2.3 a - Adaptations for transport in animals Flashcards
Features of a transport system
suitable medium to carry materials ( blood)
pump for moving the blood
valves - to prevent backflow of blood
(unidirectional blood flow(
Respiratory pigment ( in vertebrates) but not in insects
a system of vessels, arteries, veins + capillaries
Open circulatory system?
blood does not move in vessels but the tissues bathe directly in a haemocoel
( cavity filled with blood)
has long dorsal tube shaped heart
runs the entire length of a body
pumps blood at low pressure into the haemocoel materials are exchanged ( co2 + O2) between blood and body cells
blood slowly to the heart
(not efficient)
O2 diffuses directly to the tissues to the spiracles (inwards) and tracheoles (outwards)
Closed circulatory system?
Blood moves in vessels
2 types single and double
single - blood moves through heart once for example fish
ventricle of heart pumps deoxygenated blood to the gills
pressure falls
oxygenated blood carried to the tissues and deoxygenated returns to the atrium of the heart
not an efficient system
wait for blood to leave then come back
Double circulatory system?
blood passed through the heart twice in a complex circuit
mammals have a closed double circulatory system
a muscular heart under high pressure pumps blood rapidly through the vessel
organs = not in direct contact with the blood
but are bathed in tissue fluid ( glucose + oxygen)
passed into cells becoming CO2 + waste
Blood pigment = haemoglobin
Why is blood returned to the heart?
blood pressure is reduced in the lungs and wouldn’t be high enough to circulate through the rest of the body instead, blood = returned to the heart to raise its pressure, before being pumped to the body
Pulmonary?
right side of the heart pumps deoxygenated blood to the lungs via the pulmonary artery
oxygenated blood returns from the lungs to the left side of the heart
Systematic?
left sided of the heart pumps oxygenated blood to the tissues via the aorta
deoxygenated blood from body returns to the left side of the heart
In each circuit?
blood passes through the heart twice once on right and once on the left
Structure + function of blood vessels?
arteries + veins have 3 layered structure
proportions = different
inner most layer
endothelium
1 cell thick
surrounded by tunica intima - smooth , reduces friction
minimum resistance to blood flow
middle layer = tunica media contains smooth muscle + elastic fibres
In artery, tunica media is thicker sa contains more elastic fibres to accommodate blood flow at high pressure
when elastic tissue stretches, it recoils and can be felt as a pulse
when smooth muscle contracts, it regulates blood flow
outer layer, tunica externa - contains collagen fibres to resist stretching
Length of artery?
10mm - 1cm
Length of vein?
6 mm
length of capillary?
0.02 mm
Function of artery?
carry blood away from the heart
thick muscular wall withstand pressure
arteries branch into arterioles which subdivide into capillaries
Function of vein?
has a large lumen
thinner walls with less muscle
lower pressure + flow rate
veins above the heart rely on gravity to return the blood to the heart
veins below the heart are reliant on traction of muscles to pump blood back to the heart if no movement occurs, blood pools, causing deep vein thrombosis
function of capillaries?
forms a vast network which penetrates all tissues
blood from capillary collects in venules and is transferred to veins before returning to heart
Structure of capillaries?
thin walls with one layer of endothelium cells on a basement membrane
there are pores between the cells that make the capillary walls permeable to water and solutes
capillaries have a smaller diameter which decreases flowrate
decreasing flow rate facilitates exchange of materials with tissue fluids
The heart has 2 pumps?
1 - systematic
1 - pulmonary
What’s the difference between them?
one deals with oxygenated blood whilst the other deals with deoxygenated
What’s the structure?
2 atria
thin-walled chamber
2 ventricles - thick-walled pumping chambers to separate oxygenated from deoxygenated blood
What is the heart made of?
made of cardiac muscle
myogenic
What is the structure and properties of the heart?
between skeletal and smooth muscle
cells have stripes but lack long fibers
contracts rhythmically without nervous stimulation or hormonal control
Myogenic def?
never tires
What happens during embryonic development in mammals?
the 2 separate pumps grow together to form 1 overall structure
Cardiac cycle def?
the sequence of events in one heartbeat which lasts 0.08s in an adult
consists of 2 alternating contractions which are
systole
diastole
What are the 3 stages?
atrial systole
ventricular systole
diastole
Atrial systole?
atrial walls contract
blood pressure increases
blood forces the tricuspid and bicuspid valves to open, and blood flows into the ventricles
tri?
right
bi?
left
Ventricular systole?
ventricle walls contract
blood pressure increases
blood = forced upwards through the semi-lunar valves ( crescent moon-shaped)
forced through semi-lunar valves to the pulmonary artery + and the rest of the body
Pulmonary artery?
only artery
carries deoxygented blood
blood cannot flow backwards
valves prevent backflow of blood
Aorta?
only artery that has valves
preventing backflow of blood
What does a rise in ventricular pressure cause?
tricuspid + bicuspid valves to close
Diastole?
ventricles relax
volume increases
pressure decreases
which would cause backflow - pressure’s drops
prevented by the semi lunar valves
atria relac, allowing blood from vena cava + pulmonary veins enters atria
Blood moving through the heart?
1)left atrium relaxes to receive oxygenated blood from the pulmonary vein
2) when atria = full, pressure forces bicuspid valve open
3) left ventricle relaxes, allowing blood to flow from the atrium
4) left atrium contracts, expelling remaining blood
5)left atrium relaxes + bicuspid valve closes
left ventricle contracts due to strong muscular wall which exerts high pressure
6) pressure pushes blood out of the heart through the semi lunar valves into the aorta
bicuspid closes to prevent backflow of blood
Summary?
2 sides of the heart simultaenously
Atria contracts almost at the same time
Ventricles contract milliseconds later
heart beat is 1 complete contraction and relaxation
sound made by a beating heart =lub dub created by the atrioventricular valves and the semi lunar valves
if chamber = contracting, its emptying
if chamber = relaxing,its filling
left ventricle = thicker than right, muscular to pump blood around the body
semi lunar valves close under high pressure - due to the contraction
SAN? ( sino arial node
area of the heart muscle in the right atrium that initiates a wave of electrical excitation across the atria to generate contraction of the heart muscle known as a pacemaker
AVN?
atrioventricular node
right in the septum of the heart
SAN?
cluster of specialised cardiac cells from which a wave of excitation spreads over both atris so they contract almost simultaneously
Ventricles?
insulated from the atria by a thin layer of connective tissue
Only at the AVN?
allows conduction as there is no connective tissue in it
creates a delay between atrial and ventricular contractions
allows the muscles of the atria to finish contracting before the muscles of the ventricle contract