Cardiovascular Flashcards
1
Q
Where does the exchange of nutrients and waste happen?
A
Capillaries
2
Q
What are the boundaries of the mediastinum?
A
Anterior: sternum
Posterior: bodies of thoracic vertebrae
Lateral: right and left pleural cavities
3
Q
What are the divisions of the mediastinum?
A
Superior and inferior.
Inferior is further divided into anterior, middle and posterior.
4
Q
What are the layers of the heart?
A
The epicardium, myocardium and endocardium
5
Q
What is the pericardium divided into?
A
Fibrous pericardium and serous pericardium.
Serous pericardium:
- Parietal pericardium: lines interior of fibrous pericardium
- Visceral pericardium (epicardium): continues over the surface of the heart
6
Q
What are the four heart chambers?
A
2 atria and 2 ventricles
7
Q
Where does the right atrium receive blood from?
A
Superior and inferior vena cava and coronary sinus
8
Q
Where does the left atrium receive blood from?
A
The four pulmonary veins
9
Q
Which part of the atria is rough and why?
A
The anterior walls of the aria are rough because of the pectinate muscle.
10
Q
Where is the fossa ovalis located?
A
The interatrial septum
11
Q
What separates the two ventricles?
A
Interventricular septum
12
Q
What does the inner surface of both ventricles contain?
A
Trabecular carinae
13
Q
What are the cardiac valves?
A
Tricuspid, mitral, pulmonary and aortic
14
Q
How are the AV valves attached?
A
Their flaps attach to chord tendinae which is connected to the papillary muscle.
15
Q
What is the function of the semilunar valves?
A
To guard the bases of the two large arteries leaving the ventricular chambers.
16
Q
What is the fibrous skeleton?
A
Dense connective tissue that surrounds the valves of the heart and merges with their interventricular septum
17
Q
What is the function of the coronary arteries?
A
To supply blood to the myocardium
18
Q
What does the left coronary artery divide into?
A
The left anterior descending (LAD) and the circumflex branch
19
Q
Where is the LAD located and what is its function?
A
It is in the anterior interventricular sulcus and it supplies oxygenated blood to the walls of both ventricles
20
Q
Where is the circumflex branch located and what is its function?
A
It lies in the coronary sulcus and it distributes oxygenated blood to the walls of the left atrium and ventricle
21
Q
Where does the right atrium supply to?
A
Small atrial branches, the posterior interventricular and marginal branch.
22
Q
Where is the posterior interventricular located?
A
It follows the posterior interventricular sulcus
23
Q
What does the posterior interventricular artery supply?
A
It supplies the walls of the two ventricles with oxygenated blood
24
Q
Where is the marginal branch located? Where does it supply blood?
A
It is beyond the coronary sulcus and runs along the right margin
Lateral side of right ventricle
25
What does the marginal branch supply?
It transports oxygenated blood to the wall of the right ventricle
26
What is coronary anastomosis?
Both coronary arteries anastomose with each other to form a loop so that there is an ensured alternate pathway of blood
27
What is the coronary sinus?
It is where most of the deoxygenated blood from the myocardium drains into and it empties into the right atrium
28
Which are the coronary veins?
The great cardiac vein
Middle cardiac vein
Small cardiac vein
Anterior cardiac veins
29
Great Cardiac Vein
Anterior IV sulcus and drains the areas of the heart supplied by the left coronary artery (left atrium and left ventricle)
30
Middle Cardiac Vein
Posterior IV sulcus and it drains the areas supplied by the posterior IV branch of the right coronary artery (both ventricles)
31
Small Cardiac Vein
Drains the right atrium and right ventricle
32
Anterior Cardiac Vein
Drains right ventricle and opens into right atrium
33
What are the three layers of the arteries?
Tunica intima: inner epithelium
Tunica media: thick smooth layer
Tunica externa: outer connective tissue
34
What changes in the structure of the tunica media with the size of the artery?
With larger arteries, there is more elastic tissue, and less smooth muscle for stretching and better absorption of blood
35
What is the main layer in arterioles?
Tunica media
36
What is peripheral resistance?
The regulation of blood pressure by controlling the diameter size of arterioles, the pressure the blood encounters when passing through the vessels.
37
What controls the entry to the capillary beds?
Precapillary sphincters which are rings of smooth muscles which control blood flow
38
What are the types of true capillaries?
