chapter 8 - animal transport

Question 1

features of an effective transport system

Answer 1

• a fluid to carry oxygen and glucose around the body
• exchange surfaces that enable oxygen and glucose to enter and leave the blood
• a pump to create pressure that will push the fluid around the body
• tubes/vessels to carry the blood
• two circuits; one to pick up oxygen and another to take it to the tissues

Question 2

closed circulatory system

Answer 2

blood stays entirely inside vessels; a separate fluid bathes the cells called tissue fluid

Question 3

open circulatory system

Answer 3

blood is not always contained within vessels but circulates the body cavity
cells are bathed in blood

Question 4

haemocoel

Answer 4

the body cavity where blood circulates in open circulatory systems; “blood space”

Question 5

single circulatory systems

Answer 5

blood only flows through the heart once for each complete circuit of the body

Question 6

double circulatory systems

Answer 6

blood flows through the heart twice for each complete circuit of the body

Question 7

pulmonary circulation

Answer 7

blood pumped from the heart to the lungs and then returns to the heart

Question 8

systematic circulation

Answer 8

blood is pumped from the heart around the body and the returns to the heart

Question 9

function of arteries

Answer 9

carry high pressure blood away from the heart

Question 10

adaptations of arteries

Answer 10

• thick artery wall to withstand pressure
• relatively narrow lumen to maintain pressure
• inner wall is elastic and folded to allow the lumen to expand when blood flow increases
• thick layer of smooth muscle and elastic fibres for contriction and dilation

Question 11

function of capillaries

Answer 11

allows the exchange of materials between blood and tissue fluid

Question 12

adaptations of capillaries

Answer 12

• very narrow lumen to shorten the diffusion path to tissues and reduces rate of flow
• walls are one cell thick
• walls are leaky allowing plasma and dissolved substances to leave the blood

Question 13

function of veins

Answer 13

carry low pressure blood to the heart

Question 14

adaptations of veins

Answer 14

• have thinner walls as they do not need to withstand pressure
• large lumen to reduce resistance to flow
• little smooth muscle
• contains valves to prevent backflow

Question 15

function of coronary arteries

Answer 15

supply the heart muscle cells with oxygen and glucose for aerboic respiration

Question 16

cause of angina

Answer 16

restricted flow in coronary arteries

Question 17

cause of myocardial infarction (heart attack)

Answer 17

blockage of coronary arteries causing heart muscles to be deprived of oxygen and glucose leading to cell death

Question 18

features of cardiac muscle

Answer 18

• myogenic
• cells are branched
• joined by intercalated discs
• contain many mitochondria

Question 19

myogenic

Answer 19

can generate its own exitory impulse; contracts and relaxes without any stimulation from nerves

Question 20

atrial systole

Answer 20

• muscle in the walls of both atria contract
• small increase in pressure
• forces blood into ventricles through open atrioventricular valves
• ventricle fills with blood and walls stretch
• semi-lunar valves are closed preventing backflow

Question 21

ventricular systole

Answer 21

• thick, muscular ventricle walls contract
• increases pressure
• pressure in ventricles is greater than in atria
• pushes atrioventricular valves shut
• semi-lunar valves open
• blood is forced into aorta and pulmonary artery

Question 22

diastole

Answer 22

• atria and ventricles relax
• pressure in ventricles decreases
• semi-lunar valves close
• blood from veins flow into atria
• pressure in atria is higher than in ventricles
• atrioventricular valves open
• blood flows into ventricles

Question 23

role of sino-atrial node (SAN) in the cardiac cycle

Answer 23

small patch of tissue in the wall of the right atrium which initiates an electrical wave of excitation (depolarisation) which passes over the walls of both atria causing them to contract

Question 24

role of non-conducting collagen fibres between atria and ventricles

Answer 24

prevents the electrical wave passing through to the ventricles

Question 25

atrio-ventricular node (AVN)

Answer 25

a small gap in the non-conducting collagen fibres which allows the wave of depolarisation through with a small delay (0.1s)

Question 26

role of Purkyne tissue in the cardiac cycle

Answer 26

electrical wave travels down the Purkyne tissue which runs down the septum and then transmits the excitation very rapidly to the apex of the ventricles and upwards and outwards through the ventricle walls causing the muscles to contract from the bottom up

