heart and blood vessels Flashcards
what are the two major divisions of the circulatory system
pulmonary and systemic circuit
pulmonary circuit…where and what does it do
-right side of heart
- carries blood to lungs for gas exchange and back to heart
systemic circuit…where and what does it do
-left side of heart
- supplies oxygenated blood to all tissues of the body and returns it to the heart
where is the heart located
mediastinum, between lungs
base of heart
wide, superior portion of heart, large vessels attach here
apex of heart
tapered inferior end, tilts to the left
pericardium…what is it, whats the function and how is it anchored
- double walled sac encloses the heart
- allows heart to beat w/o friction
- anchored to diaphragm inferiorly and sternum anteriorly
the pericardium consists of 2 parts
fibrous pericardium- outer wall, dense irreg ct
serous pericardium - double layer
*parietal layer
*visceral layer
parietal layer
outer layer is fused to fibrous pericardium
visceral layer
called epicardium
- inner layer attaches to the surface of the heart
3 layers of heart wall
epicardium
myocardium (cardiac muscle)
endocardium
epicardium-made of and known as
-mesothelium (simple squamous) and areolar ct
- visceral layer of serrous pericardium
myocardium function
muscle spirals around heart which produces wringing motion
endocardium… what is it and made of
smooth inner lining of heart and blood vessels
- simple squamous epithelial tissue
3 types of muscle
smooth
cardiac
skeletal
cardiac muscle- location and control
- heart
- involuntary: hormones and autonomic neurons
- self-stimulating: impulses moves from cell to cell
cardiac muscle- energy and contraction
-medium energy requirements
- medium contraction but spreads quickly
-does not fatigue…depends on aerobic respiration to make atp
- rhythmical contraction
what joins intercalated discs
cardiomyocytes (branching cells)
why do intercalated discs contain gap junction
-ions flow between cytoplasm of adjoining cells
- allow each cardiomyocyte to stimulate neighbours
- entire myocardium of either 2 atria or 2 ventricles act like a single, unified cell
valve attachments
chordae tendineae
papillary muscles
trabeculae carneae
watch video on blood flow through the chambers
conduction system of heart…consists of
-cardiac conduction system
- nodal tissue
cardiac conduction system is…
intrinsic
nodal tissue, what does it do
coordinates contraction of atria and ventricles, electrical signals travel through gap junctions
what is the pacemaker
sinoatrial node-initiates heartbeat and determines heart rate
order of conduction system of heart
- sinoatrial node-upper RA, initiates heartbeat and determines heart rate
- signal spreads across to the LA
- Atrioventricular node- base of the right atrium (embedded in interatrial septum). av signals the ventricles to contract moving along bundle branches
- atrioventricular bundle (AV bundle) and bundle branches…signal leaves AV node, goes to l and r bundle branches, signal travels down interventricular septum
- subendocardial conducting network (purkinje fibers). modified cardiomyocytes specialized for electrical conduction not contraction. once they deliver electrical signal- cardiomyocytes perpetuate it themselves by gap junctions
why does the SA node fire spontaneously
ion movements
pacemaker potential
threshold and action potential
repolarization
repetition
view chart of electrical behaviour of myocardium
cardiac rhythm
-sinus rhythm…normal heartbeat triggered by SA. vagal tone-70-80bpm
-ectopic focus-region of spontaneous firing other than the SA node
*nodal rhythm-AV if SA is damaged
*if both av and sa nodes are damaged then its too slow to sustain life/ needs artificial pacemaker
what is the cardiac cycle and what happens
al the events that occur during one heartbeat
-systole: contract of heart muscle
- diastole: relaxation of heart muscle
atria contract first simultaneously
ventricles contract simultaneously second
watch a video on cardiac cycle
electrocardiogram
composite of all action potentials of nodal and myocardial cells detected, amplified and recorded by electrodes on skin
function of blood vessels and types
-transport blood and its content
- carry out gas exchange
- regulate BP
- direct blood flow
types: arteries, veins, capillaries
arteries function
thick strong walls
transport oxygenated blood
AWAY from heart
Veins function
thinner
carries deoxygenated blood BACK to heart
vasoconstriction
blood flow from arteries to capillaries is restricted and blood pressure increases
vasodilation
blood flow increases and BP decreases
capillaries
nutrient and gas exchange
capillary gas exchange…where and what
in thin capillary walls
nutrients/O2 leave and waste/CO2 enter
what influences capillary gas exchange
blood pressure
diffusion
osmotic pressure
venules function
drain blood from capillaries and merge to from veins
