Topic 6.2 The Transport System Flashcards
6.2.1 Draw and label a diagram of the heart showing the four chambers, associated blood vessels, valves and the route of blood through the heart.
Right side blood flow
- vena cava
- right atrium
- atrioventricular valve (tricuspid)
- right ventricle
- pulmonary semilunar valve
- pulmonary artery
- lungs
Left side blood flow (from lungs)
- pulmonary vein
- left atrium
- atrioventricular valve (bicuspid)
- left ventricle
- semilunar valve
- aorta
- body
- (back to vena cava; cycle restarts)
Note:
aorta → arterioles → capillaries → venules → veins → heart → lungs → back to aorta
6.2.2 State that the coronary arteries supply heart muscle with ______ and _______.
The coronary arteries supply heart muscle with oxygen and nutrients.
6.2.3 Explain the action of the heart in terms of collecting blood, pumping blood, and opening and closing of valves.
- right atrium collects (relatively deoxygentated) blood from vena cava / left atrium collects blood from pulmonary veins
- blood flows from right and left atriums into right and left ventricles, respectively, through atrioventricular valves
- blood then flows from right and left ventricles to the pulmonary artery (to lungs, where it’ll be reoxygentated) and aorta, respectively
- direction of bloodflow controlled by atrioventricular and semilunar valves
- when atria contract, blood flows through open atrioventricular valves into ventricle
- semilunar valves are closed as ventricle fills with blood
- when ventricles contract, causes a rise in pressure
- rise in pressure causes atrioventricular valves to close (to prevent back flow of blood into atria) and semilunar valves to open (allowing expulsion of blood into arteries)
- meanwhile, atria starts to fill with blood again
- ventricles stop contracting → leads to fall in pressure
- causes semilunar valves to close (preventing back flow of blood from arteries)
- when ventricular pressure drops below atrial pressure, atrioventricular valves reopen
- cycle repeats
6.2.4 Outline the control of the heartbeat in terms of myogenic muscle contraction, the role of the pacemaker, nerves, the medulla of the brain and epinephrine (adrenaline).
- myogenic muscle contraction: heart can contract by itself w/o stimulation of nerve
-
pacemaker (located in wall of right atrium) initiates contractions
- each signal from pacemaker = heartbeat
- one nerve carries messages from medulla of brain → pacemaker: speed up beating of heart
- another nerve carries messages from medulla of brain → pacemaker: slow down beating of heart
- adrenaline (epinephrine) is carried by bloodstream and signals pacemaker to increase beating of heart
6.2.5 Explain the relationship between the structure and function of arteries, capillaries and veins.
Arteries
- thick outer layer of longitudinal collagen and elastic fibres prevents leaks and bulges
- thick wall withstands high pressure
- thick layers of circular elastic fibres and muscle fibres to pump blood
- narrow lumen to maintain high pressure
Veins
- thin outer layer of longitudinal collagen and elastic fibres since pressure is low
- thin layer with few circular elastic fibres and muscle fibres as blood doesn’t flow in pulses
- thin walls so that nearby muscles can help push blood to heart
- wide lumen to accomodate slow-flowing blood
Capillaries
- wall is 1 cell thick so diffusion distance is small
- pores allow plasma to leak out and form tissue fluid
- phagocytes can also pass through pores to fight infection
- very narrow lumen so that many capillaries fit into small space, increasing surface area for diffusion
6.2.6 State that blood is composed of _____, ___________, leucocytes (__________ and __________) and _________.
Blood is composed of plasma, erythrocytes, leukocytes (phagocytes and lymphocytes) and platelets.
PEL(PL)P
6.2.7 State that the following are transported by the blood: ________, ______, ______ _______, _______, _________, ____ and ____.
NACHO UH
N utrients
A ntibodies
C arbon dioxide
H ormones
O xygen
U rea
H eat
