3.2 - adaptations for transport Flashcards
describe the vascular system of insects
- open circulatory system
- dorsal-tube shaped heart
- respiratory gases not carried in blood
what’s an open circulatory system
- transport medium pumped by heart not contained in vessels, but moves freely
- transport fluid comes into direct contact w/ cells
describe the vascular system of earthworms
- vascularisation
- closed circulatory system
- respiratory gases carried in blood
what’s a closed circulatory system
- blood pumped by heart contained in blood vessels
- blood doesn’t come into direct contact w/ cells
advantages of a closed circulatory system
- blood pressure can be maintained
- blood supply to different organs can vary
- lower volumes of transport fluid required
what type of circulatory system do fish have
single circulatory system
what’s a single circulatory system
- blood travels one circuit
- blood flows through heart + pumped around body before retuning to heart
what type of circulatory system do mammals have
double circulatory system
what’s a double circulatory system
- blood flows through heart twice in 2 circuits
- blood pumped from heart to lungs before returning to heart, then pumped around body, after which returning to heart again
what are the benefits of a double circulatory system
- maintains blood pressure around whole body
- uptake of O2 more efficient
- delivery of O2 + nutrients more efficient
- blood pressure can differ in pulmonary + systemic circuits
describe the double circulatory system in humans
blood flows through heart twice in 2 circuits:
- pulmonary circuit
- systemic circuit
name the 4 chambers of the mammalian heart
- left atrium
- right atrium
- left ventricle
- right ventricle
describe the pathway of blood around the body, naming the structures of the heart
pulmonary vein → left atrium → left ventricle → aorta → body → vena cava → right atrium →. right ventricle → pulmonary artery → lungs
where are the atrioventricular valves found + what’s their function
- found between atria + ventricles
- prevents backflow of blood from ventricles into atria
what are the 2 types of atrioventricular valves
- bicuspid (left side)
- tricuspid (right side)
where are the semilunar valves found + what’s their function
- found between ventricles + arteries
- prevents backflow of blood from arteries into ventricles
name the 5 types of blood vessel
- arteries
- arterioles
- capillaries
- venules
- veins
describe the pathway of blood through the blood vessels
heart → arteries → arterioles → capillaries → venules → veins → heart
what’s the function of arteries
carries blood away from heart to tissues, under high pressure
relate the structure of arteries to their function
- thick muscular walls to handle high pressure w/out tearing
- elastic tissue allows recoil to prevent pressure surges
- narrow lumen to maintain pressre
what’s the function of veins
carry blood towards heart under low pressure
relate the structure of veins to their function
- thin walls due to lower pressure
- valves to ensure blood doesn’t flow backwards
- less muscular + elastic tissue as they dont have to control blood flow
what’s the function of capillaries
form large network through tissue of body + connect arterioles to venules
relate the structure of capillaries to their function
- walls only one cell thick, short diffusion pathway
- v narrow, can permeate tissues + red blood cells can lie flat against wall, reducing diffusion distance
- numerous + highly branched, providing large SA
what’s the function of arterioles
connect arteries + capillaries
what’s the function of venules
connect capillaries + veins
relate the structure of arterioles + venules to their function
- branch off arteries + veins to feed blood into capillaries
- smaller than arteries + veins so change in pressure is more gradual as blood flows to capillaries
what’s the cardiac cycle
- sequence of events involved in one complete contraction + relaxation of heart
- 3 stages: atrial systole, ventricular systole, diastole
describe what happens in ventricular diastole
- heart is relaxed
- blood enters atria, increasing pressure + pushing open AV valves
- allows blood to flow into ventricles
- pressure in heart is lower than in arteries, so SL valves remain closed
describe what happens in atrial systole
- atria contract, pushing any remaining blood into ventricles
- AV valves pushed fully open
describe what happens in ventricular systole
- ventricles contract
- pressure in ventricles increases, closing AV valves to prevent backflow + opening SL valves
- blood flows into arteries
why is cardiac muscle described as myogenic
it initiates its own contraction w/out outside stimulation from nervous impulses
explain how the heart contracts
- SAN initiates + spreads impulse across atria, so they contract
- AVN receives, delays, + then conveys impulse down bundle of his
- impulse travels into purkyne fibres which branch across ventricles, so they contract from bottom up
what’s an electrocardiogram (ECG)
graph showing electrical activity in heart during cardiac cycle
explain the characteristic patterns displayed on a typical ECG
P wave - depolarisation of atria in atrial systole
QRS wave - depolarisation of ventricles during ventricular systole
T wave - repolarisation of ventricles in ventricular diastole
describe the structure + function of erythrocytes
- type of blood cell that’s anucleated + biconcave
- contains haemoglobin which enables the transport of O2 + CO2 to and from tissues
what’s plasma
- main component of blood (yellow liquid) that carries red blood cells cells
- contains proteins, nutrients, mineral ions, hormones, dissolved gases + waste
- distributes heat
describe the role of haemoglobin
present in red blood cells
O2 molecules bind to haem groups + are carried around the body, then released where they are needed in respiring tissues