Continuous capillaries: CNS, lungs, muscle tissue, and skin
Fenestrated capillaries: kidneys, small intestine, choroid plexuses, ciliary processes, and endocrine glands
Sinusoids: red bone marrow, spleen, anterior pituitary, parathyroid, and adrenal glands
39
What is the blood-brain barrier ?
Capillaries make up the BBB, it limits the ability of toxins and many medications to pass into the brain
40
What helps keep the BBB?
Tight junctions
41
Which layer of the veins is thicker?
The tunica externa
42
What is the vascular sinus?
It has no smooth muscle in order to alter its diameter.
43
The aorta and its branches?
Ascending
Arch
Thoracic
Right and left coronary arteries
Brachiocephalic trunk
Left common carotid
Left subclavian
Bronchial
Oesophageal
Posterior intercostal
Superior phrenic
Mediastinal
Pericardial
44
What is the circle of Willis?
The arteries in the brain which transport blood to the different organs and sections
45
Where does the circle of Willis originate from?
Two vertebral arteries join to form the basilar
Two internal carotid arteries
46
What is portal circulation?
Special type of vascular network connecting one capillary network into another through the portal vein.
47
What are the two types of portal circulation?
Hypophyseal portal system
Hepatic portal system: stomach and intestine to the liver
48
How do cardiac muscle fibers connect?
Through intercalated discs, desmosomes, and gap junctions.
49
What is the function of the gap junctions?
To allow the whole myocardium of the atria/ ventricles to contract as a single and coordinated unit
50
What is the cardiac conductive system?
It consists of auto-rhythmic fibers which are modified cardiomyocytes that generate action potentials that trigger heart contractions.
51
What do issues with the autorhythmic fibers lead to?
Arrhythmias
52
What are the functions of the cardiac conductive system?
To continue to generate and deliver regular impulses to cardiac muscle
To form the conduction system to ensure that cardiac chambers contract in a coordinated manner
53
What helps the heart be an effective pump?
Gap junctions and fibrous skeleton
54
What are the functions of the fibrous skeleton?
For structural foundation for valves
Prevents overstretching of valves
Serves as point of insertion for bundles
Electrical insulator between the chambers
55
What happens when the pacemaker potential reaches threshold?
It triggers an action potential (SA node)
56
Why does the SA node serve as a natural pacemaker?
Due to its fast discharge
57
Operation of Cardiac Conductive System
- SA node starts off each heartbeat
- Impulse from the SA node propagates through atria via gap junctions in the intercalated discs of atrial muscle fibers
- Atria contract
- Impulse spreads through the atria to the AV node
- At the AV node, the impulse is slightly delayed
- Impulse travels through AV bundle, bundle branches, and Purkinje fibers
- Ventricles contract
58
Why is there a delay at the AV node?
To ensure the ventricles are activated, and to ensure complete ventricular filling.
59
What causes the delay at the AV node?
The difference in cell structure.
60
What is an ECG/EKG?
Record of action potentials produced by the heart muscles during each heartbeat
61
What are the ECG waves?
P wave
QRS complex
T wave
62
What does the P wave represent?
The atrial depolarisation
63
What does the QRS complex represent?
The rapid ventricular depolarisation
64
What does the T wave represent?
The ventricular repolarisation
65
What does an enlargement of the P wave indicate?
Enlargement of the atrium
66
What does an enlargement of the Q wave indicate?
A myocardial infarction
67
What does an enlargement of the R wave indicate?
Enlargement of ventricles
68
What does an flattening of the T wave indicate?
Coronary artery disease
69
What does an elevation of the T wave indicate?
Hyperkalemia (High blood K levels)
70
Which limbs is each bipolar lead responsible for?
I = LA & RA
II = LF & RA
III = LF& LA
70
Which limbs is each bipolar lead responsible for?
I = LA & RA
II = LF & RA
III = LF& LA
71
How to calculate number of beats per minute?
Count big squares from peak to peak,
Divide 300 by it
72
What is the PR interval?
Represents the time that it takes for electrical impulse generated in the sinus to travel through atria and AV node to ventricles.
73
What is the normal PR rate?
Less than 20 seconds
74
What does the ST segment represent?
The time when the ventricular contractile fibers are depolarised during the plate phase if the action potential
75
What are the three abnormalities seen with the ST segment?
ST depression
ST elevation
Saddle shape
76
What does the cardiac cycle consist of?
Diastole = relaxation
Systole = contraction
77
What happens during atrial systole?
