Topic 1: Introduction to Physiology

Question 1

Physiology

Answer 1

Study of how the body functions

Question 2

Homeostasis

Answer 2

ability to maintain relatively stable conditions in the internal environment, despite changes in external environment

Question 3

Body and cell survival

Answer 3

conditions must be maintained within physiological limits

Question 4

Conditions controlled include

Answer 4

• pH
• temperature
• blood gases (CO2, O2)
• blood pressure (b.p.)
• intracellular + extracellular (ICF + ECF) fluid volumes

Question 5

organ systems

Answer 5

function together to maintain homeostasis

Question 6

Disease

Answer 6

failure to maintain homeostasis

Question 7

Nervous and/or endocrine system(s) control all other systems

Answer 7

Act to:

• maintain homeostasis
• permit departures from homeostasis in a controlled manner e.g. pregnancy, growth, sudden fright

Question 8

Homeostasis Regulation

Answer 8

• Change in internal environment must be detected or anticipated
• NS and/or endocrine respond altering system(s) responsible for that condition

Question 9

Types of NS/Endocrine Responses

Answer 9

• Anticipatory Responses

- Feedback Mechanisms

Question 10

Anticipatory Responses

Answer 10

• e.g. ⇑ respiratory rate at start of exercise ⇒ proprioceptors (NS sensory receptors) signal movement before a change in internal conditions (gases in blood)
• may also be learned or behavioral

Question 11

Feedback Mechanisms

Answer 11

• mechanisms that respond to change in system
• consist of set points, receptors, control areas, and effectors
• variable is monitored by receptors ⇒ info (input) fed back to control area (NS/endocrine gland) ⇒ controls the effector (output)

Question 12

Set point

Answer 12

range of values of a variable (e.g. body temp.) that do not bring about a response (i.e. “normal range”)

Question 13

Types of Feedback Mechanisms

Answer 13

• Negative Feedback

- Positive Feedback

Question 14

Negative Feedback

Answer 14

• Most common homeostatic control mechanism
• Result of “output” - variable moves back toward the set point i.e. in opposite (negative) direction to the change that triggered the response (“input”)

Question 15

Positive Feedback

Answer 15

• Less common - NOT homeostatic
• Output intensifies the input
• Continues until end point