MCAT Human Anatomy and
Physiology Exam with Complete
Solutions
A band - ANSWER-The length of the sarcomere which overlaps with the thick filament
ABO blood group - ANSWER-A method of typing blood based on the presence of A
antigens (IA), B antigens (IB), or O (no antigens, i)
absolute refractory period - ANSWER-Time where a neuron cannot fire at all, regardless
of the depolarization
absolute threshold - ANSWER-The minimum stimulus needed to generate a sensation
acetylcholinesterase - ANSWER-The enzyme which hydrolyzes acetylcholine into
choline and an acetyl group
acini - ANSWER-Epithelial cells in the gut lumen which are organized as sacs, these
are exocrine cells which secrete hormones which enter the gut through ducts
action potential - ANSWER-The generation of a moving electrochemical impulse
unidirectionally down an axon
active process - ANSWER-A process which requires muscle contraction, such as
inspiration
adipocyte - ANSWER-Fat storage cell
adipocytes - ANSWER-Fat cells
adiuretic hormone (ADH) - ANSWER-Also known as vasopressin, released by the
posterior pituitary, this hormone increases water reabsorption in the distal nephron by
making the nephron permeable to water, in response to decreased blood pressure
adrenal cortex - ANSWER-A portion of the adrenal gland that secretes glucocorticoids
such as cortisol, mineralocorticoids such as aldosterone, and some sex hormones
adrenal gland - ANSWER-A gland that is located above each kidney, which is important
in secretion of hormones
,adrenal medulla - ANSWER-Part of the sympathetic nervous system, and is
consequently responsible for releasing epinephrin (AKA adrenaline)
adrenergic tone - ANSWER-The constant release of NE (sympathetic) to the
precapillary sphincters, providing a basal level of resistance in the arterioles, which
causes a base level of blood pressure
afferent neuron - ANSWER-Also known as a sensory neuron, carries a signal from a
sensor to the CNS
albumin - ANSWER-A protein abundant in blood plasma, whose most important function
is maintaining capillary osmotic pressure
aldosterone - ANSWER-A steroid hormone produced in the adrenal cortex,triggered by
low blood osmolarity and blood volume which increases blood pressure by increasing
kidney reabsorption. This is accomplished by increasing Na+ reabsorption, as well as
causing thirst
all-or-nothing - ANSWER-Describes the tendency of a neuron to either fully fire an
action potential, or not fire at all, depending on if a specific threshold is reached
alveolar duct - ANSWER-The duct leading to the alveoli
alveolus - ANSWER-A tiny sac which is surrounded by capillaries and makes up the
respiratory zone surface
amphiarthroses - ANSWER-Semi-movable joints, gives small degrees of flexibility and a
lot of support, such as in the vertebrae
anal sphincter - ANSWER-The sphincter which controls the release of feces. Has an
internal sphincter (autonomic) and an external portion (somatic)
anergic - ANSWER-An unresponsive form of a B cell which result when they bind to
plasma-soluble proteins, as a way to stop an autoimmune reaction
angiotensin I - ANSWER-The precursor to angiotensin II, converted by angiotensin-
converting enzyme (ACE) in the lungs
angiotensin II - ANSWER-A hormone which triggers the release of aldosterone, as well
as vasoconstriction which raises blood pressure
angiotensinogen - ANSWER-The precursor to angiotensin I
anterior chamber of the eye - ANSWER-The area just past the cornea filled with
aqueous humor
,anterior pituitary - ANSWER-An endocrine gland controlled by the hypothalamus.
Releases growth hormone, prolactine, TSH, ACTH.
