Chapter 8 - Transport in animals

Question 1

pulmonary artery -> artery -> arterioles -> capillary -> venule -> veins -> pulmonary vein

Answer 1

aorta -> artery -> arterioles -> capillary -> venule -> veins -> vena cava

Question 2

Mass transport systems

Answer 2

➜ the bulk movement of materials - involves a force
➜ diffusion involved only at specific exchange sites at the start and end (lungs in gas exchange)
➜ helps with:
- bringing substances quickly from one exchange site to another
- maintain diffusion gradient
- ensure effective cell activity by keeping immediate fluid environment of cells within suitable metabolic range

Question 3

Arteries

Answer 3

➜ 3 layers: tunica adventitia/externa, tunica media and tunica intima
➜ tunica media = smooth muscle cells, thick layer of elastic tissue - thick layer
➜ tunica intima = endothelial layer (one cell thick), connective tissue and elastic fibres (to stretch and recoil to maintain high pressure)
➜ tunica adventitia = exterior of the artery and made up of collagen (to protect blood vessels from over stretching)
➜ pulse in arteries
➜ blood from heart to body
➜ small lumen
➜ oxygenated blood EXCEPT pulmonary artery

Question 4

Arterioles

Answer 4

➜ small arteries which branch from larger arteries and connect to capillaries
➜ possess a muscular layer that means they can contract and partially cut off blood flow to specific organs

➜ layer of smooth muscle - allow to expand and contract but less elastic tissue

Question 5

Capillaries

Answer 5

➜ arterioles branch into capillaries
➜ connect arterioles and venules
➜ adapted for efficient diffusion - one cell thick walls
➜ narrow lumen = reduces flow rate = reduces pressure - only big enough for RBC to pass through one at a time = short diffusion distance and allows for sufficient time for gas exchange to occur
➜ small diameter = therefore large SA:V ratio
➜ cells of the wall have gaps called pores which allow blood plasma to leak out and form tissue fluid
➜ CO2 diffuses out capillary and into alveoli one way and O2 diffuses into capillary from alveoli the other way

Question 6

Venules

Answer 6

➜ small veins which join capillaries to large veins
➜ thin walls
➜ few or no elastic fibres and a large lumen

Question 7

Veins

Answer 7

➜ take blood back to heart under low pressure
➜ tunica media = thin (no high pressure)
➜ wider lumen (allows blood to return to heart at an adequate speed, reduces friction between blood and endothelial layer of vein)
➜ little elastic or muscle tissue
➜ contain valves to prevent backflow of blood
➜ blood flow helped by the contraction of body muscles surrounding them
➜ deoxygenated blood EXCEPT pulmonary vein

Question 8

How is tissue fluid made?

Answer 8

➜ in the arteriole end of the capillary the hydrostatic pressure is greater inside than outside capillary
➜ this forces plasma to come through the permeable walls (pores) of capillary forming tissue fluid
➜ proteins and large molecules stay in the capillary
➜ as plasma leaves hydrostatic pressure reduces in capillaries so hydrostatic pressure is much lower at the venule end of the capillary
➜ at venule end water potential in capillaries is lower than the tissue fluid (more water in tissue fluid as its mainly water)
➜ lowers water potential
➜ due to high oncotic pressure water re enters capillaries from tissue fluid to venule end by osmosis

Question 9

Lymph Vessels and drainage

Answer 9

➜ left over tissue fluid has to go back to blood
➜ smallest lymph vessels = lymph capillaries
➜ excess tissue fluid goes inside lymph capillaries = once inside called lymph
➜ valves in the lymph capillaries stop lymph going back
➜ lymph gradually moves towards the main lymph vessels in the thorax (chest cavity)
➜ here it is returned to blood

Question 10

Blood flow order summary

Answer 10

Deoxygenated blood enters right atrium ➜ via superior and inferior vena cava at low pressure ➜ tricuspid valve opens ➜ blood goes into right ventricle ➜ tricuspid valve closes ➜ right ventricle contracts ➜ blood goes through semilunar valve into pulmonary artery ➜ capillary beds in lungs
➜ now oxygenated blood enters left atrium ➜ via pulmonary vein ➜ bicuspid valve opens ➜ blood goes into left ventricle ➜ bicuspid valve closes ➜ left ventricle contracts ➜ blood goes through semilunar valves into aorta and around body

Question 11

Heart

Answer 11

➜ hollow and protected in chest cavity by pericardium (tough and fibrous sac)
➜ left and right separated by wall = septum
➜ wall separating atrias = interatrial septum
➜ walls separating ventricles = interventricular septum

Question 12

Valves in heart

Answer 12

➜ right atrium and right ventricle are separated by the atrioventricular valve = tricuspid valve
➜ left atrium and left ventricle are separated by the mitral valve, which is otherwise known as the bicuspid valve
➜ right ventricle and the pulmonary artery are separated by the pulmonary valve
➜ left ventricle and aorta are separated by the aortic valve

Question 13

Coronary arteries

Answer 13

➜ heart receives blood through arteries on its surface

Question 14

Atrial Systole

Answer 14

➜ muscle of atria contracts
➜ pressure of atria increase
➜ semi lunar valves close
➜ tricuspid (right AV) and bicuspid (left AV) valve open allowing blood into ventricles
➜ pressure decrease
➜ lasts about 0.1 second

Question 15

Ventricular Systole

Answer 15

➜ muscle of ventricle contracts
➜ pressure of ventricle increase
➜ tricuspid (right) and bicuspid (left) valves close
➜ semi lunar in the aorta and the pulmonary artery open
➜ pressure decrease
➜ blood forced out aorta and pul artery
➜ lasts about 0.3 seconds

