Topic E - cardiovascular system, cardiovascular diseases and the eye

Question 1

what is the cardiovascular system?

Answer 1

• a closed system of the heart, blood and blood vessels
• made up of :
  1. systemic circulation
  2. pulmonary circulation
• responsible for :
  1. delivery of oxygen and nutrients
  2. removal of carbon dioxide and other waste products

Question 2

review diagrams in part 1 slide 9,10

Answer 2

okey

Question 3

what are the 9 important components ( in order of blood flow )

Answer 3

1. superior vena cava
2. inferior vena cava
   ( both brings deoxygenated blood into 3 )
3. right atrium
4. right ventricle
5. left atrium
6. pulmonary artery
7. pulmonary vein
8. left ventricle
9. aorta

Question 4

** very important

how does blood flow through the heart? (9)

Answer 4

1. OXYGEN-POOR blood enters the RIGHT ATRIUM[ through the superior VENA CAVA and the inferior VENA CAVA
2. blood passes through the TRICUSPID VALVE to the RIGHT ventricle
3. blood is forced through the PULMONARY VALVE to the pulmonary trunk and enters the PULMONARY ARTERIES
4. blood travels to the lungs, where carbon dioxide is unloaded and oxygen is loaded
5. OXYGEN-RICH blood returns to the heart from lung through the FOUR PULMONARY VEINS to enter the LEFT ATRIUM
6. blood passes through the BICUSPID (MITRAL) VALVE to the LEFT VENTRICLE
7. blood is forced through the AORTIC VALVE to the AORTA
8. blood travels from the aorta to the rest of the body
9. blood returns to the heart through the superior and inferior VENAE CAVAE

Question 5

what is the direction that O2 poor blood takes?

Answer 5

superior and inferior venae cavae -> right atrium -> right ventricle -> pulmonary artery -> lung

Question 6

what is the direction of O2 rich blood?

Answer 6

pulmonary vein -> left atrium -> left ventricle -> aorta -> body parts

Question 7

what are the blood vessels of the heart? (5)

Answer 7

1. superior vena cava
2. inferior vena cava
   both transports
   - deoxygenated blood
   - from other parts of body
   - to right atrium

6. pulmonary artery 
transports 
- deoxygenated blood
- from right ventricle 
- to lungs 

7. pulmonary vein 
transports 
- oxygenated blood 
- from lungs
- to left atrium 

9. aorta 
transports 
- oxygenated blood 
- from left ventricle 
- to other parts of the body

Question 8

what is the atirum systole and ventricle systole?

Answer 8

part 2 slide 4

Question 9

what is the cardiac conduction system?

Answer 9

• stimulates the heart to contract
• also known as the nodal system
• sets the basic rhythm of heartbeat
• cardiac muscle is auto-rhythmic
  ~ this means that it does not need to be stimulated by the brain to contract
• the cardiac muscle cells initiate and carry the electrical impulses as part of the conduction system that stimulates heart contraction
• nerve impulses are not needed to initiate a heart conduction

~ heart pumping -> controlled by electrical impulses -> the cardiac conduction system -> measured by ECG

Question 10

what are the components of the cardiac conduction system?

Answer 10

• SA node
• AV node
• bundle branches
• purkinje fibers
• AV bundle/bundle of His
• purkinje fibers

Question 11

what is the pathway of signals?

Answer 11

1. • a heartbeat/contraction started by SA node (sinoatrial node), located in the right atrium near the entrance of the superior vena cava.
   • this is the natural pacemaker of the heart.
   • it initiates all heartbeats and determines heart rate.
2. electrical impulses from the SA node spread throughout both atrium and stimulate them to contract and depolarize.
3. • the impulses are then passed on to the AV node (atrioventricular node), located on the other side of the right atrium, near the AV valve.
   • The AV node serves as an electrical gateway to the ventricles.
   • it delays the passage of the electrical gateway to the ventricles.
   • this delay is to ensure that the atrium have ejected al the blood into the ventricles before the ventricles contract.
4. • the impulse then goes to AV bundle (atrioventricular bundle/bundle of His.
   • this bundle is then divided into right and left bundle branches which conduct the impulses toward the apex of the heart.
5. the signals are then passed onto Purkinje fibres, turning upward and spreading throughout the ventricular myocardium to contract and depolarize.

Question 12

** important

what is the ECG (electrocardiogram)?

Answer 12

• it is a means of looking at cardiac rhythm
• a graph showing the electrical activity in the heart
• the five waves per cycle represents three electrical events :
  1. P wave ( first small wave )
• shows atrium depolarization ( contract)

2. Q,R,S waves/complex ( sharp, high wave )
   - represents ventricular depolarising (contract)
3. T wave ( same as p wave but after Q,R,S wave )
   - represents ventricular repolarising (relax)

~ atrium repolarizing (relax) = same time as ventricles depolarizing

when atirum contract, ventricle relax and vice versa
contract,deploarize = discharge
relax, reploarize = recharge

Question 13

what is the basic concept of the cardiac cycle?

