chapter 8

Question 1

what are the three general features of a circulatory system

Answer 1

1) a transport medium which can carry substances through the body
2) a pumping mechanism to pump the fluid through the circulatory system
3) vessels carry the transport medium through the circulatory system

Question 2

what are the four types of circulatory systems

Answer 2

open
single
double
closed

Question 3

explain what a open circulatory system is and how it works in invertebrates such as insects.

Answer 3

insects have an open circulatory system.
the transport medium is called haemolymph can it does not carry any respiratory gases. it only carries nitrogenous waste, food molecules and immune system cells. it is pumped directly from the heart to the hameoceol which is the body cavity.
blood flows through an open circulatory system at a low pressure.
once exchange of this food and nitrogenous waste has taken place at cells the transport medium returns to the heart through an open ended vessel.

Question 4

what is a closed circulatory system and describe how it works in fishes and humans

Answer 4

all vertebrates humans and fishes and certain invertebrates have a closed circulatory system.
the transport medium which is blood is enclosed inside vessels
gases inside the blood can leave through diffusion or by increased hydrostatic pressure (tissue fluid)
closed circulatory systems transport carbon dioxide and oxygen and oxygen is transported by haemoglobin.

Question 5

single circulatory systems

Answer 5

the blood only passes through the heart once per cycle in a single circulation system
fishes have single closed circulatory systems. blood passes through two sets of capillaries. immeditaely after being pumped from the heart, blood passes through capillaries in the gills to become oxygenated. the blood then flows through capillaries delivering oxygen to the body cells and then returns to the heart. this would not be efficient in humans as the blood is not pumped at a high enough pressure however is efficient for fish as they have the counter current flow system which ensures they remove 80 percent of oxygen from the water.

Question 6

double circulatory system

Answer 6

the blood passes through the heart twice for every cycle in the double circulatory system.
birds and most mammals have a double circulatory system.
there are two circulations
the systemic circulation and the pulmonary circuit.
one circuit of blood the pulmonary circuit carries blood from heart to lungs to become oxygenated
the other circuit the systemic circuit carries oxygenated blood from heart to tissues to transfer oxygen to body cells for respiration and to collect carbon dioxide waste from respiring tissue.
blood is pumped at high pessure from heart to lungs but not as high as through systemic circulation as too high pressure of blood could cause edema in the lungs.

Question 7

list the five types of blood vessels involved in double closed circulatory system of humans

Answer 7

-arteries
-veins
-capillaries
-arterioles
-venules

Question 8

Arteries
talk about the smooth muscle layer
the elastic layer
the collagen layer
wall thickness

Answer 8

smooth muscle layer- thicker layer than veins for constriction and dilation to control volume of blood
elastic layer- thicker than veins to maintain high blood pressure
walls can stretch and recoil in response to heartbeat.
collagen layer- collagen outer layer to provide structural support
wall thickness- thicker than veins to maintain blood pressure

Question 9

arterioles- talk about smooth muscle layer
elastic layer
collagen layer
thickness of wall

Answer 9

-arterioles have a thinner collagen wall and a thinner elastic layer as blood pressure is slightly lower however arterioles have a thicker layer of smooth muscle than arteries for constriction and dilation to control blood flow into capillaries as arterioles carry blood from arteries to capillaries.
arterioles are much smaller than arteries. the pressure of blood lowers as it enters arterioles as blood pressure needs to be lower whilst flowing through capillaries to prevent edema.

Question 10

veins
talk about smooth muscle layer
elastic layer
collagen layer
wall thickness

Answer 10

-thinner smooth muscle layer as does not control blood flow.
elastic layer isthinnner than arteries as pressure is relatively low so does not been to be mainted through alot of strecthing and recoiling.
contains lots of collagen
thin wall as pressure is much lower so low risk of vessel bursting. thiness of the wall allows vessel to be flattened which helps bblood flow to the heart.
some veins contain valves which prevent blood from flowing back towards the capillaries, if blood starts to flow backwards the valves close preventing blood from flowing any further in that direction.

Question 11

venules
collagen layer
smooth muscle layer
elastic layer
thickness of the wall

Answer 11

no collagen, no elastic layer, thin layer of smooth muscle. very thin wall several venules join to form a vein.
venules carry blood from capillaries to veins.

