loop system), feedback control system (closed-loop system), andfeedforward

controlsystem.

Feedback regulation:that is, the controlled part sends a feedback signal back to the

controlling part,so that the controlling part canchangeits ownactivities according to the

feedback signal,thereby regulating the activities of the controlled part.

Feedback includes positivefeedback and negative feedback.

Positive feedback: Feedback information from the controlled part promotes and

strengthens the activities of the controlling part, which is called positive feedback. For

example: defecation,childbirth,bloodcoagulation

Negative feedback: Feedback signals can reduce the activity of the control part,which is

called negative feedback.Such as: blood pressure, body temperature, lung

stretch,blood calcium,

Chapter1: Cell Functions

1.Cell membrane material transport methods: passive transport (simple diffusion,

facilitated diffusion), active transport

Simple diffusion:refers to the way some small molecules of fat-soluble substances

follow the concentration gradient(electrochemical gradient)from the high

concentrationsideof the membraneto the lowconcentration side.Such as: carbon

dioxide, oxygen

Facilitated diffusion: Some substances need the help of special proteins on the cell

membranetodiffusethrough the membranealong the concentration

gradient(electrochemical gradient).

The high concentration side diffuses to the low concentration side.For

example:Nachannel

Classification offacilitated diffusion: carrier-mediated dissimilatory diffusion and ion

channel-mediated dissimilatory diffusion.

Active transport:The processof transporting a substance against the concentration

gradientwith the help of carriers on the cell membraneby consumingATP.

Characteristics of active transport:(1) Transport against concentration gradient (2)

Consume energy (3) Requirecarriermediation

Active transport classification:(1)Primary active transportsuch assodium-potassium

pump,calcium pump,iodine pump(2)Secondary active transportsuch as:

Glucose andamino acidtransport

2.Classification of transmembrane signal transduction in cells:(1)Transmembrane

signal transduction mediated by ion channels(2)Transmembrane signal

transductionmediated byGprotein-coupled receptors

3.Transmembrane signal transductionmediatedby enzyme-coupled receptors

Classification ofion channel-mediated signal transduction: voltage-gated channels,

mechanical-gated channels, and chemical-gated channels.

Gprotein-coupled receptor-mediated signal transduction

Process: Receptor recognizes ligand and binds to it①②ActivatesGproteincoupled to

receptor③ActivatesGprotein effector④Producessecondmessenger Activates⑤

orinhibits protein kinase or channel that depends on second messenger

Gprotein-coupled receptor: anindependent receptor protein molecule related to the

activation ofintracellularGprotein.Gprotein: short for guanylate binding protein, which

has the function of coupling receptors and activating effector proteins.

Second messenger: A small molecule that transmits the information of extracellular signal

molecules acting on the cell membrane to the target protein in the cell.Second

messengers include:cAMP, inositol triphosphate, diacylglycerol, cyclic guanosine

monophosphate andGa2+, etc.

The first messenger:hormones.

4.Cell excitability and bioelectric phenomena

Cellexcitability: the ability of a cell to respond (have the ability to generate action

potentials) after being stimulated.

Stimulus:Various changes in the internal and external environment that cause cells,

tissues or organisms to respond.

Excitation: The reaction that occurs when a cell is stimulated (the process of generating

an action potential).

Excitable tissue: Tissue that is capable of generating action potentials when stimulated.

Threeelementsof stimulation: intensity, duration, and the rate of change of intensity

over time.

Changes in excitabilitywhen cells are excited:

Absolute refractoryperiod: complete loss of excitability, responsiveness to any

↓No response to stimulation;

Relative refractoryperiod: Excitability begins to recover and is lower than normal.

↓Stronger stimuli can cause reactions;

Supernormal stage:Excitability is higher than normal, weaker stimulation can cause

↓React;

Hypothalamic phase:Excitabilityis lower than normal.

↓

normal

Cellular bioelectricity phenomenon:A living cell haselectricalactivity whether it is in a

quiet state or in an active state.

The activity is calledbioelectricphenomenon. It includes resting potential and action

potential.

