BISC 220 Lab Exam Questions With
100% Verified Answers!!
Purkinje fibers
fibers in the ventricles that transmit impulses to the right and left ventricles, causing them
to contract
gap junctions
provide cytoplasmic channels between adjacent cells (links them)
Control of heart rhythm
1. SA node generates wave of signals causing atria to contract
2. signals delayed at AV node
3. signals pass through bundle branches to heart apex
4. signals spread throughout ventricles
what affects SA node (heart rate)
nerves, hormones, body temp, exercise
nerves effect on heart rate
Parasympathetic nerve activity --> acetylcholine --> Bradycardia (reduced heart rate)
sympathetic nerve activity --> norepinephrine --> tachycardia (increased heart rate)
hormones effect on heart rate
epinephrine (adrenaline) -> tachycardia
temperature effect on heart rate
, increased temperature: trachycardia
decreased temperature: bradycardia
exercise effect on heart rate
tachycardia
maximum heart rate
above a certain HR, the left ventricle cant fill completely before the next stroke
what does maximum heart rate depend on
mostly age, but also size and genetics
blood vessels
arteries, arterioles, capillaries, venules, veins
arteries and veins
endothelium, smooth muscle, connective tissue
capillaries
single endothelium layer covered by basement membrane
velocity of flow
the distance a fixed volume of blood travels in a given period of time. Inversely proportional to
cross sectional area
pressure
decreases throughout circulatory system, highest in aorta and lowest in vena cava
law of continuity
- volume/sec same everywhere
- velocity faster in narrower pipe
- velocity slower in wider pipe
what percent of capillaries open at any one time
100% Verified Answers!!
Purkinje fibers
fibers in the ventricles that transmit impulses to the right and left ventricles, causing them
to contract
gap junctions
provide cytoplasmic channels between adjacent cells (links them)
Control of heart rhythm
1. SA node generates wave of signals causing atria to contract
2. signals delayed at AV node
3. signals pass through bundle branches to heart apex
4. signals spread throughout ventricles
what affects SA node (heart rate)
nerves, hormones, body temp, exercise
nerves effect on heart rate
Parasympathetic nerve activity --> acetylcholine --> Bradycardia (reduced heart rate)
sympathetic nerve activity --> norepinephrine --> tachycardia (increased heart rate)
hormones effect on heart rate
epinephrine (adrenaline) -> tachycardia
temperature effect on heart rate
, increased temperature: trachycardia
decreased temperature: bradycardia
exercise effect on heart rate
tachycardia
maximum heart rate
above a certain HR, the left ventricle cant fill completely before the next stroke
what does maximum heart rate depend on
mostly age, but also size and genetics
blood vessels
arteries, arterioles, capillaries, venules, veins
arteries and veins
endothelium, smooth muscle, connective tissue
capillaries
single endothelium layer covered by basement membrane
velocity of flow
the distance a fixed volume of blood travels in a given period of time. Inversely proportional to
cross sectional area
pressure
decreases throughout circulatory system, highest in aorta and lowest in vena cava
law of continuity
- volume/sec same everywhere
- velocity faster in narrower pipe
- velocity slower in wider pipe
what percent of capillaries open at any one time
