UCSB MCDB 1B Final Exam (2026) Complete
Questions & Verified Correct Answers
8Main functions of circulatory system - CORRECT ANSWER -nutrient/gas/hormone/metabolite
transport, temperature control
Main structural elements of circulatory system - CORRECT ANSWER -pump (hear), conduits
(vessels), transport medium (blood)
How many chambers in the human heart? - CORRECT ANSWER -4; two atria, two ventricles
Direction of flow - CORRECT ANSWER -Left atrium, right atrium, pulmonary artery, lungs,
pulmonary vein, right ventricle, left ventricle
What are two phases of the cardiac cycle? - CORRECT ANSWER -"systole" - contraction,
"diastole" - relaxation
Sinoatrial node - CORRECT ANSWER -Responsible for pacemaker activity, no stimulus from
ANS required. Located at top of left atrium.
Atrioventricular node - CORRECT ANSWER -delays (~0.1 s) start of ventricular contraction.
Located on septum in right atrium
Bundle of His/Purkinje Fibers - CORRECT ANSWER -transmit action potential to ventricle
walls
How are cardiac muscle cells connected? - CORRECT ANSWER -Gap junctions, allowing for
rapid propagation of electrical signals
,Sympathetic nervous system - CORRECT ANSWER -releases epinephrine, increasing heart rate
(fight or flight response)
Parasympathetic nervous system - CORRECT ANSWER -releases acetylcholine, decreases
pacemaker activity, slows heart rate (rest and digest)
Function of norepinephrine in heart? - CORRECT ANSWER -increases permeability of Na+/K+
and Ca2+ ion channels, making resting potential rise more quickly and compressing time
between them
Function of acetylcholine in heart? - CORRECT ANSWER -Increases the permeability of K+
and decreases permeability of Ca2+ channels, slowing action potentials and spreading them out
Artery - CORRECT ANSWER -vessel carrying blood away from heart
Arterioles - CORRECT ANSWER -controls distribution of specific capillary beds
Capillaries - CORRECT ANSWER -site of exchange between blood and intersticial fluid
Venules - CORRECT ANSWER -vessels that return blood to veins
Veins - CORRECT ANSWER -vessels that return blood to heart
Features of arteries and arterioles - CORRECT ANSWER -elastic fibers allowing resistance to
high pressure, smooth muscle cells allowing from contraction/expansion to alter blood flow rate
Vein features - CORRECT ANSWER -less smooth muscle, valves to prevent backflow, no
elastin layer
, Function of pre-capillary sphincters? - CORRECT ANSWER -Control of the distribution of
blood to capillary beds by altering diameter/resistance to blood flow. Subject to both local and
systemic control
Stetch sensor mediated negative feedback loop - CORRECT ANSWER -Firing in arterial stretch
sensors decreases --> Hypothalamus releases ADH --> ADH stimulates water resorption by
kidneys --> Arterial pressure rises
Kidney mediated negative feedback loop - CORRECT ANSWER -Kidney function fails -->
kidney releases renin --> circulating renin activates angiotensin --> Angiotensin causes vessels to
constrict and stimulates thirst --> arterial pressure rises
Locally mediated positive feedback loop - CORRECT ANSWER -Arterial pressure falls -->
decreases blood flow to tissue --> local accumulation of metabolic wastes --> auto-regulatory
widening of vessels -- > arterial pressure falls
What causes the widening of a tree trunk? - CORRECT ANSWER -Activity in the apical
meristem
How does a plant cell grow? - CORRECT ANSWER -Hydrostatic pressure (turgor) stretches cell
walls
Plasmodesmata - CORRECT ANSWER -permanent connections between adjacent cells. Can be
gated to alter effective pore size and affect connectivity
Where are plasmodesmata located? - CORRECT ANSWER -Pit fields in the secondary cell wall
Moving from the inside of the cell out, what are the parts of the cell wall? - CORRECT
ANSWER -Plasma membrane, secondary cell wall, primary cell wall, middle lamella
Questions & Verified Correct Answers
8Main functions of circulatory system - CORRECT ANSWER -nutrient/gas/hormone/metabolite
transport, temperature control
Main structural elements of circulatory system - CORRECT ANSWER -pump (hear), conduits
(vessels), transport medium (blood)
How many chambers in the human heart? - CORRECT ANSWER -4; two atria, two ventricles
Direction of flow - CORRECT ANSWER -Left atrium, right atrium, pulmonary artery, lungs,
pulmonary vein, right ventricle, left ventricle
What are two phases of the cardiac cycle? - CORRECT ANSWER -"systole" - contraction,
"diastole" - relaxation
Sinoatrial node - CORRECT ANSWER -Responsible for pacemaker activity, no stimulus from
ANS required. Located at top of left atrium.
