Transport in Mammals

Question 1

What is the mammalian circulatory system?

Answer 1

the closed, double circulation system by which blood is transported around the mammalian body, consisting of a heart, blood, and blood vessels

Question 2

What are the structural features of arteries?

Answer 2

tunica intima (very smooth, squamous epithelium cells), tunica media (smooth muscle, collagen, elastic fibres), tunica externa (elastic and collagen fibres)

Question 3

What are the functional features of arteries?

Answer 3

strength, elasticity, thick walls, fast transportation of blood, even out blood flow

Question 4

What are the structural features of veins?

Answer 4

tunica intima, media, and externa, but media has far fewer elastic and muscle fibres, semilunar valves

Question 5

What are the functional features of veins?

Answer 5

to return blood to the heart, do not have to withstand high pressure, blood is squeezed up by the tensing of muscles, and kept from running back down by semilunar valves

Question 6

What are the structural features of capillaries?

Answer 6

very small, form a network throughout tissues called capillary beds, thin walls with a single layer of endothelial cells with gaps between them

Question 7

What are the functional features of capillaries?

Answer 7

carry blood to and from cells, connect arteries and veins

Question 8

What are red blood cells?

Answer 8

formed in bone marrow, fragile, biconcave disc, very small, very flexible, no nucleus, mitochondria, or endoplasmic reticulum, carriers of haemoglobin

Question 9

What are lymphocytes?

Answer 9

a type of white blood cell with a large nucleus and small amount of cytoplasm, which destroys microorganisms in different ways, one being the secretion of antibodies

Question 10

What is blood?

Answer 10

made of blood plasma, red and white blood cells, and platelets

Question 11

What is tissue fluid?

Answer 11

leaked plasma from the gaps in cells in capillary walls which seep into the gaps between tissue cells, with far fewer proteins, no red blood cells, and some white blood cells

Question 12

What is lymph?

Answer 12

the fluid inside lymphatics

Question 13

What is blood plasma?

Answer 13

the pale yellow liquid in blood, composed of mostly water, solutes such as glucose and urea, and plasma proteins

Question 14

What is the role of haemoglobin in the blood?

Answer 14

to transport oxygen from the alveoli in the lungs all over the body inside red blood cells

Question 15

What is carbonic anhydrase?

Answer 15

the enzyme in red blood cells that catalyses the reaction: CO2 + H2O > H2CO3

Question 16

What is haemoglobinic acid, HHb?

Answer 16

the compound which forms when haemoglobin combines with the hydrogen ions formed in the dissociation of carbonic acid

Question 17

What is carbaminohaemoglobin?

Answer 17

the compound formed when carbon dioxide in the red blood cells combine with the amine groups of haemoglobin, ten percent of carbon dioxide in the blood is carried this way, this reaction reverses in the alveoli to free haemoglobin so that it can combine with oxygen once again

Question 18

What is the Bohr effect?

Answer 18

higher partial pressure of carbon dioxide causes haemoglobin to release oxygen more readily, plotted on a graph this shifts the curve below and to the right of the normal curve

Question 19

What is the significance of the Bohr effect?

Answer 19

maintains ph of blood by mopping up hydrogen ions from the dissociation of carbon dioxide, causes haemoglobin to release oxygen more readily

Question 20

How does high altitude affect the cardiovascular system?

Answer 20

less oxygen partial pressure at higher altitudes means less oxygen carried in the blood, which can cause altitude sickness, adaptations include higher red blood cell counts, broad chests with larger lung capacity, larger right side of heart, and more haemoglobin

Question 21

What is the internal structure of the mammalian heart?

Answer 21

the left and right atria and left and right ventricles, the left and right side of the heart is separated by the septum, the atria and ventricles are separated by the atrioventricular valves, bicuspid on the left, and tricuspid on the right

Question 22

What is the external structure of the mammalian heart?

