homeostasis

Question 1

what is homeostasis?

Answer 1

Maintenance of a constant internal environment

Question 2

optimum conditions for a cell to work

Answer 2

• Working at a particular temperature
• Surrounded by fluid of a particular pH
• Given constant supply of oxygen and glucose
• Wastes are constantly removed

Question 3

Aspects of internal environment that need to regulate

Answer 3

• Core body temp
• pH and concentration of dissolved substances in the body fluids
• Conc. of blood glucose
• Conc. of oxygen and carbon dioxide in the blood and other body fluids
• Blood pressure
• Concentration of metabolic wastes

All need to be maintained within very narrow limits

Question 4

how is homeostasis maintained?

Answer 4

• Maintenance involved both input and output of balanced materials and energy
• All systems of the body contribute to homeostasis
• Body must be able to sense changes in internal and external environments → compensate for the changes
• Nervous and endocrine systems = main sensory and controlling body systems
• Operate through feedback systems

Question 5

what is a feedback system?

Answer 5

circular situation in which the body responds to a change or stimulus

Question 6

feedbacks systems are either…

Answer 6

negative or positive
Depends on whether the response decreases or increases the original stimulus

Question 7

blood glucose levels fall (stimulus) from exercise

Answer 7

• Liver responds by releasing more glucose into the blood (response)
  
  • Caused blood glucose to go up (opposite of the initial fall in glucose)
  • Blood glucose is maintained within acceptable range for efficient cellular functioning

Question 8

feedback system order

Answer 8

stimulus, receptor/s, modulator, effector/s, response/s, feedback

Question 9

Influence of Nervous System and Endocrine System

Answer 9

• Homeostatic mechanisms controlled by nervous and endocrine systems
• Body detect when the body begins to deviate from it’s normal balanced state
  
  • NS sends electrical msgs → appropriate organs to counteract change
  • Glands of ES secrete hormones into blood

Question 10

negative feedback

Answer 10

Negative feedback = response has the effect of reducing or eliminating the stimulus that caused it
- Also called steady state control systems (they return the body to a steady state)

Question 11

negative feedback with temp.

Answer 11

• Temperature, blood glucose and body temp fluctuate around a normal level = dynamic equilibrium
• The point around which conditions fluctuate/level at which a variable is to be maintained = set pointAircon = 22 degBody temp = 37 deg
• Upper and lower limits between which the levels fluctuate = tolerance limitsBody will function normally within these limits

Question 12

positive feed back has no…

Answer 12

No role in homeostasis

Question 13

When positive feedback occurs…

Answer 13

response to stimulus reinforces and intensifies the stimulus → even greater response → great stimulus

Question 14

positive feedback: childbirth

Answer 14

• Labour initiated by secretion of oxytocin
• Can be harmful

Question 15

positive feedback: high fever

Answer 15

• Small rise in body temp beneficial to fighting infection
• If body temp rises about 42C → dangerous FL

High body temp → Higher metabolic rate that produces more heat → raises temp higher