Human Physiology

HR)

Brijesh Kumar B.Sc. , PDGM (Marketing &

GOALS 1. To understand the important

functions of the various organ systems 2. To acquire the ability to problem solving and critical thinking 3. To discern the value of laboratory equipment and procedures as diagnostic aids

GOALS 4. To develop the attitude and habit

essential to the practice of medicine and continuing medical education Sensitivity to colleagues, society, and patient ii. Sensitivity to difference iii. Sensitivity to responsibility to CME iv. Integrity i.

PHYSIOLOGY  Physiology stated broadly and

simply is the study of how living organisms work  It deals with the functions of

living beings and the  Integration on how the different organ systems work together to accomplish complex tasks

PHYSIOLOGY

Claude Bernard “After carrying out an analysis of phenomena, we must always reconstruct our physiological synthesis so as to see the joint action of all the parts we have isolated.”

PHYSIOLOGY and LIFE  Physiology deals with the

functions of living things thus it deals with life itself  Life is the interplay of the organism

to its environment  It explains the physical and chemical factors that are responsible for the origin, development and progression of life

ATTRIBUTES OF THE HUMAN BODY 1. Organization 2. Irritability 3. Contractility 4. Nutrition 5. Respiration 6. Excretion 7. Metabolism and Growth 8. Reproduction

HUMAN BODY 1. Solid component  

Cell Tissues

- master tissues

- vegetative tissues  

Organs Systems

1. Liquid component 

2 Major fluid compartments

FLUID COMPARTMENTS ECF

ICF

7.4-7.45

pH

7.35-7.4

308 mOsm/L

Osmolarity

308 mOsm/L

Na+, Ca++

Cations

K+, Mg++

Cl-

Anions

PO4-

14L

Volume

28L

1/3 of TBF ISF – 11L Plasma – 3L Internal Environment

2/3 of TBF

HOMEOSTASIS  The maintenance of the body

in a stse of relative constancy in the internal environment  CONTROL SYSTEM – works on 1. Cellular level 2. Organismal level 3. Throughout the entire body

CHARACTERISTICS 1. Reflex in nature 2. Operates on a feedback

mechanism, mostly (-); rarely (+) 3. Amplification or Gain 4. Oscillation – driving, waxing, damped

CELL and its FUNCTIONS  Cells, like the human body has 1. 2. 3. 4.

Division of labor Specialization Mutual interaction Centralized control

 Cell – basic living unit of the body 1. Nucleus 2. Cytoplasm

PROTOPLASM The different substances that make up the cell. It is composed of 1. Water – principal fluid medium 2. Electrolytes - Major cations and 3. Proteins anions - Next to water, most 4. Lipids-Phospholipids and cholesterol abundant 5. Carbohydrates -Triglycerides and natural fats - 2 types - Little structural a.Structural function

PHYSICAL STRUCTURE of the CELL  Contains highly organized

physical structures called Organelles  Covered with a membrane are

the nucleus, endoplasmic reticulum, mitochondria, lysosomes, and Golgi apparatus

CELL MEMBRANE  It envelopes the cell  It is composed mostly of 1. Proteins – 55% 2. Lipids – 42% Phospholipids – 25% Cholesterol – 13% Other Lipids – 4% 1. Carbohydrates – 3%

CELL MEMBRANE 1. Lipid Membrane - Basic structure is a bilayer a. Phospholipid part 1. Hydrophilic part -

Water soluble Consists of the head group Phosphate portion

1. Hydrophobic part -

Fat soluble Consists of the 2 chain group Fatty acyl portion

CELL MEMBRANE Phospholipid Bilayer  Primarily responsible for the

passive permeability properties of the membrane  Choline containing  lecithin (phosphatidylcholine)  Sphingomyelin

 Aminophospholipids  Phosphatidylserine  Phosphatidylethanolamine

CELL MEMBRANE 

Others  Phosphatidylglycerol  Phosphatidylinositol  cardiolipin



Cholesterol



Glycolipids

LIPID BILAYER Features 1. It is fluid and not solid so portions of the membrane can flow literally from one point to another 2. Substances dissolved or floating in the lipid bilayer diffuse to all areas of the cell membrane 3. Lipid soluble substances easily cross the lipid bilayer 4. Water soluble substances do not dissolve in the lipid bilayer; they cross the membrane through water-filled channels, pores, or carriers

2 MEMBRANE PROTEINS a. Mostly Glycoproteins b. Fibronectin – integrins

2 types of Proteins 1. Integral proteins 2. Peripheral proteins

MEMBRANE PROTEINS Functions 1. Anchor 2. Pumps 3. Carriers 4. Ion channels 5. Receptors 6. Enzymes 7. Antibody processing

MEMBRANE CARBOHYDRATES  They are referred to as the cell

Glycocalyx  In combination with lipids – glycolipids  With proteins - glycoproteins

MEMBRANE CARBOHYDRATES Functions 1. Bring (-) charge to the cell 2. Attachment of one cell to the other 3. Act as receptor substances for binding hormones 4. Immune reactions or antigens

CYTOPLASM and its ORGANELLES 



Cytosol is the clear fluid of the cytoplasm where the particles are dispersed It contains mainly dissolved proteins, electrolytes and glucose, secretory granules and the organelles 1. Endoplasmic Reticulum (ER) a. Granular ER b. Agranular ER 2. Golgi Apparatus 3. Lysosomes

ORGANELLES 4. Peroxisomes 5. Mitochondria Other structures include: a. Filaments • •

a.