Answer 13

• is a complete contraction and relaxation of the heart ( the heartbeat)
• can be repeated 70-80x/min ( average ~75x/min )
• systole: contraction
• diastole: relaxation
• the right/left atrium go through systole and diastole together at the same time, same for the ventricles and the valves

Question 14

*** important

what are the four phrases of the cardiac cycle?

Answer 14

1. atrial systole
   - atrium contracts and depolarize, blood is pushed into the ventricles
2. ventricular diastole
   - ventricle relax and repolarize, blood flow from the atrium to the ventricle passively
3. atrial diastole
   - relax and repolarize, blood flow back to atrium
4. ventricular systole
   - contract and depolarize. blood is pumped out and pushed through the pulmonary and aortic valves into the pulmonary trunk and aorta

Question 15

what is the cardiac cycle?

Answer 15

• the event of one comlete heartbeat
• average heart beats/rate is around 75 beats per minute
• one cardiac cycle is around 0.8 second

female ~72-80 beats
male ~64-72
athletes ~ 40-60

Question 16

what are the three types of heartbeat

Answer 16

• too fast : tachycardia
• above 100 beats per minute
• normal heartbeat/rate
• *60-100 beats per minute
• too slow : bradycardia
  below 60 beats per minute

Question 17

what are the three types of heartbeat

Answer 17

• too fast : tachycardia
• above 100 beats per minute
• normal heartbeat/rate
• *60-100 beats per minute
• too slow : bradycardia
  below 60 beats per minute

Question 18

what is the heart beat sound?

Answer 18

• “lubb-dupp”

Lubb (S1) - closure of mitral and tricuspid valves

Dupp (S2) - closure of pulmonary and aortic valves

• the pause corresponds to the heart beats/heart rate

Question 19

what is the cardiac output (CO)?

Answer 19

= amount of blood pumped by each ventricle of heart in one minute (normal CO ~4-6 litres/min)

CO = heart rate x stroke volume
= 75beats/min x 70ml/beat = 5,250 ml

(stroke vol = vol of blood pumped by each ventricle in one contraction )

Question 20

how is the heart rate (HR) regulated during physical/emotional stress moments ?
- eg exercise,excitement,fear,anxiety, etc

Answer 20

sympathetic neurons stimulated from CCC and extend down to the spinal cord via thoracic region , innervate the SA and AV node and portions of the myocardium

norepinephrine is secreted and increases HR and stregthen the contraction of the myocardium

Question 21

how is the heart rate (HR) regulated during sad moments eg depression,grief etc

Answer 21

parasympathetic neurons stimulated from CCC via vagus nerve and innervate SA and AV node

acetylcholine is scereted and slows down HR

Question 22

why does the heart not experience fatigue?

Answer 22

• cardiac muscle cells has the following adaptations that enables them to use aerobic respiration almost exclusively :
  1. have many large mitochondria to perform aerobic respiration
  2. rich in myoglobin (protein for storing oxygen)
  3. rich in glycogen (a starch that can be converted to glucose to be used as fuel )

4. can use a variety of fuels as energy source
   eg glucose,fatty acids, amino acids, ketones

Question 23

what are the vessel anatomy and functions of the 3 blood vessel?
(ACV)

Answer 23

arteries
- carry blood away from the heart to capillaries (smallest arteries = arterioles)
~ rmb A for away

capillaries

• allow for the exchange of materials between the blood and tissues.
• it is a microscopic vessel composed of a single layer of endothelial cells.
• it is absent in certain tissues eg cartilage,epidermis,lens,cornea

veins
- delivers blood from the capillaries back to the heart (smallest veins = venules )

systemic routes :
heart - > arteries -> arterioles -> capillaries -> venules -> veins -> heart

arteries,arterioles = o2 rich blood
capillaries = exchange of material
venules, veins = o2 poor blood

Question 24

how does the exchange of materials occur between blood in capillaries and tissue cells?

Answer 24

~ cells needs oxygen and nutrient to perform their metabolic functions and co2/waste needs to be removed
~tissue fluid (interstitial fluid) lies between tissue cells and capillaries
~ oxygen and nutrient diffuse from blood in capillaries into the tissue fluid and into body cells
~ co2/metabolic wastes diffuse in the opposite direction

Question 25

how does blood flow to a capillary bed?

