Unit 1: Introduction to Physiology

NRS237 Principles of PhysiologyDr. Moattar Raza Rizvi

• Physiology is the science of studying the functional activities and its mechanisms in biological body.

• For example: why can heart automatically beat?• Physiology derived from two Greek words –

physis = nature; logos = study

What is Physiology?

• Aristotle emphasized the relationship between structure and function

• Galen was the first to perform experiments to understand the function of the body; so known to be father of physiology

• The first “physiologist” of the world, in the modern sense, was William Harvey. In the 17th century William Harvey first describes the circulatory system and its interaction with the body

• Claude Bernard (1813-1878) propounded the concept of milieu interieur or internal environment and established physiology as the scientific basis of medicine.

• THE FATHER OF MODERN PHYSIOLOGY IS THE FRENCH PHYSIOLOGIST CLAUDE BERNARD

The History of Physiology

• Physiology can be divided into viral physiology, bacterial physiology, cellular physiology, plant physiology, human physiology, and many more subdivisions.

• Human physiology is the science of studying the rule of physiological functions in human body.

Field of Physiology

Teleological:•What is purpose or function? •Why does something exist? •Why does it need to be done?

Mechanistic:•What are processes involved?•How does something work?

Function and Process: Teleological vs. Mechanistic Approach to Science

Distinguish between Process & FunctionProcess

• How do we breathe?

• How does blood flow?

• How do RBCs transport O2?

• Why do we breathe?

• Why does blood flow?

• Why do RBC transport O2?

Integrate both for complete picture!

Function

Levels of Structural Organization

Cell Structure and Function

Cell Structure and Function

Cell Structure and Function

Power house of cell

Levels of Structural Organization

Key Themes in Physiology:

1. Homeostasis• Body systems work together (Integration of

function) • Internal vs. external failure of homeostasis

2.Communication and movement across cell membranes • Vital to integration & homeostasis • Cells communicate with other cells, tissues &

organs

Organ System

Integumentary System

DEFINITION The integument (skin) and structures derived from it (hair, nails, and oil sweat glands).

FUNCTIONS Protects the body, regulates body temperature, eliminates wastes, and receives certain stimuli (tactile, temperature, and pain).

Organ SystemDEFINITION Bones, cartilage, and ligaments (which steady the bones at the joints).

FUNCTIONS Provides body support and protection, permits movement and leverage, produces blood cells (hematopoiesis), and stores minerals.

Organ SystemDEFINITION Skeletal muscles of the body and their tendinous attachments.

FUNCTIONS Effects body movements, maintains posture, and produces body heat.

Organ SystemDEFINITION Consists of the lymphatic vessels, lymph nodes, and other lymphatic organs.

FUNCTIONS Removes foreign substances from the blood and lymph, combats disease, maintains tissue fluid balance, and absorbs dietary fats from the digestive tract.

Returns tissue fluids to the heart

Organ System

DEFINITION The body organs concerned with movement of respiratory gases (O2 and CO2) to andfrom the pulmonary blood (the blood within the lungs).

FUNCTIONS Supplies oxygen to the blood and eliminates carbon dioxide; also helps to regulate acid–base balance.

Pharynx is part of digestive and respiratory system

Organ SystemDEFINITION The body organs that render ingested foods absorbable.

FUNCTIONS Mechanically and chemically breaks down foods for cellular use and eliminates undigested wastes.

Organ SystemDEFINITION Brain, spinal cord, nerves, and sensory organs such as the eye and the ear.

FUNCTIONS Detects and responds to changes in internal and external environments, enables reasoning and memory, and regulates body activities.

Organ SystemDEFINITION The hormone-producing glands.•Hypothalamus•Pineal gland•Pituitary gland•Thyroid •Parathyroid •Thymus•Adrenal gland•Pancreas•Ovaries•Testes

FUNCTIONS Controls and integrates body functions via hormones secreted into the bloodstream.

Organ SystemDEFINITION The heart and the vessels that carry blood or blood constituents (lymph) through the body.

FUNCTIONS Transports respiratory gases, nutrients, wastes, and hormones; protects against disease and fluid loss; helps regulate body temperature and acid–base balance.

Organ SystemDEFINITION The organs that operate to remove wastes from the blood and to eliminate urine from the body.

FUNCTIONS Removes various wastes from the blood; regulates the chemical composition, volume, and electrolyte balance of the blood; helps maintain the acid–base balance of the body.

Organ System

DEFINITION The body organs that produce, store, and transport reproductive cells (gametes, or sperm and ova).FUNCTIONS Reproduce the organism, produce sex hormones.

Digestive system Takes in nutrients, breaks them down, and eliminates unabsorbed matter (feces)

Respiratory systemTakes in oxygen and eliminates carbon dioxide

Food O2 CO2

Cardiovascular systemVia the blood, distributes oxygen and nutrients to all body cells and delivers wastes and carbon dioxide to disposal organs

Interstitial fluid

Nutrients

Urinary systemEliminates nitrogenouswastes andexcess ions

Nutrients and wastes pass between blood and cells via the interstitial fluid

Integumentary system Protects the body as a whole from the external environment

Blood

Heart

Feces Urine

CO2

O2

•All cells depend on organ systems to meet their survival needs.

