SfM - Homeostasis

Question 1

What is a tissue?

Answer 1

groups of cells that share the same characteristics or specialisations

Question 2

what is an organ?

Answer 2

collections of tissues, usually of different cell types. Link to perform a particular function

Question 3

what does the cardiovascular system do?

Answer 3

deliver O2 and nutrients to cells, removes waste from cells

Question 4

role of respiratory system?

Answer 4

acquires O2 (gives oxygen to blood) and disposes of CO2

Question 5

Gastrointestinal system

Answer 5

acquires nutrients and disposes of waste via faeces

Question 6

renal system

Answer 6

disposes of waste via urine

Question 7

musculoskeletal system

Answer 7

sources nutrients, removes us from danger and protects us from threat

Question 8

immune system

Answer 8

protects us from infection

Question 9

nervous system

Answer 9

co-ordinates all our bodily systems

Question 10

endocrine system

Answer 10

co-ordinates other systems, major role in allowing access to nutrients

Question 11

reproductive system

Answer 11

ensures continuation of life, however, does produce steroid hormones required for metabolism

Question 12

what is the definition of homeostasis?

Answer 12

as energy demand increases, the supply of substrates required to produce energy must also increase (need enough to meet that demand). Aim to prevent disturbance in the system

Question 13

what happens when homeostasis isn’t maintained?

Answer 13

Failure to adequately correct imbalances results in illness and disease

Question 14

what are the common everyday challenges to internal environment?

Answer 14

external temperature
diet
exercise

Question 15

what are the three mechanisms involved in maintaining homeostasis?

Answer 15

negative feedback
feedforward
positive feedback

Question 16

how does homeostasis work after eating?

Answer 16

after meal –> blood glucose increased –> insulin released –> increased glucose uptake by cells –> BG concentration falls –> reduced insulin production

Question 17

what happens in diabetes?

Answer 17

after meal –> blood glucose increased –> no insulin produced/lack of effect –> lack of glucose uptake in cells leads body to perceive starvation –> increased liver production of glucose –> even greater increase in BG

Question 18

what percentage of the body is water?

Answer 18

60%

Question 19

How much water to do we gain/lose in a day?

Answer 19

2550
Gained = drinking, eating, metabolic
Lost = insensible loss, sweat, faeces, urine

Question 20

where is the water spread in our body?

Answer 20

intracellular fluid & extracellular fluid (interstitial fluid + plasma)

Question 21

what is the purpose of the capillary wall?

Answer 21

separates plasma and interstitial fluid, allows water to move freely but blood products can not

Question 22

what is the purpose of the cell membrane?

Answer 22

separates intracellular fluid and interstitial fluid, allows water to move freely but no ions can pass w/o channels and transporters

Question 23

how is water distributed across these compartments?

Answer 23

1/3 ECF (80% interstitial/20% plasma)

2/3 ICF

Question 24

how do we measure body fluid volumes?

Answer 24

dilution principle

c=mass of contrast/volume

Question 25

how do we measure compartments?

Answer 25

plasma volume = evans blue or albumin (confine test to plasma)
extracellular volume = inulin, sucrose, mannitol, N+, Cl- (substance can’t cross cell membrane)
total body water = heavy/deuterated water

Question 26

what is the composition of ECF/ICF?

Answer 26

Na = low ICF/high ECF
K = high ICF/low ECF
Cl = low ICF/high ECF
HCO3 = higher ECF
phosphates/sulphates = high ICF/low ECF 
protein = high ICF/low ECF (comes from plasma in ECF)

Question 27

how can homeostasis go wrong?

Answer 27

ECF-K+ conc. increases outwith the normal range –> leads to loss of conc gradient between ECF/ICF –> disrupts nerve and muscle function –> ventricular fibrillation and death
ESSENTIAL TO REGULATE ECF K+

Question 28

Terminology 
hyper?
hypo?
aemia?
uria?
glyc?

Answer 28

hyper = greater than norm
hypo = lower than norm
aemia = in the blood
uria = in the urine
glyc = related to glucose