S1W1 L1: Gross and cellular structure of heart Flashcards
type of muscle cardiac muscle/ heart is formed from
striated
loacted
behind sternum, 12-14cm ling
three circulation circuits
pulmonary
coronary
systemic
all run in parallel, little/ no connection between 3 circuits
coronary circulation: how is oxygenated blood supplied to the heart muscle
left and right coronary arteries, branch directly from aorta base
anastomosis
surgical or natural connection between coronary arteries that supply blood to heart muscle
coronary circulation: where does the venous blood from myocardium drain
coronary sinus then into right atrium, then to lungs via pulmonary circuit for reoxygenation
what does the aortic arch connect
ascending aorta and descending aorta
three elastic arteries that originate along the aortic arch:
brachiocephalic trunk
left common carotid artery
left subclavian artery
what does the brachiocephalic trunk branch into
right subclavian artery
right common carotid artery
where does brachiocephalic trunk supply
right arm and right side of head
where does left common carotid artery supply
head and brain
where does left subclavian artery supply
left arm
what does descending aorta supply
thorax and abdomen
what does the descending aorta split into and what does this supply
two common iliac, supplies the pelvic area
what do the common iliac run into
femoral artery
unpaired arteries which run off abdominal aorta and supply gastro-intestinal system
superior mesenteric
inferior mesenteric
celiac trunk
what is the heart enclosed in (double walled sac)
pericardium
fibrous pericardium
outer layer, protects, anchors and prevents the heart overfilling with blood
serous pericardium
inner layer, extends to cover the epicardial surface of the muscular wall of heart
pericardial cavity
filled with fluid, allows gliding motions of membranes, reduction of friction, means heart can stay mobile
right AV valve
tricuspid
left AV vavle
biscuspid/ mitral
semilunar valves
each have three cusps
located at the entrance of the outflow tracts: pulmonary artery and aorta
papillary muscles
attach to AV valves
important for stopping efflux of valves, help to create tension on valves to make sure they remain shut
do not pull valves closed
fibroblasts
contained within extracellular matrix
provide mechanical support for heart, help to provide fixture for contractile cells
endothelial types of endothelial cells in heart
endothelial (contribute to lining of blood vessels) and smooth muscle (in coronary arteries and veins)
contractile cells
atrial and ventricular cardiomyocytes
conduction cells
generation and passing electrical impulses through heart
features of cardiomyocytes
rich in glycogen and myoglobin
large number of mitochondria
reflects high energy demand
how are myocytes connected
intercalated disc
two roles of intercolated disc
mechanical coupling
electrical coupling
mechanical coupling: desmosome
cell to cell adhesion junction
provides mechanical strength and stability
small gap between membranes of adjacent cells filled with connective tissue
usually occur on transverse sections of intercalated discs
electrical coupling: gap junction
longitudinal
connexins
allow passage of ions and small molecules between cells
what do gap junction allow
ionic currents to pass through cells
AP evoked
heart behaves as a single cell functional syncytium
cardiac muscle obeys all or nothing principle
what are the two pathways that excitability from the SAN spread through atrial tissue to the AVN
- cell to cell via intercalated discs
- internodal tract
spread of excitation in heart:
- SAN
- AVN
- ventricles