Organ systems work cooperatively to perform necessary life functions

Organ Systems Interrelationships

• In average young adult male:

Body composition

Body composition % of body weight

Protein, & related substances 18%

Fat 15%

Mineral 7%

Water 60%

Body Fluids

• Water content in body is divided into 2 compartments:

1. Extracellular fluid (ECF): (internal environment or the milieu intérieur)

- fluid outside the cells. 1/3 volume of fluids in body ( 33% of total body water). - contains ions & nutrients needed for cellular life.

Extracellular fluid is further divided into A. Interstitial Fluid: Fluid between the cellsB. Plasma: Fluid portion of blood

2. Intracellular fluid (ICF): - fluid inside the cells. 2/3 volume of fluids in body ( 67% of total body water).

Body Fluids

Fluid Compartments 60% of body weight

Extracellular fluid

( 1/3) 33% of TBW

20% of body wt

Intracellular fluid

( 2/3) 67% of TBW

40% of body wt

Interstitial fluid

75% of ECF 15% of body

wt

Plasma 25% of ECF 5% of body

wt

Transcellular fluidCSF

Intraocular

PleuralPeritonea

lPericardia

lSynovialDigestive secretion

s

Fluid Compartments

Body Fluid Compartments

Q. Calculate TBW for a 70 kg man.

TBW = 60% of body weight TBW = 60% X 70 = 42 L of water

• 28 liters intracellular fluid (ICF) – (2/3rd)• 14 liters extracellular fluid (ECF)- (1/3rd)

-3 liters plasma-11 liters interstitial fluid (ISF)

Example: How to calculate total body water (TBW)?

ECFCations:Na+ (142mmol/L)K+ (4.2)Mg2+ (0.8)

Anions:Cl- (108)HCO3

- (24)

Nutrients:

O2, glucose, fatty acids, &

amino acids.

Wastes:

CO2, Urea, uric acid,

excess water, & ions.

ICFCations: Na+ (14)K+ (140)Mg2+ (20)

Anions:Cl- (4)HCO3

- (10)Phosphate ions

Nutrients: High concentrations of proteins.

Differences between ECF & ICF

How Substances Enter and Leave the Cell

How Substances Enter and Leave the Cell

Passive Transport Processes (No cellular energy expended)

Passive transport: Don’t use career protein

Diffusion is movement driven by concentration differences

Diffusion is movement driven by concentration differences

Passive Transport Processes (No cellular energy expended)

Osmosis: Passive transport: Don’t use career protein

Active Transport Processes (Require ATP or other energy sources)

Active transport: Use career protein

Na+ K- pumps 3 Na+ out and 2K+ inside the cell

Active Transport Processes (Require ATP or other energy sources)

Active Transport Processes (Require ATP or other energy sources)

Form vesicle

Homeostasis

Homeostasis homeo-, the same) is the existence and maintenance of a relatively constant environment within the body despite fluctuations in either the external environment or the internal environment.

Walter Cannon coined the term "homeostasis" (1929)

Homeostatic Regulation

This process of adjustment (called homeostatic regulation) involves:1.a receptor (which receives information about a change in the environment),2.a control center (which receives and processes information from the receptor), and3.an effector (which responds to signals from the control center by either opposing or enhancing the stimulus).

1. Receptor2. Afferent Pathway3. Integrating or control center4. Efferent Pathway5. Effector

Feedback

The signal sent by the effector is called feedback; feedback can be either negative or positive.•Negative feedback: when the effector opposes the stimulus (such as a dropping temperature) and reverses the direction of change (causing the temperature to rise). Example: Decrease in Blood Glucose and Blood pressure•Positive feedback: when the effector reinforces the stimulus (such as uterine contractions during childbirth, which trigger the release of the hormone oxytocin) and amplifies the direction of change (causing even greater contractions and further release of oxytocin). Example: Blood clotting, protein digestion, a temperature of 100.2F causes further increase

Negative Feedback Control of Car Speed

Negative Feedback – Temp RegulationResponse to Heat Stress1.Thermoreceptors in skin detect a rise in body temperature2.Nervous system in brain sends message to hypothalamus3.Hypothalamus response:

Sweating: Sweat glands to initiate sweating – evaporation of sweat cools bodyVasodilation: Blood vessels to dilate – more blood glows to skin, which has been cooled by evaporation

Negative Feedback – Temp Regulation

Effector

Effector

Regulator center

Negative Feedback – Temp Regulation1.Thermoreceptors in the skin send a message to

the hypothalamus2.Hypothalamus response:– Vasoconstriction: Constricts smooth muscle of

arterioles – blood flow is limited, heat loss from skin is reduced

– Piloerection: Constricts smooth muscle around hair follicles, causing hair to stand on end – erect hair traps warm air next to skin

– shivering : Skeletal muscles to initiate rhythmic contractions (10 – 20x per minute)

Negative Feedback – Temp Regulation

Regulator center

Effector

Effector

Positive Feedback during childbirth

Carry Home Message1.Negative Feedback: Example

1.Decrease in blood glucose2.Decrease in blood pressure

2.Positive Feedback: Example1.Clotting2.Protein digestion3.A temperature of 100.2 0F causes further increase