Transport In Animals Flashcards
How does an open circulatory system work in insects?
Fluid is pumped directly at low pressure from one main long dorsal tube chapes heart running the length of the body.
Haemolymph bathes tissues directly to allow exchange of substances
When heart relaxes, haemolymph is sucked slowly back to heart
No respiratory pigment as o2 diffuses directly to respiring cells through tracheal system .
How does the closed circulatory system work in mammals and fish?
Blood circulates in fully enclosed blood vessels
Heart is a muscular pump and pushes blood at high pressure and with rapid flow rate
Organs are not in direct contact with blood but are bathed in tissue fluid
Contains respiratory pigment haemoglobin which carries o2
Differences between open or closed circulatory systems
Blood pressure is low in open and high in closed
Haemolymph bathes organs directly in open whereas blood is contained in blood vessels so no direct contact in closed
Blood is pumped to dorsal tubular heart in spaces in body haemocoel cavity in open whereas blood is always within vessels in closed
Blood transported directly to tissues in open whereas blood transported from lungs to heart then body tissues in closed
What is the difference between a single and double circulatory system and give examples
Single- blood passes through heart once in one complete circuit (EG- FISH)
Double- blood passes through heart twice in one complete circulation (EG- MAMMALS)
What are the two circuits in double circulation called?
Pulmonary- all blood vessels involved in transporting all the blood from heart to lungs
Systemic- all blood vessels involved in transporting blood from heart to rest of body EXCLUDING THE LUNGS
What are the advantages of double circulatory system?
Maintains high blood pressure in systemic circulation - increases rate of flow so increased o2 supply to tissues
Allows lower pressure in pulmonary circulation - important because if pressure was too high fluid would build up in lungs
Rapid circulation - o2 and other nutrient can be transported to body tissues quickly and waste can be removed quickly .
Why is it important oxygenated and deoxygenated blood is kept separate ?
To maintain a steep conc gradient for o2 at the tissues and c02 in lungs for gas exchange .
Define an artery and explain the structure
Transports blood away from the heart
Large tunica externa- made from collagen fibres to prevent the overstretching of the elastic fibres
Large tunica media - contains elastic fibres that stretch when the heart contracts and recoil when the heart relaxes to maintain a rich blood flow . It also has smooth muscle which reduces friction between blood and inside of artery
Tunica intima and endothelium that lines the lumen - smooth surface to reduce friction between blood and inside of artery
Small lumen - where the blood flows through . High levels of saturated fatty acids increase LDL particles . Too many can build up an atheroma which reduces lumen size and restrict blood flow to tissues (atherosclerosis)
What is a vein and explain the structure ?
Transports blood to the heart
Irregular shape
Small tunica externa- thinner than artery
Small tunica media- thinner than artery
Smaller tunica intima
Endothelium - smooth surface reduces friction between blood and vessels
Wider lumen than artery - can deliver large volumes of blood back to heart
Contain pocket valves to ensure blood only flows in one direction
Contains fewer elastic fibres than artery
What is a capillary and explain the structure
Smallest vessels that allow exchange of substances with body cells
Thin endothelium wall made from squamous epithelium . Wall permeable to water and dissolved substances like glucose and oxygen
Large cross sectional area .
Blood plasma fluid - fluid can get out of walls of capillary and become tissue fluid
Red blood cells pressed against capillary wall - reduces diffusion distance of O2 and increases time for gas exchange
Why do veins above the heart have no valves
Gravity will draw blood down towards the heart
What is the aorta?
Largest artery and transports blood from heart to body
What is the vena cava
Two veins that carry deoxygenated blood to heart from the upper and lower parts of body
What are the pulmonary arteries ?
Transport deoxygenated blood from heart to lungs where gas exchange takes place
What are pulmonary veins ?
Transports oxygenated blood from lungs back to the heart
What are the coronary arteries?
Supply heart cells with oxygenated blood and glucose
What are coronary veins
Remove deoxygenated blood from cardiac muscle
Summarise blood flow through the heart and around body
Lungs turns blood oxygenated and blood travels to heart in pulmonary vein
Blood enters left atrium
Left atrium contracts (atrial systole) and blood forced into left ventricle through bicuspid valve
Ventricle contracts (ventricular systole ) and bicuspid closes blood forced up into aorta through semi lunar valve
Oxygenated blood leaves heart via aorta and travel to body tissues through open semi lunar valve
Deoxygenated blood from body returns to heart tissues in vena cava
Deoxygenated blood moves from vena cavas into right atrium (diastole)
Right atrium contracts blood moves into right ventricle through tricuspid valve
Right ventricle contracts closing tricuspid valve and forces blood into pulmonary artery through semilunar valve
Deoxygenated blood travels in pulmonary artery towards lungs
Summarise the cardiac cycle
Atria in diastole as they fill up with blood
Atrial pressure higher than ventricular pressure
Av valves open and blood goes into ventricles
Atrial systole occurs forcing blood into ventricles
Ventricular systole - AV valve close
Ventricular pressure higher than atrial pressure so semi lunar valves open . Blood travels in artery
Artery pressure above ventricle pressure do semi lunar valves close to prevent back flow of blood back into ventricles
What is stroke volume?
Volume of blood pumped from left ventricle per beat (APPROX 70 )
What happens to pressure in AV and semi lunar valves in heart
Av valves open when pressure in atria is greater than ventricles
Av valves close when pressure of blood in ventricles is higher than in atria
Semi lunar valves open when pressure in ventricles greater than aorta and pulmonary . They close when pressure in arteries is greater than in ventricles and blood tries to flow back wards
Summarise blood pressure changes in vessels
Arteries - highest pressure occurs in aorta closest to heart . There is a rhythmic rise and fall corresponding to ventricular contraction and relaxation
Arterioles- friction with vessel walls cause drip in pressure . Arterioles have large cross sectional area and narrow lumen causing decrease in aortic pressure . The pressure in Arterioles depends on if they are constricted or dilated
Capillaries - small diameter and friction with walls reduces flow of blood and decreases pressure . Some fluid is forced out of capillaries into the tissues which further reduces blood flow and pressure in capillaries.
Veins - return blood to heart is non rhythmic as the veins are too far from the heart to be affected by contraction and relaxation
Pressure in veins is low but not zero due to massaging effect of the skeletal muscle
Summarise control of heart beat
Heart muscle is myogenic - muscle generates its own contraction, has an inbuilt pacemaker that sends waves of depolarisation causing cardiac muscle to contract without needing to be stimulated by a nerve.
1) wall of right atrium has specialised fibres called sino arterial node which acts as a pace maker
2) wave of depolarisation arises at SAN and they spread over the two atria causing them to contract simultaneously
3) waves of depolarisation are prevented in ventricles by a layer of connective tissue to allow atria to finish contracting
4) after a 0.1 second delay , waves of depolarisation reach the atrio ventricular node . This passes the waves of depolarisation to ventricles
5) Waves of depolarisation are passed down the bundle of his to the apex of heart. Bundle of his branch out into purkunje fibres in ventricular walls which carry waves of depolarisation up through ventricle muscle
6) this causes cardiac muscle in each ventricle to contract from apex up and blood forced up and out of heart.
What is used to monitor heart rhythm
Electrocardiogram