Atrioventricular node - CORRECT ANSWER -delays (~0.1 s) start of ventricular contraction.
Located on septum in right atrium
Bundle of His/Purkinje Fibers - CORRECT ANSWER -transmit action potential to ventricle
walls
How are cardiac muscle cells connected? - CORRECT ANSWER -Gap junctions, allowing for
rapid propagation of electrical signals
,Sympathetic nervous system - CORRECT ANSWER -releases epinephrine, increasing heart rate
(fight or flight response)
Parasympathetic nervous system - CORRECT ANSWER -releases acetylcholine, decreases
pacemaker activity, slows heart rate (rest and digest)
Function of norepinephrine in heart? - CORRECT ANSWER -increases permeability of Na+/K+
and Ca2+ ion channels, making resting potential rise more quickly and compressing time
between them
Function of acetylcholine in heart? - CORRECT ANSWER -Increases the permeability of K+
and decreases permeability of Ca2+ channels, slowing action potentials and spreading them out
Artery - CORRECT ANSWER -vessel carrying blood away from heart
Arterioles - CORRECT ANSWER -controls distribution of specific capillary beds
Capillaries - CORRECT ANSWER -site of exchange between blood and intersticial fluid
Venules - CORRECT ANSWER -vessels that return blood to veins
Veins - CORRECT ANSWER -vessels that return blood to heart
Features of arteries and arterioles - CORRECT ANSWER -elastic fibers allowing resistance to
high pressure, smooth muscle cells allowing from contraction/expansion to alter blood flow rate
Vein features - CORRECT ANSWER -less smooth muscle, valves to prevent backflow, no
elastin layer
, Function of pre-capillary sphincters? - CORRECT ANSWER -Control of the distribution of
blood to capillary beds by altering diameter/resistance to blood flow. Subject to both local and
systemic control
Stetch sensor mediated negative feedback loop - CORRECT ANSWER -Firing in arterial stretch
sensors decreases --> Hypothalamus releases ADH --> ADH stimulates water resorption by
kidneys --> Arterial pressure rises
Kidney mediated negative feedback loop - CORRECT ANSWER -Kidney function fails -->
kidney releases renin --> circulating renin activates angiotensin --> Angiotensin causes vessels to
constrict and stimulates thirst --> arterial pressure rises
Locally mediated positive feedback loop - CORRECT ANSWER -Arterial pressure falls -->
decreases blood flow to tissue --> local accumulation of metabolic wastes --> auto-regulatory
widening of vessels -- > arterial pressure falls
What causes the widening of a tree trunk? - CORRECT ANSWER -Activity in the apical
meristem
How does a plant cell grow? - CORRECT ANSWER -Hydrostatic pressure (turgor) stretches cell
walls
Plasmodesmata - CORRECT ANSWER -permanent connections between adjacent cells. Can be
gated to alter effective pore size and affect connectivity
Where are plasmodesmata located? - CORRECT ANSWER -Pit fields in the secondary cell wall
Moving from the inside of the cell out, what are the parts of the cell wall? - CORRECT
ANSWER -Plasma membrane, secondary cell wall, primary cell wall, middle lamella
