Lecture: Anatomy 6: Principles of the cardiorespiratory system

Question 1

How are heart contractions regulated?

Answer 1

Heart contractions are intrinsically generated and rate of is modified by autonomic nervous system (ANS).

Question 2

How does the parasympathetic nervous system affect heart rate?

Answer 2

Decreases heart rate (Vagus nerve)

Question 3

How does the sympathetic nervous system affect heart rate?

Answer 3

Increases heart rate

Question 4

What are the 3 layers of the heart wall?

Answer 4

• Epicardium (visceral pericardium)
• Myocardium
• Endocardium

Question 5

What is the epicardium?

Answer 5

Thin outer layer of heart

Question 6

What is the myocardium?

Answer 6

Thickest inner layer of heart

Question 7

What is the endocardium?

Answer 7

Innermost layer of heart which lines the chamber.

Question 8

How does blood flow into the heart to the lungs?

Answer 8

Superior and inferior vena cava, right atrium, right ventricle, pulmonary artery, lungs

Question 9

What are the valves in the right side of the heart?

Answer 9

Pulmonary valve and Tricuspid valve

Question 10

How does blood flow out of the heart and around the body?

Answer 10

Pulmonary veins, left atrium, left ventricle, aorta, body

Question 11

What are the valves in the left side of the heart?

Answer 11

Aortic valve and Bicuspid (mitral) valve

Question 12

Describe the blood leaving the heart towards the lungs

Answer 12

Deoxygenated

Question 13

Describe the blood leaving the heart for the body

Answer 13

Oxygenated

Question 14

Describe the composition of cardiac muscle (myocardium)

Answer 14

Cardiac Muscle (Myocardium) has a striated appearance with intercalated discs (fascia adherens, desmosomes, and gap junctions). Normally mononucleated.

Question 15

What are the components of the respiratory tract?

Answer 15

Trachea          
Main bronchi           
Secondary (lobar) bronchi (3 x right, 2 x left)           
Tertiary (segmental) bronchi            
Bronchioles            
Alveoli

Question 16

Describe the right lung lobe

Answer 16

3 lobes with horizontal and oblique fissures

Question 17

Describe the left lung lobe

Answer 17

• 2 lobes with oblique fissures
• Impression for the heart (the cardiac notch)
• Lingula; tongue-shaped region of the left lung.

Question 18

Describe the composition of smooth muscle

Answer 18

Smooth muscle is not striated and not branching. Spindle shaped with one central nucleus per cell. Smooth muscle is under involuntary control.

Question 19

Where is smooth muscle found?

Answer 19

Found in walls of tubular structures and hollow viscera.

Question 20

What are the functions of smooth muscle?

Answer 20

Functions:
• Regulates diameter
• Propels liquids and solids
• Expels contents

Question 21

What is the endothelium?

Answer 21

A monolayer of squamous (flattened) epithelial cells that covers the entire inside of the vascular system. In contact with blood.

Question 22

What are the functions of the endothelium?

Answer 22

Functions:
• Control vascular tone and vessel diameter
• Regulate permeability
• Angiogenesis (formation of new blood vessels)
• Regulate clotting (by releasing clotting factors)
• Regulate immune response

Question 23

What is an atherosclerosis?

Answer 23

Narrowing of arteries (myocardial infarction) or rupture of plaque causing a thrombus. Common in coronary arteries.

Question 24

What is a thrombosis?

Answer 24

Blood clot (thrombus) e.g., rupture of atherosclerotic plaque or deep venous thrombosis.

Question 25

What is an embolism?

Answer 25

Stray blood clot (embolism) e.g., pulmonary embolism or stroke.

Question 26

What are the 3 layers of blood vessels?

Answer 26

1. Tunica Intima 2. Tunic Media 3. Tunica Externa (adventitia)

Question 27

Describe the structure of the tunic intima in blood vessels

Answer 27

Inner most layer (lined by endothelium). Composed of connective tissue which reduces friction for blood flow.

Question 28

Describe the structure of the tunic media in blood vessels

Answer 28

Middle layer. Composed of primarily smooth muscle and connective tissue (collagen and elastin). Controls size and shape of artery/vessels.

Question 29

Describe the structure of the tunic externa in blood vessels

Answer 29

Outer most layer. Composed of primarily collagen and contains nerves and vessels (vasa vasorum). Connects artery to surrounding structures.

Question 30

What factors aid the return of blood against gravity?

Answer 30

* Valves * Arteriovenous pump * Musculovenous pump * Respiratory pump

Question 31

What are valves?

Answer 31

Valves are inward projection of intima, strengthened by collagen and elastic fibres.

Question 32

What are the consequences of dilation of the veins?

Answer 32

Dilation of veins can mean valves don’t close, resulting in varicose veins.

Question 33

Describe the structure of large elastic arteries (conducting)

Answer 33

* Large diameter (>10mm) * Supplied by vasa vasorum; arteries are so thick that they require their own blood supply * Tunica media contains many layers of elastin; provides force to support surges of blood flow

Question 34

Describe the structure of medium muscular arteries (distributing)

Answer 34

* Smaller diameter (0.1mm-10mm) * Thick layer of smooth muscle in tunica media * Responsible for vasoconstriction, vasodilation and pulsatile contractions

Question 35

Describe the structure of small arteries and arterioles (resistance)

Answer 35

* Narrow lumina * Decreased thickness of all layers and tunica media is predominantly smooth muscle, 1-2 cell layers in thickness * Tonus dictates degree of filling of capillary beds, and this dictates blood flow

Question 36

Describe the structure of capillaries (exchange)

Answer 36

* Endothelial layer composed of only tunica initima * Two types: continuous and fenestrated * Function: allow exchange between blood and extracellular fluid

Question 37

Describe the structure of venules

Answer 37

* Microscopic (8-100µm) * Progressively increase lumen diameter * No elastin * Very thin tunica externa and media * Function: drain capillary beds

Question 38

Describe the structure of veins

Answer 38

* Under lower pressure so tunica media is thinner than arteries * More variable * Smaller veins are TRIBUTARIES of larger veins * Large veins have well developed tunica adventitia/ externa

Question 39

How do arteries branch into veins?

Answer 39

``` Large elastic arteries Medium muscular arteries Small arteries and arterioles Capillaries Venules Veins ```

Question 40

What are the 2 types of capillaries?

Answer 40

1. Continuous | 2. Fenestrated (pores where more exchange takes place)

Question 41

Where are fenestrated capillaries more commonly found?

Answer 41

Endocrine glands, the intestines, pancreas and kidney