Circulation

Question 1

Why do animals need a circulatory system?

Answer 1

• oxygen and nutrients must be transported around the body to tissues and organs
• waste products must be removed
• communications via hormones
• temperature regulation and reproduction

Question 2

Describe the SA:V ratio of animals without a circulatory system.

Answer 2

Very high. They will be very flat with a thin body wall

Question 3

What happens if oxygen is provided by diffusion only?

Answer 3

No oxygen will reach centre of animal

Question 4

What process allows animals with a circulatory system to transport oxygen?

Answer 4

Convection

Question 5

What is convection?

Answer 5

Bulk movement of fluid

Question 6

What does convection usually assist?

Answer 6

Usually assists diffusion

Question 7

Is a concentration always maintained by convection? Why or why not?

Answer 7

Yes, due to continual motion.

Question 8

Which is faster: diffusion or convection?

Answer 8

Convection is much faster, .

Question 9

Describe an open circulatory system. In what types of animals are there open circulation systems?

Answer 9

• open vessels, cells bathed directly in blood plasma (haemolymph)
• found in invertebrates, e.g crab, beetle, moth

Question 10

What is a disadvantage of an open circulatory system?

Answer 10

It is non-selective.

Question 11

Describe a closed circulatory system. In what animals are these present?

Answer 11

-blood remains in closed vessels
- extracellular fluid bathes cells
- limited exchange between blood and extracellular fluid
- blood and extracellular fluid are SEPARATE
— commonly in vertebrates and earthworm

Question 12

What is an advantage of closed circulation?

Answer 12

Very selective, blood flows in preferential direction

Question 13

What separates blood from cells in a closed circulatory system?

Answer 13

Vessels and extracellular fluid

Question 14

What processes work together in closed circulation?

Answer 14

Convection and diffusion

Question 15

What powers the convection of blood in closed circulation?

Answer 15

The heart.

Question 16

What forms of energy are needed and transferred by the heart?

Answer 16

• requires metabolic (chemical) energy for muscle contraction
• potential energy contributes to blood pressure
• kinetic energy contributes to blood flow

Question 17

What are the general features of hearts?

Answer 17

• several chambers in sequence
• sequential contraction
• one way flow using valves

Question 18

Describe the pressure changes in blood flow in the heart.

Answer 18

Blood flows from high to low pressure.

Question 19

What drives movement of blood through heart?

Answer 19

Pressure changes

Question 20

Atrium always does the ____ to the ventricle?

Answer 20

Opposite

Question 21

What is the function of the valves in the heart?

Answer 21

Prevent backflow of blood.

Question 22

What is systole and diastole?

Answer 22

Systole - contraction of heart, expels blood

Diastole - relaxation of heart, refills with blood

Question 23

What are the two sources of heart contraction?

Answer 23

1. Muscle: myogenic. Can contract without nerve input

2. Nerves: neurogenic. Requires electric signal

Question 24

Are myogenic or neurogenic hearts allowed to be transplanted? Explain why.

Answer 24

Only myogenic as they can keep beating regardless of cut off nerves.

Question 25

What type of muscle is vertebrate cardiac muscle?

Answer 25

Striated muscle consisting of stripes that are actin and myosin ready to contract.

Question 26

What are heart muscle cells interconnected?

Answer 26

Via intercalated discs.

Question 27

What are desmosomes and gpa junctions in the heart?

Answer 27

Desmosomes - strong connections | Gap junctions - electrical connections

Question 28

What is the sinoatrial node in the heart?

Answer 28

The pacemaker.

Question 29

Describe the process of action potential conduction in the mammalian heart in steps.

Answer 29

1. Action potential starts in sinoatrial node (pacemaker), causing contraction over both atrium. 2. This action potential triggers atrioventricular node (0.1 sec delay) 3. Rapid conduction of AP down AV bundle (middle of ventricles) and to Purkinje fibres (on far side of ventricles). 4. Ventricular contraction propagated from apex expels blood: systole

Question 30

In the body, what does blood pick up and lose?

Answer 30

Picks up CO2 | Loses O2

Question 31

In the lungs, what does blood pick up and lose?

Answer 31

Picks up O2 | Loses CO2

Question 32

Where does blood flowing into the right and left atrium come from?

Answer 32

Blood entering right atrium comes form body | Blood entering left atrium comes from lungs

Question 33

Where does blood from the right and left ventricle flow to?

Answer 33

right: Flows to lungs Left: flows to body

Question 34

Which ventricle has higher pressure?

Answer 34

Right ventricle has low pressure, left ventricle has high pressure

Question 35

Describe the process of fish blood circulation with the heart.

Answer 35

Blood picks up O2 and loses CO2 in gills. This blood is transferred to the body where O2 is lost and CO2 is picked up. Blood from the body is transferred into the heart. Blood coming from the heart has higher pressure than blood coming from the gills.

Question 36

Predict the structure of a fish heart.

Answer 36

Single atrium, single ventricle

Question 37

Describe the properties of arteries.

Answer 37

- elastic which dampens flow pulse and prevents absence of blood - high pressure and velocity

Question 38

Describe the muscle of arterioles.

Answer 38

- smooth muscle which regulates blood flow and pressure

Question 39

Describe the properties of capillaries.

Answer 39

- exchange vessels - low pressure, low velocity - very thin wall only comprised of endothelium - very high SA:V ratio

Question 40

Describe the properties of veins.

Answer 40

- low pressure, relatively high velocity - some smooth muscle, small resistance changes and large volumes of blood - veins contain valves to ensure that blood flows in one direction.

Question 41

Why don’t arteries have valves?

Answer 41

Because blood pressure from the heart is so strong that it already flows in one direction

Question 42

Describe two diseases associated with the arteries. What do both diseases reduce?

Answer 42

Arteriosclerosis: hardening of arteries Atherosclerosis: fatty deposits Both diseases reduce elasticity of arteries

Question 43

What are capillaries? What is it formed by?

Answer 43

- site of exchange Formed by a rolled endothelial cell.

Question 44

Name the locations where capillaries don’t leak vs do leak. | Where is leaked fluid transported to?

Answer 44

Don’t leak: blood, brain barrier Do leak: kidney, spleen, bone marrow, Leaked fluid is transported back to heart via lymphatic system

Question 45

What processes enable exchange across capillaries?

Answer 45

- diffusion - filtration - pinocytosis Active transport in placenta

Question 46

What are baroreceptors? Explain what they do when there is high nad low pressure.

Answer 46

Regulate blood pressure. High pressure causes lower heart rate and lower resistance Low pressure causes higher heart rate and higher resistance

Question 47

What are chemoreceptors? Explain what they do in situations where there is low O2 and low pH, high CO2. AND high O2 and high pH, low CO2.

Answer 47

Regulate O2 in carotid body and CO2 and pH in aortic body. Low O2- increase breathing rate High O2- decrease breathing rate

Question 48

What do baroreceptors and chemoreceptors feed into? What do they regulate?

Answer 48

``` Feed into vasomotor centre in brain stem Regulation of: - respiration - heart rate, cardiac output - blood pressure - vascular tone (constriction of blood vessel walls) ```