Resting potential:The potential difference between the inside and outside of the cell

membrane when the cell is at rest,also called membrane potential or transmembrane

resting potential.Resting potentialpolarity: positive outside and negative inside.

Action potential:When an excitable cell is excited by stimulation,the

rapidandreversiblepotential change ofthe cell membrane based on the resting

potentialis called action potential.

Mechanism of resting potential generation:(1) Concentration difference and potential

difference exist on both sides of the membrane(2) Membrane permeability(3)The

membrane hasselective permeabilityto ionsin the resting state

Action potential generation mechanism: (1) Polarization: the potential state on both

sides of the membrane is positive outside and negative inside (2) Depolarization:the

process in whichthe absolute valueof the membrane potentialgradually

decreases(3)Repolarization:the process in which the potential difference on both

sides of the membrane changes from positive inside to negative outside(4)

Repolarization:the membranepotentialreturns to the polarized state (5)

Hyperpolarization: the state in which the absolute value of the membrane potential is

higher than the resting potential

Spike:A large potential change that occurs and disappears rapidly in the first part of the

action potential curve.

Afterpotential: negative afterpotential (afterdepolarization); positive afterpotential

(afterhyperpolarization).Overshoot:The part of membrane potential that is higher than

zero is called overshoot.

Threshold potential:The critical value that can further induce action potential

depolarization is called threshold potential.

Conduction ofexcitation in acell: the local current theory; saltatory conduction

5.Classification of excitation transmission between cells: classic synaptic transmission,

junction transmission, electrical synapse

Classical synaptic transmission: Synapse-transmission betweenneurons

Synapse:The site where the axon terminal of one neuron meets the cell body or process

of another neuron.

The synapse consists of:presynaptic membrane, synaptic cleft, and postsynaptic

membrane.

Synaptic body:It is formedby the axon terminal of the previous neuron of the

synapse,which is dividedinto many small branches. Each branch is formed by a

spherical swelling at theend.The classic synaptic transmission process:(1)

Presynaptic process:The nerve impulse(action potential)is transmitted to the axon

terminal,the presynapticmembranedepolarizes,theCa2+channel opens, Ca2+flows

in, andCa2+-dependent neurotransmitters are released into the synaptic cleft.(2)

Postsynapticprocess: Neurotransmittersbind toreceptors(chemically gated

channels)on the postsynaptic membrane, causingthe permeability of a certain ion

channel on the postsynaptic membrane tochange, andthe postsynaptic membrane

undergoes a certain degree of depolarization or hyperpolarization. This potential change

is also called postsynaptic potential.

Junctional transmission: Nerve-skeletal musclejunction: Motor end plate Prejunctional

membrane: Vesicles contain acetylcholine (ACh)

Joint gap: about50--60nm

Postjunctional membrane: also known as end plate membrane (AChreceptors and

acetylcholinesterase are present)

Characteristics ofclassical synaptic transmission andneuromuscularjunction

transmission: (1) unidirectional (2) time delay (3) susceptible to

Environmental and drug effects (4)Fatigue

Chapter 2Blood

Plasma:contains fibrinogen, light yellow, includes (water, plasma protein and low

molecular weight substances).Serum: does not containfibrinogen.

Hematocrit: The percentage of whole blood volume occupied by red blood cells.

Isotonic solution: A solution with the same osmotic pressure as cells and

plasma.PHof5%glucose, 0.9% NlCl,1.9%ureaplasma:7.35~7.45. Tolerance

limit:7.00~7.80

Functionsof blood:

1.Maintaining homeostasis of the internal environment: Bloodcan achieve

nutrition,transportation, and participation in the bodythrough various components in

blood cells and plasma.

It has functions such asfluid regulation,defense protection and acid-base buffering.

2.Nutritional function: Protein in plasma plays a role in nutritional reserve.

3.Transport function: binding protein

4.Participate in humoral regulation: Hormones secreted by secretory glands in the

bodyaretransported by blood and act on corresponding target cells,changing their

Activity.

