Topic 1 - INTRO TO PHYSIOLOGY

Question 1

What is physiology?

Answer 1

study of how the body functions

Question 2

What is Homeostasis

Answer 2

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

• cells can only survive within a narrow range of conditions
• body conditions must be maintained within physiological limits
• conditions controlled include:
  
  1. pH, temperature
  2. CO₂
  3. O₂
  4. blood pressure
  5. ICF + ECF volumes

Question 3

Homeostasis

organ systems function together to ______________

Answer 3

maintain homeostasis

Question 4

Homeostasis

disease = ?

Answer 4

failure to maintain homeostasis

Question 5

homeostasis

nervous and/or endocrine system(s) control what?

and act to what?

Answer 5

all other systems (control systems).

act to:

1. maintain homeostasis
2. permit departures from homeostasis in a controlled manner

e.g. pregnancy, growth, sudden fright

Question 6

Homeostasis regulation:

Answer 6

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

Question 7

Homeostasis regulation

what are 2 the types of Nervous System/Endocrine responses?

Answer 7

1. anticipatory responses
2. feedback machanisms

Question 8

Homeostasis Regulation

NS/Endocrine responses:

Anticipatory responses

Answer 8

• e.g. increased respiratory rate at start of excercise → proprioreceptors (NS senesory receptors) signal movement before a change in internal conditions occurs (gases in blood)
• may also be learned or behavioral
  
  • e.g. put on coat

Question 9

Homeostasis Regulation

NS/Endocrine responses:

Feedback mechanisms

Answer 9

• mechanisms that respond to a change in the system
• consist of set points receptors, control areas and effectors
• set point = range of values of variable (e.g. body temperature) that do not bring about a response (i.e “normal range”)
• variable is monitored by receptors ⇒ info (input) fed back control area (NS, endocrine gland) controls the effector (output)

Question 10

Homeostasis Regulation

NS/Endocrine responses:

What are the two types of feedback mechanisms?

Answer 10

1. negative feedback
2. positive feedback

Question 11

Homeostasis Regulation

NS/Endocrine responses:

Feedback mechanisms ► Negative feedback

Answer 11

• 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
• e.g. body temp (=variable): set point = 36 - 37.8ºC. If increased temp. (40º):
• result = increased core blood to decrease skin surface and sweat evaporates = heat loss & temp. (opposite direction of change)
• e.g. 2: decreased temperature ⇒ shiver ⇒ increased temperature.
• set point can change e.g. in fever

Question 12

Homeostasis Regulation

NS/Endocrine responses:

Feedback mechanisms ► Positive feedback

Answer 12

• less common - NOT homeostatic
• output intensifies the input
• e.g. childbirth - labour
• continues until endpoint (=baby born)

Question 13

set point can change

true or false?

Answer 13

true