Hypertension Flashcards
Where does the apex beat of the heart take place?
in the left ventricle
Where is the apex (base of left ventricle) of the heart located?
in the 5th intercostal spaces
close to the mid clavicular line
How much does the heart weigh?
300g
The heart is the size of a ________.
fist
Where is the heart located?
middle mediastinum
The heart is protected by…
the rib cage
The heart is ________ to the lungs
medial
What is the function of the vena cava?
allows the influx of blood from the body in deoxygenated state
Arteries carry blood ________
away from the heart
The pericardium is divided into __________ and ___________ pericardium
fibrous
serous
Serous pericardium is divided into ___________ and ___________ pericardium
parietal
viseral
What is between the parietal and visceral pericardial layers of the serous pericardium?
pericardial fluid
The _________ serous pericardium is closest the the fibrous pericardium
parietal
The serous pericardium is designed to allow…
the heart to move against its surface
What are the chambers of the heart?
2 atria
2 ventricles
What separates the left and right ventricles?
the intraventricular septum
What ventricle has the thickest walls?
the left ventricle
Venous blood returns from which vessels into the right atrium?
superior vena cava
inferior vena cava
What valve is located between the right atrium and the right ventricle?
tricuspid valve
What valve is located between the left atrium and the left ventricle?
mitral valve
biscuspid valve
The heart sits within the ___________ space where it contracts and relaxes.
pericardial
The heart has a two pump system, namely…
pulmonary (to the lungs)
systemic (to rest of the body)
Briefly describe the two pump system of the heart
deoxygenated blood returned to heart by body
heart sends blood to lungs via pulmonary artery
gas exchange occurs in lungs
heart receives oxygenated blood via pulmonary vein
oxygenated blood is pumped to rest of the body via the aorta
What is diastole?
relaxation of the chamber
filling of chamber with blood
What prevents the heart from collapsing during diastole?
the resting pressure
What is systole?
contraction of the chamber
ejection of the blood
What is the normal blood pressure?
120/80 mmHg
What is the normal blood pressure?
120/80 mmHg
What are the atrioventricular valves?
[valves between the chambers of the heart]
tricuspid (right AVV)
Mitral/ bicuspid (left AVV)
What are chordae tendinae?
these are fibrous connections between the valve leaflets and the papillary muscles
What are papillary muscles?
these are pilar-like muscles which are seen within the cavity of the ventricles
What is the function of the chordae tendinae and papillary muscles?
they ensure that there is no backflow during ventricular contraction
Ventricles contract from the ________ upwards
apex
What are the semilunar valves ?
Pulmonary valve (right hand side with pulmomary artery)
Aortic valve (left side)
What is the function of the coronary arteries?
supply the myocardium
Where do coronary arteries originate from?
the aortic root
aortic sinus
Coronary arteries are ___________ diastole
open
Innervation of coronary arteries is controlled by ______________.
autonomic vagus regulation
cranial nerve X
The left coronary arteries tend to look after what part of the heart?
the front part of the heart
The right coronary arteries tend to look after what part of the heart?
right ventricle
Distal right coronary artery looks specifically after the back of the heart (some of the front of the heart)
Name the coronary arteries of the heart
Left main coronary artery; circumflex coronary artery, left anterior descending coronary artery
Right coronary artery: distal right coronary artery
What is an end artery? Give examples
is an artery that is the only supply of oxygenated blood to a portion of tissue
coronary arteries
opthalamic arteries
What are the layers of the heart?
Pericardium
Myocardium
Endocardium
The endocardium is made up of …
squamous epithelium
The myocardium consists of __________ and ______________.
cardiomyocytes
pacemaker cells (set electrical rhythm)
The pericardium consists of _____________ and __________________ membranes
serous (parietal and visceral) membranes
fibrous membranes
State the features of cardiomyocytes
short, fat cells
1 central nucleus
abundant mitochondria
intercalated discs
co-odrinated contraction
What facilitates the co-ordinated contraction of cardio-myocytes?
they are joined by desmosomes
Cardiomyocytes are joined end to end by _____________.
intercalated discs
The action potential in the heart is generated by …
cells of the SAN (sinoatrial node)
Action potential generation is automatic however it can be altered by ______________.
autonomic vagus innervation
What is the normal resting heart rate ?
60-100 bpm
What is the resting membrane membrane potential of the heart?
