Cardiovascular and Circulatory Systems

Question 1

Circulatory System

Answer 1

CV System + Lymphatic System

Function
- Distribution of gases and other molecules
- Chemical signalling
- Mediate information and host defence responses

Question 2

CV System - 3 main components

Answer 2

Arterial System - Arteries carry blood away from heart
Heart - pump of system
Venous System - Veins carry blood towards heart

Question 3

Pulmonary Circulation

Answer 3

Lungs oxygenate the blood

RV to the Lungs via the pulmonary arteries and back to LA via the pulmonary veins

Question 4

Systemic Circulation

Answer 4

LV to the rest of the body via the aorta and branches

Question 5

Heart

Answer 5

Muscular double pump
- Systole (contraction)
- Diastole (relaxation)

Vena cavae (x2) –> RA –> RV –> Pulmonary Arteries –> Lungs –> Pulmonary Veins (x4) –> LA –> LV –> Aorta –> Rest of Body

Question 6

Walls of Heart

Answer 6

Epicardium (external) - outermost serous pericardium
Myocardium (middle) - muscular layer
Endocardium (internal) - continuous with basal membrane of blood vessels connecting with heart

Question 7

Heart Chambers

Answer 7

Right Atrium
RIght Ventricle
Left Atrium
Left Ventricle

Question 8

Great Vessels

Answer 8

Superior and Inferior Vena cava
Pulmonary Trunk
Aorta
Pulmonary veins

Question 9

Valves

Answer 9

Atrioventricular (2/3 cusps)
- Left = Mitral
- Right = Tricuspid

Semilunar
- Aortic (LV)
- Pulmonary (RV)

Question 10

Conduction System of Heart

Answer 10

1. Electrical impulse starts spontaneously at SA node (causing both atria to contract)
2. Travels to Atrioventricular Node at atrioventricular septum
3. Travels down right and left bundles in Bundles of His
4. Spreads out to myocardium through conducting fibres (causing both ventricles to contract)

Question 11

Blood Vessels

Answer 11

Arteries –> Arterioles –> Capillaries –> Venules –> Veins

3 layers:
- Tunica intima (internal) - endothelium
- Tunica media (middle) - smooth muscle and elastic fibres
- Tunica adventitia (external) - connective tissue

Question 12

Arteries

Answer 12

Often part of a neurovascular bundle - artery/vein/nerve
High pressure (80-100mmHg)
Deeper than veins

Round lumen, pulsatile, carry oxygenated blood
Give rise to arterioles
Bifurcate or trifurcate
Supply a territory
Common or Trunk - divide again

Question 13

Arterioles

Answer 13

Smooth muscle in arterioles can contract to narrow lumen

Vasodilation - relaxation of SM and widening lumen –> Increase Blood flow

Vasoconstriction - contraction of SM to reduce blood flow

Sympathetic Tone
- Background low level of contraction of SM
- Due to tonic (continuous) conduction of action potentials to arterioles by sympathetic nerves
- Arteriolar SM contraction can help to reduce blood loss following injury

Question 14

Anastomoses

Answer 14

Direct connections between small arteries and small veins, with no capillary section between them

E.g. Circle of Willis is an arterial anastomosis of the brain (may prevent strokes)

Question 15

End Arteries and Infarction

Answer 15

End artery –> only arterial blood supply to a given area
Untreated occlusion of end artery –> infarction
Infarction - irreversible cell death due to hypoxia caused by loss of arterial blood supply

Question 16

Aorta

Answer 16

Oxygen-rich arterial blood enters aorta first

Receives blood at high BP during systole
Its elastic walls expand under this pressure
Elastic recoil maintains peripheral flow during diastole
Aorta has many branches which supply body

Question 17

4 parts of aorta

Answer 17

• Ascending aorta
• Arch of Aorta
• Descending aorta
• Abdominal aorta

Question 18

Branches of Arch of Aorta

Answer 18

Brachiocephalic trunk
Left common carotid artery
Left subclavian artery

Question 19

Upper Limb Blood Supply

Answer 19

Left Subclavian artery
Left Axillary artery
Left Brachial artery
Left Radial artery
Left Ulnar artery

Question 20

Branches to supply abdominal organs

Answer 20

Common Iliac arteries (L&R)
Internal Iliac artery
External Iliac artery

Question 21

Peripheral Pulses

Answer 21

Carotid
Brachial
Radial
Femoral
Popliteal
Dorsalis pedis

Question 22

Veins

Answer 22

Often run in a neuromuscular junction
De-oxygenated blood
Low pressure and non-pulsatile
Drain blood away from territory
Have tributaries
Thin walled which collapse when empty
Valves

Question 23

Venous return

Answer 23

Venous blood flow assisted by:
- Venous valves
- Skeletal muscles
- Venae comitantes (arterial pulsation pushes venous blood along)

Question 24

2 Sets of Veins

Answer 24

Superficial Veins - smaller and run in superficial fascia
Deep Veins - larger and run deep to deep fascia and in cavities

Question 25

Two main venous systems

Answer 25

Portal Venous system - drains venous blood from GI tract and associated organs to portal vein
Systemic Venous system - drains venous blood from all other organs and tissues into superior or inferior vena cava

Question 26

Capillaries

Answer 26

Extnesive vascular networks
Lined with single layer of endothelial cells
Allow only one RBC through at a time
Allow exchange of gases, metabolites and waste products

Excess fluid from capillary squeezed out into lymph capillary where it get transports back to large veins in neck

Question 27

Lymphatic Circulation

Answer 27

Lymphatic capillaries collect tissue fluid
Called lymph once in lymphatic capillaries
Lymphatic carry lymph through lymph nodes
Eventually lymph is returned to large veins n root of neck

Right lymphatic drains lymph into right venous angle
Thoracic duct drains lymph into left venous angle

Question 28

Lymph nodes

Answer 28

Normal –> cannot usually be palpated
Infection/Cancer –> usually enlarge and can be palpated