Introduction to Physiology

Physiology Science of body functions Science of body functions Homeostatic Example: shivering Homeostatic Example: shivering shivering elevates a low body temperature shivering elevates a low body temperature when body temperature drops below normal, a reflex pathway causes involuntary oscillating skeletal muscle contractions which produce heat when body temperature drops below normal, a reflex pathway causes involuntary oscillating skeletal muscle contractions which produce heat

Body Systems Groups of organs that perform related functions and interact to accomplish a common activity essential to survival of the whole body Groups of organs that perform related functions and interact to accomplish a common activity essential to survival of the whole body Do not act in isolation from one another Do not act in isolation from one another Human body has 11 systems Human body has 11 systems

Body Systems

Role of Body Systems in Homeostasis

Homeostasis Defined as maintenance of a relatively stable internal environment Defined as maintenance of a relatively stable internal environment Homeostasis is essential for survival and function of all cells Homeostasis is essential for survival and function of all cells Each cell contributes to maintenance of a relatively stable internal environment Each cell contributes to maintenance of a relatively stable internal environment

Basic Cell Functions Sensing and responding to changes in surrounding environment Sensing and responding to changes in surrounding environment Control exchange of materials between cell and its surrounding environment Control exchange of materials between cell and its surrounding environment Perform chemical reactions that provide energy for the cell Perform chemical reactions that provide energy for the cell Synthesize needed cellular components Synthesize needed cellular components

Homeostasis Body cells are in contained in watery internal environment through which life-sustaining exchanges are made

Homeostasis

Control of Homeostasis Homeostasis is continually being disrupted by Homeostasis is continually being disrupted by External stimuli External stimuli heat, cold, lack of oxygen, pathogens, toxins heat, cold, lack of oxygen, pathogens, toxins Internal stimuli Internal stimuli Body temperature Body temperature Blood pressure Blood pressure Concentration of water, glucose, salts, oxygen, etc. Concentration of water, glucose, salts, oxygen, etc. Physical and psychological distresses Physical and psychological distresses Disruptions can be mild to severe Disruptions can be mild to severe If homeostasis is not maintained, death may result If homeostasis is not maintained, death may result

Control of Homeostasis

Homeostasis of Blood Pressure Baroreceptors in walls of blood vessels detect an increase in BP Baroreceptors in walls of blood vessels detect an increase in BP Brain receives input and signals blood vessels and heart Brain receives input and signals blood vessels and heart Blood vessels dilate, HR decreases Blood vessels dilate, HR decreases BP decreases BP decreases

YOUR TURN Consider other situations: Describe another situation in which Homeostasis plays a role. What is the Normal situation? What is the Normal situation? Suggest how the body may be put out of Normal state. Suggest how the body may be put out of Normal state. Predict how the body will respond to return to normal. Predict how the body will respond to return to normal.