5.Defense and protection function: White blood cells have the function of

phagocytosisanddecompositionof foreign bacteria and necrotic tissue in the body;

lymphocytes and various immune substances in plasma can fight or eliminate toxins or

bacteria;various coagulation factors,anticoagulantsand fiber system substancesin

plasmaparticipate inthe physiological hemostasis process ofcoagulation-fibrinolysis.

White blood cells:They are divided into granulocytes and agranulocytesaccording to the

presenceorabsence of special chromophilic granules in their

cytoplasm.Granulocytesare further divided into neutrophils(red and blue),

eosinophils(red)and basophils (blue)according tothe reaction characteristics of the

granules they contain to the dye;agranulocytes can be divided intomonocytes and

lymphocytes.

Platelets: Characteristics: colorless and transparent, no nucleus, disc-shaped or rod-

shaped bodies, adhesion, aggregation, release reaction, contraction,adsorption.

Physiological functions: 1.Participate in coagulation2.Participate in physiological

hemostasis3.Ensure the integrity of vascular endothelium.

Blood coagulation:the process of blood coagulating from a sol state into a blood clot.

Blood coagulation process: the first stage is the formation of prothrombin activator; the

second stageis the action of prothrombin on prothrombin activator

Inthe third stage, fibrinogen is converted into fibrin under the action of thrombin.

Influencing factors:Blood coagulation is affected by many factors. In addition to the

coagulation factors that directly participate in the blood coagulation process, temperature,

contact

Thesmoothness of the contact surfacecan also affect the blood coagulation process.

Chapter 3: Blood Circulation

Cardiac cycle:The activity cycleof the heartconsisting of one contraction and relaxation.

Heart rate: The number of heart beats per minute (beats/min).

The first heart sound: occurs at the beginning of the systole, also known as the systolic

sound.Itisadeep, long-lastingsound.

Second heart sound: occurs at the beginning of diastole, also known as diastolic heart

sound.Itishigh-pitchedandshort-lasting.Factorsaffecting cardiac output: stroke

volume, heart rate

Factors thataffect strokevolume: preload, myocardial contractility, and afterload

Characteristics ofmyocardial cells: contractility and automatic rhythm

Thephysiological characteristics of myocardiumare: excitability, automaticity,

conductivity and contractility

Normal pacemaker: sinoatrial node

Ectopic pacemakers:pacemakers other than the sinoatrial node.They are located in

any part of the cardiac conduction systemandcan be divided into atrial,junctional,

ventricular...In the case of significant abnormalities,ordinary myocardial cells can also

have autonomyandbecomeectopic pacemakers.

Blood pressure:The lateral pressure exerted on the blood vessel walls by blood flowing

through the blood vessels.

Factors thataffect arterialblood pressure:

A. Stroke volume:Stroke volume ↑ --- → Systolic pressure ↑ ↑Diastolic pressure ↑Pulse

pressure ↑

Stroke volume↑---→Systolic pressure↓↓Diastolic pressure↓Pulse pressure↑

B.Heart rate:Heart rate ↑ --- → Systolic pressure ↓Diastolic pressure ↑Pulse pressure ↓

C.Peripheralresistance:

Peripheral resistance↑---→Systolic pressure↑Diastolic pressure↑↑Pulse

pressure↓Peripheral resistance↓---→Systolic pressure↓Diastolic pressure↓↓Pulse

pressure↑

D. Elasticity of large artery wall:Strong elasticity --- → Systolic pressure ↓Diastolic

pressure ↑Pulse pressure ↓

Weak elasticity --- → Systolic pressure ↑Diastolic pressure ↓Pulse pressure ↑

E. Circulating blood volume: Circulating blood volume ↑ --- → Systolic pressure

↑↑Diastolic pressure ↑Pulse pressure ↑

Chapter4: Breathing

Respiration:The process of gas exchange between the body and the external

environment is called respiration.External respiration: In physiology, ventilation and gas

exchange ofrespiratory organsare collectively called external respiration.Internal

respiration:Tissuegas exchange is called internal respiration.