-90mV
How is the resting membrane potential of the cell generated?
outside of the cell is more positive than inside of the cell
this is usually due to the action of Na+/K+ pumps; 3 Na+ out and 1 K+ in; this a potential difference
Briefly describe mechanism of action of the SAN?
the “door” opens
allows diffusion of Na+ ions in an attempt to neutralises the inside of the cell
What are the phases of action potentials of cardiac muscles?
phase 4
phase 0
phase 1
phase 2
phase 3
Describe what occurs in phase 4 of an action potential
Na+, Ca2+ channels are closed
Open K+ rectifier channels to keep the membrane potential stable at -90mV
Describe what occurs in phase 0 of an action potential
Rapid influx of Na+ through open fast Na+ channels
approaching 0mV
threshold potential of -50mV is reached (or not)
full depolarisation (+40mV)
Describe what occurs in phase 1 of an action potential
Transient K+ channels open and K+ efflux occurs to return the membrane potential to 0mV
Describe what occurs in phase 2 of an action potential
influx of Ca2+ through L type Ca2+ channels is electrically balanced by K+ efflux through delayed rectifer channels
Describe what occurs in phase 3 of an action potential
Ca2+ channels close but the delayed rectifier channels remain open and the membrane potential can return to -90mV
Briefly describe the electrophysiology of the heart (include how contraction is stimulated)
action potential generated by the SAN
atria depolarises then contracts
the signal reaches the AVN (atrioventricular node)
there is a delay at AVN to ensure ventricles are adequately filled
The action potential then travels down the bundle of His and then up through the purkinje fibres
This stimulates depolarisation of ventricles
Ventricles contract
The atrioventricular node (AVN) is described to be the …
relay station
Normal heart rate values are _________
60-100 bpm
number of times the heart beats per minute
What is the standard/normal cardiac output value?
5L/min
What is the stroke volume?
the amount of blood in ventricles at the moment it beats
volume of blood pumped out of the left ventricle during each systolic contraction
Cardiac output can be calculated by…
HR x SV
the amount of blood the heart pumps in 1 minute
Mean arterial pressure (mmHg) is calculated by
CO x SVR (systemic vascular resistance)
Pdias + 1/3 (Psyst - Pdias)
the average arterial pressure throughout the cardiac cycle (diastole and systole)
Pdias- pressure at diastole
Psyst- pressure at systole
Define essential hypertension
Essential hypertension is defined as a BP of 140/90mmHg with no secondary cause identified
a blood test must be performed to eliminate secondary causes
Give examples of secondary causes of hypertension
renal artery stenosis - renin released by kidneys as sensitive to hypotension/hypovolaemia
endocrine disorders
medication
cancers
pregnancy
heart injury
What are the risk factors for hypertension
obesity
aerobic exercise <3x per week
alcohol intake
smoking
diabetes
afro-carribean
age >60 years
family history
sleep apnoea
dyslipidaemia
high salt intake
What are the causes of hypertension?
excess sodium ions
dysregulation of renin- angiotensin- aldosterone
increases sympathetic drive (stress, catecholamine driven event)
insulin resistance
increased periperal resistance (narrow arteries)
endothelial dysfunction- high blood pressure can lead to endothelial damage
What causes small vessel atherosclerosis?
thrombosis
endothelial injury
inflammatory cascade
oxidative stress (ROS)
autonomic regulation
genetic predisposition
age
(all increase peripheral resistance)
What is small vessel atherosclerosis (SVA)?
occurs in microcirculation
building of atheroma
narrowing of the lumen
What is the presentation of hypertension?
asymptomatic
usually picked up on picked up on opportunistic screening
What are the end-organ damage symptoms of hypertension?
visual changes
renal failure
angina (ischaemic heart disease, chest pain)
sensory and/or motor deficit
List some complications of hypertension
coronary heart disease
cerebrovascular accident
left ventricular hypertrophy
heart failure
retinopathy
peripheral artery disease (SVA)
Kidney disease - microvasculature of kidneys
vascular dementia
What are the investigations for hypertension?
Electrocardiogram
fasting glucose (diabetes)
eGFR (kidney disorder?)
fasting lipid panel
urinalysis (cytology, culture, microscopy)
Check for endocrine disorders i.e. insulin
What are some modifiable risk factors of hypertension ?
stop smoking
lose weight
diet modification
reduce alcohol intake
exercise
What kinds of medication are administered for hypertension?
calcium channel blockers
E.g. nifedipine