Question 12

capillaries
smooth muscle layer
collagen layer
elastic layer
thickness of wall

Answer 12

no smooth muscle, no elastic tissue
no collagen layer
one cell thick consisting of one layer of flattened endothelium.
provides a short diffusion distance between exchanging material between blood and cells.
they are very small but numerous, provide a large surface area for the diffusion of substances into and out of blood
red blood cells are pushed against the endothelium which slows the movmement of blood allowing more time for gas exchange.
adaptationsof capillaries
-increase surface area for diffusion
-thin layer of flattened endothelium and so short diffusion distance for gas exchange between cells and blood
- the capillaries are very narrow and one red blood cell thick, the red blood cell is pushed against the endothelium which slows down the movmement of blod and allows more time for gas exchange.
-narrow diameter to slow blood flow.
the pressing against the walls of the red blood cells maximises diffusion

Question 13

Tissue fluid- what is it

Answer 13

the fluid surrounding the tissue, plasma that has been forced out of capillary at arteriole end due to high hydrostatic pressure.

Question 14

what are the two pressures that interact to form tissue fluid

Answer 14

hydrostatic pressure- pressure exerted by liquid
oncotic pressure- osmotic effect which causes water to leave the blood in the capillaries

Question 15

arteriole end of the capillary

Answer 15

-at the arteriole end of the capillary, as the diamater of the arteriole is larger than the diameter of the capillary, blood enters the capillary at a high hydrostatic pressure. this forces plasma out of the capillaries forcing out glucose, amino acids, fatty and ions out of the capillary. larger molecules such as plasma proteins however are too large to fit through the endothelium and so these remain inside the capillary and lower the water potential of the blood inside the capillary

Question 16

venule end of the capillary

Answer 16

as the blood pressure decreases when flowing through the capillaries, the hydrostatic pressure falls and as the plasma proteins have loweredthe water potential inside the capillary, the oncotic pressure is higher than the effect of the hydrostatic pressure and so tissue fluid will be rebasorbed into the capillary as plasma.

Question 17

what is the reason for the high hydrostatic pressure at the arteriole end of the capillary

Answer 17

the diameter of the arteriole is wider than the diameter of the capillary and so the blood is now going to have to flow through a smaller space, leading to a high hydrostatic pressure.

Question 18

what is lymph how is it formed

Answer 18

when the oncotic pressure is higher than the hydrostatic pressure at the venule end of the capillary, the water from the tissue fluid is reabsorbed into the capillary until equilibrium of the water potential is reached and so the remaining liquid outside the capillary is called lymph.

Question 19

how is the composition of lymph different or similar to plasma

Answer 19

lymph has a similar composition to plasma however does not contain soluble plasma proteins unlike the plasma. but does contain glucose, amino acids, fatty acids and ions like the plasma. lymph also has less oxygen as this has been absorbed by the body cells.

Question 20

fully explain how tissue fluid is formed and how lymph is formed?
key words- tissue fluid, lymph, capillary, arteriole end, venule end, hydrostatic pressure, oncotic pressure, plasma, reabsorption.

Answer 20

The arteriole end of the capillary has a wider diameter than the capillary and so the blood is flowing through a smaller space at the same pressure, this leads to an increase in hydrostatic pressure at the arteriole end which forces out blood plasma. This forces out glucose, amino acids, fatty acids and ions out of the capillary. This is now referred to as tissue fluid as it surrounds the tissues. As there is a loss of liquid, this results in a lower hydrostatic pressure at the venule end of the capillary. Plasma proteins remained in the capillary as they were too large to fit through the endothelium and so they lower the water poetntial of the blood plasma in the capillary. Water from the tissue fluid is reabsorbed until equilibrium is reached. The liquid remianing outside of the capillary is called lymph and this has a similar composition to plasma however lacks plasma proteins and oxygen as this has been absorbed by the body cells. the lymph is drained in the lymph nodes and ultimately drained in the chest.

Question 21

the heart definition

Answer 21

an organ which is made of cardiac muscle and pumps blood around the body

Question 22

what is important about the cardiac muscle.

Answer 22

cardiac muscle is myogenic, it contracts without signals from the brain and never fatigues.

Question 23

what are the roles of the heart’s own vessels.

Answer 23

• coronary arteries supply the heart muscle with oxygen and nutrients for respiration to provide ATP so that the cardiac muscle can contract and relax
  -cardiac veins- remove carbon dioxide and waste from the respiring heart muscle

Question 24

what is the name of the membranes that surround the heart

Answer 24

pericardial membranes- inelastic membranes prevent the heart from filling and swelling with blood

Question 25

the internal structures of the heart
left ventricle
right ventricle
the two atria

Answer 25

the left ventricle has a thicker muscular wall as blood is pumped from the left ventricle all around the body at a high pressure so that it reaches all areas.
The right ventricle has a thinner muscular wall as blood needs to be flowing slowly to allow time for gaseous exchange and to prevent edema.
the atria both have very thin muscular walls because they only pump blood to the ventricles so minimal pressure and force is required.

