MEMBRANE PERMEABILITY (L1)

Download Report

Transcript MEMBRANE PERMEABILITY (L1)

Introduction to
Human Physiology
Abdul Aleem Khan
1
2
WHAT IT “IS” HOW IT “WORKS”
3
A branch of science that deals
with the functioning of Human
body
How does the heart beat ?
How do we breathe ?
How do we see ?
How do we remember ?
How do we move ?
How do we reproduce?
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)
6
Atoms
Molecules
Organelles
Cells
Tissues
Organs
Systems
Organism
7
8
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)

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 cells
Three different types of muscle cells
Fat Storage cells
Nerve cells that transmit electrical
impulses
Cells for reproduction

11
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.”
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
14
15
• 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
Body Water
Intracellular fluid
(inside cells)
Extracellular fluid
(outside cells)
Plasma
(inside
blood vessels)
Interstitial Fluid
(outside
blood vessels)
16
Major Elements % body wt
Oxygen
65%
Carbon
18%
Water
Hydrogen
10%
Nitrogen
3.4%
= 60% adult male
Mineral Elements
= 50% adult female
Sodium
0.17%
0.28%
Principal organic constituents Potassium
Chloride
0.16%
Calcium
1.5%
• carbohydrates  sugars
Magnesium
0.05%
• fats  fatty acids
Phosphorus
1.2%
• proteins  amino acids
0.25%
• nucleic acids  nuclotides Sulphur
Trace Elements
Iron
0.007%
Zinc
0.002%
17
Nutrients and
oxygen are
distributed by the
blood
Metabolic wastes
are eliminated by
the urinary and
respiratory
systems
18
19
Maintenance of constancy of the
Internal Environment
Walter Cannon
(1929)
20
Open Loop Systems
Control center
Effector
Controlled
variable
Closed Loop Systems
(Feedback Systems)
Control center
(Set point)
Effector
Controlled
variable
Sensor
1.
Feedback Systems are of two types:
21
Negative feedback 2.
Positive feedback
Maintenance of constancy of the
Internal Environment
22
23
• 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.
24
Negative feedback loop requires
Sensor (Detector): specific to variable needing to be controlled
Comparator (Control system): reference point for sensor to
compare against
Effector: if sensor  comparator  Error Signal  restore
variable to desired level
Disturbance
Comparator
(reference point)
Error
signal
Effector
Controlled
variable
Sensor
25
 Homeostatic range -oscillation around setpoint
 Change in setpoint
1.
Acclimatization
2.
Biorhythms26
The response
reverses
the original stimulus.
Example:Blood
pressure and
blood glucose
regulation
The response
enhances
the original stimulus
Example child birth
27
Composed of
1.Detector
2.Control system
3.Effector
The effector
response
Decreases or
increases
the effect of the
original
stimulus
28
Stimulus: change
in BP
Receptors:
Baroreceptors
Control Center:
Brain
Effector: Heart
29
30
31
32
•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
33
•Negative feedback - error signal 
reduces deviation from reference point
•Positive feedback - error signal 
increases deviation from reference point
(vicious circle)
Error
signal +
disturbance
+
controlled
variable
effector
sensor
34
Stimulus: stretch
of the uterus
Receptors:
stretch receptors
(cervix)
Control Center:
Brain
Effector: Uterus
35
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.
37