introduction_to_physiology slides of doctor mustafa shehabat

8/3/2019 Introduction_to_physiology Slides of Doctor Mustafa Shehabat

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Introduction To HumanPhysiology

Prepared by:Dr.Mustafa Al-Shehabat


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The science that is concerned with the function

of the living organism and its parts, and of

the physical and chemical processes involved.

Human Physiology


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The Human Body - A Complex

Society of Differentiated Cells

Cells:the basic structural and functional unit

(~ 100 trillion)

Tissues:(e.g. muscles, epithelial, nervous )

Organs:(e.g. kidney, heart, liver, pancreas)

Organ systems:(e.g. cardiovascular, urinary)


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Regulation and Integration

Exists at all levels of organization

Cells:e.g., genes, repressor proteins,transcription factors, membrane

transport

Tissues

Organ systems:e.g., nervous and endocrine

systems


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Human physiology is a science which analyzesthe body functions and their interaction with

the environment

Humans are influenced by the external

environment in which they live


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Physical :Heat, light,

sound,motion andradiation

Chemical :Food,water,O2, CO2,drugs

Biological :Microorganisms

Psychosocial environment

Environmenta

lInputs

Sensoryorgans

Skin

Respiratory system

Digestivesystem

Contact

Systems

Nervoussystem:somatic andautonomic

Endocrinesystem

Control

Circulation

Blood

Kidney

Homeostasis

Metabolism

Blood pH

Fluids andelectrolytes

Internal

environment

Physiologica

l adaptation

Physicalwork

Mental work

Reproduction

Psychosocial

adaptation

Functional

outputs

Functional relationships of body systems


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Human body interacts with the externalenvironment through contact systems

Examples:

Respiratory system with atmospheric air

Digestive system with food and drink

Skin with the external temperature

Sensory organs with smell , taste or sounds


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Homeostasis

The maintenance of a stable

milieu interieur

Claude Bernard (1813 - 1878)


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General

Organizationof the Circulatory

System


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Exchange Between the Capillaries

and Interstitial Fluid


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Internal environment and homeostasisThe cells of the body live in a fluid environmentwhich is tissue fluid (interstitial fluid) whichrepresents the internal environment

The functions of all the organ systems of thebody is to ensure that the physical andchemical characteristics of the tissue fluid

remain constant


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Exchange Between the Capillaries

and Interstitial Fluid


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Homeostasis refers to the constancy or steadystate of the internal environment

Homeostatic mechanisms refer to all the automaticphysiological processes which occur in responseto changes in the external or internalenvironments and which tend to correct alldeviations from the normal

Physiological processes called homeostatic

mechanisms precisely regulate the temperature,pH and the concentration of chemicalcomponents of the internal environment


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The body fluids

Cell water = 25 litersInterstitial

fluid = 12 liters

Intravascular fluid = 3

litersCellwall

Total Body water = 40 liters

Intracellular fluid = 25 liters Extracellular fluid = 15 liters


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Transport across the cell membrane


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barrier to water and water-soluble substances

ions glucoseH

2O

urea

Lipid Bilayer:

CO2

O2N2

halothane


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Cell Membrane

ions

glucose

H2O

urea

but, other molecules still get across!

CO2

O2N2

halothane


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Molecular Gradients

Na+

K+

Mg

2+

Ca2+

H+

HCO3-

Cl-

SO42-

PO3-

protein

inside

(in mM)

14

140

0.510-4

(pH 7.2)

10

5-15

2

75

40

outside

(in mM)

142

4

1-21-2

(pH 7.4)

28

110

1

4

5


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provide specificity to a

membrane

provide function

K+

ion channels carrier proteins

Proteins:


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Diffusion Active Transport

occurs down a concn.gradient

no mediator or involves

a channel or carrier

no additional energy

occurs against a concn.

gradient

involves a carrier

requires ENERGY


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(a) lipid-soluble molecules move readily across the membrane

(rate depends on lipid solubility)

(b) water-soluble molecules cross via channels or pores

(a) (b)

Simple Diffusion


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un-gated

determined by size, shape, distribution of charge, etc.

Characteristics:

Na+

in

outNa+ and other ions

gated

voltage (e.g. voltage-dependent Na+

channels) chemically (e.g. nicotinic ACh receptor channels)

Ion Channels


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Rate of diffusion is limited by

Vmax of the carrier

protein the density of carrier

proteins in the membrane

(i.e., number per unit area)

Facilitated Diffusion

(also called carrier mediated diffusion)


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Factors that affectthe net rate of diffusion:

1. Concentration difference (Co-Ci)

net diffusion (Co-Ci)


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Osmosis:-Net diffusion of water -

Osmosis occurs from pure water toward a water/salt solution. Water moves down

its concn gradient.


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Active Transport

Primary Active Transport

molecules are pumped against a concentration

gradient at the expense of energy (ATP)

direct use of energy

Secondary Active Transport transport is driven by the energy stored in the

concentration gradient of another molecule (Na+)

indirect use of energy


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Primary Active Transport

carrier protein located on the plasma membrane of

all cells

plays an important role in regulating osmotic balance

by maintaining Na+ and K+ balance (inhibition by

ouabain causes cells to swell and burst!)

requires one to two thirds of cells energy!

1. Na+/K+ ATPase


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subunit 100,000 MW

binds ATP, 3 Na+, and 2 K+

subunit 55,000 MW function ???

Transport is electrogenic but contributes

less than 10% to the membrane potential

Figure 4-11; Guyton & Hall


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Secondary Active Transport

1. Co-transport (co-porters): substance is transported

in the same direction as the driver ion (Na+)

Examples:

inside

outside

Na+ AA Na+ gluc 2 HCO3-Na+


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2. Counter-transport (anti-porters): substance istransported in the opposite direction as the driver ion (Na+)

Examples:

Na+

Ca2+

Na+

H+ Cl-/H+

Na+/HCO3-

outside

inside

introduction_to_physiology slides of doctor mustafa shehabat

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