homeostasis

Question 1

describe the term homeostasis

Answer 1

Defined as maintenance of a stable internal environment. Internal conditions do vary but within narrow limits In general, a body is in homeostasis when its needs are adequately met & it is functioning smoothly. Each cell contributes to maintenance of homeostasis which is essential for survival

Question 2

Describe the components of the body fluid compartments

Answer 2

•Body cells are in contained in watery internal environment through which life-sustaining exchanges are made
•Extracellular fluid (ECF
)•Fluid environment in which the cells live (fluid outside the cells)
•Two components-
•Plasma and interstitial fluid (ISF)
•Intracellular fluid (ICF)
•Fluid contained within all bod

Question 3

examples of other extracellular compartments in the body that are distinct from the interstitial fluid and plasma

Answer 3

• Synovial fluid
• Amniotic fluid
• Cerebrospinal fluid
• Vitreous humour

Question 4

Identify 7 factors of the internal environment maintained by homeostasis

Answer 4

• Concentration of nutrient molecules
• Concentration of O2 and CO2
• Concentration of waste products
• pH
• Concentration of water and electrolytes
• Volume & pressure
• Temperature

Question 5

what is feedback and the types of feedback

Answer 5

Refers to responses made after change has been detected
•Types of feedback systems-
•Negative – stimulus causes a response that leads to a decrease of the original stimulus. Involved in maintaining homeostasis
•Positive – stimulus causes a response that leads to an enhancement of the original stimulus. The processes is enforced until it interrupted

Question 6

what is feedforward

Answer 6

Term used for responses made in anticipation of a change, e.g. increased cardiac output in anticipation of exercise AND increased saliva production on anticipation of food

Question 7

what can disruptions in homeostasis lead too

Answer 7

-Can lead to illness and death
•Pathophysiology
•Abnormal functioning of the body associated with disease

Question 8

explain negative feedback using specific examples (pancreatic hormones) Low blood glucose levels

Answer 8

low blood glucose levels-

• stimulus- declining blood glucose level
• low blood glucose level detected by glucagon- releasing cells of pancreas
• glucagon- releasing cells of pancreas stimulated to release glucagon into the blood; target is the liver
• liver breaks down glycogen stores and releases glucose to the blood
• blood glucose level rises to set point; stimulus for glucagon release diminishes and body returns to homeostasis

Question 9

explain negative feedback using specific examples (pancreatic hormones) High blood glucose levels

Answer 9

high blood glucose levels-

• high blood glucose level detected by insulin- secreting cells of pancreas
• insulin- secreting cells of pancreas stimulated to release insulin into the blood
• most body cells take up more glucose and the liver takes up glucose and stores it as glycogen
• blood glucose level declines to a set point; stimulus for insulin release diminishes and body returns to homeostasis

Question 10

explain negative feedback using specific examples (pancreatic hormones) High blood glucose levels

Answer 10

high blood glucose levels-

• high blood glucose level detected by insulin- secreting cells of pancreas
• insulin- secreting cells of pancreas stimulated to release insulin into the blood
• most body cells take up more glucose and the liver takes up glucose and stores it as glycogen
• 2 HOURS LATER-
• blood glucose level declines to a set point; stimulus for insulin release diminishes and body returns to homeostasis

Question 11

what are the normal blood glucose levels

Answer 11

5mmol/L

Question 12

what is the low glucose level

Answer 12

4-5mmol/L

Question 13

what is the high glucose level

Answer 13

7.8mmol/L

Question 14

explain positive feedback using specific examples

Answer 14

positive feedback amplify a change from the normal level
the effectors respond to further increase the level away from the normal level
blood clotting-
1) break or tear in blood vessel wall
2)clotting occurs as platelets adhere to site and release chemicals
3)released chemicals attract more platelets
4)clotting proceeds until break is sealed by newly formed clot

Question 15

negative feedback input/output

Answer 15

• Main type of homeostatic control
• Opposes the initial change as the output shuts off the original stimulus
• These mechanisms cause the variable to change in a direction opposite to that of the initial change, returning it to its original “ideal” value or set point

Question 16

positive feedback input/output

Answer 16

• The response enhances the original stimulus so that the output is increased
• The changes occur in the same direction as the initial disturbance, so the disturbance moves further from the original value
• The blood clotting mechanisms enhance the original stimulus so that the output is increased, and an end point is reached. After this equilibrium is restored again
• Positive feedback usually controls infrequent events that do not require continuous adjustment