Module 2 Flashcards
describe the base of the heart
- superior
- wide surface
- posterior to sternum
describe the apex of the base
- inferior tip
- 12-14 cm from base
what cavity is the heart located in
- thoracic cavity
- anterior mediastinum
what is the pericardium
and its different layers
covers the heart
double walled sac
- outer parietal pericardium
- inner visceral pericardium or epicardium
What are the three layers of the heart wall
- Epicardium
covers the heart - Endocardium
endothelium covers inner surfaces - Myocardium
muscular wall
features of the two 2 superior atria
- thin walled
0 receiving chambers - externally separated from ventricles by the coronary sulcus
features of the 2 ventricles
- thick walled
- discharging chambers
- externally separated from each other by inter ventricular sulcus
where does the right atria revise deoxygenated blood from
- superior vena cava (from regions superior to diaphragm)
- inferior vena cava (from regions inferior to diaphragm)
- coronary sinus
(from coronary blood supply)
where does the left atria receive oxygenated blood from
- right and left pulmonary veins from the lungs
which vessels take blood away from the ventricles
- pulmonary trunk
- aorta
how are internal ventricles separated from the atria
- via atrioventricular valves
(right = tricuspid)
(left = bicuspid)
what does the chord tendinea anchor
atrioventricular valves
what are the chord tendinae attached to
- papillary muscles
which side of the ventricular muscle is thicker
- left = thicker
- generates 4-6X more force
- contracts from bottom - up
role of atrioventricular valves
- prevent back flow of blood into atria when ventricles contract
- tensing of chordae tendinea and contraction of papillary muscles stop valves from everting
role of semilunar valves
- forced open when ventricles contract
- close when ventricles relay and blood in arteries try to flow backwards
role of coronary circulation
- supply blood to the myocardium as blood flowing through the heart doesn’t nourish tissue
where does the left coronary artery give rise to
anterior interventicular artery which supplied anterior ventricles
where does the right coronary artery give rise to
the posterior inter ventricular artery which supplies posterior ventricles
when does blood move into the coronary arteries
when the ventricles relax and blood in the aorta attempts to move backwards towards the heart
role of the great cardiac vein
drain the anterior regions supplied by the anterior inter ventricular artery
role of the middle cardiac vein
drains the posterior area supplied by the posterior interventricular artery
where do all veins drain to and then where does this drain to ?
- coronary sinus
- drains into right atrium
characteristics of angina pectoris
- temporary deficiency of myocardial blood supply (narrowed coronary vessels)
- thoracic pain
- increased physical demand on the heart
- myocardial cells weaken
characteristics of myocardial infarcation
- prolonged coronary artery blockage
- myocardium replaced by scar tissue
- weakens heart
what type of pump is the left side of heart
systemic
what type of pump is the right side of the heart
pulmonary
what pressure gradient does blood move
down
from an area of high pressure to low
what is the pathway of blood through the heart
- blood enters via: superior and inferior vena cava, coronary sinus - right atrium - tricuspid valve - right ventricle - pulmonary semilunar valve - pulmonary trunk - to lungs
- to heart
- four pulmonary veins
- left atrium
- left ventricle
- aortic semilunar valve
- aorta
what two factors influence electrical events in the cardiac cycle
- autonomic nervous system
- intrinsic conduction system (hearts own electrical system)
what components make up the intrinsic conduction system
- Sinoatrial Node
- Atrioventricular node
- Atrioventricular bundle
- Bundle Branches
- Purkinje fibres
intrinsic conduction system - role of sinoatrial node
- acts as pacemaker and determines heart rate
intrinsic conduction system - role of atrioventricular node
- pauses here for atria to complete contraction
intrinsic conduction system - atrioventricular bundle
- connects atria and ventricles
intrinsic conduction system - bundle branches
- conduct the impulses through inter ventricular septum
intrinsic conduction system - Purkinje Fibres
- penetrate ventricle walls
- depolarise ventricular myocardium
role of cardioacceleratory centre and where does it supply sympathetic input to
- increase heart rate and force of contraction
- sympathetic input via thoracic spinal cord to SA and AV node, Myocardium, Coronary arteries
role of cardioinhibitory centre and where does it supply parasympathetic input
- decreases heart rate
- parasympathetic input via vagus nerve to SA and AV nodes
describe electrocardiography
- detects cardiac electrical events
- electrodes placed on 12 parts of body
- composite of all the action potentials generated by the heart
ECG - P wave
- depolarisation of the atria
- beginning at the SA node
ECG - QRS complex
- depolarisation of the ventricles
- atrial repolarisation
ECG - T wave
- repolarisation of the ventricles
what can changes in an ECG pattern reveal
- if conduction pathway is normal
- if heart is enlarged
- if certain regions are damaged
- cause of chest pain
systole
contraction
diastole
relaxation
how long is the cardiac cycle
one complete heart beat
List the 8 stages in the cardiac cycle
- All chambers relaxed - ventricles partially filled
- Atrial Systole - contracts completely filling relaxed ventricles
- Atrial Systole ends and atrial diastole egos
- Ventricular Systole (part1) - beings at apex, closes Av valves but pressure not great enough to open SL valves = isovolumetric contraction
- Ventricular Systole (part2) - SL valves open from increased pressure = ventricular ejection
- Ventricular diastole (early) - ventricles relax, arterial blood flows backwards = SL closes
- Isovolumetric Relaxation - no change in blood volume, blood flows backwards and Av valves remain closed
- Ventricular diastole (late) - al heart chambers relaxed. AV valves open, blood moves passively from atria to the ventricles
what is the average resting heart rate
75bpm
what occurs in the cardiac cycle when heart rate increases
- all phases shortened
- especially ventricular diastole
- blood volume pumped by heart is reduced
What does the sound of Lubb s1 mean
closure of AV valves
what does the sound of Dupp s2 mean
closure of SL valves
what does a heart murmur mean
blood back flow through incompetent valve
correlating electrical and mechanical events - P wave
atrial depolarisation to atrial systole
correlating electrical and mechanical events - QRS complex
ventricular depolarisation to ventricular systole
correlating electrical and mechanical events - T wave
ventricular diastole
