Introduction to Human Physiology
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Transcript of Introduction to Human Physiology
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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.
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Exams and marks
250 marks:125 final exam45 practical30 oral40 midterm10 shock exam
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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.
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Body-Fluid CompartmentsH20:60% 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%)
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Body water
Cell water= 40% Interstitial fluid=15%
In
tra
vasc
ula
r flu
id=
5%
Capillary wall
Sto
mac
h& in
test
ine
lungs
Kidneys &skin
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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
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Intracellular fluid Extra cellular fluid
ICF Plasma ISF CATIONS mmol/L
Na 10 145 150
K 155 4.5 4.0
Ca 0.001 2.5 1.5
Mg 13 1 1ANIONS mmol/L
Cl 3 115 110
HCO3 10 28 27
HPO3 50 1 1
Glucose 1 4-6 4-6
Proteins ratio 4 1 O-1
Osmolality Osmol/L 300 300 300
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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
9gmTime is allowed for uniform diffusionA sample is withdrawn to determine the concentration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
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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
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Homeostasis
The internal environment is the interstitial fluid that surrounds the cells
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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.
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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
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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 existenceFailure of homeostasis often leads to
diseases and death.
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Body water
Cell water= 40% Interstitial fluid=15%
In
tra
vasc
ula
r flu
id=
5%
Capillary wall
Sto
mac
h& in
test
ine
lungs
Kidneys &skin
Cell membrane
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Exchange and communication are key conceptsfor understanding physiological homeostasis.
ICF ISF plasma organs
external environment
internal environment
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Toxic Chemicals
TraumaViruses
Bacteria
CancerAutoimmune
DiseaseSickle cell anemia
Diabetes
Homeostasis: The body’s ability to maintain a stable internal environment.
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Example for homeostasis
Cells consumes glucose & O2Cells 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
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CellUnit of function of living organismCells with similar properties….… tissue.Different tissues……organs.Complementary organs…..systemsThe structure of the cell varies according
to the function (specialization)No typical cellAll cells are formed of mass of
protoplasm surrounded by cell membrane
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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)
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Phospholipids
Fatty acid
Phosphate
Flexibility & selective permeability
Fatty acid tails– hydrophobic
Phosphate group head – hydrophilic
Arranged as a bilayer
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Phospholipid bilayer
polarhydrophilicheads
nonpolarhydrophobictails
polarhydrophilicheads
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Protein:
*Hydrophilic & hydrophobic
*Integral & peripheralCholesterol: permeability & toughness CHO: recognition sites & attach cells
togetherGlycoprotein Glycolipid
Peripheralprotein
Cholesterol
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Functions of membrane proteins 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
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Many Functions of Membrane Proteins
Outside
Plasmamembrane
InsideTransporter Cell surface
receptorEnzymeactivity
Cell surface identity marker
Attachment to thecytoskeleton
Cell adhesion
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Intercellular connectionsbinding and channel junctions
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Gap junctions: for rapid propagation of electrical activityallow rapid passage of ions and molecules up to MW1000 diameter is regulated by Ca, pH, hormones and drugs
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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
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2007-2008
Movement across the Cell Membrane
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DiffusionAll molecules are in constant motion
Diffusion: Passive movement from high low concentration
Diffusion: Passive movement from high low concentration
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Diffusion across cell membrane 1- simple diffusion: with concentration gradient- no energy- no carrierDiffusion 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 moleculesCharacters: Specificity competition rate increases with concentration
gradient up to maximum more sensitive to temperature
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AS Biology, Cell membranes and Transport
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Facilitated Diffusion
Diffusion through protein channels– channels move specific molecules across
cell membrane– no energy needed
open channel = fast transport
facilitated = with help
high
low
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Osmosis is diffusion of waterDiffusion 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 mosmol280 mosmol is due to Na, Cl & HCO320 mosmol is due to proteinTonicity: is the osmolality of a solution relative to
the plasmaPlasma proteins of blood is called oncotic
pressure. It is important for capillary circulation ®ulation of ECF
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Concentration of waterDirection of osmosis is determined by
comparing total solute concentrations
– Hypertonic - more solute, less water
– Hypotonic - less solute, more water
– Isotonic - equal solute, equal water
hypotonic hypertonic
water
net movement of water
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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 swellBut the Na+/ K+ pump prevents cell
rupture
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Donnan effect4K+ 4K+
4Cl- 2Cl- & 2 Ptn-
3Cl- 3Cl-& 2Ptn-
3K+ 5K+
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3. Gibbs-Donnan Equilibrium - YouTube.flv
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Active Transport
“The Doorman”“The Doorman”
conformational change
Against concentration gradientNeeds carrier proteinEnergy is needed
ATP
low
high
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symportantiport
Active transportMany models & mechanisms
ATP ATP
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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
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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 pumpedout of the cell.
Outside of cell
Inside of cell
Na+
K+
Sodium–potassiumpump
Figure 5.13 Primary Active Transport: The Sodium–Potassium Pump
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Getting through cell membranePassive 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 transportdiffusion against concentration gradient
low highuses a protein pump requires ATP
Vesicular transport
ATP
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Transport summary
simplediffusion
facilitateddiffusion
activetransport
ATP
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How about large molecules?Moving large molecules into & out of
cell– through vesicles & vacuoles– endocytosis
• phagocytosis = “cellular eating”• pinocytosis = “cellular drinking”
– exocytosis
exocytosis
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Endocytosis
phagocytosis
pinocytosis
receptor-mediated endocytosis
fuse with lysosome for digestion
non-specificprocess
triggered bymolecular signal
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Exocytosis The opposite of endocytosis is exocytosis. Large molecules that are manufactured in the cell are released through the cell membrane.
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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.
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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.
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Clatherin mediated endocytosis
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Endocytosis and Exocytosis
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Endocytosis
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Any Questions??
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Quiz i. Explain the transport function of the plasma membrane protein 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
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
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Endocytosis and Exocytosis
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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
A] 3 main types of communication:1- intercellular gap junctions2- neural neurotransmitters3- endocrine communication, paracrine, autocrine B] messengers bind receptorsC] intracellular effects through:1- opening channels2- activation of adenyl cyclase3- increase free intracellular Ca2+
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Intercellular communications
Gap Junctions SynapticParacrine &
Autocrine Endocrine
Directly from cell to cell
Across synaptic cleft
By diffusion in interstitial fluid
By circulating body fluids
Local Local Local diffusion Systemic
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Regulating systems
1- endocrine system: slow prolonged effect2- nervous system: rapid short effect
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The neuronThe basic structural unit of the nervous system.Structure: The somaThe dendrites: antenna like processesThe axon: hillock, terminal buttons
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Types of nerve fibersa- 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 beginsThere is space called synaptic cleft Chemical transmitters are released
at synapses