Download Introduction to Human Physiology

Introduction to Human
Physiology
What is physiology?
It is the science that deals with the function
of organs and systems and the way they do
this functions and the way they integrate.
Exams and marks
250 marks:
125 final exam
45 practical
30 oral
40 midterm
10 shock exam
Man and the environment
External environment:
(variable surroundings)
The environment man lives in,
interacts with (benefits and
hazards)
Major environmental factors are:
oxygen, water, food, physical
factors, social factors, micro
organisms and parasites.
Body-Fluid Compartments
H20:
60% of TB.Wt. in adult male. 75% of TB.Wt in infants
Less than 60% in adult female and obese people
TBW is disributed as:
Intracellular compartment (ICF)
Extracellular compartment (ECF)
Fluid inside the cells
Fluid outside the cells
2/3 of TBW.
1/3 of TBW
40% of TB.Wt
20% of TB.Wt
2 Subdivisions:
Blood plasma IVF (5%)
Interstitial fluid ISF (15%)
Body water
Interstitial
fluid=15%
Stomach& intestine
Cell water= 40%
Intravascular fluid=5%
lungs
Capillary wall
Kidneys &skin
 The concentration of the minerals in the
intracellular fluid is different from the
concentration of them in the extra cellular
fluid.
 The total blood volume is 8% of TBWt
Intracellular fluid
Extra cellular fluid
ICF
Plasma
ISF
Na
K
10
155
145
4.5
150
4.0
Ca
Mg
0.001
13
2.5
1
1.5
1
Cl
HCO3
3
10
115
28
110
27
HPO3
Glucose
50
1
1
4-6
1
4-6
Proteins ratio
4
1
O-1
Osmolality Osmol/L
300
300
300
CATIONS mmol/L
ANIONS mmol/L
Determination of the volumes of water in the body
Fick`s principle
Indicator: inert, non toxic, not utilized by tissues.
 Known amount of indicator is injected intravenously
9gm
 Time is allowed for uniform diffusion
 A sample is withdrawn to determine the concentration
in the plasma 3gm/L
Volume of the compartment (volume of the distribution)
= amount injected / concentration in plasma
9 gm/3gm/L= 3L
Application:
1- TBW:
Heavy water (D2O) deuterium oxide
2- ECF:
Inulin (polysaccharide fiber) or Na thiocyanate
(NaSCN)
3- Plasma:
Evan`s blue or radioactive plasma proteins
4- ICF: TBW- ECF
5-ISF: ECF-Plasma volume
Homeostasis
The internal environment is the
interstitial fluid that surrounds the
cells
The internal environment
The human body consists of
organs& tissues that are formed of
cells.
The cell is the smallest unit of life.
The cell is surrounded by interstitial
fluid (Internal Environment).
The composition of the internal
environment should remain
constant within narrow limits.
Internal environment
All the life processes have only one
goal, that is to keep the internal
environment constant, and this fixity
of the internal environment is
necessary condition for life
Homeostasis:
 It is all the physiological processes that are
carried out by all body systems.
 It is to insure that chemical and physical
structure of the internal environment is kept
constant in spite of external (e.g.: temp,
oxygen tension, pressure) or internal
(e.g.: increased muscular activity) changes.
 It deals with all automatic reactions which
take place to correct all deviations from
normal
 It is a necessary condition for the existence
 Failure of homeostasis often leads to
diseases and death.
Body water
Interstitial
fluid=15%
Stomach& intestine
Cell water= 40%
Intravascular fluid=5%
lungs
Capillary wall
Kidneys &skin
Cell membrane
ICF
ISF
plasma
organs
internal environment
external
environment
Exchange and communication are key concepts
for understanding physiological homeostasis.
Homeostasis: The body’s ability to maintain a stable internal environment.
Toxic
Chemicals
Trauma
Viruses
Bacteria
Cancer
Autoimmune
Disease
Sickle cell anemia
Diabetes
Example for homeostasis
Cells consumes glucose & O2
Cells takes glucose & O2 from ISF
(1st exchange through cell membrane)
ISF takes these substances from
blood
(2nd exchange through capillary wall)
Blood brings new nutrients & O2
from systems from external
environment
Cell
 Unit of function of living organism
 Cells with similar properties….… tissue.
 Different tissues……organs.
