transport in animals- cardiac cycle and circulation

Question 1

what is an open circulatory system

Answer 1

blood does not flow through vessels but pumped into large spaces in body cavity

Question 2

name a group of organisms with an open circulatory system

Answer 2

Insects

Question 3

assess the similarities and differences in vascular systems between earthworms and insects

Answer 3

Earthworms:

• closed circulation
• pumps
• vascularisation
• carriage of respiratory gases in blood

Insects:

• Open circulatory system
• dorsal tube shaped heart
• blood does not carry respiratory gases

Question 4

what is a single circulatory system and where is it found

Answer 4

blood passes throught the heart once in a total circuit of the body

deoxygenated blood pumped to gills (oxygenated) then goes directly to the organs and back to the heart

Fish

Question 5

what are the three main types of blood vessels

Answer 5

Arteries
veins
capillaries

Question 6

through which blood vessels does the blood pass after leaving the heart until it returns back to the heart

Answer 6

Artery
Arteriole
Capillary
venule
vein

Question 7

describe the physiology of an artery

Answer 7

carries blood away from the heart under high pressure

relatively small lumen

endothelium
lots of elastic tissue
thick smooth muscle
outer layer-collagen +elastic fibres

Question 8

describe the physiology of a veins

Answer 8

carries blood to the heart
relatively large lumen

endothelium
thin smooth muscle
outer layer-collagen +elastic fibres

Question 9

explain how the semi lunar valve works in veins and what its purpose is

Answer 9

blood has enough pressure to open the valve
back flow of blood causes the valve to shut
this prevents the blood flowing backwards in the vein

Question 10

what is a double circulation system

Answer 10

blood passes through the heart twice in each circuit of the body
(lungs and somatic)

Question 11

which vessels go into the right atrium

Answer 11

(superior and inferior) vena cava

Question 12

which vessel goes out from the right ventricle

Answer 12

pulmonary artery

Question 13

which vessels go into the left atrium

Answer 13

pulmonary vein

Question 14

which vessels go into the left ventricle

Answer 14

aorta

Question 15

explain the cardiac cycle

Answer 15

Atrial systole
the atria is full of blood and ventricles are relaxed
atria contract
atrio-ventricular valves opens due to pressure of blood

ventricular systole

• atria relaxes
• the ventricles contract- forcing blood into the pulmonary artery and aorta
• av valve closed by pressure of ventricular contraction so that blood doesnt go back into the atria (lub)
• semi lunar valve opens
• blood flows into the pulmonary artery and aorta

Diastole
ventricles relax
pressure in ventricles drops below arteries
semi lunar valve closes (dub)
all heart muscle relaxes
blood from pulmonary veins and vena cava flow into atria

Question 16

explain how the heart is myogenic

Answer 16

myogenic meants that it can cause its own contraction without innervation

sino-atrial node (pace maker of heart) depolarises sends impulse to both atria and atrio ventricular node (AVN).
AVN generates its own impulse which pass down Bundle of His (in septum) and Purkinje fibres to the apex of the heart.
this causes the contraction of the ventricles

Question 17

what is the function of red blood cells

Answer 17

carry oxygen around the body

Question 18

how is carbon dioxide carried around the body

Answer 18

CO2 diffuses into the red blood cell
reacts with H2O to form H2CO3 which dissociates into H+ and HCO3-
the H+ combines with Hb to make HHb (haemoglobonic acid) this decreases the affinity for O2 which is released from Hb
HCO3 diffuses out of the cell down its concentration gradient.
cl- ions diffuse into the rbc to balance the loss of charge (chloride shift)

Question 19

what is the bohr effect

Answer 19

oxygen dissociation curve- move to the right - lower affinity for O2
move to the left higher affinity for O2

higher CO2 partial pressures lowers the affinity of Hb to O2 (moves the dissociation curve to the right)