Cardiovascular system lecture 13&14

Question 1

functions of cardiorespiratory system

Answer 1

• To carry oxygen to cells and to collect carbon dioxide
• To carry nutrients to cells and to collect waste
• To pick up oxygen from the lungs
• To pick up nutrients from the intestines
• To carry hormones and other signalling substances
• Thermoregulation

Question 2

cardiorespiratory system

Answer 2

• The heart comprises two, side-by-side
pumps, serving different blood circuits
• The heart and lungs comprise the pulmonary circuit
• The systemic circuit moves blood to and from capillaries at cells
• By definition, arteries take blood away from
the heart; veins take blood towards the heart

Question 3

circulatory system- blood’s journey

Answer 3

oxygenated blood from lungs to left atrium, through left atrioventricular valve (mitral valve) to left ventricle then through aortic valve to rest of body

deoxygenated blood from body to right atrium, through right atrioventricular valve to right ventricle, through pulmonary valve to lungs

Question 4

valve that separates left atrium and ventricle

Answer 4

mitral valve

Question 5

valve that separates right atrium and ventricle

Answer 5

tricuspid valve

Question 6

early diastole

Answer 6

AV valves open
semilunar valves closed
all chamber relaxed, ventricles filling

Question 7

atrial systole

Answer 7

AV valves open
semilunar valves closed
L+R atria contract; further ventricular filling

Question 8

ventricular contraction

Answer 8

AV and semilunar valves closed

L+R ventricles start to contract

Question 9

ventricular ejection

Answer 9

AV valves closed
semilunar valves open
L+R ventricles fully contract; blood leaves heart

Question 10

ventricular relaxation

Answer 10

AV and semilunar valves closed

ventricles relax

Question 11

Atrioventricular valves

Answer 11

(prevent backflow into atria)
• Tricuspid valve (right AV valve)
• Mitral valve or bicuspid valve (left AV valve)

Question 12

Semilunar valves (prevent backflow into ventricles)

Answer 12

• Aortic valve (between left ventricle and aorta)

* Pulmonary valve (between right ventricle and pulmonary artery)

Question 13

intercostal space

Answer 13

the space between the ribs

Question 14

where to listen to Aortic valve

Answer 14

2nd intercostal space, right sternal margin

Question 15

where to listen to Pulmonary valve

Answer 15

2nd intercostal space, left sternal margin

Question 16

where to listen to Tricuspid valve

Answer 16

5th intercostal space, right sternal margin

Question 17

where to listen to Mitral valve

Answer 17

5th intercostal space, in line with middle of clavicle

Question 18

Chordae tendineae

Answer 18

• Largely collagen, with elastin
components
• As ventricles contract, tricuspid and
mitral valves close
• Pressure in ventricles increases
dramatically
• Chordae tendinae prevent the eversion of the valves into the lower pressure atria

Question 19

ventricles

Answer 19

• Ventricles have thick walls, since they
pump blood over long distances
– LV pumps to the body
– R V pumps to the lungs
• Thickness can be diagnostic
– pumping to body requires more effort, so left ventricle usually thicker
– in arteriosclerosis, LV distended
– in emphysema, RV has to pump harder and becomes even larger

Question 20

coronary circulation

Answer 20

• Shortest circulation in the body
• Arterial supply via left and right coronary arteries
• Both arise from base of aorta, and both divide to run anteriorly and posteriorly
• Blood from the coronary circulation is returned to the heart via the coronary sinus
• Blood is emptied into right atrium via
– superior vena cava (blood from body superior to diaphragm)
– inferior vena cava (blood from body inferior to diaphragm)
– coronary sinus (blood from myocardium

Question 21

innervation of the heart

Answer 21

• Because the heart needs to be both excited and calmed as appropriate, innervation is via the sympathetic (via spinal nerves) and parasympathetic (via vagus) components of the ANS
• Depolarisation initiated at sinoatrial node
• Travels via atrial myocardium to atrioventricular node
• AV bundle
• Left and right bundle branches
• Purkinje fibres

Question 22

Hepatic portal system

Answer 22

• Special set of veins that carry blood from capillary beds in the intestines to capillary beds in the liver
• It is the only part of the venous system that does not carry blood from capillary beds straight back to the heart

Question 23

difference between arteries and veins

Answer 23

• Arteries “beat” along with the heart and blood pressure is high
• Arteries have thick, muscular walls; veins have thin, non-muscular walls
• At any one time, veins contain about 70% of the body’s blood
• Veins have low blood pressure and flow is powered by gravity – but only on the way down!
• Bringing blood back to the heart from the lower extremities against gravity is difficult
• Veins have valves that prevent backflow, which helps blood move against gravity (arteries do not)
• Muscular movements in surrounding structures help blood move against gravity
• If muscles aren’t working, blood collects in veins and valves fail (varicose veins) blood into the veins, and there is nothing to send it back

Question 24

capillaries

Answer 24

• about 1 m m long, with an internal diameter of about 10µm
• This is just large enough for red blood cells to pass through in single file
• Capillaries can be divided into three structural types:
1. Continuous capillaries
2. Fenestrated capillaries
3. Sinusoidal capillaries

Question 25

Continuous capillaries

Answer 25

* Most c o m m o n * Abundant in skin, muscles * Adjacent cells are joined by tight junctions * Tight junctions are actually loose enough to allow limited movement of fluids and small solutes in and out of the capillaries * Capillaries in the brain are an exception: tight junctions really are tight; this is the blood-brain

