3.2 Transport in Animals

Question 1

why do multicellular animals need transport system?

Answer 1

. small surface area to volume ration

. short diffusion distance

. high metabolic rate

. size of larger animals

Question 2

what are the different types of circulatory systems?

Answer 2

. open- blood is not enclosed within vessels

. closed- blood is enclose within vessels

. single- blood passes the heart once

. double- blood passes the heart twice.

Question 3

what is the structure and function of the arteries?

Answer 3

. carry blood away from the heart to the rest of the body at high pressure

. thick wallsans small lumen to withstand high blood pressure

. elastic tissue which allows them to stretch and recoil which smooths blood flow

. smooth muscle enables them to vary blood flow

. smooth endothelium to reduce friction and ease flow of blood

Question 4

what is the structure and function of the arterioles?

Answer 4

. branch off arteries

. have thinner and less muscular walls . . their role is to feed blood into capillaries

Question 5

what is the structure and function of the capillaries?

Answer 5

.smallest blood vessels

. site of metabolic exchange

. only one cell thick for fast exchange of substances as it reduces diffusion distance

. walls are leaky to let fluid proteins to leak out

Question 6

what is the structure and function of the venules?

Answer 6

larger than capillaries but smaller than veins

Question 7

what is the structure and function of the veins?

Answer 7

. carry blood from the body to the heart at low pressure

. contain a wide lumen to maximise volume of blood carried to the heart . . thin walled as blood is under low pressure

. valves to prevent backflow of blood, . no pulse of blood meaning there’s little elastic tissue or smooth muscle as there is no need for stretching and recoiling

Question 8

what is tissue fluid?

Answer 8

• contains dissolved oxygen and nutrients which it
  supplies the tissues withexchange for waste products such as carbon dioxide.
• enables exchange of substances between blood and cells.

Question 9

how does tissue fluid form from plasma?

Answer 9

1. at arterial end hydrostatic is greater than, oncotic and fluid / plasma moves, out capillary
2. at venous end hydrostatic is lower than, oncotic so tissue fluid moves into capillary

Question 10

remaining tissue fluid goes to the lymphatic system, what is this?

Answer 10

drains waste products from tissue fluid

Question 11

what is the difference in composition in the blood, tissue fluid and lymph?

Answer 11

blood : contains erythrocytes, neutrophills, platelets, proteins, water and dissolved solutes

tissue fluid: contains few neutrophills, few proteins, water, and dissolved solutes

lymph: contains neutrophills, water and dissolved solutes

Question 12

what is the external structure of the heart?

Answer 12

• superior vena cava
• inferior vena cava
• aorta

-pulmonary veins

• coronary arteries
• pulmonary arteries

Question 13

what is the internal structure of the heart?

Answer 13

• superior and inferior vena cava
• left and right atrium
• left and right ventricle
• aorta
• pulmonary veins
• pulmonary arteries
• AV valves
• Semilunar valves

Question 14

describe atrial systole

Answer 14

• ventricles are relaxed
• atria contract, decreases volume and increases the pressure
• blood is pushed into the ventricles through the AV valves
• there is a slight increase in ventricular pressure and volume as blood is ejected into the ventricles

Question 15

describe ventricular systole

Answer 15

• atria relax
• ventricles contract, increases pressure in the ventricles than the aorta so the AV valves close, to prevent back flow of blood
• this high pressure in the ventricles cause the Semi-lunar valves to open and blood is forced out into the pulmonary artery and aorta

Question 16

describe diastole

Answer 16

• ventricles and atria relax
• the high pressure in the pulmonary and aorta cause the Semi-lunar valve to close, to prevent back flow of blood
• atria fills with blood, increasing their pressure
• ventricles continue to relax

Question 17

describe how heart action is initiated by the SAN

Answer 17

• generaties a wave of excitation that spreads to the atrial walls to contract

Question 18

describe how heart action is initiated by the AVN

Answer 18

• Depolarisation passed into conducting fibres, known as Bundle of His.
• Purkinje fibres carry the wave upwards to the ventricles
• This delay enable the ventricles to fill with a sufficient amount of blood before contracting.