Question 16

Diastole

Answer 16

➜ pressure in ventricle decrease
➜ semi lunar valves in aorta and pulmonary artery close
➜ all heart muscles relax
➜ blood flows into atria from vena cava and the pulmonary vein
➜ blood pressure remains low in atria and ventricles
➜ lasts about 0.4 seconds

Question 17

Analysing cardiac cycle

Answer 17

LOOK AT GRAPHS BASED ON CARDIAC CYCLE

Question 18

Nodes SAN

Answer 18

• SAN (sinoatrial node) contains myogenic cells that self-depolarise and initiate a wave of depolarisation along the atrial wall.
• This causes the atrial wall to contract (atrial systole).
• Wave of depolarisation is blocked by non-conducting tissue (Annulus fibrosus) which prevents the depolarisation spreading from the atrium to the ventricles = so atria and ventricle dont contract at same time

Question 19

Nodes AVN

Answer 19

• Wave of depolarisation passes through the AVN (atrioventricular node), an area of conducting tissue between atria and ventricle, which passes wave of depolarisation down the septum through the bundle of His
• Bundle of His spreads out into purkyne fibres to carry this wave of depolarisation and initiate depolarisation from the apex of the heart to the top, resulting in ventricular systole, contracting the ventricular walls.

Question 20

ECG

Answer 20

➜ P wave = contraction (depolarisation) of atria
➜ QRS complex = contraction (depolarisation) of ventricles - largest wave
➜ T wave = relaxation (repolarisation) of the ventricles and atria (diastole)
➜ U wave - scientists uncertain but know it exists
➜ big wave = more electrical charge = stronger contraction

Question 21

Heart rate

Answer 21

➜ number of times a heart beats per minute

Question 22

Stroke volume

Answer 22

➜ volume of blood pumped out of the left ventricle during one cardiac cycle

Question 23

Calculating cardiac output

Answer 23

Cardiac output = heart rate x stroke volume

Question 24

Tachycardia

Answer 24

➜ heartbeat TOOO fast MF
➜ resting rate = over 100 bpm

Question 25

Bradycardia

Answer 25

➜ heartbeat TOOO slow
➜ resting rate = below 60 bpm
➜ fit individuals/athletes have low heart rate = not dangerous

Question 26

Ectopic heartbeat

Answer 26

➜ extra heartbeat
➜ atria contracts too early
➜ possible contraction of ventricle too early
➜ occasional irregular heartbeats is normal in a healthy person but dangerous if its frequent

Question 27

Fibrillation

Answer 27

➜ occurs like during anxiety attack
➜ a really IRREGULAR heartbeat
➜ atria or ventricles completely lose their rhythm
➜ stop contracting properly
➜ lead to chest pain, fainting, lack of pulse or even death

Question 28

Haemoglobin

Answer 28

➜ RBC = erythrocytes
➜ large protein = quaternary structure = 4 polypeptide chains
➜ haem group = contains iron
➜ high affinity for O2
➜ each Hb can carry 4 O2 molecules -oxyhaemoglobin
➜ first O2 binding = hardest, then successive O2 is easier = cooperative binding
➜ reversible reaction

Question 29

Haemoglobin saturation and Partial pressure

Answer 29

➜ partial pressure of O2 (pO2) = measure of O2 conc
➜ (pCO2) measure of CO2 conc
➜ haemoglobin = high affinity = binds easily = dissociates slowly (vice versa use ur brain)
➜ O2 loads onto Hb to form HbO8 when there’s high pO2
➜ HbO8 unloads O2 when there’s low pO2
➜ O2 enters capillaries at the alveoli in the lungs - alveoli = high pO2 so O2 loads onto Hb
➜ cells respire so O2 used up = lowers pO2
➜ red blood cells deliver HbO8 to respiring tissues, where it unloads O2
➜ Hb returns to lungs to pick up more O2

Question 30

Shape of curve for haemoglobin

Answer 30

➜ starts of as shallow curve = hard for first O2 to bind = this is at low pO2
➜ becomes steeper as second O2 (medium pO2) is much easier and becomes easier for third one asw = at high pO2
➜ as there is only one binding site left for 4th O2 it takes longer to bind so graph levels off

Question 31

Fetal haemoglobin

Answer 31

➜ fetal Hb has a higher affinity for O2 than adult Hb
➜ fetus gets O2 from mother’s blood across placenta
➜ when blood reaches mother’s placenta = O2 saturation decreased (used up by mother) - so fetal haemoglobin can bind to oxygen at low pO2
➜ for fetus to get enough O2 to survive, its Hb has higher affinity so its better at absorbing O2
➜ If it was same as adult Hb then blood wouldn’t be saturated enough
➜ on curve = shifts to left of adult one

Question 32

Carbon Dioxide Transport

Answer 32

➜ some CO2 bind to haemoglobin - carbaminohaemoglobin
OR
➜ CO2 diffuse into red blood cells - reacts with water ➜ carbonic acid = catalysed by carbonic anhydrase
➜ carbonic acid dissociates to give hydrogen (H+) ions and hydrogencarbonate ions (HCO3-)
➜ increase in H+ cause HbO8 to unload its O2 so it can take in H+ ions - this forms haemoglobinic acid
➜ HCO3- ions diffuse out of red blood cells and transported in blood plasma
➜ to compensate loss of HCO3-, Cl- ions diffuse into red blood cells = chloride shift
➜ prevents any change in pH
➜ when blood reaches lungs the low pCO2 causes some HCO3- and H+ ions to recombine into CO2 and H2O
➜ CO2 diffuses into alveoli and breathed out