- Depolarisation of the SA node causes atrial depolarisation
- 2 Atrial depolarisation cause atrial systole
- Atrium contains about 130mL at the end of diastole
78
What is isovolumetric contraction?
- Also known as Ventricular systole
- QRS complex in ECG
- Ventricular depolarisation --> Ventricular systole.
79
What happens during ventricular systole?
Pressure in the ventricles rises sharply and pushes blood against the AV valve, forcing them to shut. This causes the first heart sound.
The AV valves bulge into atria, causing a sharp rise in atrial pressure
80
Which valves are opened/closed during isovolumetric contraction?
All valves are closed
81
When does ventricular ejection happen?
When the left ventricular pressure surpasses the aortic pressure at about 80mmHg and the right ventricular pressure rises above the pulmonary trunk (20mmHg)
82
Which valves are open/closed during ventricular ejection?
The SL valves open and the AV valves are closed
83
What is the pressure of the ventricles at isovolumetric ejection?
Left ventricle: 120mmHg
Right ventricle: 25 to 30mmHg
84
How much blood is ejected from the ventricles during ventricular ejection?
About 70mL
85
What is stroke volume?
End diastolic volume - End systolic volume
86
What is the stroke volume at rest?
70mL
87
What is isovolumetric relaxation?
As the ventricles relax, pressure decreases, and blood flows into the aorta and pulmonary trunk. In order to prevent back flow the valves close giving rise to the second sound.
88
Which two phases cause the heart sounds?
Ventricular systole and Isovolumetric relaxation (early diastole)
89
Why are AV valves open during isovolumetric relaxation?
To permit ventricular filling
90
What is ventricular filling?
Blood flowing into the heart throughout the diastole, filling the atria a the ventricles. The pressure in the ventricles remains low.
91
When do the AV valves open?
When the ventricular pressure is lower than the atrial pressure.
92
What are the stages of the heart cycle?
Atrial contraction, Isovolumetric Contraction., Ventricular Ejection, Isovolumetric Relaxation, Ventricular Filling
93
What are the rates for a normal systolic and diastolic blood pressure?
Systolic = 110 to 130
Diastolic = 70 to 90
94
What is cardiac output?
The amount of blood ejected from each ventricle per minute.
95
What is peripheral resistance?
The amount of friction blood encounters as it flows through vessels
96
Where is the cardiovascular centre situated?
In the medulla oblongata
97
What are baroreceptors?
Receptors that are responsive to stretching and send inhibitory stimuli to vasomotor Centre
98
What are chemoreceptors?
Receptors that are responsive to changes in oxygen and carbon dioxide concentrations in the blood. They send stimulatory stimuli to vasomotor centre.
99
What are the factors increasing heart rate?
Catecholamines and thyroid hormones
Adrenaline and noradrenaline
Body temperature
Chemoreceptors stimulation
Emotions
Physical exercise
During inspiration
100
What are the factors decreasing heart rate?
Drugs like β blockers, Ca++ channel blockers, digoxin
Carotid massage
Massage of eyeball
Expiration
101
What is the stroke volume?
The amount of blood pumped out of each ventricle per beat which is 70mL
102
What are the three factors affecting stroke volume?
Increasing ventricular preload: the degree of stretch on the heart before it contracts.
Increasing myocardial contractility: the forcefulness of contraction of individual ventricular muscle fiber.
Decreasing afterload: the pressure that must be exceeded before ejection of blood from the ventricles can occur.
103
When does preload increase?
Hypervolemia
Regulation of cardiac valves
Heart failure
104
When does afterload increase?
Hypertension
Vasoconstriction
105
What happens when afterload increases?
Cardiac workload increases
106
What is Frank-Starling Law?
The stroke volume of the ventricle will increase as the ventricular volume increases due to myocyte stretch causing a more forceful systolic contraction.
107
How does Frank-Straling Law affect preload?
The more the heart fills with blood during diastole, the greater the force of contraction during systole
108
What does ventricular end diastolic volume depend on?
Venous return
Atrial systole
Duration of diastole
Diseases such as:
Aortic regurgitation
Heart failure
109
What happens if venous return increases?
Cardiac output increases
110
What happens to the duration of diastole when heart rate increases?
It decreases
111
What happens when the duration of diastole decreases?
Less filling means a smaller end-diastolic volume and the ventricles may contract before they are adequately filled.
112
What happens to the cardiac output when the heart rate is extremely high?
