what are the 3 branches of the aortic arch?
braciocephallic trunk, left common carotid artery, left subclavian artery
what are the two parts of the pericardium?
fibrous pericardium and serous pericardium
describe the fibrous pericardium
continuous with central tendon of the diaphragm, tough connective tissue which prevents over filling of the heart
describe the serous pericardium
- two layers: parietal and visceral
- visceral layer forms outter layer of the heart called the epicardium
- each layer is mesothelium
what is the pericardial cavity?
- found between inner and outter serous layer
- contains lubricating serous fluid
what are the functions of the pericardium?
- fixes heart in mediastinum and limits its motion
- its inextensible nature prevents overfilling of the heart
- serous fluid provides lubrication between inner and outter pericardium
- protection from infection
what is trabecular carnae where are they found?
- a series of irregular muscular elevations
- found in the inflow portion of the ventricle
what are the 3 layers of the heart wall?
endocardium, myocardium, epicardium
describe the endocardial layer of the heart
- inner most layer of the heart, lines cavities and valves
- regulates contractions
- simple squamous epithelial
- subendocardial layer lies just below and is were pukyne fibres can be found
describe the myocardium layer of the heart
- responsible for contractions of the heart
- is made up of cardiac muscle which is involuntary
- subepicardial layer lies between the myocardium and epicardium
desribe the epicardium
- outter most layer of the heart formed by viseral layer of serous pericardium
- connective tissue and fat secretes small amounts of serous fluid
- simple squamous epithelium
what is the coronary sinus?
- large venous structure located on the posterior aspect of the heart
- responsible for most venous drainage
what are the tributaries of the coronary sinus?
great cardiac vein, anterior cardiac vein, posterior interventricular vein, posterior cardiac vein
what is the conduction system of the heart?
- sinoatrial node depolarises and send signals for the atria to contract and the ventricles fill with blood
- impulse travels to AV, it pauses for ventricles to fill (bundle of His)
- impulse to purkyne fibres to cause contrcation of the ventricles
what is diastole?
- the filling of the ventricles
what is systole?
- ventricles contract and blood is forced out into aorta or pulmonary artery
what does it mean if a celll is depolarised?
- the cell becomes positivley charged
what are the phases for the sino atrial node to fire an action potential?
PHASE 4: spontaneous depolarisation, slow influx of positive ions
PHASE 0: depolarisation, rapid influx of Ca2+, action potential
PHASE 3: efflux of K+, CA2+ stop moving, repolarisation
what are the phases of ventricle muscle cells contracting (purkyne fibres)?
PHASE 0: depolarisation, rapid influx of positive ions
PHASE 1: partial repolarisation
PHASE 2: plateau phase, K+ efflux, Ca 2+ influx
PHASE 3: repolarisation
PHASE 4: ions go back to original place, ventricle diastole
what are the 3 reflexes that regulate blood pressure in the body?
baroreceptor reflex, chemoreceptor reflex, cardiopulmonary reflex
what happens in the baroreceptor reflex?
- barorecpetors are sensory nerve ending which monitor the degree of stretch in the aortic arch and carotid sinus
- when stretched they fire an action potential in afferent fibres
- high blood pressure detected, parasympathetic nervous system is activates to decrease heart rate along with increasing vasodilation of vessels, to decrease blood pressure
- low blood presuure detected, sympathetic nervous system works to increase heart rate along with vasoconstriction to increase blood pressure
why can baroreceptors not regulate blood pressure longterm?
Baroreceptors cannot regulate blood pressure long-term. This is because the mechanism that triggers baroreceptors resets itself once a more adequate blood pressure is restored.
how is blood pressure sustained in the long term?
Renin-Angiotensin-Aldosterone System, ADH(antidiuretic hormone)/ vasopressin
what is the role of renin in the Renin-Angiotensin-Aldosterone System?
- renin is a peptide hormone which is released by the juxtaglomerular cells in the kidney glomerulus
- renin is released in response to: sympathetic stimulation, decrease in sodium chloride to the distal convulated tubule, decreased blood flow to kidney
- Renin facilitates the conversion of angiotensinogen to angiotensin I. This is then converted to angiotensin II using angiotensin-converting enzyme (ACE).
