"The noblest pleasure is
the joy of understanding."
- Leonardo Da Vinci
Animal Physiology
Dr. Rai Khalid Farooq
farooq@asab.nust.edu.pk
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Physiology
Physiology from Ancient Greek (physis), meaning "nature, origin", and (-logia), meaning
"study of” is the scientific study of normal function in living systems
Physiology is the study of mechanical, physical and biochemical properties of living
organisms, it incorporates a significant amount of anatomy, the science of body structure
and their inter-relationship
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A sub-discipline of biology, its focus is in how organisms, organ systems, organs, cells,
and bio-molecules carry out the chemical or physical functions that exist in a living system
Animal physiology (including that of human)
Plant physiology
Cellular physiology
Microbial physiology (see microbial metabolism)
Bacterial and viral physiology
Nobel Prize in Physiology or Medicine is awarded to those who make significant
achievements in this discipline since 1901 by the Royal Swedish Academy of Sciences
In medicine, a physiologic state is one occurring from normal body function, rather than
pathologically.
Dilemma of form & function
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Levels of organization of human body
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Chemical and Molecular Level
Other Elements:
Hydrogen
62%
Oxygen
26%
Carbon
10%
Nitrogen
1.5%
Calcium
Phosphorus
Potassium
Sodium
Sulfur
Chlorine
Magnesium
Iron
Iodine
Trace elements
0.2%
0.2%
0.06%
0.06%
0.05%
0.04%
0.03%
0.0005%
0.0000003%
(see caption)
Water
67%
Proteins
Lipids 20%
10%
Carbohydrates 3%
Molecular composition
of the human body
Elemental composition
of the human body
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Levels of Organization: Cellular
• Basic units of
structure and function
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Levels of Organization: Tissue
Epithelial tissue
Connective tissue
Muscle tissue
Nervous tissue
• Cells with similar
functions grouped into
the 4 primary tissues
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Skin—The Largest Organ
• Outer layer of protective cornified epidermis
• Next layer the dermis contains connective tissue, glands, blood
vessels (BVs), nerves
• Inner layer the hypodermis contains adipose tissue, BVs, nerves
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Stem Cells
• Most cells in organs are highly specialized or differentiated
• Many organs retain small populations of adult stem cells
– less differentiated so can become many cell types
Example: bone marrow stem cells can give rise to all of the different
blood cell types
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Body-Fluid Compartments
• Our body has both intracellular and extracellular
compartments:
Intracellular - inside cells (cytoplasm)
Extracellular - outside cells (blood plasma, interstitial fluid)
• Compartments separated by the cell’s plasma membrane
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Origin of Nutrients in the Extracellular fluid
• Respiratory system
– O2
Gastrointestinal tract
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Carbohydrates
Fatty acids
Amino acids
Others
Liver& other organs
– Substances into useable forms
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Origin of Nutrients in the Extracellular fluid
• Musculoskeletal system
Removal of Metabolic End–products.
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CO2 (by lung)
Urea, uric acid, excess water and ions
(kidneys)
others
Regulation of body functions.
• Nervous system
– Sensory input portion
– CNS
– Motor output portion
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Origin of Nutrients in the Extracellular fluid
• Hormonal system
• Reproductive system
Automaticity of body
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100 Trillion of Cells
Organs
Internal environment
Homeostasis
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Levels of Organization: Organ System
Organism
Level
Organ System Level
Skeletal
Muscular
Nervous
Endocrine
Cardiovascular
Lymphoid
Respiratory
Digestive
Urinary
Integumentary
Reproductive
The heart
Organ
Level
Cardiac
muscle
tissue
Atoms in
combination
Tissue Level
Heart muscle cell
Complex protein
molecules
Protein filaments
Chemical or
Molecular Levels
Cellular Level
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Levels of Organization: Organ System
Organism
Level
Organ System Level
Endocrine
Nervous
Muscular
Skeletal
Integumentary
Cardiovascular
Lymphoid
Respiratory
Digestive
Urinary
Reproductive
• Organs located in different regions of the body that perform
related functions are grouped into systems
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Organismal Level
Atoms
Organelle
Molecule
Smooth muscle cell
2 Cellular level
Cells are made up
of molecules.