The carbon dioxide will decrease due to the reduction in ventricular filling and reduced cardiac contractility due to insufficient oxygen supply.
113
What do positive inotropic and negative inotropic do?
Directly increase and decrease the stroke volume respectively
114
What are some examples of positive inotropic?
Epinephrine and Nor epinephrine
Digitalis
Calcium
Caffeine
Thyroxin
Glucagon
Sympathetic stimulation
115
What are some examples of negative inotropic?
Acetylcholine
Potassium
Hypoxia
Hypercapnia
Acidosis
Drugs: β blockers and Ca++ channel blockers
116
Which conditions can increase afterload due to high resistance?
Systemic hypertension
Atherosclerosis
Aortic valve stenosis
Coarctation of aorta
117
What are the physiological regulations of blood pressure?
Short Term Regulation & Long Term Regulation
118
What is short term regulation?
Involves cardiovascular centre and catecholamines
119
What does the short term regulation affect?
Cardiac output and peripheral resistance
120
What is long term regulation?
Involves the kidneys in controlling the intravascular volume and the peripheral resistance
121
What happens to the baroreceptors when the blood pressure falls?
They are stretched less and they send nerve impulses at a slower rate to the cardiovascular centre.
122
How does the cardiovascular centre respond to blood pressure dropping?
- Decrease in parasympathetic stimulation of the heart by way of motor axons of the vagus nerves
- Increase in sympathetic stimulation of the heart via cardiac accelerator nerves
- Increase in secretion of epinephrine and norepinephrine
123
How does the cardiovascular's response to low blood pressure affect the body?
It will increase contractility, stroke volume, heart rate and peripheral resistance which will then increase blood pressure
124
Hormonal Regulation of Blood Pressure: Epinephrine and Norepinephrine
Response to sympathetic stimulation: the adrenal medulla releases catecholamines
They increase cardiac output by increasing the rate and force of heart contractions
125
What does the release of catecholamines during regulation of blood pressure cause?
They cause vasoconstriction of arterioles and veins in the skin and abdominal organs
Vasodilation of arterioles and veins in cardiac and skeletal muscles
126
What hormone has similar effects to the heart as catecholamines?
Thyroxin hormone
127
What is the long term regulation of blood pressure?
Mainly controlling the amount of intravascular fluid and thus increasing blood volume
128
What does the increase of blood volume do?
Increases the venous return and thus stroke volume
129
Does long term regulation affect peripheral resistance?
Yes
130
When does the RAA system take place?
When blood volume falls or blood flow to the kidneys decreases.
131
What happens in the RAA system?
It causes the juxtaglomerular cells to secrete renin into the bloodstream.
In sequence, renin and angiotensin-converting enzyme (ACE) (from the lungs) act on their substrates to produce the active hormone angiotensin II
132
What is the function of angiotensin II?
To raise the blood pressure in two different ways
133
What are the two ways in which angiotensin II can raise blood pressure?
Angiotensin II is a potent vasoconstrictor; raises blood pressure by increasing vascular resistance
Angiotensin II also stimulates the secretion of aldosterone, which increases the reabsorption of sodium ions and water by the kidneys. The water reabsorption increases the total blood volume.
134
Long Term Regulation: ADH
ADH is produced by the hypothalamus and released from the posterior pituitary in response to dehydration or decreased blood volume.
135
What are two of the functions of ADH which help with low blood pressure?
It causes vasoconstriction, which increases blood pressure. It is called vasopressin.
It also promotes reabsorption of water from the lumen of kidney tubules into the bloodstream. This leads to an increase in blood volume and a decrease in urine output.
136
Long Term Regulation: Atrial natriuretic peptide (ANP)
Vasodilation
Promoting the loss of salt and water in the urine, decreases the blood volume
137
Where is ANP released from?
Cells in the atria of the heart
138
What is the function of ANP?
To lower blood pressure
139
What are common drugs for prevention of hypertension?
Diuretics
Beta-blockers (decrease activity of the heart)
Calcium channel blockers (reduce the amount of calcium entering the heart)
140
Why is calcium necessary for the heart?
Helps contract the muscle lining of the heart
141
What are the four different types of shock?
Hypovolemic: decreased blood volume
Cardiogenic: poor heart function
Vascular: inappropriate vasodilation
Obstructive: obstruction of blood flow
142
What is shock?
The failure of the cardiovascular system to deliver enough O2 and nutrients to meet the cellular metabolic needs