Answer 25

1. arterioles have circular, smooth muscle cells that act as precapillary sphincters to control blood flow 2. some arterioles connect directly to small veins (venules), forming arteriovenous shunt 3. capillaries walls are a single endothelial cell thick, allowing for the exchange of materials between blood and tissue fluid

Question 26

*** important what are the similarities that arteries and veins share? (3)

Answer 26

they both have three distinct layers (structure) 1. tunica externa - connective tissue (outer layer) - provides elasticity 2. tunica media - smooth muscle ( middle,thickest layer ) - provide support and produce changes to the diameter 3. tunica interna - endothelium ( inner layer )

Question 27

*** important what are the differences between arteries and veins? (5)

Answer 27

(A=artery, V=vein) 1. blood speed/velocity A : blood travels faster, high velocity V : blood travels slower, low velocity 2. muscle layer A : has more smooth muscle and connective tissue - thicker muscular layer to withstand higher blood pressure V : thin msuclar layer 3. lumen size (goes tgt w point2) A : smaller lumen,thicker wall V : larger lumen, thinner wall 4. pressure,volume of blood and valves A : - carries blood FROM heart hence has a higher pressure and need to reach cells fast - low volume of blood - no valves V: - carries blood TO heart hence lower pressure - high volume of blood - has valves ( to prevent backflow of blood due to low pressure ) 5. appearance A : appears lighter in colour as it is O2 rich V : appears darker as it is CO2 rich

Question 28

explain blood flow

Answer 28

- blood flows from areas of higher to lower pressure - blood pressure is the greatest in ventricles and lowest in atria ~ contraction of ventricles creates blood pressure and propels blood through arteries ~ pressure declines as arteries branches into increasing number of smaller and smaller arteries and finally capillaries ~ by the time blood has left capillaries and entered veins, there is very little blood pressure remaining to return the blood to the heart - the return of venous blood is assisted by 3 additional forces

Question 29

how does venous blood return to the heart? | 3 forces

Answer 29

skeletal muscle contraction - it compresses the veins from one valve segment to another and on toward the heart. - important in legs and arms respiratory movements - it aids the movement of blood upwards towards the heart in abdominal and thoracic cavities - the downwards contraction of diaphragm during inspiration decreases pressure with abdominal cavities - so the abdominal vein (higher pressure) forces blood upwards to thoracic veins gravity (eg upper body parts, superior to heart) - it aids the return of blood in veins superior to the heart

Question 30

what is blood pressure (BP)?

Answer 30

- refers to arterial blood pressure in the systemic circuit in aorta and its branches - it is greatest during ventricular contraction (systole) and is called systolic blood pressure (~120mmHg) - it is lowest during ventricular relaxation (diastole) and is called the diastolic blood pressure (~80 mmHg) ~ the difference between the two is called pulse pressure (means pulse could indicate heart rate) ~ BP is measured using sphygmomanometer)

Question 31

what is systolic and diastolic blood pressure?

Answer 31

systolic blood pressure : - pressure extended on the arteries when the heart beats diastolic blood pressure : - pressure on the arteries when the heart rests between beats normal BP :120/80mmHg prehypertension : > 120/80 mmHg hypertension (HT) : >140/90 mmHg malignant hypertension : >180/110 mmHg

Question 32

*** important!! | what are the factors affecting blood pressure (BP)? 4

Answer 32

~ anyt that increases 'burden' of the heart will cause an increase in BP 1. cardiac output = amount of blood pumped by each ventricle of the heart in one minute - changes in CO will change BP as the blood volume or heart rate changes 2. blood volume (low vol = low bp and vice versa ) - may be decreased by severe haemorrhage, vomiting, diarrhoea, or reduced water intake, and reduced BP due to loss of fluid - if the body retains too much fluid, blood volume and BP increase 3. peripheral resistance (PR) - artery wall flexibility and diameter - it is the friction of blood against walls of blood vessels - when arterioles change diameters, it alters PR and controls BP ~ when it constricts, PR and BP increases ~ when it dilates, PR and BP decreases 4. blood viscosity - it is the resistance of a liquid to flow - it is determined by concentration of blood cells and plasma proteins - increase in either of their concentration leads to increase in blood viscosity and BP ~thickness/high concentration = high BP

Question 33

what are the effects of aging/hypertension on the heart?

Answer 33

- heart becomes less efficient due to decreased resting stroke volume - so there will be lower CO - the vessel walls thicken and become less elastic - vascular resistance increases with age in individuals with hypertension - CO decreases as heart rate decreases

Question 34

what is hypertension (HT) ?

Answer 34

- refers to chronic high blood pressure - may be caused by many factors, but persistent stress and smoking are the 2 common ones - it is the most common disease affecting the heart and blood vessels *- HT : when BP is greater than 140/90 mmHg *- pre-HT : 120-139/80-89 mmHg - usually no symptoms unless BP is very high ~ may lead to : - organ damages eg heart and kidney - kidney disease - heart attack - stroke - poor vision - hypertensive retinopahty (bleeding in the eye, ischemic changes due to blockage ) - can weaken small arteries and cause aneurysms (weaken arteries, balloon out, and even rupture ) - treatment : medications and lifestyle change (lose weight, reduce salt intake, reduce stress, stop smoking,exercise )

Question 35

what are the cardiovascular diseases that impact the eyes? | HASHG

Answer 35

1. hypertension 2. atherosclerosis 3. stroke 4. hyperlipidemia 5. giant cell arteritis