Pressure in the pleural cavity:negative pressure

Formation mechanism:end of inspiration and end of expiration

Intrathoracic pressure=intrapulmonary pressure–lung recoil force =atmospheric

pressure–lung recoil force=–recoil force

Vital capacity:The amount of air exhaled after a forceful inhalation and exhalation.

Lung capacity=vital capacity+residual volume(the amount of gas contained in the

lungs)Oxygentransport:

Physical dissolution:1.5%

Chemical bonding:Hb+O2=HbO2

CO2Transport:

Physical dissolution (5%)

Chemically bound bicarbonate (87%), carbamidohemoglobin (7%)

Hb-NH2+CO2=Hb·NHCOOH

Oxygendissociation curve

The curveshowingthe relationship betweenPO2andHboxygen saturation

is"S"shaped. It reflectsthe combination ofO2andHbunderdifferentPO2.PO2:8.0

～13.3kPa(60～100mmHg) is relatively flat-in high mountains, respiratory diseases

PO2: 5.3～8.0kPa(40～60mmHg)steeper-arterial bloodtissue fluid

PO2: 2.0 ～5.3kPa(15 ～40mmHg), steepest-when tissue metabolism is enhanced,

there is sufficient oxygen supply.Factors affecting the shift of the oxygen dissociation

curve: the influence of temperature, the influence of pHvalue andPCO2,the influence

ofDPG

Chapter5: Digestion and Absorption

Digestion:The process by which food is broken down into small molecules that can be

absorbed and utilized in the digestive tract.

Absorption:The process by which food enters the blood and lymph circulation through

the digestive tract mucosa after digestion.General characteristics ofdigestive

tractsmooth muscle:

aLow excitability and slow contraction speed;

b.Greater stretchability;

c.Continuous tension;

d.Sensitive to chemical, thermal and stretch stimulation, but not to electrical stimulation;

eTherhythmic movement originates from the smooth muscle itself and is also regulated

by the nervous system.

Neuralinnervation of the digestive tract

aNeuromodulation: extrinsic neuromodulation and intrinsic neuromodulation

bHumoralregulation:systemic hormone regulation and gastrointestinal hormone

regulation

Gastrointestinalmotility:

1.Tensorycontraction and receptive relaxation;

aToniccontraction; the smooth muscle of the digestive tract is persistently in a state of

weak contraction.

bGastric receptive relaxation: When chewing and swallowing food, the receptors are

stimulated,causingthe stomach wall smooth muscle to relax reflexively.

The stomach capacity increases. The afferent and efferent nerves of this reflex are both

vagus nerves, so it is also called vagal-vagalreflex.

2.Peristalsis

aGastric peristalsis: alternating contraction and relaxation of smooth muscle. Starts in

the middle of the stomach. Affected by slow waves.

bGastric emptying: The process of gastric chyme being discharged from the stomach

into the duodenum.

cSmall intestinal peristalsis: The circular andlongitudinalmuscles of the small intestine

contract in sequence from the beginning to the end of thesmallintestine.

Eatfoodslowly.

dPeristaltic impulse: It is fast and can push food from the beginning to the end of the

small intestine.

eSwing: Rhythmic contraction and relaxation of longitudinal muscles. The chyme and

digestive juice are fully mixed, which is conducive to digestion.

3.SegmentalMovement

It is common in the small intestineand large intestine, and is a rhythmic contraction and

relaxation activity mainly based on circular muscles.

Rumen:The main digestion site for nutrients in ruminants, mainly by microorganisms.

Composition, properties and physiological characteristics of gastric juice:

Properties: Colorless and transparent, strong acidity (pH0.9-1.5)

Ingredients:Inorganic substances(hydrochloric acid, sodium chloride, potassium

chloride) organic substances (digestive enzymes, mucin, intrinsic factor)

Characteristics:When secretion rate is high, it is highly acidic and watery; when hungry, it

is less acidic and more viscous.