Tubules

∀ • •

a.

13 tubulin protofilaments Myosin I, II, MTOCs α ,β ,δ tubulins Kinesia Dynein

nucleus

INTERCELLULAR CONNECTIONS 1. Tight Junctions  Tight  Leaky

1. Gap Junctions

CELLULAR TRANSPORT SYSTEM A. Transport across but NOT through

Membranes 1. Endocytosis  Energy requiring  Receptor-ligand complex  Sample:cholesterol & LDL receptors  V-SNARES and T-SNARES  2 forms: pinocytosis

phagocytosis 1. Exocytosis

CELLULAR TRANSPORT SYSTEM B. Cellular Transport through

Membranes 1. Diffusion  No energy needed  Downhill  2 pathways  Through intermolecular intertices  Through channels or transport proteins

RATE OF DIFFUSION Determined by: 1. Amount of substance available 2. Velocity of kinetic motion 3. Range of diffusion – distance and time 4. Member of openings in the membrane

DIFFUSION COEFFICIENT Diffusion Coefficient = D Proportional to the speed with which the diffusing molecule can move in the surrounding medium  Size of molecule  Small molecule 1/(MW1/2)  Larger molecule 1/(MW1/3)  Spherical molecule  Viscosity of the medium

Stokes – Einstein Equation D= KT / 6π rη Fick’s Law of Diffusion J = (-) DA (∆ c/ ∆ x)

DIFFUSION PERMEABILITY of the C ELLULAR MEMBRANE

1. Permeable to lipid-soluble molecules 2. Impermeable to water-soluble molecule 

Ions are also relatively insoluble in lipid solvents; diffusion is through protein channels: a. Ion specific b. Allows small ions only c. Others – diameter, shape, charge

a. Ion channels are controlled by: a. Voltage difference b. Chemical or ligand-gated

CELLULAR TRANSPORT THROUGH MEMBRANE Osmosis  Semi-permeable membrane  Osmotic pressure  Van’t Hoff’s Law of O.P.

π = RT (φ ic) Isoosmotic Solutions  Hypoosmotic  Hyperosmotic

PREDICTORS OF VOLUME CHANGES 1. The steady-state volume of the cell

is determined only by the concentration of impermeant solutes in the ECF 2. Permeant solutes cause only transient changes in cell volume 3. The greater the permeabilty of the membranes to the permeant solute, the more rapid the time course

TRANSPORT THROUGH MEMBRANES Protein-Mediated Transport Properties 1. More rapid transport 2. Shows saturation kinetics 3. Mediating protein has chemical specificity 4. Structurally related molecules may compete for transport 5. Transport may be inhibited by compounds that are not structurally related 

In the form of carrier proteins or transporters or channels

TRANSPORT THROUGH MEMBRANES Facilitated Transport System  Movement of solutes from an area of higher concentration to an area of lower concentration with the use of transporters  No energy required  Can’t move substances against a concentration gradient  They act to equalize concentrations of the transported substance on the 2 sides of the membrane  Show saturation kinetics  Phloretin inhibits sugar uptake while insulin stimulates it

ACTIVE TRANSPORT 1. With the use of Transporters 2. With the use of channels a. Voltage b. Ligand-gated

Types: 1. Primary 2. Secondary a. Cotransport – symport b. Countertransport - antiport

OTHER MEMBRANE TRANSPORT PROCESSES 1. Ion-transporting ATPases

3 Major classes 1. P-type 2. V-type 3. F-type

1. Ca++ transport

Ca++ ATPase Calmodulin 1. Na+-Ca++ exchanger

OTHER MEMBRANE TRANSPORT PROCESSES 4. Na+-H+ exchanger 5. Anion exchanger 6. Na+,K+,Cl- cotransport 7. Facilitated Transport of Glucose 8. Amino Acid Transport 9. ABC (ATP-binding cassette) transporters Cystic Fibrosis Transmembrane Regulator (CFTR) b. Multiple Drug Resistance (MDR) Transporter a.

TRANSPORT ACROSS EPITHELIA  Epithelia are polarized  Transport properties differ from

one side to the other side of membrane  With tight and leaky junctions  2 types of pathways 1. Transcellular 2. Paracellular

Thank You