Question 27

hormonal changes that can affect heart rate by changing pace of SAN

Answer 27

adrenaline released into bloodstream causing heart rate to increase

Question 28

nervous changes that affect heart rate by changing pace of SAN

Answer 28

cardiovascular centre in medulla oblongata connects to SAN vagus nerve causes SAN to reduce accelerans nerve causes SAN to increase

Question 29

bradycardia

Answer 29

long T-P, slow heart rate (below 60bpm), severe cases may require a pacemaker

Question 30

tachycardia

Answer 30

short T-P, fast heart rate (over 100bpm), can occur during exercise/stress, severe cases may require medication or surgery

Question 31

ectopic heartbeat

Answer 31

heartbeat is irregular apart from one ectopic heartbeat, ventricle has contracted too soon and a compensatory pause follows

Question 32

atrial fibrilation

Answer 32

rapid irregular electrical impulses in atria, atria contract too fast but not fully, no distinguishable P waves, normal QRS complex

Question 33

ventricular fibrilation

Answer 33

rapid and irregular electrical activity, ventricles unable to contract in a synchronised manner, immediate loss of cardiac output, unless advanced life support is rapidly provided this rhythm is fatal

Question 34

cardiac output calculation

Answer 34

cardiac output = stroke volume x heart rate

Question 35

tissue fluid

Answer 35

fluid that bathes cells in tissues, formed from plasma that leaks out of capillaries, essential for exchange of materials between cells and blood

Question 36

formation of tissue fluid

Answer 36

- at arteriole end, blood is at high hydrostatic pressure - pushes fluid through gaps in capillary walls - tissue fluid has small hydrostatic pressure in opposite direction - oncotic pressure acting inwards due to presence of plasma proteins - net pressure forcing fluid out of capillary

Question 37

oncotic pressure

Answer 37

pressure created by the osmotic effects of the plasma protein

Question 38

hydrostatic pressure

Answer 38

pressure exerted by a fluid

Question 39

returning of tissue fluid

Answer 39

- at venule end, hydrostatic blood pressure is much lower - plasma proteins too large to fit out through gaps in walls so oncotic pressure stays the same - net movement of fluid into capillary due to higher oncotic pressure than hydrostatic

Question 40

how is fluid returned to the blood system? (if not returned directly to capillaries)

Answer 40

via a series of tubes called lymph vessels

Question 41

lymph vessels

Answer 41

tiny blind-ending vessels found in almost all tissues of the body

Question 42

haemoglobin

Answer 42

a globular protein made of 4 polypeptide chains, each containing a haem prosthetic group, can contain 8 oxygen molecules

Question 43

taking up oxygen

Answer 43

- in alveoli, oxygen molecules diffuse into blood plasma - oxygen binds to haemoglobin forming oxyhaemoglobin - taking oxygen out of solution maintains a steep concentration gradient - more oxygen enters blood

Question 44

releasing oxygen

Answer 44

oxyhaemoglobin dissociates releasing oxygen

Question 45

ways that CO2 is carried in blood

Answer 45

1. dissolved in blood plasma 2. combines directly with haemoglobin forming carbaminohaemoglobin 3. diffuses into erythrocytes where carbonic anhydrase catalyses the coversion of CO2 and H2O into H2CO3

Question 46

the chlorine shift

Answer 46

hydrogen carbonate ions diffuse out of the erythrocyte into the plasma which causes chloride ions to enter the erythrocyte to balance the charge

Question 47

the bohr effect

Answer 47

haemoglobin takes up H+ ions (from CO2 reacting with water) to form haemoglobinic acid which reduces the affinity of haemoglobin for oxygen so oxyhaemoglobin releases its oxygen

Question 48

myoglobin

Answer 48

a pigment fount in skeletal muscles that acts as an oxygen store in the muscles

Question 49

differences between fetal and adult haemoglobin

Answer 49

fetal haemoglobin has a higher affinity for oxygen because the partial pressure in the placenta is very low

Question 50

explain why an oxygen dissociation curve is sigmodial (s shaped)

Answer 50

- co-operative binding of oyxgen to haemoglobin - first oxygen cannot bind easily - this changes the shape of haemoglobin - following oxygens bind more easily - first oxygen is the hardest to remove from oxyhaemoglobin