Lesson 2: transport

Question 1

structure and adaptations of capillaries

Answer 1

• Lumen is very narrow - red blood cells travel in a single file line.
• Walls are thin - Substances can be exchanged across a short distance by diffusion.
• Highly branched - This provides a large surface area for diffusion.

Question 2

structure and adaptations of arteries

Answer 2

• Collagen - Provides strength to prevent the vessel from bursting and to maintain vessel shape.
• Elastic fibres - Contain elastin that lets them stretch and recoil to minimise changes in pressure.
• narrow lumen - maintain high blood pressure

Question 3

structure and adaptations of veins

Answer 3

• thinner walls - allow veins to be easily compressed, aiding the flow of blood.
• wide lumen - maximize volume of blood flow.
• Valves - prevent backflow

Question 4

ability to differentiate between them using a microscope picture

Difference between veins and arteries in structure

refer to 20 of lesson 2 topic 5

compare their walls. lumen, shape, inner surface corrugation and wall fiber visibility

Answer 4

Arteries:
* walls: thick
* lumen: narrow
* shape: circular
* Inner surface corrugation: yes
* wall fibers visible: yes

Veins:
* walls: thin
* lumen: wide
* shape: flattened
* Inner surface corrugation: no
* wall fibers visible: no

Question 5

Methods of measuring pulse rate

Answer 5

• Locating your radial artery with your middle and index finger and counting. Usually on your wrist or neck.
• Using a stethoscope and counting heart beats
• Digital pulse monitors

Question 6

Consequences of occlusions of coronary arteries/coronary heart disease

Answer 6

Heart attacks

Question 7

Causes of occlusions of coronary arteries/coronary heart disease

Answer 7

Build-up of plaque, a fatty substance that hardens overtime narrowing the diameter of the coronary artery which reduces blood flow to the heart.
It can also rupture, exposing and damaging the tissue underneath and resulting in the formation of a blood clot, or thrombus, which can further restrict blood flow.

Question 8

Function of tissue fluid

Answer 8

transports substances from capillaries to cells

Question 9

composition of tissue fluid

Answer 9

oxygen, water and nutrients

Question 10

difference in composition of tissue fluid and plasma

Answer 10

tissue fluid does not have plasma proteins, platelets and red blood cells

Question 11

Explain how tissue fluid is formed

Answer 11

• Tissue fluid is forced out of capillary at arteriole end due to high pressure called hydrostatic pressure
• the loss of water and the concentration of plasma proteins in the capillary lowers its water potential called onotic pressure.
• some of the water diffuses back into the capillary at the venule end via osmosis

Question 12

What happens to excess tissue fluid?

Answer 12

flows into the lymphatic system where it becomes lymph

Question 13

advantages of single circulatory system

Answer 13

Less complex
does not require complex organs

Question 14

advantages of double circulatory system

Answer 14

The heart can pump blood further around the body
High pressure
Fast flow of blood

Question 15

What are the steps of blood flow in the heart?

Answer 15

Vena cava
Right atrium
AV valve (tricuspid valve)
Right Ventricle
SL Valve
Pulmonary artery
Lungs
Pulmonary vein
Left Atrium
AV valve (bicuspid valve=
Left ventricle
SL valve
Aorta
Body

Question 16

disadvantages of single circulatory system

Answer 16

Low blood pressure
Slow movement of blood
Activity level of the animal tends to be low

Question 17

What are the three main stages of the cardiac cycle?

Answer 17

Atrial Systole
Ventricular Systole
Diastole

Question 18

What does the diastole stage consist of?

Answer 18

The ventricles and atria relax.
The semi-lunar valves close.
Blood flows passively into the atria.

Question 18

what is Systolic pressure?

Answer 18

pressure in the arteries during ventricular systole

Question 18

What does the ventricular systole stage consist of?

Answer 18

• The ventricles contract, and the atria relax.
• The ventricular pressure increases.
• The semi-lunar valves open, and the atrioventricular valves close.
• Blood flows into the arteries.

Question 18

What does the atrial systole stage consist of?

Answer 18

• The ventricles relax, and the atria contract.
• This increases the atrial pressure.
• The atrioventricular valves open.
• Blood flows into the ventricles.

Question 19

What is Diastolic pressure?

Answer 19

pressure in the arteries during diastole

Question 20

Which one is at the top of the fraction, diastolic or systolic pressure?

Answer 20

systolic pressure

Question 21

What is the role of valves?

Answer 21

prevents backflow

Question 22

what happens to valves when there is high pressure behind it?

Answer 22

opens

Question 23

what happens to valves when there is high pressure in front of it?

Answer 23

closes

Question 24

explain the steps of control of the cardiac cycle

Answer 24

• Sinoatrial node (SAN) - This initiates the heartbeat by stimulating the atria to contract. A layer of collagen fibres prevents direct electrical flow from the atria to the ventricles.
• Atrioventricular node (AVN) - This picks up the electrical activity from the SAN and imposes a slight delay.
• Bundle of His - This receives electrical activity from the AVN and conducts the wave of excitation to the heart’s apex (base).
• Purkyne fibres - These branch off the bundle of His, causing the right and left ventricles to contract from the bottom upwards.

Question 25

Explain the stages of an EGC showing the various stages of the cardiac cycle

refer to slide 64, lesson 2 of topic 5

Answer 25

P wave - Atrial systole
QRS - Ventricular systole
T wave - Diastole

Question 26

Name all the heart problems and what happens

Answer 26

• Bradycardia – slow heart beat, less than 60 bpm
• Tachycardia – fast heart rate, more than 100 bpm
• Ectopic beat – extra beats follows by gaps
• Atrial fibrillation – irregular rhythm