Question 26

cardiac cycle
diastole
atrial systole
ventricular systole

Question 27

cardiac cycle definition

Answer 27

sequence of events that take place in one heartbeat.

Question 28

diastole

Answer 28

the atria and ventricular muscles are relaxed.
blood will enter the atria through the vena cava and the pulmonary vein.
asthe blood has flown into the atria this increases the pressure inside the atria

Question 29

atrial systole

Answer 29

the muscular walls contract.
this increases the pressure further causing the atrioventricular valves to open
blood flows into the ventricles
the ventricular muscular walls are relaxed
ventricular diastole.

Question 30

ventricular systole

Answer 30

after a short delay, the ventricular muscle contracts increasing the pressure of the ventricles beyond that of the atria and so the atrioventricular valves close and the semi lunar valves open pushing blood from the ventricles into the pulmonary artery and aorta

Question 31

explain the whole process of the cardiac cycle

Answer 31

the cardiac cycle involves the diastole, atrial systole and ventricular systole.
in the diastole, the atrial and ventricular muscular walls are relaxed. Blood enters the atria from the pulmonary vein and the vena cava. the flow of blood into the atria increases the pressure.
atrial systole- the muscular wall of the atria begin to contract increasing the pressure further and causing the atrioventricular valves to open pushing the blood through the atria into the ventricles. the ventricular muscle walls are relaxed ( ventricular diastole)
ventricular systole- after a short delay the ventricular muscular wall begins contracting the increasing the pressure beyond that of the atria and so closing the atrioventricular vlaves and opening the semi lunar valves pushing blood into the aorta and pulmonary artery.

Question 32

cardiac output definition

Answer 32

the volume of blood which leaves one ventricle in one minute

Question 33

formula of cardiac output

Answer 33

stroke volume x heart rate
stroke volume- volume of blood that leaves the heart in one beat dm^3
heart rate- beats min^-1

Question 34

electrical activity of the heart
SAN
AVN
Bundle of his
purkyne fibres

Answer 34

1) the SAN releases a wave of depolarisation across the atria causing them to contract.
2) The avn releases another wave of depolarisation after it recieves the first however there is a layer of non conducting tissue between the atria and ventricles so the electrical exitation must be passed down to the bundle of his.
3) the bundle of his conducts a wave of depolarisation down the septum and purkyne fibres
4) the apex and walls of ventricles contract. This allowed time for the atria to completely empty before the ventricles were filled.
5) the muscles relax and the cells repolarise.

Question 35

electrocardiograms- what are they used for

Answer 35

can measure the waves of depolarisation (electrical activity of the heart) which can be interpreted to identify any irregularities in the heart rythm.
the ecg does dont directly measure electrical activity, it measures tiny electrical differences in the skin which are caused by electrical activity of the heart.
electrodes are stuck to clean skin

Question 36

abnormal heart rythms
-tachychardia
-bradychardia
-ectopic heartbeat
-fibrillation

Answer 36

tachychardia- the heart rate is too fast, the heart is beating over 100bpm. normal during exercise but abnormal during rest
bradychardia- heart rate is too slow heart is beating less than 60bpm. many athletes may have bradychardia as they are so fit that their cardiac muscle can contract harder so fewer contractions are needed. if heart rate drops too low an artifical pacemaker may be needed. to regulate the heart rate.
fibrillation- irregular rythm of the heart.
ecotopic heartbeat- additional heartbeats that are not in rhythm

Question 37

what is myoglobin

Answer 37

consists of a single polypeptide chain and is found in muscles in vetebrates.

Question 38

oxyhaemoglobin dissociation curve what does it show

Answer 38

it shows that in high partial pressures of oxygen for example in the alveoli, haemoglobin loads oxygen and at low partial pressures of oxygen, haemoglobin unloads oxygen e.g in respiring tissue the curve shows that the percentage saturation is low when partial pressures of o2 is low this is because the haemoglobin has a lower affinity of oxygen as it is unloading oxygen at respiring tissue. it shows that haemoglobin has a higher affinity for oxygen at higher partial pressures as haemoglobin loads oxygen at the alveoli.

Question 39

co-operative binding-

Answer 39

the co-operative nature of oxygen binding to haemoglobin is due to the haemoglobin changing shape when the oxygen first binds. this makes it easier for further oxygens to bind.

Question 40

the chloride shift

Answer 40

-maintaining the electrical balance of red blood cells as hco3- diffuse out of red blood cells into blood plasma and cl- ions from blood plasma diffuse into red blood cell.