The heart

Question 1

give two features of cardiac muscle

Answer 1

myogenic- can contract and relax without nervous or hormone stimulation

never fatigues- as long as it has O2 and glucose

Question 2

what happens if the cardiac muscles run out of O2

Answer 2

respire anaerobically- produce lactic acid= heart attacks!!

Question 3

how can blocked coronary arteries cause heart attacks

Answer 3

blocked means they cannot carry oxygenated blood to cardiac muscle
cardiac muscle receive no O2
they respire anaerobically- produce lactic acid- heart attack

Question 4

why does the right ventricle have a thinner wall than the left ventricle

Answer 4

RV pumps blood to lungs, LV pumps blood to whole body= to lungs is shorter distance

blood from RV flowing at lower pressure- prevents damage to capillaries in lungs
lower pressure so moving slower- allows more time for gas exchange

Question 5

what is the only vein that carries oxygenated blood

Answer 5

pulmonary vein
from LUNGS to LA

Question 6

what is the only artery that carries DEoxygenated blood

Answer 6

pulmonary artery
from RV to LUNGS

Question 7

when do AV valves:
- open
- close

Answer 7

• open when pressure is greater BEHIND
• close when pressure is greater IN FRONT

Question 8

describe the function of the septum

Answer 8

seperates deoxygenated and oxygenated blood

maintains high O2 concentration in oxygenated blood

maintains concentration gradient- enables diffusion at respiring cells

Question 9

why is there a delay between atrial systole and ventricular systole?

Answer 9

all the blood needs to leave the atrium and enter ventricle
atrium walls recoil to push all blood into the ventricle

Question 10

when do semi lunar valves:
- open
- close

Answer 10

open when pressure is greater in ventricles

close when pressure is greater in artery

Question 11

what is meant by correlation

Answer 11

a relationship between variables

Question 12

what is meant by causation

Answer 12

when one variable has an influence on another variable

Question 13

describe the effects of smoking on blood

Answer 13

• nicotine- stimulates adrenaline- raises blood pressure and heart rate - damage to artery walls and fatty deposit build ups
• carbon monoxide- binds to Hb- reduces capacity of Hb to carry O2

Question 14

describe the influence of blood cholesterol on the heart

Answer 14

high density lipoproteins= low conc cholesterol :)

low density lipoproteins= high conc cholesterol- fatty deposit build up

Question 15

describe the effect of diet on heart

Answer 15

• high salt increases blood pressure- damage to artery walls
• lots of saturated fats- low density lipoproteins- higher conc blood cholesterol- fatty deposit build up

Question 16

function of:
- muscle layer
- elastic layer
- thin endothelium

Answer 16

• muscle layer- constricts and dilates to control volume of blood flowing
• elastic layer- stretches and recoils- maintains blood pressure
• thin endothelium- allows diffusion

Question 17

why is the muscle layer in arterioles relatively thicker than arteries

Answer 17

needs to constrict to narrow the lumen as arterioles carry blood into the capillaries- need to reduce blood flow

Question 18

why is elastic layer in arterioles relatively thinner than arteries

Answer 18

carrying blood at lower pressure than arteries

Question 19

describe 3 features of capillary structure and how they relate to function

Answer 19

• thin outer wall- endothelial layer 1 cell thick- SHORT diffusion distance
• lots of capillaries, and highly branched- HIGH SA
• narrow diameter- no cell is far from capillary- SHORT diffusion distance
• narrow lumen- red blood cells flattened against capillary wall- SHORT diffusion distance
• spaces between endothelial cells- allow white blood cells to escape and deal with infections

Question 20

why do capillaries have fibrous tissue around them

Answer 20

to prevent cells and and proteins from leaking out

Question 21

list the 2 routes by which tissue fluid returns to bloodstream

Answer 21

via lymphatic system

via capillaries

Question 22

state what forces tissue fluid out of blood plasma in capillaries and into surrounding tissues

Answer 22

hydrostatic pressure due to pumping of the heart

Question 23

how are the contents of the lymphatic system moved

Answer 23

• hydrostatic pressure of tissue fluid that has left the capillaries
• contraction of body muscles which squeezes the lymph vessels