 Complementary organs…..systems
 The structure of the cell varies according
to the function (specialization)
 No typical cell
 All cells are formed of mass of
protoplasm surrounded by cell
membrane
The Cell Membrane
*Very thin (7.5-10 nm) *Elastic *Semipermeable
* Dynamic * EM: lipid bilayer & proteins *Made of
proteins 55%, phospholipids 25%, cholesterol
13%, other lipids 4% &CHO 3%,
*amphipathic (hydrophilic & hydrophobic)
Phospholipids
Flexibility & selective permeability
Fatty acid tails
– hydrophobic
Phosphate
Phosphate group head
– hydrophilic
Arranged as a bilayer
Fatty acid
Phospholipid bilayer
polar
hydrophilic
heads
nonpolar
hydrophobic
tails
polar
hydrophilic
heads
 Protein:
*Hydrophilic & hydrophobic
*Integral & peripheral
 Cholesterol: permeability & toughness
 CHO: recognition sites & attach cells
Glycoprotein
Glycolipid
together
Cholesterol
Peripheral
protein
Functions of membrane proteins
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1- structural ptns
2- passive channels: ungated & gated(voltage / ligand)
3- carriers for facilitated diffusion
4- carriers for active transport (uniport /symport/ antiport)
5- receptors: number & sensitivity change
6- enzymes
7- identity ptns
8-intercellular connections: a. binding j: tight & desmosomes
b. gap j
 9- cell adhesion molecules
 10- fixation of cytoskeleton
Many Functions of Membrane Proteins
Outside
Plasma
membrane
Inside
Transporter
Enzyme
activity
Cell surface
receptor
Cell surface
identity marker
Cell adhesion
Attachment to the
cytoskeleton
Intercellular connections
binding and channel junctions
Gap junctions: for rapid propagation of electrical activity
allow rapid passage of ions and molecules up to MW1000
diameter is regulated by Ca, pH, hormones and drugs
Membrane carbohydrates
Play a key role in cell-cell recognition
– ability of a cell to distinguish one cell
from another
• antigens
– important in organ &
tissue development
– basis for rejection of
foreign cells by
immune system
Movement across the
Cell Membrane
2007-2008
Diffusion
 All molecules are in constant motion
Diffusion:
Passive movement from high  low concentration
Diffusion across cell membrane
 1- simple diffusion:
with concentration gradient- no energy- no carrier
Diffusion rate α con gradient x surface area x temp /√mol wt x distance
1- through lipid bilayer:
Lipid soluble sub
Water
Lipid insoluble sub (urea)
2- through protein channels:
Ions electrically charged
hydrated
Each protein channel is specific through diameter, shape, electrical
charge & gates
Selective permeability
gating
 2- facilitated diffusion:
with conc. gradient, passive, carrier for large molecules
Characters: Specificity competition rate increases with concentration
gradient up to maximum more sensitive to temperature
AS Biology, Cell membranes and
Transport
34
Facilitated Diffusion
 Diffusion through protein channels
– channels move specific molecules across
cell membrane
facilitated = with help
– no energy needed
open channel = fast transport
high
low
Osmosis is diffusion of water
Diffusion of water from
high concentration of water to
low concentration of water
– across a
semi-permeable
membrane
– The pressure necessary to stop solvent mol movements=
osmotic pressure
– The numbers of particles per unit volume of fluid
– Measured in mmHg
– Osmole osmolarity osmolality
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The osmolarity of ICF=that ECF=300 mosmol
280 mosmol is due to Na, Cl & HCO3
20 mosmol is due to protein
Tonicity: is the osmolality of a solution relative to
the plasma
 Plasma proteins of blood is called oncotic
pressure. It is important for capillary circulation
&regulation of ECF
Concentration of water
Direction of osmosis is determined
by comparing total solute
concentrations
– Hypertonic - more solute, less water
– Hypotonic - less solute, more water
– Isotonic - equal solute, equal water
water
hypotonic
hypertonic
net movement of water
Donnan effect
The protein anions inside the cells
are non diffusible hinder the
diffusion of diffusible cations
More osmotically active particles
inside the cell
The cell tends to swell
But the Na+/ K+ pump prevents cell
rupture
Donnan effect
4K+
4Cl-
4K+
2Cl- & 2 Ptn-
3Cl3K+
3Cl-& 2Ptn5K+
3. Gibbs-Donnan Equilibrium - YouTube.flv
Active Transport
 Against concentration gradient
 Needs carrier protein
 Energy is needed
low
conformational change
ATP
high
“The Doorman”
Active transport
Many models & mechanisms
ATP
ATP
antiport
symport
Active transport
 1ry active:
*eg Na+/K+ pump
*α &β subunits
*α subunit contains 2 binding sites for K+ on the outside
& 3 binding sites for Na+ on the inside & an ATP
binding site
*β subunit has ATPase activity.
