Homeostasis

Question 1

Define Homeostasis

Answer 1

the ability or tendancy of a living organism, cell or tissue to keep the conditions inside the same despite any changes in the conditions around it, or maintaining a state of internal balance

Question 2

What needs to be maintained constant in the internal environment?

Answer 2

• concentration of oxygen, co2, salt and electrolytes -concentration of nutrients, waste products- pH-temperature -volume and pressure

Question 3

What does pilorelaxation do?

Answer 3

allow the air to move quickly across the skin so when the fan yourself you cool down quicker

Question 4

What causes positive feedback to stop?

Answer 4

when the initiator ceases- for example the cervix stops stretching when the baby is born as the baby has stopped pushing against the cervix

Question 5

What causes negative feedback to stop?

Answer 5

when the effector stops-for example when blood glucose levels drop insulin stops being produced

Question 6

What is core body temperature?

Answer 6

36.5 degrees to 37.5 degrees- normal

Question 7

Mild hypothermia

Answer 7

32 degrees to 36.5 degrees

Question 8

Severe hypothermia

Answer 8

28 degrees to 32 degrees

Question 9

What are the normal pH for the body?

Answer 9

7.35-7.45

Question 10

What 2 major organs are responsible for maintaining acid base balance?

Answer 10

lungs- respiratory balance kidneys- metabolic balance

Question 11

What is the gastric pH?

Answer 11

1.5 - 3.5

Question 12

What happens when the stomach loses its protection and what is it?

Answer 12

gastric ulceration and perforationmucus

Question 13

What happens if gastric acid gets into the oesophagus?

Answer 13

oesophagitisstricture

Question 14

What are the limits of human tissue survival?

Answer 14

pH 6.8 to 7.8

Question 15

What does a change in [H+] by a factor of 2 do?

Answer 15

this causes a pH change of 0.3

Question 16

What is the [H+] at pH 7.4?

Answer 16

40nm

Question 17

What is the [H+] at pH 7.0?

Answer 17

100nm

Question 18

What buffer system do erythrocytes use?

Answer 18

carbonic acid- bicarbonate

Question 19

what do most cells use as a buffering system?

Answer 19

sodium phosphate buffering system

Question 20

What does a blood gas analysis do?

Answer 20

it analysis the gases of the blood and the pH and the electrolytes in the blood

Question 21

Where does water end up?

Answer 21

60% fluids Male 50% fluids Female -2/3 intracellular fluid -1/3 extracellular fluid -75% interstitial fluid -25% plasma

Question 22

[Hypo]- refers to the state of the cell inside

Answer 22

less water inside the cell than outsidethe cell will eventually inflate and burst less water inside the cell

Question 23

[iso]tonic

Answer 23

the same amount of water inside and outside the cell on both sides of the plasma membrane

Question 24

[hyper]tonic

Answer 24

more water inside the cell than outside water moves out the cell will shrink

Question 25

how is water movement across the plasma membrane controlled?

Answer 25

different aquaprotein isoforms exist often on different sides of cells have different affinties for water- some slow, some fast-allow discrete water flow-regulated by the amount of glycerol in the cell

Question 26

What is osmolality?

Answer 26

a function of the concentration of particles in a solution

miliosmoles per kg

Question 27

What is oedema? and peripheral oedema

Answer 27

fluid retention swollen ankles or ankle swelling occurs when the hydrostatic pressure > osmotic pressure