Hydrochloric acid:(Parietal cells---HCL)

Function: (1) Activate pepsinogen

(2) Favorableproteindigestion (swelling and denaturation)

(3) Inhibit andkill bacteria in the stomach

(4) Promotessecretion of secretion, bile, and small intestinal fluid

(5) It isbeneficialforthe absorption of iron and calcium

Physiologicalroleofbile(secreted by the gallbladder):

a.Bile salt is a coenzyme of pancreatic lipase,increasing its activityb.Reduces fat

surface tension and emulsifies fat

ccombines with fatty acids to promote absorption

dPromotes absorption of fat-soluble vitamins

eNeutralizes gastric acid and maintains intestinalpH

Chapter 7

Urine production: includingglomerularfiltration, reabsorption by the renal tubules and

collecting ducts, and secretion by the renal tubules and collecting ducts.

(1) The formation of primary urineWhen blood flows through the glomerulus,except for

blood cells and large molecular proteins,all other substances can be

The final urineglomerularfiltratepassesthroughthe renal tubulesandcollecting

vessels.

The fluid that is reabsorbed and secreted through the urine tubes and finally excreted

from the body is calledfinal urine.

Factors affecting urine formation: Factors affecting primary urine formation:1.Filtration

membrane area and its permeability(1) Filtration area

Glomerulus inflammation→capillary lumen narrowing or obstruction→working

glomerulus↓→ filtration area↓→ urine volume↓

(2) Filtration membrane permeabilityhypoxia or poisoning → increased permeability →

proteinuria and hematuria

2. Glomerular effective filtration pressure(1) Glomerular capillary blood pressureArterial

blood pressure↓→ Glomerular capillary blood pressure↓→

Effective filtration pressure↓→urine volume↓such as trauma,burns, andbleeding

(2) Plasma colloid pressurePlasma protein↓→ colloid osmotic pressure↓→ effective

filtration pressure↑→urine volume↑

(3) Glomerular intracapsular pressure↑→Effective filtration pressure↓→Urine

volume↓

3.Decreasedrenal blood flowand decreased urine volume

Factors affecting final urine production:1.Renal autoregulation(1)Vascular myogenic

autoregulation(2) Tubular fluidsoluteconcentration

(Osmotic diuresis)Solute concentration↑→ Osmotic pressure↑→ Water

reabsorption↑→ Urine volume↑(3) Glomerular-tubular balance

2.The role of renal sympathetic nerves(1)The adrenal medulla releasesNEandE,

causing vasoconstriction of the afferentandefferent arteriolesanda decreasein renal

bloodflow.(2) Juxtaglomerular cells release renin,increasing the renal tubular

reabsorptionof Na+,Cl-, and water.(3) Proximal tubules andloops of Henle increase

the reabsorptionof Na+, Cl-,and water.

3. Fluid regulation of renal function(1) Antidiuretic hormone(2) Aldosterone(3) Atrial

natriuretic peptide(4) Parathyroid hormone

Adrenaline

Chapter 8

Neuron:A nerve cellisthe basic structural and functional unit of the nervous

system.Itconsists of a cell body and a process.

To be stimulated andto transmit excitement.

Glial cells:All cells except neurons thatare widely distributed inthe central nervous

system.

Neurotransmitter:asignaling substancereleased from the presynaptic

membranethatcan specifically act on the postsynaptic membrane

receptorsandproduce postsynapticpotentials

Neuromodulators:Chemical substancesproducedby neuronsthat increase or decrease

the effect of information transmission.

Receptor:A special biological moleculeon or inside the cell membrane that

canspecifically bindto certain chemical

substances(transmitters,modulators,hormones)and inducebiologicaleffects.

Characteristics of nerve fiber conduction of excitement:(1) Structural and functional

integrity:The conductionofnerve impulsesmustbe carried out on a nerve fiber with

complete structure and function.(2) Insulation:The conduction of excitement between

adjacent nerve fibers does not interfere with each other.(3) Bidirectionality:The action

potential generated at any point on the nerve fiber can be transmitted to both ends along

the nerve fiber at the same time.(4) Relative fatigue resistance:Compared with

synaptic transmission, the conduction of excitement on nerve fibers is not prone to

fatigue. (5) Non-attenuation: When nerve fibersconduct impulses, no matter how long

the conduction distance is, the size, frequency and speed of the conducted impulses

remain unchanged.

