transport in animals🦒🐘🐠 Flashcards
role of the san and avn in the cardiac cycle
san- pacemaker/initiates heartbeat, sends impulse over atria
avn- delays impulse, sends impulse down bundle of his
artery and vein wall differences
- artery has smaller lumen
- artery has thicker wall
- artery has no valves
- artery has more muscle
- artery has more collagen
- artery has endothelium folded
how is high hydrostatic pressure in the arteries generated in the heart
contraction of ventricle
why does hydrostatic pressure of the blood drop as the blood moves away from the heart
- more vessels
- vessels have larger total lumen
- reduced resistance to blood flow
- arteries stretch
- loss of fluid from capillaries
describe what happens to blood plasma at arterial end of capillary
- plasma moves out of capillary down pressure gradient
- forms tissue fluid
- plasma proteins remain in capillary as too large to pass through wall
how are hydrogencarbonate ions produced
- co2 diffuses into erythrocyte, reacts with water to form carbonic acid -catalysed by carbonic anhydrase
- carbonic acid dissociates to form h+ and hco3- ions
what is single circulatory system
blood passes through heart once for each circulation
what is closed circulatory system
blood is maintained inside blood vessels
describe how the action of the heart is initiated and coordinated
- SAN initiates excitation
- wave of excitation spreads over atrial wall
- atrial systole
- delay at AVN
- excitation spreads down septum through Bundle of His
- ventricular systole from apex through purkinje fibres
what is tachycardia and bradycardia
tachycardia- increase in heart rate
bradycardia-decrease in heart rate
in a condition where electrical signals leak from atria directly to top of ventricles, causing ventricles to contract twice for every atrial contraction. what effect might this have on blood flow
- less blood leaves heart for every contraction
- as ventricles are not full before contracting
in the fetus blood flows directly from right to left atrium why
- lungs not functioning
- blood oxygenated in placenta
- lungs bypassed
difference between adult and fetal hb and why is it essential
- higher affinity for o2
- must be able to bind to o2 at lower po2
why no erythrocytes in tissue fluid
-too large to pass through gaps in capillary walls
role of haemoglobin in transporting oxygen
- hb has high affinity for oxygen
- oxygen binds to hb in lungs
- forms oxyhaemoglobin
- oxygen released in tissues
what is the bohr effect
- high concentrations of carbon dioxide in the blood reduce the amount of oxygen transported by haemoglobin
- co2 reduced hb affinity for o2
- alters shape of hb
- more o2 released
how does smoking affect cardiovascular system
- nicotine
- increases stickiness of platelets
- thrombosis
- reduced blood flow
- carbon monoxide
- combines with hb
- reduced o2 carrying capacity of blood
- atherosclerosis
- increased blood pressure
- CHD
why is fetal hb more saturated at lower po2
- placenta has low po2
- adult hb releases o2 at low po2
- fetal hb has higher affinity for o2
- fetal hb still able to take up o2 at low po2 in placenta
how do substances disssolved in blood plasma enter tissue fluid from capillaries
- hydrostatic pressure inside capillaries is higher than in tissue fluid
- capillary walls are leaky
- diffusion down concentration gradient
- plasma forced out of capillary
- small molecules leave with plasma as a result of mass flow
describe pressure changes in blood as it flows from aorta to veins
- pressure drops as distance from heart increases
- greatest pressure drop when blood flows through arteries
- pressure is constant in veins
explain what causes change in pressure from aorta to arteries and from arteries to capillaries
- blood flows into larger number of vessels
- total cross sectional area of arteries is greater than that of aorta
- total cross sectional area of capillaries is greater than that of arteries
advantages of keeping blood inside vessels
- maintain pressure
- increase rate of flow
how is artery wall adapted to withstand and maintain pressure
withstand- folded endothelium
- thick wall
- collagen
- which provides strength
maintain- smooth muscle narrows lumen
-elastin to cause recoil
why is left ventricle thicker than left atrium
- more muscle to create more force
- because needs to create higher pressure
- to push blood against greater resistance
- as it pumps blood to all parts of body
how do pressure changes in the heart cause the AV valves to close
- ventricle contracts
- raises ventricular pressure
- pressure greater in ventricles than in atria