Question 26

Fenestrated capillaries

Answer 26

* Similar to continuous capillaries, but with pores in some cells * Much more permeable * Common in the small intestine (where capillaries pick up nutrients from digested food) and in endocrine organs (where hormones enter the circulatory system) and in the kidney

Question 27

Sinusoidal capillaries

Answer 27

* Very leaky * Found only in liver, bone marrow, spleen and adrenal medulla * Have fenestrations and fewer tight junctions, allowing large molecules and even blood cells to pass in and out * Lining contains macrophages that destroy bacteria * Irregular shape of lumen slows blood, giving time for all of this to occur

Question 28

thermoregulation

Answer 28

• Central channels are vessels that traverse a capillary bed and connect arterioles to venules • They consist of a metarteriole and a thoroughfare channel • Contraction of precapillary sphincters forces the blood directly from the metarteriole to the thoroughfare channel, bypassing the rest of the capillary bed • Important in thermoregulation and in the control of blood pressure • In many animals, including humans, the circulatory system also controls temperature via countercurrent heat exchange • At low external temperatures, blood flows through veins intimately associated with arteries • The warm blood from the heart transfers heat to the cooler blood returning from the extremities • This cools arterial blood and warms the venous blood, minimising heat loss to the environment

Question 29

Capillary hydrostatic pressure (CHP)

Answer 29

forces fluid out of the circulatory system, but | pressure drops moving from arterial to venous end of capillaries

Question 30

Blood colloid osmotic pressure (BCOP)

Answer 30

tends to pull water and solutes into capillaries

Question 31

Net filtration pressure (NFP)

Answer 31

is the difference between these

Question 32

foetal circulation

Answer 32

• No gas exchange in lungs; pulmonary vessels vasoconstricted • Three shunts ‘short-circuit’ circulation: – ductus venosus – foramen ovale – ductus arterosus

Question 33

Ductus venosus

Answer 33

Connects umbilical vein to inferior vena cava | bypassing liver

Question 34

Foramen ovale

Answer 34

Right atrium to left atrium (bypassing lungs)

Question 35

Ductus arteriosus

Answer 35

Pulmonary trunk and aorta (bypassing lungs)

Question 36

Circulatory events at birth

Answer 36

``` • Umbilical artery and vein close • 1 Ductus venosus Vein through liver closes (leaving hepatic portal system as remnant) 2. Foramen ovale Foramen ovale in heart closes (called fossa ovalis in adult heart) 3. Ductus arteriosus Ductus arteriosus closes (leaving ligamentum arteriosum) ```

Question 37

name the Ischaemic heart diseases

Answer 37

* Coronary artery occlusions | * Myocardial infarction

Question 38

name the Valvular heart diseases

Answer 38

* Degenerative valvular diseases * Rheumatic heart disease * Bacterial endocarditis

Question 39

name the different shocks

Answer 39

* Hypovoleamic shock * Cardiogenic shock * Septiceamic shock * Anaphylactic shock

Question 40

Ischaemic Heart Diseases

Answer 40

* This is a generic name for a group of closely related syndromes that result from myocardial ischaemia. * In over 90%, this is due to a reduction in coronary blood flow. (Decrease in supply) * Other conditions arise as a result of increases in demand e.g. hypertrophy, shock, increase heart rate, etc.

Question 41

Diminished Coronary Perfusion

Answer 41

* Fixed coronary obstruction * More than 90% of patients with IHD * One or more lesions that causes at least 75% reduction of the cross-sectional area of at least one of the major epicardial arteries.

Question 42

Angina Pectoris

Answer 42

``` • This is a symptom complex. Symptoms caused by transient myocardial ischaemia that falls short of inducing the cellular necrosis that defines myocardial infarction. • Three variants:- • Stable angina • Prinzmental angina • Unstable angina ```

Question 43

Effects of ischaemia on myocytes

Answer 43

* Onset of AT P Depletion * Loss of contractility * AT P reduced * to 50% of normal * To 10% of normal * Irreversible injury * Microvascular injury

Question 44

Laboratory detection of myocardial infarction

Answer 44

• This is based on the measurement of intracellular macromolecules leaked from the damaged myocytes into the circulation • Creatine kinase – particularly the M B isoenzyme • Lactate dehydrogenase • Troponin – Troponin I and Troponin T

Question 45

Effects of valvular disease

Answer 45

• Stenosis – tightening of the valvular opening resulting in decreased flow of blood through the opening. • Incompetence – incomplete closure of the valvular opening, allowing backflow of blood through the valvular opening • Mixed.

Question 46

Rheumatic fever

Answer 46

• Once the most common cause of valvular heart disease. • It is an acute immunologically mediated , multi-system inflammatory disease that occurs a few weeks after an episode of Group A (ß-hemolytic) streptococcal pharyngitis.

Question 47

what is shock

Answer 47

A state of generalised hypoperfusion of all cells and tissues due to reduction in blood volume or cardiac output or redistribution of blood resulting in an inadequate effective circulating volume • A systemic (whole body) event resulting from failure of the circulatory system • It is at first reversible, but if protracted leads to irreversible injury and death.

Question 48

causes of shock

Answer 48

* Hypovoleamia * Cardiogenic (pump failure) * Anaphylactic (peripheral pooling) (return failure) * Septic (Septiceamic) – Complex reasons

Question 49

Vicious circle of pathology

Answer 49

pump failure vessel injury peripheral pooling and repeat