Question 19

how to calculate cardiac output

Answer 19

heart rate x stroke volume

Question 20

What do the different waves mean in ECG’s

Answer 20

• QRS complex : activation of ventricles
• P wave : activation of atria
• T wave : recovery wave

Question 21

what are some examples of ECG’s ?

Answer 21

• fast heartbeat : tachycardia
• slow heartbeat : bradycardia
• irregular heartbeat : fibrillation
• extra heartbeat : ectopic heartbeat

Question 22

Define oxygen association

Answer 22

in the lungs, at high pO2 Hb affinity increases and binds easily with O2

Question 23

Define oxygen dissociation

Answer 23

in the blood, pO2 decreases and Hb affinity decreases so O2 is released to respiring cells and tissues

Question 24

Define affinity and its relation with oxygen

Answer 24

• Affinity is how well substances combine (liking for another substance)
• Hb has a high affinity for O2 in lungs because the high O2 lvls whereas Hb releases O2 in blood because O2 lvls decrease

Question 25

describe the oxygen dissociation curve

Answer 25

-shows the rate at which oxygen associates, and also dissociates, with haemoglobin at different partial pressures of oxygen (pO2) - when pO2 lvls are high Hb has a higher affinity for O2 and so will associate - when pO2 lvls are low Hb releases O2 and dissociates

Question 26

why does respiration do to the availability of oxygen?

Answer 26

- Decreases partial pressure, in turn decreasing affinity of oxygen for haemoglobin. - As a result, oxygen gets released to respiring tissues where needed.

Question 27

how is carbon dioxide transported?

Answer 27

- CO2 reacts with water to form carbonic acid, catalaysed by carbonic anhydrase - carbonic acid dissociates into hydrogen and hydrogencarbonate ions - the increase of hydrogen ions means that oxyhaemoglobin unloads its O2 so haemoglobin takes hydrogen ions - this forms haemoglobonic acid - this process stops the cell's acidity from increasing - the hydrogen carbonate ions diffuse out of the red blood cells and transported to the blood plasma (chloride shift) - when blood reaches the lung the low pCO2, the process is reversed - H2CO3 -> H20 + CO2 - CO2 diffuses into alveoli and is breathed out

Question 28

what is the chloride shift?

Answer 28

HCO3- ions move out of red blood cells into the blood plasma RBC are more +ve Cl- ions move into RBC to prevent an electrical imbalance

Question 29

what is the Bohr effect?

Answer 29

more CO2 produced so more O2 released

Question 30

what effect does tachycardia have on blood flow

Answer 30

- ventricles dont have enough time to refill - less blood leaves ventricles to rest of body/lungs

Question 31

what is the difference between fetal and adult haemoglobin

Answer 31

fetal Hb has a higher affinity for oxygen must be able to bind to oxygen at lower pO2 in placenta

Question 32

why does tissue fluid not contain erythrocytes

Answer 32

too big to pass through gaps in endothelial cells

Question 33

describe and explain how substances that are dissolved in the blood plasma e.g Oxygen and glucose enter tissue fluid from the capillaries

Answer 33

capillary walls are leaky diffuse down a concentration gradient high hydrostatic pressure pushes plasma out of the capillaries into the surrounding tissue fluid

Question 34

why is the cartilage essential in the trachea

Answer 34

strength and support to prevent it from collapsing flexible to keep airway open

Question 35

what are two advantages for keeping the blood enclosed within vessels

Answer 35

maintain high blood pressure increase rate of blood flow to and from heart

Question 36

why is the left ventricle wall thicker than left atrium wall

Answer 36

needs to create a higher pressure to push blood against greater friction pumps blood to all parts of body