21 - anatomy and function of the heart Flashcards

Question

what does the aorta do?

Answer 1

- Transports oxygenated blood away from the left ventricle in the heart to the rest of the body - Blood first flows from the left ventricle to the ascending aorta - The aortic arch branched into the carotid and subclavian arteries and transports blood to the upper parts of the body - The descending aorta transports blood to the lower regions of the body.

Answer 2

- Transports deoxygenated blood away from the right ventricle in the heart to the lungs - Blood first flows into the pulmonary trunk which branches into the right and left pulmonary arteries

Answer 3

- Transports deoxygenated blood to the right atrium of the heart, from the rest of the body - Superior vena cava transports blood from the upper body - Inferior vena cava transports blood from the lower body

Answer 4

- Transports oxygenated blood to the left atrium in the heart, from the lungs - 4 branches: 2 right and 2 left pulmonary veins

Answer 5

Semi-lunar valves - Aortic value - controls flow of blood from ventricle to rest of body - Pulmonary valve - controls flow of blood right ventricle to lungs Atrio-ventricular valves - Mitral valve - controls flow of blood from atrium to left ventricle - Tri-cuspid valve - controls flow of blood right atrium to right ventricle

Answer 6

Sits at the base of the aortic root 3 leaflets (or cusps) - Left coronary artery - Right coronary artery - Non-coronary artery Coronary ostium - To right and left coronary arteries - Allows blood to flow to the heart muscle Aortic sinus - Facilitates closure of the valve

Answer 7

Called 'mitral' because its shaped like a mitral (a bishops hat) 2 leaflets - Anterior leaflet - Posterior leaflet Papillary muscles and chordae tendineae - Pulls the leaflets to prevent them inverting into the atrium.

Answer 8

The heart has its own pacemaker known as the sinoatrial mode (SA node) which controls the contraction of the muscle fibres. The SA node consists of a group of specialised muscle cells which spontaneously depolarise. The conductions travels as follows: - The SA node - located in the wall of the right atrium - Internodal pathways atrioventricular node (AV node) - located in the atrium and ventricular junction - Bundle of HIS - Left and right bundle branch (RBB and LBB) - Purkinje fibres

Answer 9

- Blood returning to the right atrium is known as venous return - Pressure in atria exceeds pressure in ventricles - Atrioventricular valves open - Ventricles passively fill with blood from atria - 90% of total ventricular filling - Aortic and pulmonary pressures fall - Pressure difference between atria and ventricles decreases - This leads to a decrease in rate of filling

Answer 10

- Atria contracts - Final 10% of ventricular filling. Ventricular filling at a maximum (typically 120 ml) - End diastolic volume (EDV) - Pressure in ventricles exceed atrium - Atrioventricular valved close - The degree of ventricular stretching is known as preload, the greater the tension produced by the ventricles.

Answer 11

- All valves closed - Ventricles begin to contract - Iso-volumetric contraction - as there is no change in volume in the ventricles - Pressure in ventricles rises sharply

Answer 12

- Pressure in ventricle exceed that of arteries - Semi-lunar valves open - Blood is ejected rapidly to the aorta and pulmonary arteries - The amount of blood ejected into the arteries from the ventricles is known as stroke volume. Its approximately 70 ml - The cardiac output is the stroke volume per minute for the left ventricle

Answer 13

percentage ratio of stroke volume to end diagnostic volume.

Answer 14

- As ventricle empties, the pressure drops below that of the arteries - All valves close - Ventricles and atria relax - Blood remaining in ventricles at end of systole is called the end systolic volume (ESV)

Answer 15

- Sympathetic innervation - norepinephrine released to accelerate the heart rate - Parasympathetic innervation - acetylcholine released to slow down the heart rate - SA node, AV node and atrial muscle cells innervated equally - Ventricular muscles cells innervated more by sympathetic fibres

Answer 16

control the rate of spontaneous depolarisation of the SA node and repolarisation period

Answer 17

an increase in the venous return. De-oxygenated blood returning to the right atrium will stretch the muscles fibres of the SA node more which leads to more rapid depolarisation --> increased heart rate.

Answer 18

End diastolic volume (EDV) Affected by two things: filling time and venous return (preload) Filling time Affected by the heart rate - A decreased heart rate increased ventricular filling time - A faster heart rate leaves little time for filling Preload - Increased venous return increases the end diastolic volume which increases the stretching of the ventricular walls --> a higher preload --> increased force of contraction End systolic volume (ESV) Affected by three things: preload, contractility and afterload. Contractility (inotropy) - Sympathetic - positive inotropy – increase of calcium ion uptake by cardiac muscle fibres in the ventricle → increased force of contraction → decreased ESV→ increased stroke volume. - Parasympathetic – negative isotropy – inhibition of calcium ion uptake by cardiac muscle fibres in the ventricle → decreased force of contraction → increased ESV → decreased stroke volume. Afterload - Tension produced by the ventricles to overcome the pressure in the arteries and open the semi-lunar valves. - Increases with increased pressure in aorta. Greater the afterload → longer the period of iso-volumetric contraction → increased ESV → decreased stroke volume.

21 - anatomy and function of the heart Flashcards

(42 cards)