2.5- structure and function of arteries, capillaries and veins

Question 1

3 types of blood vessels

Answer 1

arteries

capillaries

veins

Question 2

how does blood circulate around the body?

Answer 2

heart –> arteries –> veins

Question 3

what happens to blood pressure as it moves away from the heart?

Answer 3

decrease in blood pressure

Question 4

what is the central cavity of a blood vessel called?

Answer 4

lumen

Question 5

what is the endothelium?

Answer 5

a thin layer of epithelial cells

Question 6

what is the lumen of a blood vessel lined with?

Answer 6

a thin layer of epithelial cells called endothelium

Question 7

where do the arteries carry the blood and at what pressure?

Answer 7

away from the heart

at a high pressure

Question 8

what makes up the outer layer of an artery?

Answer 8

thick outer layer of connective tissue containing elastic fibres

Question 9

what makes up the inner layer of an artery?

Answer 9

smooth muscle with more elastic fibres

Question 10

what does the elastic walls of an artery do?

Answer 10

stretch and recoil to accommodate the surge of blood after each heart contraction

Question 11

what are small arteries called?

Answer 11

arterioles

Question 12

what can the smooth muscles in the walls of arterioles do and what does this allow for ?

Answer 12

contract or become relaxed depending on the body’s requirements

allows the changing demands of the tissues to be met

Question 13

what happens during vasodilation, when and what does it allow for?

Answer 13

vasodilation occurs in arterioles leading to working muscles during strenuous exercise

allows an increase in blood flow to the skeletal muscles involved in the exercise

Question 14

what happens during vasoconstriction, when and what does it allow for?

Answer 14

vasoconstriction occurs in arterioles leading to abdominal organs such as the small intestine during strenuous exercise

allows for reduced blood flow to these parts

Question 15

what are small veins called?

Answer 15

venules

Question 16

where is blood passed to from the arterioles and how?

Answer 16

arterioles –> venules

passes through a dense network of tiny microscopic capillaries

Question 17

what is the most numerous blood vessel in the body?

Answer 17

capillaries

Question 18

what are capillaries referred to as and why?

Answer 18

exchange vessels

all exchange of substances between blood and living tissues take place through their thin walls

Question 19

what are the thin walls of capillaries composed of and how thick are they?

Answer 19

epithelial cells

one cell thick

Question 20

where do veins carry blood?

Answer 20

back to the heart

Question 21

what differences are there between the walls of a vein and an artery and why?

Answer 21

veins have thinner muscular layer and layers of elastic fibres

because blood flows along a vein at low pressure

Question 22

how are the lumen of a vein different to an artery and what does this do?

Answer 22

veins have wider lumen

reduces resistance of the flow of blood to a minimum

Question 23

what is the purpose of valves in the veins?

Answer 23

prevent backflow of blood

Question 24

3 features of a red blood cell

Answer 24

biconcave shape

no nucleus

no nucleus to make room for haemoglobin

Question 25

4 things that make up **blood**

Answer 25

red blood cells white blood cells platelets (^bathed in plasma)

Question 26

what is **plasma** and what 5 **substances** does it contain?

Answer 26

watery yellow fluid containing many dissolved substances glucose amino acids respiratory gases plasma protein useful ions

Question 27

**when** is blood at a **higher pressure** than blood in the capillaries?

Answer 27

when blood arrives at the arteriole side of a capillary bed

Question 28

**when** is tissue fluid formed?

Answer 28

when blood is forced into narrow exchange vessels it undergoes a form of pressure filtration and much of the plasma is squeezed out through the thin walls

Question 29

how are tissue fluid and blood plasma **different** and **why**?

Answer 29

tissue fluid does not contain plasma proteins because plasma proteins are too large to be filtered through the capillary walls

Question 30

**why** are all living cells constantly **bathed** in tissue fluid?

Answer 30

because the network of capillaries in a capillary bed is so dense that they are all close to a blood capillary

Question 31

**how** do nearby cells become supplied with their requirements?

Answer 31

nearby cells become supplied with their requirements due to tissue fluid containing a high concentration of soluble food molecules, dissolved oxygen and useful ions and diffuse down a concentration gradient into nearby cells

Question 32

what happens at the **same** **time** as nearby cells being supplied with their requirements?

Answer 32

co² and other metabolic wastes diffuse out of the cells into tissue fluid to be excreted

Question 33

where does much of tissue fluid **return**?

Answer 33

returns to the blood in the capillaries at the venule side of the capillary bed

Question 34

what brings about the **return** of tissue fluid and **how**?

Answer 34

osmosis with water passing from a region of higher water concentration to a region of lower water concentration

Question 35

2 things that **enter** the bloodstream by **diffusion**

Answer 35

carbon dioxide metabolic wastes

Question 36

where does the **excess tissue fluid go** that doesn't return to the blood capillaries?

Answer 36

excess tissue fluid is absorbed by thin walled lymphatic vessels

Question 37

what do lymphatic vessels **have** and **where** are they located?

Answer 37

have blind ends located in the connective tissue among living cells

Question 38

what is tissue fluid called once in a **lymphatic vessel**?

Answer 38

lymph

Question 39

how is lymph **collected**?

Answer 39

by a vast network of tiny lymph vessels which unite to form larger vessels

Question 40

**what** brings about the flow of lymph in the lymphatic system and **how**?

Answer 40

the vessels being periodically compressed when muscles contract during breathing, locomotion and other body movements

Question 41

what do valves in larger lymph vessels **do**?

Answer 41

prevent backflow of lymph

Question 42

where do larger lymph vessels **return** their contents and **how**?

Answer 42

via two lymphatic ducts enter the veins coming from the arms

Question 43

what is the lymphatic system **regarded** **as** and what are the 2 reasons **why**?

Answer 43

specialised part of the cardiovascular system consists of lymph fluid that is derived from blood consists of a system of vessels that return lymph to the bloodstream