The connection mode of central neurons:synaptic transmission,single-line connection,

divergent and convergent connection,locking and ring connection

Characteristics of excitation propagation within the central nervous system:(1) One-

way propagation(2) Central delay(3) Summation(4) Changes in excitation

rhythm(5)

Post-release(6) Localization and diffusion(7) Sensitivity and fatigability

Postsynaptic inhibition: The postsynaptic membrane becomes hyperpolarized,making it

difficult for the postsynaptic neuron to depolarize and thus reducing its excitability,hence

the name postsynaptic inhibition. This hyperpolarized potential change is called inhibitory

postsynaptic potential(IPSP).

It is mainly divided into(1)afferent collateral inhibition.After the sensory afferent fiber

enters the spinal cord,itexcites aneuronandsends out collaterals to excite another

inhibitory neuron.The activity of the latter inhibits the other

neuron.(2)recurrentinhibition.When the central neuron is excited, the efferent

impulse is transmitted along the axon and at the same time excites an

inhibitoryinterneuronthrough the collateral branches of the axon. The latterin turn

inhibits the original excited neuron and other neurons in the same center.

Characteristics of receptors (1) Appropriate stimulation(2) Transduction function of

receptors(3) Coding function of receptors(4)Adaptation phenomenonof receptors

Somatic sensory afferent pathways:spinalcord, thalamus, cerebral cortex(1) Somatic

sensory afferent pathways in the spinal cord and lower brainstem(2)

Thalamic sensory and projection systems (3) Delocalization ofsomaticsensory

representation in the cerebral cortex

Thalamic nuclei: specific sensory relay nuclei, association nuclei, nonspecific nuclei

Thalamic sensory projection system:(1) Specific projection systemThe fibersemitted

from the specific sensory relay nuclei and most of the associative nuclei of the

thalamusareprojectedto specific areas of the cerebral cortex in a point-to-point

manner.Function:Produce specific sensationsandstimulatethe cerebral cortex to

send out nerve impulses(2) Non-specific projection systemThe fibers emitted from the

non-specific nuclei of the thalamusarediffusely projected to a wide area of the cerebral

cortexaftermultiple exchanges in thebrainstemreticular system.There is nopoint-to-

pointprojectionrelationship. Function:Maintain and change the excitability of the

cerebral cortex (wakefulness)

Motor regulation of the cerebral cortex:regulating the voluntary movement of the

body(1) Characteristics of the motor area of the cerebral cortex:cross

innervation,precise functional positioning,different sizes of positioning areas of each

muscle in the motor area,and significant differencesin the sizeof the

corticalrepresentativeareas of the motor areas of different livestock(2) The pyramidal

systemis the conduction bundle of the motor neurons of the ventral horn of the spinal

cord, which is emitted from the cerebral cortex through the medullary pyramids and then

tothe spinal cord.Function:enables muscles to move voluntarilyandcomplete fine

movements. (3) Extrapyramidal system:Some subcortical nuclei do not pass through

the medullary pyramids,but control the activity of spinal cord motor neurons through the

posterior pathway,so it is called the extrapyramidal system.Function: regulate

muscletension and coordinated movement of muscle groups to maintain normal posture.

The nervous system regulates visceral activities.The nerves that regulate visceral

activities were once called the autonomic nervous system or the visceral

nervoussystem.

The autonomic nervoussystem consists of the sympathetic and parasympathetic

nervous systems

Sympathetic and parasympathetic nervesstructural features andfunctional

characteristics

Chapter 9: Endocrine

1.Endocrine: endocrine glands or endocrine cells synthesize and secrete certain special

chemicals (chemical messengers)through the blood

The processof circulating or diffusingto the corresponding target cells and regulating

their physiological functions.

