Ch26 The Heart And Blood Vessels

Question 1

Why do we need a circulatory system?

Answer 1

Small organisms (amoeba) have no circulatory system
-diffusion work to transport nutrients in organisms that are only a few cells thick

Larger organisms need a circulatory system to supply cells with materials they require

Question 2

Two types of circulatory systems

Answer 2

Open blood system
Closed circulatory system

Question 3

Open blood system

Answer 3

Heart pumps blood into open ended blood vessels
Eg crab, lobsters, insects, snails

Question 4

Closed circulatory system

Answer 4

Blood remains in a continuous system of blood vessels
Eg. Humans

Question 5

Advantages of a closed system

Answer 5

1. Blood can be pumped around the body faster
   - allows nutrients and oxygen to reach cells faster, which allows the animal to be more active
2. Allows blood flow to different organs to be increased or decreased
   - eg. more blood can be supplied to leg muscles when running

Question 6

Composition human circulatory system

Answer 6

Blood
The heart
Blood vessels

Question 7

3 types of blood vessels

Answer 7

Arteries
Veins
Capillaries

Question 8

Arteries

Answer 8

Carry blood away from the heart
Divide into smaller vessels called arterioles

Question 9

Veins

Answer 9

Carry blood to the heart
Small veins -> venules

Question 10

Capillaries

Answer 10

Link arteries and veins

Question 11

Artery structure

Answer 11

• Carry blood under high pressure
• Have a thick muscle layer
• Have a narrow lumen

Question 12

Veins structure

Answer 12

• Carry blood under low pressure
• Have a thinner muscle layer
• Have a wide lumen

Question 13

Middle of arteries and veins

Answer 13

Lumen

Question 14

3 layers in the walls of arteries and veins

Answer 14

1. Outer layer of tough, inelastic protein (collagen)
   - prevents wall from over-expansion
2. Middle layer of muscle and elastic fibres
   - allows vessels to expand during exercise or when we are hot
3. Inner, single layer of cells -> endothelium

Question 15

Venous bleeding

Answer 15

Steady flow
Maroon coloured blood

Question 16

Arterial bleeding

Answer 16

Spurting
Bright red blood

Question 17

Blood pressure

Answer 17

The force exerted by the blood against the walls of the blood vessels (mainly arteries)

Question 18

Valve function

Answer 18

Prevent backflow in veins

Question 19

Blood pressure in arteries

Answer 19

Highest in arteries when the heart contracts

Question 20

What causes a pulse

Answer 20

As the heart contracts, blood pressure is highest in arteries and this pressure causes the artery to expand slightly and is detected as a pulse

Question 21

Blood pressure in veins

Answer 21

Blood pressure in veins is low, blood flow is slow

Question 22

How do skeletal muscles help blood flow

Answer 22

When skeletal muscles contract, they squeeze on the veins pushing blood along

Question 23

Arterioles

Answer 23

Connect arteries and capillaries

Question 24

Venules

Answer 24

Connect capillaries and veins

Question 25

Capillaries

Answer 25

Tiny vessels whose walls are made of a single layer of endothelial cells

Question 26

Artery points

Answer 26

-Carry blood away from the heart -Blood under high pressure -Thick walls -small lumen -blood flow in pulses -valves absent -blood high in oxygen (except pulmonary artery)

Question 27

Veins

Answer 27

-Carry blood to the heart -Blood under low pressure -Thin wall -Large lumen -Blood flows smoothly (no pulse) -Valves present -Blood low in oxygen (except pulmonary vein)

Question 28

Draw diagram of a heart

Question 29

Atria

Answer 29

- Have thin walls as they only pump blood a short distance to the ventricles

Question 30

Ventricles

Answer 30

-right ventricle pumps blood to lungs -left ventricle pumps blood to head and body

Question 31

Which ventricle is thicker and why

Answer 31

Wall of Left ventricle is thicker as blood travels further from here

Question 32

What are atria and ventricles separated by

Answer 32

Atria and ventricles are separated by valves which are held in place by tendons

Question 33

3 valves

Answer 33

Tricuspid Bicuspid Semilunar

Question 34

Tricuspid valve

Answer 34

Right side valve - 3 flaps Prevents back flow into right atrium

Question 35

Bicuspid valve

Answer 35

Left side valve - 2 flaps Prevents backflow into left atrium

Question 36

Semilunar valves

Answer 36

Allow blood into aorta and pulmonary artery Prevents backflow into heart

Question 37

Deoxygenated blood flow in the heart

Answer 37

-enters through vena cava -enters right atrium -moves into right ventricle -leaves through the pulmonary artery ( to lungs )

Question 38

Oxygenated blood flow in the heart

Answer 38

-enters through the pulmonary veins -into left atrium -moves into left ventricle -leaves through aorta (to head and body)

Question 39

Double circulation

Answer 39

The septum in the heart separates oxygenated and deoxygenated blood -pulmonary circuit -systemic circuit

Question 40

Pulmonary circuit

Answer 40

Pumps blood to the lungs and back to the heart

Question 41

Systemic circuit

Answer 41

Pumps blood to the head and body and back to the heart Longer so, the walls of the left ventricle are thicker

Question 42

Advantages of double circulation

Answer 42

-allows separation of oxygen-rich and oxygen-poor blood -ensures blood pressure is high enough to reach all parts of the body

Question 43

Portal system

Answer 43

A blood pathway that begins and ends in capillaries -the hepatic portal vein connects the stomach and intestines to the liver (8cm)

Question 44

How is heart muscle supplied with blood

Answer 44

By coronary arteries - they branch from the aorta just above the semi-lunar valves

Question 45

How is blood drained from heart muscle

Answer 45

By the coronary veins - they return blood directly to the right atrium

Question 46

Blockage of coronary arteries

Answer 46

Causes chest pain - angina Sometimes causes heart attack