- pressure generated by ventricular contraction pushes valves shut
which component of mammalian circulatory system maintains pressure
aorta/arteries
which component of the mammalian circulatory system is the exchange surface
capillaries
what detail would a scaning electron microscope reveal in a blood smear
3D shape
surface detail
what are the benefits of bohr shift to actively respiring tissue
- actively respiring tissue needs more oxygen
- for aerobic respiration
- actively respiring tissue produces more carbon dioxide
- hb is involved in the transport of co2
- less hb available to combine with o2
- bohr shift causes more o2 to be released
explain gas exchange in fish
- mouth opens buccal cavity expands
- buccal cavity vol increases pressure decreases
- water moves into buccal cavity down pressure gradient
- opercular cavity expands opercular valves are shut
- opercular cavity vol increases pressure decreases
- water moves from buccal cavity to opercular cavity across gills down pressure gradient
- both buccal and opercular cavity constrict
- vol decreases and pressure increases in both
- water pushes valves open and leaves opercular cavity to outside down pressure gradient
adaptations of gills for gas exchange
- lamallae increase surface area
- secondary lamallae on lamallae increase sa
- short diffusion distance between blood and water
- good blood supply maintains concentration gradient
- thin layers for short diffusion distance
- countercurrent exchange system (blood and water flow in opposite directions) maintains concentration gradient
how to dissect fish gill
- remove operculum
- cut out a gill arch which contains the gill filaments
- place in petri dish containing water
difference between mammal and insect gas exchange
- mammal trachae lined with cartilage, insect lined with chitin
- insect trachae branch into tracheoles, mammal trachae branches into bronchi
- mammals have one trachae insects have multiple
explain movement of fluid in and out of capillary
- at arterial end hydrostatic pressure is greater than oncotic pressure so plasma moves out of capillary
- at venous end hydrostatic pressure is lower than oncotic pressure so tissue fluid moves into capillary
where does right semilunar valve lead to
pulmonary artery
why do people with a hole in the septum of the heart easily become tired
- blood leaks from left to right
- less oxygen carried to tissues
- less aerobic respiration
- more oxygenated blood delivered to lungs
- less oxygenated blood pumped around body
heart valves make lub sound at beginning of ventricular systole, what is happening
atrioventricular valves closing and blood leaving ventricles
in mammals where is oxygenated blood
- pulmonary vein
- left side of heart
- aorta
in mammals where is deoxygenated blood
- vena cava
- right side of heart
- pulmonary artery
advantages of double circulation
- only passes through one capillary network before returning to heart (has to pass through two in single)
- blood pressure drops in capillary network
- so double has higher pressure and speed of flow
- maintains steeper concentration gradient
describe insect circulatory system
- open
- haemolymph carried directly from heart to body cavity (haemocoel)
- direct exchange between haemolymph and cells
- haemolymph returns to heart via open ended vessel
how does blood flow through arterioles
arteries-> arterioles-> capillaries
how does blood flow venules
capillaries-> venules-> veins
what is hydrostatic pressure
pressure exerted by a liquid
what is oncotic pressure
osmotic pressure exerted by plasma proteins within a blood vessel, it usually pulls water into the circulatory system
at what end of capillary does tissue fluid form
arteriole
-hydrostatic greater than oncotic
why is tissue fluid reabsorbed
- at venous end, the hydrostatic pressure within capillary is reduced
- water potential gradient between the capillary and the tissue fluid remains the same as at the arterial end
- water begins to flow back into the capillary from the tissue fluid
how does lymph form
- some tissue fluid reenters lymph capillaries instead of regular capillaries
- lymph capillaries have closed capillaries and large pores
- larger molecules that cant enter capillaries enter lymph
- liquid moves along by compression
- backflow prevented by valves
- lymph reenters bloodstream through veins close to heart
- plasma proteins reenter blood through lymph
- lipids transported from gut to blood via lymph
why does tissue fluid not have plasma proteins
water potential lowered so tissue fluid would not be able to be reabsorbed
how does heart receive blood
coronary arteries on surface
