Transcript dd1236da5f12106

A warm welcome for my young
doctors.
OBJECTIVES OF THE INTRODUCTORY COURSE
Functional organization of the human body.
Homeostasis.
Describe the divisions of body fluids into intracellular, extracellular and
intravascular compartments.
Describe the structure of the cell membrane.
Processes of transport across membranes.
Resting Membrane Potentials
Action Potentials
Neuromuscular Transmission and Muscle Contraction.
Skeletal muscles, properties
Smooth Muscle, Special Properties
Describe the general organization of the autonomic nervous system
Homeostatic Control Systems
and cell membrane
By Dr. Nazish
OBJECTIVES
1.
Functional organization of the human body.
2. Homeostasis
3. Physiological control systems, negative feedback,
positive feed back and feed forward mechanisms.
Maintenance of constant internal
environment is called as
homeostasis.
ICF
Interstitial fluid Plasma
11.2 liters
2.8 liters
ECF
33% (14 liters)
Factors homeostatically maintained
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Concentration of nutrient molecules.
Concentration of oxygen and carbon dioxide.
Concentration of waste products.
Concentration of water salts and electrolytes.
Volume and pressure
Temperature.
Contribution of the body systems to
homeostasis
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Circulatory system
Digestive system
Respiratory system
Urinary system
Skeletal system
Integumantory system
Nervous system
Immune system
Endocrine system
Reproductive system
• Extrinsic control system
• Intrinsic control system
Negative feedback opposes an initial
change.
The commonest control system.
It maintains homeostasis.
• Components are:
• Sensor: monitors the magnitude of a controlled
variable.
• Control center compares a sensor’s input with a
set point. (Comparator)
• The effector makes a response to produce a
desired effect.
Amna was performing tawaf in the month of June when she
started feeling very hot because of increased body
temperature.
But after a lapse of few minutes she sweated profusely and
started feeling better.
(detected by)
Deviation in
controlled variable relieves
Sensor
Negative
feedback
Integrator
(sends instructions to)
Negative feedback to
shut off the system
responsible for the
response
Effector(s)
Compensatory response
Controlled variable
restored to normal
Fall in
temperature
below set point
Fall in the
temperature below
set point
Negative
Temperature
feedback
relieves
Negative feedback
mechanism
monitoring
nerve cells
Temperature
control center
Increased heat production
Through shivering and other means
Amna was performing tawaf in the month of June when she
started feeling very hot because of increased body
temperature.
But after a lapse of few minutes she sweated profusely and
started feeling better.
Which mechanism helped in bringing amna’s
body temperature back to normal.
Fall in Blood
Pressure
below set point
Pressure
monitoring
nerve cells
Negative
feedback
Cardiovascular
control centers
relieves
Negative feedback to
shut off the system
responsible for the
response
Heart and
blood
vessels
Increase in Blood
Pressure to normal
A 25 years old full term pregnant lady started having labour
pains, she was taken to the gynecologist, after being
examined she was admitted to the labour room.
Intensity and severity of the labour pains kept on
increasing, resulting in the dilatation of cervix.
Cervix was dilated fully after strong labour pains of three
hours.
Finally she gave birth to a baby girl after a very strong
uterine contraction
Positive feedback amplifies an
initial change.
An output is enhanced.
A controlled variable moves in the direction of an
initial change.
Moves the controlled factor away from a steady
state
Less frequent
Examples:
1. During the birth of a baby.
2. Depolarization beyond threshold during an
action potential
Positive feedback
Initial
stimulus
Response
+
Positive feedback
cycle
↑ stimulus
Outside factor
required to shut off
+ feedback cycle
stimulus
A 25 years old full term pregnant lady started having labour
pains, she was taken to the gynecologist, after being
examined she was admitted to the labour room.
Intensity and severity of the labour pains kept on
increasing, resulting in the dilatation of cervix.
Cervix was dilated fully after strong labour pains of three
hours.
Finally she gave birth to a baby girl after a very strong
uterine contraction.
Which mechanism is responsible for causing increased
intensity and frequency of labour pains?
Feed-forward control
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Allows the body to anticipate change and
maintain stability
• Examples:
1. Watering of mouth (Salivation) as a result of
sight, smell or thought of food
2. Rise in respiration before exercise
3. Increased secretion of Insulin as a result of
presence of food in digestive tract avoids
excessive rise of glucose in blood after meal
Disruption in homeostasis can lead
to illness and death.
Pathophysiology is the abnormal
functioning of the body during
disease.
• Negative feedback: a change in a controlled
variable triggers a response that opposes the
Summary
change – driving the variable in opposite
direction of the initial change.
• Positive feedback: a change in a controlled
variable triggers a response that reinforces the
change – driving the variable in the same
direction as of the initial change.
• Feed forward: brings about a response in
anticipation of a change in regulated variable
Smile is the best gift
which costs nothing
and you can give it to every one.
So keep smiling
Because Allah loves you
THANK YOU
and
Have a nice day