Endocrine type:(1) Endocrine: chemical messengers----blood circulation----target

cells

(2) Neurosecretion: presynaptic membrane of nerve cells ---- chemical messengers

----postsynapticcells

(3) Neuroendocrine: nerve cells ---- chemical messengers ---- blood circulation ---- target

cells

(4) Paracrine: cells ---- chemical messengers ---- diffusion into interstitial fluid

----adjacenttarget cells

(5) Self-secretion: cells ---- chemical messengers ---- intercellular fluid ----cells

2.Hormone: A chemical substance (chemical messenger)secreted by endocrine cells or

endocrine glands, transported to target cells or target organs through diffusion or blood

circulation, andregulating their biological functions.

Hormone classification: (1) Peptide/protein hormonessuch as hypothalamic hormone,

calcitonin, insulin; growth hormone, prolactin, etc.

(2) Amine hormonessuch as thyroxine, adrenaline, etc.

(3) Lipid hormones Steroid hormones①such as aldosterone, cortisol, sex hormones,

progesterone, etc.

Sterol hormones②such as 1,25-dihydroxyvitaminD Fatty acid derivatives③such as

prostaglandins, thromboxanes, etc.

Functionsof hormones: Maintaining homeostasis, regulating metabolism, maintaining

growth, promoting cell differentiation and maturation, and regulating reproduction

Generalcharacteristics of hormones: information transmission function, specificity of

action, high efficiency of action, and synergistic or antagonistic effects between

hormones.

Mechanism of action of hormones:(1) Mechanism of action of nitrogen-containing

hormones-second messenger theory (2) Mechanism of action of steroid hormones-

—Gene expression theory (3) Mechanism of actionof thyroxine

3.Hypothalamus

The neurosecretory cellsofthe hypothalamusrefer to the neurons in the hypothalamus

that have secretory functions.

Classification:(1) Neuroendocrine large cells,mainly distributed in the supraoptic

nucleus and paraventricular nucleus of the anterior region(terminatingat the

neurohypophysis to formthe hypothalamus-pituitary tract) (2) Neuroendocrine small

cells, mainly distributed in the arcuate nucleus, suprachiasmatic nucleus, ventromedial

nucleus, etc.

Classification of hypothalamic hormones: (1)Hypothalamus-pituitary tract: oxytocin

(OXT)----secreted by the paraventricular nucleus;vasopressin (VP)or antidiuretic

hormone(ADH)----secreted by the supraoptic nucleus (2) Hypothalamic pituitary

region: 6releasing factors and3release inhibitoryfactors: adrenocorticotropic hormone

(ACTH) releasing hormoneCRH,

Thyroid stimulating hormone (TSH) releasing hormoneTRH,

Gonadotropin (FSH, LH) releasing hormoneGnRH,

Growth hormone (GH) releasing hormoneGHRH,somatostatinSS,

Prolactin (PRL) releasing factorPRF,prolactin (PRL) release inhibitory factorPIF,

Melanocyte stimulating hormone (MSH) releasing factorMRF,melanocyte stimulating

hormone (MSH) release inhibitory factorMIF

Hormones secreted by the pituitary gland: growth hormoneGH, prolactinPRL, thyroid

stimulating hormoneTSH, follicle stimulating hormoneFSH,luteinizing hormoneLH,

adrenocorticotropic hormoneACTH

4.Thyroid hormone synthesis process:iodine accumulation (secondary active transport),

iodine activation, tyrosine iodination and iodinated tyrosine

Acidcoupling.

Physiological effects of thyroid hormones:(1) Regulation of metabolism:oxidative heat

production,effects on sugar metabolism,effects on fat metabolism,effects on protein

metabolism,effects on water and salt transport; (2) Regulation of growth and

development:growth promotion, promotion ofallergic reactions,effects on the

development of the nervous system, effects on gonadal development and effects on

other organs.

Regulation of thyroid function:(1) Hypothalamic-pituitary-thyroid axis (2) Feedback

regulation (3) Regulation of other hormones(4)

Effect ofiodine intake onthyroid function.

