exam 2 class 12 Flashcards
The pointed apex of heart angles down to left side of the body, while broader base lies just behind
breastbone, or sternum
the heart lies on what side?
ventral side sandwiched
between two lungs,
with its apex resting
on diaphragm
what does the thin layer of clear pericardial fluid do?
lubricates external surface of
heart as it beats within sac
pulmonary veins are hidden
behind?
other major blood
vessels
Inflammation of pericardium is?
pericarditis
aorta and pulmonary trunk
(artery) direct blood from?
the heart to tissues and lungs
the venae cavae
and pulmonary veins return?
blood to heart
circuit that takes blood to the lungs and gills
pulmonary
what are the two circulation circuits?
pulmonary
systemic
circuit that takes blood to the body
systemic
what partial pressures very in the circulatory system?
partial pressures of O2 and CO2
Left and right sides of the heart are separated by?
septum
what Two sets of heart valves ensure this one-way
flow?
atrioventricular valves
semilunar valves
valves between
the atria and ventricles
Atrioventricular (AV)
crescent-moon shape,
between the ventricles and their arteries
Semilunar (SL)
valves
slightly thickened at the edge and connect on ventricular side to collagenous tendons
Aortic valve flaps
tethered to ventricular muscle known as the
papillary muscle.
chordae tendineae
the valve that separates the right atrium and right ventricle has three
flaps and is called ?
tricuspid valve
The valve between the left atrium and left ventricle has only two flaps?
bicuspid valve
(also known as mitral valve)
valve is between left ventricle and the aorta
SLV valve
or aortic semilunar valve
lies between right ventricle and pulmonary trunk
Pulmonary valve
has three
cuplike leaflets that snap closed when blood attempting to flow
back into ventricles fills them
semilunar valve
what kind of blood in coronary circulation
is much lower in oxygen content than venous blood returning through
venae cavae?
venous blood
Cardiac muscle consumes _______ of oxygen delivered to it by the blood, more than twice the amount extracted by other cells in the body
70–80%
Bulk of heart is composed of ?
cardiac muscle cells, or myocardium
Signal for myocardial contraction comes not
from the nervous system but from specialized
myocardial cells called?
autorhythmic cells
also pace makers
The signal for contraction is _________, originating within the heart muscle itself
myogenic
how are cardiac muscles different form skeletal muscles?
- cardiac muscle fiber are much smaller
- cardiac ,muscle cells branch and join more cells
- Gap junctions onnect cardiac muscle
cells to one another
4.mitochondria occupy 1/3 of the cell volume
intercalated disks have two components?
desmosomes and gap junctions
- The filaments slide past one another
- The sarcomere shortens with no change in lengths of the thin (actin) and thick (myosin) filaments themselves
contraction of sarcomere
Thin filaments also contain proteins?
troponin
and tropomyosin
these work together to block myosin binding sites on actin
troponin and tropomyosin
When calcium ions bind to troponin
the myosin binding site on actin is exposed, and contractions can begin
The force generated by cardiac muscle is proportional to?
the number of cross
bridges that are active
The number of active cross bridges is determined by how much _______ is
bound to troponin
Ca2+
If cytosolic Ca2+ concentrations are low?
some cross bridges are not
activated and contraction force is small
Extracellular fluid?
more Na+ and Cl-
interior of membrane?
lower Na+ & Cl- , higher K+
Action potential depends on?
a voltage-gated channel
The rapid depolarization
phase of the action potential is the result of?
entry Na+, and the steep
repolarization phase
is due to K+ leaving the
cell
myocardial contractile cell has longer action potential due to?
Ca2+ entry
what phase? resting membrane potential
Phase 4
what phase? depolarization
Phase 0:
what phase? initial repolarization
Phase 1:
what phase? the plateau
phase 2
