7.3 MASS TRANSPORT- circulatory system

why do multicellular organisms require a cardiovascular system?

it would take days for molecules to diffuse through a large animal through diffusion. so they need a circulatory system with a pump to transport materials quickly around their bodies

what is a mass flow system

the transport of substances in a flow of fluid

what is an example of mass flow systems in plants

transport of materials in the xylem and phloem

what do mass flow systems work alongside?

specialised exchange systems like lungs, gills, leaves

the need for a mass transport system with a pump depends on what 2 things?

surface area to volume ratio

how metabolically active the organism is, e.g. flight

in humans, where does the right side of the heart pump to?

lungs only- pulmonary circulation

in humans, where does the left side of the heart pump blood to?

the rest of the body- systemic circulation

what is a closed circuit system

the transport medium is confined to vessels

what system do vertebrates have

closed circuit system

what does the vena cava do

carry deoxygenated blood from the body to the heart

what does the pulmonary vein do

carries oxygenated blood from the lungs to the heart

what does the pulmonary artery do?

carries deoxygenated blood to the lungs

what does the aorta do

carries oxygenated blood to the body

what does the hepatic artery do

bring oxygenated blood to liver

what does hepatic portal vein do

carries blood from stomach and intestines to the liver

what does the hepatic vein do

carries deoxygenated blood from the liver to the heart

what does the renal artery do

carries oxygenated blood into kidneys

what does the renal vein do

carries deoxygenated blood away from the kidneys

what percentage of plasma is water

90 percent

what are 2 properties of blood

good solvent, high heat capacity

what are the 5 functions of blood

transport- dissolves gases, hormones, soluble food, enzymes, antibodies, blood cells

maintains body temperature- distribute heat around body.

buffers ph- blood must stay at 6.8-7.4 or it will damage cells

regulation of body fluid electrolytes- excess ions are removed from the body in urine, ma contain 10g NaCl per day

defence: by white blood cells and blood clotting

what is the top liquid part of this blood sample?

plasma- liquid part of blood. a dilute solution of salts, glucose, amino acids, vitamins, urea, proteins, fats

what is the first small layer in this blood sample?

white blood cells involved in the immune system

what is the second small layer in this blood sample?

platelets involved in blood clotting

what is the bottom liquid in this blood sample?

red blood cells involved in carrying oxygen

what do arteries do

carry blood away from the heart and into centrioles

what are atrioles

smaller arteries that control blood flow from arteries to capillaries

what are capillaries

tiny vessels that link atrioles to veins

what do veins do?

carry blood from capillaries to heart

what 5 things do arteries/arterioles/veins have similar in structure? (simplified)

tough fibrous outer layer, muscle layer, elastic layer, thin inner lining, lumen

what does the tough fibrous outer layer do in arteries/arterioles/veins?

resists pressure changes from both within and outside

what does the muscle layer do in arteries/atrioles/veins?

can contract and therefore controls the flow of blood

what does the elastic layer do in arteries/arterioles/veins?

helps to maintain blood pressure by stretching and recoiling

what does the thin inner lining (endothelium) do in arteries/arterioles/veins?

smooth to reduce friction, thin to allow diffusion

what is the lumen in arteries/arterioles/veins?

central cavity of blood vessels, blood flows through

function of capillaries

allows exchange of materials between the blood and the tissues via tissue fluid

do veins and venules have thick or thin walls

thin walls, mainly collagen, since blood at low pressure

do capillaries have thick or thin walls

very thin, permeable walls, only one cell think to allow exchange of materials

do arteries and arterioles have thick or thin walls and why

thick walls, smooth elastic layers: resist higher pressure

muscle layer to aid pumping

how large is the lumen in veins and venules?

large to reduce resistance to flow

how large is the lumen in capillaries

very small- blood cells must distort to pass through and so slow down

how big is the lumen in arteries/arterioles

small lumen to maintain high pressure

do veins and venules have valves

many valves to prevent backflow

do capillaries have valves

no

do arteries and arterioles have valves

no

what is the blood pressure in the veins and venules

lower pressure

what is the blood pressure in the capillaries

blood pressure falls

what is the blood pressure in arteries and arterioles

high

is the blood oxygenated in the veins and venules?

usually deoxygenated, except pulmonary vein

is the blood oxygenated in the capillaries

changes from oxygenated to deoxygenated, except in lungs

is blood oxygenated in arteries and arterioles?

