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Introduction to Human Physiology Abdul Aleem Khan. Le Milieu Int é rieur And Homeostasis I and II. STRUCTURE. FUNCTION. WHAT IT “IS”. HOW IT “WORKS”. What is human Physiology. A branch of science that deals with the functioning of Human body How does the heart beat ? - PowerPoint PPT Presentation
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Introduction to Human Physiology
Abdul Aleem Khan
1
Le Milieu Intérieur And
Homeostasis I and II
2
WHAT IT “IS”
HOW IT “WORKS”
3
A branch of science that deals with the functioning
of Human bodyHow does the heart beat ?
How do we breathe ? How do we see ?
How do we remember ? How do we move ?
How do we reproduce?
What is human Physiology
4
To answer these global questions it is essential to understand that the functional unit of the body is
the cell.How cells (like muscle, nerve)
function? And how similar and dis-similar
types of cells work together at various organisational levels
(integration) as a whole organism
All most all life processes are governed by laws of physics and
chemistry 5
• Integumentary Physiology (system) • Cardiovascular Physiology (system) • Respiratory Physiology (system) • Gastrointestinal Physiology (system) • Renal Physiology (system) • Reproductive Physiology (system) • Musculo-skeletal Physiology (system) • Neurophysiology Nervous system • Endocrine Physiology (system) • Immune Physiology (system)
Divisions of Physiology
6
Atoms
Molecules
Organelles
Cells
Tissues
Organs
SystemsOrganism
Various levels of structural organization
7
8
A Cell
9
The cell is the basic structural and functional unit of living organisms
The activity of an organism depends on both the individual and collective activity of its cells
The biochemical activities of cells are dictated by their specific subcellular structures (principle of complementarity)
Continuity of life has a cellular basis (cells come from cells)
Cell theory
10
There is really no “typical” cell. Cells have different shapes, different sizes, different functions, different life spans.
Stem cells is pluripotent. Examples of Specialized cells:
Many different types of blood cellsThree different types of muscle cellsFat Storage cellsNerve cells that transmit electrical impulsesCells for reproduction
Cell Diversity
11
Cells internal Environoment
12
“La fixité du milieu intérieur est la condition
de la vie libre.”
“The fixity of the internal environment is the condition for free
life.”
Claude Bernard
(1813-1878)
13
Claude Bernard in 1829 said: The proper functioning of the cells depends on
precise regulation of
the composition of their
surrounding fluid.
Surrounding fluid = Internal environment
= Le Milieu interier
Internal
Environment
14
Internal
Environment
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•Water is main solvent in living cells•Hydrophilic molecules dissolve in water•Hydrophobic molecules do not dissolve in
water•Amphiphilic - molecule part
hydrophilic/part hydrophobic
Intracellular fluid(inside cells)
Body Water
Plasma(inside
blood vessels)
Interstitial Fluid(outside
blood vessels)
Extracellular fluid(outside cells)
Body water
16
Major Elements % body wtOxygen 65%Carbon 18%Hydrogen 10%Nitrogen 3.4%Mineral ElementsSodium 0.17%Potassium 0.28%Chloride 0.16%Calcium 1.5%Magnesium 0.05%Phosphorus 1.2%Sulphur 0.25%Trace ElementsIron 0.007%Zinc 0.002%
Principal organic constituents
• carbohydrates sugars• fats fatty acids• proteins amino acids• nucleic acids nuclotides
Water = 60% adult male= 50% adult female
Chemical composition of body
17
Nutrients and oxygen are distributed by the blood
Metabolic wastes are eliminated by the urinary and respiratory systems
Organ system
Interrelationship
18
Co-ordination of Organ System
19
Walter Cannon(1929)
Homeostasis
Maintenance of constancy of the Internal Environment
20
Control Systems
Open Loop Systems
Closed Loop Systems (Feedback Systems)
Control center(Set point) Effector Controlled
variable
Sensor
Control center Effector Controlledvariable
Feedback Systems are of two types: 1. Negative feedback 2. Positive
feedback 21
Maintenance of constancy of the Internal Environment
Homeostasis
22
Physiological variables
maintained by controlled systems
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•Process of maintaining the composition of the internal body compartments within fairly strict limits (ion concentrations, pH, osmolarity, temperature etc).
•Require regulatory mechanisms to defend against changes in external environment and changes due to activity.
•Cellular homeostasis - intracellular fluid composition
•Organismal homeostasis - extracellular fluid composition.
•Control system designed to maintain level of given variable (concentration, temperature, pressure) within defined range following disturbance.
Homeostasis
24
Negative feedback loop requiresSensor (Detector): specific to variable needing to be controlledComparator (Control system): reference point for sensor to compare againstEffector: if sensor comparator Error Signal restore variable to desired level
Comparator(reference point) Effector Controlled
variable
Sensor
DisturbanceErrorsignal
Feedback loop
25
Homeostatic range -oscillation around setpoint
Change in setpoint1. Acclimatization 2. Biorhythms
Homeostasic
Setpoint
26
The response reverses
the original stimulus.
Example:Blood pressure and blood glucose
regulation
The response enhances
the original stimulus
Example child birth
Negative
feedback System
Negative feedback System
27
Maintenance of body
temperatureComposed of 1.Detector2.Control system3.Effector
The effector response Decreases or increases the effect of the original stimulus
28
Stimulus: change in BPReceptors:
BaroreceptorsControl
Center: BrainEffector: Heart
Negative feedback System
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Negative feedback System
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Negative feedback System
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Negative feedback System
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•Negative feedback control is initiated after variable is disturbed
•Amount of correction to be applied, is assessed by magnitude of error signal incomplete correction
•Overcorrection oscillations in controlled variable
•Disadvantages overcome by multiple regulatory mechanisms.
Regulation of blood [glucose]Insulin [glucose]blood
Glucagon [glucose]blood
Limitation of negative
feedback
33
•Negative feedback - error signal reduces deviation from reference point
•Positive feedback - error signal increases deviation from reference point (vicious circle)
controlledvariable
disturbance
effector
sensor
++Errorsignal
Positive
feedback
34
Stimulus: stretch of the
uterusReceptors:
stretch receptors (cervix)
Control Center: Brain
Effector: Uterus
Positive feedback System
35
Positive feedback
System
36
Homeostasis is the ability to maintain a relatively stable internal environment in an ever-changing outside world.
The internal environment of the body is in a dynamic state of equilibrium.
Concepts of homeostasis dynamic.Chemical, thermal, and neural
factors interact to maintain homeostasis.
Homeostasis
37