Animal Physiology

Dr. Kashif AsgharEmail: drkashifasghar@gmail.com

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Marks distribution

Total Marks:100• Sessional-I:15• Sessional-II:15• Final Exam:50• Practical Exam:10• Practical Notebook:10

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Pathophysiology: how physiological processes are altered in disease or injury

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Physiology

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How Organism function 5

Levels of organization of human body

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Molecular compositionof the human body

Water67%

Proteins20%

Carbohydrates 3%

Lipids10%

Elemental compositionof the human body

Hydrogen62%

Oxygen26%

Carbon10%

Nitrogen1.5%

Other Elements:

CalciumPhosphorusPotassiumSodiumSulfurChlorineMagnesiumIronIodineTrace elements

0.2%0.2%0.06%0.06%0.05%0.04%0.03%0.0005%0.0000003%(see caption)

Chemical and Molecular Level

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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 typesExample: 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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Organismal Level

Chemical levelAtoms combine to form molecules.

Cellular level Cells are made up of molecules.

Tissue levelTissues consist of similar types of cells

Organ levelOrgans are made up of different types of tissues.

Organ system level Organ systems consist of different organs that work together closely.

Organismal levelThe human organism is made up of many organ systems.

Cardiovascular system

OrganelleMoleculeAtomsSmooth muscle cell

Smooth muscle tissue

Connective tissue

Blood vessel(organ)

HeartBloodvessels

Epithelialtissue

Smooth muscle tissue

1 2

3

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• Arist (384 – 322 BCE) – speculated on body function

• Erasistratus (304 -~250 BCE) considered the father of physiology - applied physical laws to the study of human function

• Galen (130 -201 A.D.) - believed the working body was not understandable without knowledge of its structure

• William Harvey (1578–1657)-blood pumped in a closed system of vessels

• Claude Bernard (1813 – 1878) – internal environment remains constant despite everchanging external environment

• Walter Cannon (1871 – 1945) – coined the term ‘homeostasis’

History of Physiology

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Introduction to basic concepts of physiology

• Scientific Method

• Levels of Organization

• Homeostasis

- Feedback loops

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Homeostasis

• Our organ systems work together to maintain homeostasis despite constant challenges

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Homeostasis

• Maintenance of a state of dynamic constancy– internal conditions are stabilized above and below a physiological set

point by negative feedback loops

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Homeostasis and Negative Feedback Loops

All physiological parameters have a set point ‘X’• Sensor: Detects deviation from set point

• Integrating center: Determines response

• Effector: Produces response to re-establish X

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Homeostasis• Negative feedback loops – body temperature, blood sugar,

blood pressureExample: control of body temperature Set point: 37 °C

Sensor: Temperature receptorsIntegrating center: BrainEffector: sweat glands/muscles

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Control of blood glucose level (Insulin & Glucagon)

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Homeostasis: Negative FeedbackExample: control of blood sugarSet point: 5 mmol/LSensor: pancreatic cellsIntegration: Endocrine systemEffector: insulin and glucagon

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Homeostasis: Negative FeedbackExample: control of blood pressureSet point: normal blood pressure Sensor: barorecptorsIntegration Center: brainEffector: heart / arteries

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Homeostasis and Positive Feedback

• Does not maintain homeostasis and is rare

• Occurs when the body needs to amplify a process– Producing blood clots– Creates the LH surge that causes

ovulation– Between the uterus and oxytocin

secretion during childbirth

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Positive Feedback: Vicious circles & death

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Circulatory system

Extracellular fluid transport systemMovement of blood through circulatory systemMovement of fluid between blood capillaries and cells

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• Respiratory system– O2

Gastrointestinal tract– Carbohydrates– Fatty acids– Amino acids– Others

Liver& other organs– Substances into useable forms

Origin of Nutrients in the Extracellular fluid

0.4-2.0 µM

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• Musculoskeletal system

Removal of Metabolic End–products.• 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

Origin of Nutrients in the Extracellular fluid

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• Hormonal system• Reproductive system

100 Trillion of Cells Organs Internal environment Homeostasis

Origin of Nutrients in the Extracellular fluid

Automaticity of body

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Some important constituents and physical characteristics of the extracellular fluid

Normal value

Normal range Approximate nonlethal limits

Units

OxygenCarbon dioxideSodium ionPotassium ionCalcium ionChloride ionBicarbonate ionGlucoseBody temperatureAcid-base

40 40142

4.2 1.2108 28 8537.0 7.4

35-45 35-45138-146 3.8-5.0 1.0-1.4103-112 24-32 75-95

37.0 7.3-7.5

10-1000 5-80115-175 1.5-9.0 0.5-2.0 70-130 8-45

20-150018.3-43.3 6.9-8.0

mmHgmmHgmmol/Lmmol/Lmmol/Lmmol/Lmmol/Lmg/dl

C°pH

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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

• Simple diffusion

• Facilitated diffusion

• Osmosis

• Filtration

Active (Physiological)

Require cellular energy

• Active transport

• Endocytosis

• Exocytosis

• Transcytosis55

Simple Diffusion

• Movement of substances from regions of higher concentration to regions of lower concentration

• Oxygen, carbon dioxide and lipid-soluble substances

Time

Solute molecule

Water molecule

A B A B

(2) (3)

Permeablemembrane

A B

(1)56

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 concentrationof nonpermeable solutes increases

• Isotonic – same osmotic pressure

• Hypertonic – higher osmotic pressure (water loss)

• Hypotonic – lower osmotic pressure (water gain)

(b)

(a)

(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

Larger molecules

Smaller molecules

Bloodpressure Blood

flow

Tissue fluid

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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: Sodium-Potassium 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 VPhagocytizedparticle

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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

Nucleus

Endoplasmicreticulum

Golgiapparatus

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Transcytosis

• Endocytosis followed by exocytosis• Transports a substance rapidly through a cell• HIV crossing a cell layer

Viruses budHIV

Exocytosis

Receptor-mediated endocytosis

HIV-infectedwhite blood cells Anal or

vaginal canal

Lining of anusor vagina(epithelial cells)

Virus infectswhite blood cells onother side of lining

Receptor-mediatedendocytosis

Cellmembrane

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