1 Chemical level
Atoms combine to
form molecules.
Cardiovascular
system
Heart
Blood
vessels
Blood vessel
(organ)
Smooth muscle tissue
3 Tissue level
Tissues consist of
similar types of cells
Smooth muscle tissue
Connective tissue
Epithelial
tissue
4 Organ level
Organs are made up of
different types of tissues.
6 Organismal level
The human organism
is made up of many
organ systems.
5 Organ system level
Organ systems consist of
different organs that work
together closely.
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Cellular functions
Water
Protoplasm
Proteins
Ions
Lipids
Carbs
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Cell membrane
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Transport of ions & molecules through
the cell membrane
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Chemical composition of extracellular
&intracellular fluid
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Movements Into & Out of the Cell
Passive (Physical)
Require no cellular
energy
Active (Physiological)
Require cellular energy
• Active transport
• Simple diffusion
• Endocytosis
• Facilitated diffusion
• Exocytosis
• Osmosis
• Transcytosis
• Filtration
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Simple Diffusion
• Movement of substances from regions of higher concentration
to regions of lower concentration
• Oxygen, carbon dioxide and lipid-soluble substances
Solute molecule
Permeable
membrane
A
B
(1)
Water molecule
A
B
(2)
Time
A
B
(3)
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Facilitated Diffusion
•Diffusion across a membrane with the help of a channel or carrier
molecule
• Glucose and amino acids
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Osmosis and Osmotic Pressure
Osmotic Pressure – ability of osmosis to generate enough
pressure to move a volume of water
Osmotic pressure increases as the concentration
of nonpermeable solutes increases
(a)
• Isotonic – same osmotic pressure
(b)
• Hypertonic – higher osmotic pressure (water
loss)
• Hypotonic – lower osmotic pressure (water
gain)
(c)
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Filtration
• Smaller molecules are forced through porous membranes
• Hydrostatic pressure important in the body
• Molecules leaving blood capillaries
Capillary wall
Blood
pressure
Tissue fluid
Blood
flow
Larger molecules
Smaller molecules
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Active Transport
• Carrier molecules transport substances across a membrane
from regions of lower concentration to regions of higher
concentration
• Sugars, amino acids, sodium ions, potassium ions, etc.
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Active Transport: SodiumPotassium Pump
•Active transport mechanism
• Creates balance by “pumping” three (3) sodium (Na+) OUT and
two (2) potassium (K+) into the cell
• 3:2 ratio
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Secondary Active Transport
• Uses the energy stored in a concentration gradient
– the gradient is established through active transport
• Symporters move substances in the same direction while
• Antiporters move substances in opposite directions
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Endocytosis
• Cell engulfs a substance by forming a vesicle around the
substance
• Pinocytosis – substance is mostly water
• Phagocytosis – substance is a solid
• Receptor-mediated endocytosis – requires the substance to
bind to a membrane-bound receptor
Particle
Phagocytized
particle
V
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Exocytosis
• Reverse of endocytosis
• Substances in a vesicle fuse with cell membrane
• Contents released outside the cell
• Release of neurotransmitters from nerve cells
Endoplasmic
reticulum
Golgi
apparatus
Nucleus
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Transcytosis
• Endocytosis followed by exocytosis
• Transports a substance rapidly through a cell
• HIV crossing a cell layer
HIV-infected
white blood cells
Anal or
vaginal canal
Viruses bud
HIV
Receptor-mediated endocytosis
Lining of anus
or vagina
(epithelial cells)
Cell
membrane
Exocytosis
Receptor-mediated
endocytosis
Virus infects
white blood cells on
other side of lining
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Basics of anatomical
terminology
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