Blood

Question 1

What are open an closed circulatory systems?

Answer 1

Open: blood not always in vessels, closed: blood always in vessels

Question 2

What is the difference between constrict and contract?

Answer 2

Contract = becomes shorter, constrict = becomes narrower

Question 3

How does blood flow in insects where there is a muscular pumping organ similar to the heart?

Answer 3

long, muscular tube under the dorsal (upper) surface of the insect, blood enters heart through pores: ostia, heart pumps blood towards head by peristalsis, blood pours into body, bathes tissue

Question 4

What do larger/more active insects have attached to their hearts?

Answer 4

Locusts, open ended tubes attached to direct blood flow towards active body parts like leg/wing muscles

Question 5

How is it possible for insects to survive with an open system?

Answer 5

Small, blood doesn’t travel far and doesn’t have to transport O2 or CO2 (separate system for this)

Question 6

Why would an open circulatory system not be sufficient in a larger organism?

Answer 6

Blood needs to transport O2 and CO2 and blood pressure is too low, flow is slow, parts of the body wouldn’t receive sufficient O2 or nutrients

Question 7

What is the purpose of tissue fluid? What does this enable the heart to do?

Answer 7

bathes tissues and fluid, heart can pump blood at a higher pressure so it flows quicker

Question 8

What system do fish have?

Answer 8

Single, closed system, blood stays in vessels: heart to arteries to gills to veins to body to veins to heart

Question 9

What do all types of blood vessels have?

Answer 9

Inner layer/lining, made of single layer of cells: endothelium, smooth to reduce friction with flowing blood

Question 10

In a cross section of an artery, what are the different layers from inside to out?

Answer 10

lumen, endothelium, elastic fibres, smooth muscle, collagen fibres

Question 11

Which way do the arteries carry the blood? How high is the blood pressure?

Answer 11

Away from heart, high pressure so artery wall has to withstand pressure

Question 12

What are the lumen and wall of the artery like?

Answer 12

Small lumen to maintain high pressure, wall is thick and contains collagen fibres to give strength

Question 13

What does the elastic tissue in the artery wall do?

Answer 13

Allows wall to stretch and recoil when heart pumps, felt as pulse where arteries are near skin, recoil keeps high pressure while heart relaxes

Question 14

What does the smooth muscle in the artery wall do?

Answer 14

can contract and constrict the artery, constriction narrows lumen -in arterioles this is used to limit blood flow to certain tissues to redirect to other tissues

Question 15

How is the endothelium arranged in the arteries?

Answer 15

folded and can unfold when artery stretches

Question 16

In a cross section of a vein, what are the different layers from inside to out?

Answer 16

lumen (larger than in artery), endothelium, elastic fibres, smooth muscle, collagen fibres

Question 17

Where do veins carry blood? What pressure is the blood at?

Answer 17

Blood back to the heart, low pressure so walls don’t need to be thick

Question 18

How does the lumen, collagen layers, smooth muscle and elastic tissue in veins compare to that of arteries?

Answer 18

Lumen relatively large and layers of wall are thinner, no need to stretch and recoil

Question 19

What is the main feature of the veins?

Answer 19

contain valves to prevent blood flowing in opposite direction, as walls are thin, the vein can be flattened by action of surrounding skeletal muscle, pressure is applied to blood focing blood to move along in vale direction

Question 20

What do capillaries consist of?

Answer 20

Lumen and endothelium, walls are very thin (single layer of flattened endothelial cells)

Question 21

What is the purpose of capillaries?

Answer 21

Allow exchange of material between the blood and cells of tissue via the tissue fluid

Question 22

How narrow is the lumen of the capillary?

Answer 22

diameter same as RBC (7um), ensures RBCs squeezed as pass along capillary helps to give up their O2, reduces diffusion path

Question 23

What dissolved substances does blood plasma contain?

Answer 23

O2, CO2, salts, glucose, fatty and amino acids, hormones and plasma proteins

Question 24

What cells travel in the blood?

Answer 24

RBCs: erythrocytes, various WBCs: leucocytes and fragments: platelets

Question 25

What is tissue fluid made up of?

Answer 25

some phagocytic WBCs, some hormones and proteins secreted by body cells, no fats

Question 26

What is the role of the tissues fluid?

Answer 26

transport O2 and nutrients from the blood to the cells and carry CO2 and other wastes back to the blood

Question 27

What happens to an artery when it reaches the tissues?

Answer 27

Branches into smaller arterioles, then into network of capillaries which eventually link up with venules to carry blood back to veins

Question 28

What is the pressure like at the arterial end of a capillary?

Answer 28

High pressure die to contraction of heart muscle, hydrostatic pressure, tend to push blood fluid out of capillaries via tiny gaps in the wall

Question 29

What does the fluid that leaves the blood in the capillaries consist of?

Answer 29

plasma with dissolved nutrients and O2

RBCs, plasma proteins, platelets and most WBCs remain in blood (all too large)

Question 30

What is the fluid that leaves the capillary known as? What does this fluid do?

Answer 30

Tissue fluid, surrounds body cells so exchange of gases and nutrients can occur across membranes (diffusion and facilitated diffusion)

Question 31

How does tissue fluid return to the blood?

Answer 31

tissue fluid has some hydrostatic pressure which tends to push the fluid back into the capillaries

Question 32

Why does water from the tissue fluid tend to move back into the blood?

Answer 32

blood and tissue fluid contain solutes so negative water potential but water potential of tissue fluid is less negative than blood so water back into blood by osmosis

Question 33

What is the pressure like at the venous end of the capillary?

Answer 33

Blood has lost hydrostatic pressure, combined effect of tissue fluid pressure and osmotic force of plasma proteins moves fluid back into capillary carrying with it dissolved waste substances (CO2)

Question 34

What happens to tissue fluid which doesn’t return to the blood?

Answer 34

Some drained to lymphatic system, number of vessels/tubes similar to capillaries, start in tissues and drain excess fluid in larger vessels which rejoin blood system in chest

Question 35

What does the lymph fluid contain?

Answer 35

lymphocytes, some proteins, more fats than in blood (absorbed from intestines)

Question 36

Where are lymphocytes produced?

Answer 36

Lymph nodes, swellings at intervals along lymphatic system, filter bacteria and foreign material from lymph fluid

Question 37

What do lymphocytes do?

Answer 37

engulf and destroy the foreign material and bacteria, part of immune system protecting body from infection

Question 38

How much glucose, amino acids, O2 and CO2 does the blood, tissue fluid and lymph have?

Answer 38

Blood: 80-120 mg/100cm3, more, more, little
TF: less, less, less, more
Lymph: less, less, less, more