5.Parathyroid hormonePTH: It is secreted by parathyroid chief cells and is an important

hormone that regulates blood calcium and blood phosphorus levels.Physiological

function: Increases blood calcium and decreases blood phosphorus. Target organs are

bones, kidneys and intestines.

(1) Effect on bones: PTHpromotes the dissolution of calcium and phosphorus in bones

into the blood, increasing blood calcium;

(2) Effects on the kidneys:①PTHpromotes the reabsorption of calcium by the renal

tubules and increases the excretion of urinary phosphorus;②Activates the renal tubules

1α-hydroxylase, promotingthe production of1,25-dihydroxyvitaminD;

(3) Effect on the intestine:PTHpromotes the absorption of calcium in the small intestine.

6.CalcitoninCT:secretedby thyroidCcells. Its physiological function is to reduce blood

calcium and blood phosphorus.

Function:(1) Effect on bones:CTinhibits osteoclast activity and promotes bone

formation;

(2) Effects on the kidneys:CTinhibits the reabsorption of calcium and phosphorus by the

renal tubules;

(3) Effects on the digestive tract: Inhibitsthe productionof1,25-dihydroxyvitaminDand

inhibits the absorption of calcium in the small intestine.

7.1,25-dihydroxyvitaminD: Its main function is to increase blood calcium and

phosphorus levels.

Formation process: dehydrocholesterol,ultraviolet irradiation under the

skin,vitaminD(cholecalciferol),25-hydroxylasein the liver,

25-hydroxycholecalciferol,α-hydroxylasein the kidney, 1,25-

Dihydroxyvitamin D3

8.Adrenal glands: include adrenal cortex and adrenal medulla.

Adrenal cortical hormones:mineralocorticoids(secreted by zona

glomerulosa),glucocorticoids(secreted by zona fasciculata),sex hormones(secreted

by zona reticularis

secretion)

Physiological effects of glucocorticoids:(1) Regulating metabolism of

substances①Sugar metabolism: increasing blood sugar②Protein

metabolism:promotingprotein decomposition Fat metabolism③:promoting fat

decomposition④Water and salt metabolism:retaining sodium and excreting

potassium;(2)Effects on certain tissues and organs: maintainingthe normal activities

of various organs and tissues (3) Participating instress response: during stress,

glucocorticoids increase and the body's adaptability is enhanced.

Physiological effects of mineralocorticoids:(1) Retaining sodium and excreting

potassium, promotingthe reabsorption ofsodium andNaby the distal convoluted tubules

and collecting ducts of the kidneys, and inhibitingthe reabsorption of K and H.

(2)ReducingtheexcretionofNain sweat, saliva and gastric juice.

9.Hormones secreted by pancreatic islets:insulin (secreted byBcells),

glucagon(secreted byAcells),somatostatin (secretedbyDcells

secretion), pancreatic polypeptide (secreted byFcells).

Insulin(secretedby pancreaticBcells)physiological functions:promote

anabolism,promote nutrient storage and regulate blood sugar concentration.

(1) Regulation of glucose metabolism: Promotethe synthesis of liver glycogen and

muscle glycogen, enhancethe uptakeand utilization of glucose by skeletal muscle and

adipose tissue, and lower blood sugar;(2) Regulation of fat metabolism: Promote the

synthesis and storage of fat, inhibit fat decomposition,reduce free fatty acids in the

blood, andreduce the production of ketone bodies; (3) Regulation of protein

metabolism: Promote protein synthesis,inhibit

Inhibits protein decomposition and promotes growth.Insulin is also called"storage

hormone".

The physiological functions ofglucagon(secretedby pancreaticAcells):(1) promote

glycogenolysisandincrease blood sugar;(2) promote protein

(3) Promotes fat decomposition.Glucagonisalso known asthe "mobilizing hormone".

10.Somatostatin (SS): secreted by pancreaticDcells. Reduces glucagon and insulin

levels.Pancreatic polypeptide: secreted by pancreaticFcells, reduces liver glycogen

reserves, and inhibits gastrointestinal digestion.

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