usually oxygenated except in pulmonary artery

what are the 2 phases of the cardiac cycle

systole, diastole

what is the cardiac cycle (definition)

the sequence of coordinated contractions of the different chambers of the heart

why is the coordination of the contractions so important?

there wouldnt be the right pressure

what is the mass flow system that multicellular organisms use

circulatory system/cardivascular system

how is mass flow achieved in animals

use muscular contraction- either of body muscles or a specialised pumping organ e.g. heart

mass flow in plants (1 main point, 3 sub)

rely on natural/passive processes like evaporation of water:

mechanism to maintain mass flow movement in one direction

means of controlling flow in transport medium for changing needs of different parts of an organism

mechanism for mass flow of water

features of a transport system

• suitable medium to carry materials e.g. blood- liquid based- water dissolves substances, moved around easily, can be gas in lungs

• transport medium moved in bulk over large distances- more rapid than diffusion.

• closed system of tubular vessels that contain transport medium, forms branching network, distribute it to all parts of an organism

what is the heart made of

cardiac muscle

what is cardiac muscle made of

myocytes

what do myocytes do

when receive electrical impulse, they contract together, causing heartbeat.

constantly active so have great oxygen requirements, so fed by numerous capillaries from two coronary arteries.

what do blockages in the coronary arteries cause

myocardial infarction (heart attack)- caused by lack of oxygen to cardiac muscle

what is the order of the cardiac systole

diastole, atrial systole, ventricular systole

what happens in diastole

• Atria + ventricles are relaxed (cardiac diastole).

• Blood returns to heart via pulmonary veins/vena cava and enters atria.

• Pressure in atria is greater than in the ventricles.

• Atrioventricular (AV) valves open.

• Semilunar valves closed.

• Blood flows passively from atria into ventricles.

what happens in atrial systole

• Atria contract.

• Ventricles remain relaxed.

• Pressure in the atria increases.

• Atrioventricular (AV) valves are open.

• Semilunar valves are closed.

• Blood is forced/pumped from the atria into the ventricles.

• This completes ventricular filling.

what happens in ventricular systole

• Ventricles contract and their walls thicken.

• Ventricular pressure increases.

• Atrioventricular (AV) valves close.

• Semilunar valves open.

• Blood is forced from the right ventricle into the pulmonary artery and from the left ventricle into the aorta.

• Atria remain relaxed and fill with blood.

explain how the highest blood pressure is produced in the left ventricle

thick muscular wall causes stronger contractions

some babies are born with a hole between the right and left ventricles. these babies are unable to get enough oxygen to their tissues. suggest why

deoxygenated blood and oxygenated blood mix

lower volume of oxygenated blood leaving the left ventricle

not enough oxygenated blood reaching tissues to respire

what is the function of the coronary arteries

blood vessels that provide oxygen and glucose to the heart itself as a muscle

the rise and fall in blood pressure in the aorta is greater than in the small arteries. suggest why

aorta flows directly out of left ventricle, therefore has much higher pressure

pressure increases and decreases as ventricles contract and relax

aorta has thick elastic tissue which can stretch and recall, maintains constant pressure so blood flowing through smaller arteries is more constant

what is happening at the pink line? (describe changes in atrial pressure)

• Atrial pressure relatively low throughout- thin muscular walls, contract with less force than ventricles.

• Pressure rises during atrial systole- atria contract, force blood into ventricles.

• Pressure falls- atria relax and the atrioventricular (AV) valves close.

• Blood returns to atria from veins, atria fill, pressure gradually increases.

• When AV valves open, blood flows into ventricles and atrial pressure decreases slightly.

whats happening at the green line?

ventricular volume rises as atria contract and ventricles fill with blood

drops suddenly as blood is forced out into aorta when semilunar valve opens

volume increases again as ventricles fill with blood

whats happening at the yellow line?

ventricular pressure is low at first, gradual increase as ventricles fill with blood as atria contract

left av valves close causing a large pressure rise as muscular ventricular walls contract

as pressure rises above the aortas pressure, blood is forced into aorta through the semilunar valves.

pressure falls as ventricles empty and walls relax

what is happening at the light pink line?

aortic pressure rises when ventricles contract as blood is forced into aorta

pressure gradually falls, never below 12kpa because of the elasticity of its walls, creating a recoil action.

recoil action is essential as blood is constantly delivered to tissues

recoil produced temporary rise in pressure at the start of relaxation phase