Answer 22

the aorta, pulmonary arteries, venae cavae, pulmonary veins, and coronary arteries can be seen on the surface of the heart

Question 23

What are the wall thicknesses of the heart chambers?

Answer 23

walls of the ventricles are much thicker than atria as they need to develop more force, the right ventricle wall is less thick than the left as less pressure is needed to send blood to the lungs

Question 24

What is the cardiac cycle?

Answer 24

the sequence of events in one heartbeat, atrial systole, ventricular systole, ventricular diastole

Question 25

What is atrial systole?

Answer 25

both atria contract, blood flows into the ventricles, backflow is prevented by semilunar valves in the veins, pressure is not that great

Question 26

What is ventricular systole?

Answer 26

ventricles contract, atrioventricular valves are pushed shut by pressurised blood, semilunar valves in aorta and pulmonary artery are pushed open, blood flows from ventricles into arteries

Question 27

How is heart action initiated?

Answer 27

SAN muscle cells contract, producing an excitation wave which makes the muscles in the atrial walls contract simultaneously

Question 28

How is heart action controlled?

Answer 28

a band of fibres between the atria and the ventricles do not conduct the excitation wave, the only way from the atria to the ventricle walls is through the AVN, which passes the wave to the Purkyne tissue after 0.1 seconds, it passes down the septum and causes ventricles to contract from bottom up

Question 29

What is the atrioventricular node?

Answer 29

a patch of conducting fibres in the septum, also known as AVN

Question 30

What is Purkyne tissue?

Answer 30

a bunch of conducting fibres which run down the septum between the ventricles

Question 31

What is an arteriole?

Answer 31

a smaller vessel that an artery branches into, containing a larger proportion of smooth muscle, which can contract to control blood flow into tissues

Question 32

What is a venule?

Answer 32

a smaller vessel that branches into a vein

Question 33

What is a semilunar valve?

Answer 33

a half-moon shaped valve formed from the endothelium of veins, which allow blood to move towards the heart, but not away from it

Question 34

What is oedema?

Answer 34

an excess of fluid which accumulates in the tissues due to too high blood pressure

Question 35

What are lymphatics?

Answer 35

the vessels which collect the ten percent of fluid which does not seep back into the capillaries, and return it to the blood system

Question 36

What are the structural features of lymphatics?

Answer 36

blind-ending vessels containing tiny valves wide enough to allow protein molecules to pass through, and to allow tissue fluid in, but not out, join to form lymph vessels

Question 37

Where is lymph transported?

Answer 37

the subclavian veins

Question 38

What are lymph nodes?

Answer 38

present along the lymph vessels, some white blood cells in the nodes remove bacteria, while others secrete antibodies

Question 39

What are phagocytes?

Answer 39

a type of white blood cell which destroy microorganisms by phagocytosis, neutrophils and monocytes are types of phagocytes

Question 40

What are white blood cells?

Answer 40

made in the bone marrow, have a nucleus, most are larger than red blood cells (excepts lymphocytes), spherical or irregular in shape

Question 41

What is the haemoglobin dissociation curve?

Answer 41

the percentage saturation of a sample of haemoglobin with oxygen plotted against the partial pressure of oxygen, where the partial pressure of oxygen is higher, the percentage saturation of haemoglobin will be higher

Question 42

Why is the haemoglobin dissociation curve S-shaped?

Answer 42

each time an oxygen molecule combines with a haem group, the shape of the molecule distorts, making it easier for successive molecules to bind, causing the curve to rise very steeply

Question 43

What is ventricular diastole?

Answer 43

atria and ventricles relax, semilunar valves in aorta and pulmonary artery are pushed shut, blood flows from veins through atria

Question 44

What is the sinoatrial node?

Answer 44

a myogenic patch of muscle in the right atrial wall, also known as SAN or pacemaker, the natural rhythm of contraction of SAN muscle cells is slightly faster than other cardiac muscle cells