 2ry active:
*eg Glucose transport 2ry to active transport of Na
1st Na pumped out ….creates concentration gradient…
Na & glucose bind a carrier…transports them to inside
Figure 5.13 Primary Active Transport: The Sodium–Potassium Pump
In active transport, energy is used to move a solute against its concentration gradient.
For each molecule of ATP used, 2 K+ are pumped into the cell and 3 Na+ are pumped
out of the cell.
K+
Outside of cell
Sodium–
potassium
pump
Inside of cell
Na+
Getting through cell membrane
 Passive Transport
Simple diffusion
 diffusion of nonpolar, hydrophobic molecules
 lipids
 high  low concentration gradient
Facilitated transport
 diffusion of polar, hydrophilic molecules
 through a protein carrier
 high  low concentration gradient
 Active transport
 diffusion against concentration gradient
 low  high
 uses a protein pump
 requires ATP
 Vesicular transport
ATP
Transport summary
simple
diffusion
facilitated
diffusion
active
transport
ATP
How about large molecules?
Moving large molecules into & out of
cell
– through vesicles & vacuoles
– endocytosis
• phagocytosis = “cellular eating”
• pinocytosis = “cellular drinking”
– exocytosis
exocytosis
Endocytosis
phagocytosis
fuse with
lysosome for
digestion
pinocytosis
non-specific
process
receptor-mediated
endocytosis
triggered by
molecular
signal
Exocytosis
The opposite of endocytosis is exocytosis. Large molecules that are
manufactured in the cell are released through the cell membrane.
AS Biology, Cell membranes and
Transport
53
These are carrier proteins. They do not extend through the membrane.
They bond and drag molecules through the bilipid layer and release
them on the opposite side.
AS Biology, Cell membranes and
Transport
54
Vesicle-mediated transport
Vesicles and vacuoles that fuse with the cell membrane may be utilized
to release or transport chemicals out of the cell or to allow them to enter
a cell. Exocytosis is the term applied when transport is out of the cell.
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Cell Membrane - Function - Endocytosis
The cell membrane can also engulf structures that are much too large to fit through the
pores in the membrane proteins this process is known as endocytosis. In this process the
membrane itself wraps around the particle and pinches off a vesicle inside the cell. In this
animation an ameba engulfs a food particle.
56
Clatherin mediated endocytosis
Endocytosis and Exocytosis
Endocytosis
Any Questions??
Quiz
 i. Explain the transport function of the plasma membrane protein
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ii. 1- Glucose transport into the intestinal cells can be increased by:
a. increase temperature
b. increase galactose concentration
c. increase concentration gradient for glucose without limits
d. increase the thickness of the cell membrane
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2- Concerning the body water compartments:
a. the intravascular compartment is the largest compartment
b. the interstitial fluid is the internal environment
c. Ca2+ is the main cation intracellularly
d. protein is more in the interstitial fluid than in the plasma
 3- Inulin is used for direct measuring the volume of:
 a. ECF b. IVF
c. total body water d. plasma volume
Endocytosis and Exocytosis
Receptor Proteins
These proteins are used in intercellular communication. In this animation you can
see the a hormone binding to the receptor. This causes the receptor protein release a
signal to perform some action.
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Intracellular communications
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A] 3 main types of communication:
1- intercellular gap junctions
2- neural neurotransmitters
3- endocrine communication, paracrine, autocrine
B] messengers bind receptors
C] intracellular effects through:
1- opening channels
2- activation of adenyl cyclase
3- increase free intracellular Ca2+
Intercellular communications
Gap Junctions
Synaptic
Paracrine &
Autocrine
Directly from
cell to cell
Across
synaptic cleft
By diffusion in
interstitial fluid
By circulating
body fluids
Local
Local
Local diffusion
Systemic
Endocrine
Regulating systems
 1- endocrine system: slow prolonged effect
 2- nervous system: rapid short effect
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The neuron
The basic structural unit of the nervous system.
Structure:
The soma
The dendrites: antenna like processes
The axon: hillock, terminal buttons
Types of nerve fibers
a- myelinated nerve fiber:
 Covered by myelin sheath
b- unmyelinated nerve fiber:
 Myelin sheath is absent
Synapses:
 it is the site where the axon of one neuron ends &
the dendrites of another begins
 There is space called synaptic cleft
 Chemical transmitters are released
at synapses