The Heart Flashcards
What are the key functions of the heart?
- transport of oxygen
- transport of nutrients
- removal of waste products
- immune system
- paracrine system
Describe the structure of the heart
the heart is a dual pump driving 2 parallel circulatory systems –> pulmonary circulation & systemic circulation
Describe the function of the Vena Cava
- carries deoxygenated blood from the heart
- superior vena cava carries blood from the head & upper body
- inferior vena cava carries blood from the lower body
Describe the function of the pulmonary veins
carries oxygenated blood from the lungs to the heart
Describe the function of the aorta
carries oxygenated blood from the heart to the body
Describe the function of the pulmonary artery
carries deoxygenated blood from the heart to the lungs
Describe the atria
- receives incoming blood from veins
- contraction of atria pushes blood into ventricles
- thin walls
- valves prevent blood from ventricles going back into atria
Describe the ventricles
- responsible for pumping blood through arteries
- thick muscular walls
- left ventricle has thicker wall as it does more work
- two ventricles are separated by a muscular septum
What are the 2 kinds of semilunar valves ?
- pulmonary valve
- aortic valve
Describe the pulmonary valve
regulates blood flow from the right ventricle into the pulmonary artery
Describe the aortic valve
regulates the blood flow from the left ventricle into the aorta
What are the 2 types of atrioventricular valves ?
- mitral valve
- tricuspid valve
Describe the mitral valve
- regulates blood flow from the left atrium into the left ventricle
- 2 leaflets = bicuspid
Describe the tricuspid valve
- regulates blood flow from the right atrium
- 3 leaflets = tricuspid
How are the atrioventricular valves connected to the ventricle wall ?
via chordae tendineae and regulated by papillary muscles
Describe the coronary vasculature
- supplies oxygenated blood to the heart muscle
- coronary arteries branch off from the aorta
What are the 5 components of the heart wall ?
- Pericardium
- Pericardial cavity
- Epicardium
- Myocardium
- Endocardium
Describe the pericardium
outer layer of connective tissue
Describe the epicardium
role in homeostasis & regeneration
Describe the myocardium
- the contractile part of the heart
- made up of cardiomyocytes, fibroblasts, vascular endothelium & monocytes/macrophages
Describe cardiomyocytes
- contractile heart muscle
- striated muscle cells containing filaments of contractile proteins
- 30% of all heart cells
- 70-80% by volume
- linked via gap junctions
Describe Fibroblasts
- function to maintain structure and in homeostasis
- forms scar tissue
- 13% of all heart cells
- 1-2% by volume
Describe vascular endothelium
- forms the walls of vasculature supplying blood to heart muscle
- 55% of all heart cells
- 3-5% by volume
Describe monocytes/macrophages
- involved in the immune system
- 4% of all heart cells
Define systole
squeezing
Define diastole
dilation
Define traverse tubule
extension of plasma membrane into cell permitting fast transmission of action potential
What are the key components of the conduction system ?
- Sino-atrial node
- atrio-ventricular node
- right bundle of His
- purkinje fibres
- left bundle of his
Describe the function of the Sino-atrial node
- located in the right atrium
- specialised cardiomyocytes with the ability to generate action potentials
- these impulses are then transmitted to the atria myocardium & to the atrio-ventricular node
Describe the function of the atrioventricular node
- located at the base of the right atrium at the atria-ventricular junction
- atria are electrically isolated from ventricles –> AV node is the pathway between them
- function is to delay transmission of impulse till atria are fully contracted
Describe the function of the Bundle of His
- transmits the impulse to the apex of the heart without depolarising cardiomyocytes en route
- important that contraction of the ventricles begins at the apex, forcing blood towards the aorta & pulmonary artery
How does the neural input influence the SA node & regulate heart rate ?
- heart rate is controlled by the cardiovascular centre of the hindbrain
- 2 nerves connect the hindbrain to the SA node
- the vagus nerve releases acetylcholine onto the SA node which reduces heart rate
- accelerens nerve releases norepinephrine onto the SA node which increases heart rate
What is a heart attack?
- blockage of one of the arteries which supplies the heart itself with oxygenated blood
- leads to the death of a region of heart muscle
What causes a heart attack ?
- atherosclerosis = build up of fatty plagues within artery walls, constricting blood flow
- rupture of plaque leads to formation of a blood clot which can dislodge & cause acute disease
Describe congenital heart disease
- malformations which are present at birth
- affects 1 in 100 newborns
- causes by an error during embryonic development
Blockage of which vessel causes a heart attack ?
coronary artery
