The heart structure and electrical function Flashcards
flow of deoxygenated blood
Organs& tissue -> right atrium-> right ventricle-> pulmonary artery -> Lung
flow of oxygenated blood
Lung -> pulmonary vein -> left atrium -> left ventricle -> Organs and tissue
the left ventricle pumps ?
systemic blood to the rest of the body -oxygenated
right ventricle pumps?
Pulmonary blood to the lungs for gas exchange (02 and CO2) -> deoxygenated
how many heart chambers, atrium and ventricles
4 chambers, 2 atria, 2 ventricles
how does blood go into the right ventricle
blood from vena cavae (superior and inferior) drain via the tricuspid valve into the right ventricle
what are atria
thin walled muscle that serve to top up filling of the ventricles
what are the tricuspid valves (right AV)
tethered by fibrous chordee & papillary muscle which contracts at the same time as ventricles- >prevents valves from bulging as the ventricles contract
right ventricle into pulmonary artery
ejects blood into the pulmonary arters via pocket like cups of the pulmonary valve
Atrioventricular valves (AV) & Semilunar valves
- Mitral and Tricuspid valves
- pulmonary and aortic valves
Systolic
contraction phase, high pressure
Diastolic
relaxation phase, low pressure
cardiac muscle
striated (like skeletal muscle), involuntary (like smooth muscle),
have a nucleus (unlike skeletal) -> cells form syncytium and are elctrically coupled together
how can APs pass from cell to cell
via intercalated disks- cells are linked by gap junctions
how is enery supplied in the cardiac muscle cell (cardiac myocyte)
in the cell is a contractile machinary based n actin and myosin (like skeletal muscle) and mitochondria
what causes the cardiac muscles to contract
-> APs from cardiomyocytes: are electrically active
AP in cardiomyocytes
- rising phase-> depolarization opens Na+ channels
- Na+ channels close- K+ channels open
- slow Ca2+ channels open -> balance loss of positive charge via K+ channels
- open K+ channels repolarize the cell
- resting phase: K+ movement is balanced by chemical and electrostatic forces
AP causing cardiac muscle contraction
APs travel through cardiac cells in the heart -> Gap junctions between cells allow electrical signal to travel through cardiac tissue -> a wave of coordinated muscle contraction
neuronal control of the heart rate- balance between ?
the influence of sympathetic and parasympathetic nervous system and the natural rate of depolarization on the SA node
sympatehtic influence
Noradrenaline (NA):increases heart rate
parasympathetic influence (vagus)
Acetylcholine (ACh):nslows heart rate
pacemaker cells are influenced by para/ sympathetic activity
parasympathetic: hyperpolarizes pacemaker activity -> increases time period
Sympatehtic : increases pacemaker activity -> reduces time to next AP