antibody - ANSWER-An immune protein, composed of a constant region and a variable
(antigen binding) region
antigen - ANSWER-The molecule an antibody binds to, important in recognition
aortic semilunar valve - ANSWER-The valve between the left ventricle and the aorta
apical surface - ANSWER-The side of the epithelial cell which faces the GI lumen
appendicular components - ANSWER-All bones not associated with the axial skeleton
appendix - ANSWER-An organ which traps foreign pathogens which enter through
digestion, located at the beginning of the large intestine (cecum)
arteries - ANSWER-Blood vessels which carry blood away from the heart at high
pressure
arterioles - ANSWER-A branching off arteries which are surrounded by thin layers of
smooth muscle. These blood vessels represent the highest cumulative drop in blood
pressure
articular cartilage - ANSWER-A type of hyaline cardilate which lines joints, and makes
the contact between bones very smooth
ascending loop of Henle - ANSWER-Portion of the loop of Henle which has ion active
transporters, and creates the countercurrent gradient needed for concentrating urine
atrioventricular valve - ANSWER-A one-way valve between an atrium and a ventricle
auditory cortex - ANSWER-The center in the temporal lobe which processes auditory
stimulation
auditory hair cell - ANSWER-A mechanoreceptor cell located in the inner ear that
responds to vibrations on a sensitive membrane
autoimmune reaction - ANSWER-Process where immune cells attack normal body cells
or proteins
autonomic nervous system - ANSWER-The portion of the peripheral nervous system
involved in unconscious responses and activities
AV node - ANSWER-The connecting pathway between atria and ventricles, which
causes a slight delay in the transmission of potential from the atria to the ventricles
, axial skeleton - ANSWER-Composed of the skull, vertebrae, and the rib cage
B cell - ANSWER-A type of lymphocyte which matures into a plasma cell and produces
antibodies
B cells - ANSWER-A lymphocyte which produces an antibody on its surface. Binding of
an antigen to this cell's antibody causes proliferation into plasma cells and memory cells
basal nuclei - ANSWER-A portion of the brain located in the cerebrum, and composed
of gray matter, inhibits voluntary movement (along with the cerebellum's excitation of
movement) and facilitates procedural learning
basolateral surface - ANSWER-The endothelium which faces opposite the apical
surface
basophil - ANSWER-A granulocyte which stores and releases histamine, present in the
allergic response
bicarbonate - ANSWER-The principal buffer system in the blood, maintaining a constant
pH of about 7.4, produced by the reaction between carbon dioxide and water
bicuspid valve - ANSWER-The AV valve between the left atrium and left ventricle
bile - ANSWER-A fluid containing acids made from cholesterols and amphipathic salts,
and is used as a vehicle for waste excretion by the liver, as well as the digestion of fats
bilirubin - ANSWER-A breakdown product of heme, which produces the yellow color in
urine
bioplar neuron - ANSWER-A neuron with only one dendrite
bipolar cells - ANSWER-Cells which synapse with rods and cones and transmit
information to ganglia, have only one axon and one dendrite
Bohr effect - ANSWER-The decrease in hemoglobin's affinity caused by low pH (high
H+ conc), increased PCO2, increased temperature, and high altitude. This mechanism
releases oxygen where needed
bolus - ANSWER-A ball of food moving down the GI tract
bone composition - ANSWER-Bone is composed of collagen and hydroxyapatite
bone marrow - ANSWER-The site of synthesis of all cells in the blood from a common
progenitor
Physiology Exam with Complete
Solutions
A band - ANSWER-The length of the sarcomere which overlaps with the thick filament
ABO blood group - ANSWER-A method of typing blood based on the presence of A
antigens (IA), B antigens (IB), or O (no antigens, i)
absolute refractory period - ANSWER-Time where a neuron cannot fire at all, regardless
of the depolarization
absolute threshold - ANSWER-The minimum stimulus needed to generate a sensation
acetylcholinesterase - ANSWER-The enzyme which hydrolyzes acetylcholine into
choline and an acetyl group
acini - ANSWER-Epithelial cells in the gut lumen which are organized as sacs, these
are exocrine cells which secrete hormones which enter the gut through ducts
action potential - ANSWER-The generation of a moving electrochemical impulse
unidirectionally down an axon
active process - ANSWER-A process which requires muscle contraction, such as
inspiration
adipocyte - ANSWER-Fat storage cell
adipocytes - ANSWER-Fat cells
adiuretic hormone (ADH) - ANSWER-Also known as vasopressin, released by the
posterior pituitary, this hormone increases water reabsorption in the distal nephron by
making the nephron permeable to water, in response to decreased blood pressure
adrenal cortex - ANSWER-A portion of the adrenal gland that secretes glucocorticoids
such as cortisol, mineralocorticoids such as aldosterone, and some sex hormones
adrenal gland - ANSWER-A gland that is located above each kidney, which is important
in secretion of hormones
,adrenal medulla - ANSWER-Part of the sympathetic nervous system, and is
consequently responsible for releasing epinephrin (AKA adrenaline)
adrenergic tone - ANSWER-The constant release of NE (sympathetic) to the
precapillary sphincters, providing a basal level of resistance in the arterioles, which
causes a base level of blood pressure
afferent neuron - ANSWER-Also known as a sensory neuron, carries a signal from a
sensor to the CNS
albumin - ANSWER-A protein abundant in blood plasma, whose most important function
is maintaining capillary osmotic pressure
aldosterone - ANSWER-A steroid hormone produced in the adrenal cortex,triggered by
low blood osmolarity and blood volume which increases blood pressure by increasing
kidney reabsorption. This is accomplished by increasing Na+ reabsorption, as well as
causing thirst
all-or-nothing - ANSWER-Describes the tendency of a neuron to either fully fire an
action potential, or not fire at all, depending on if a specific threshold is reached
alveolar duct - ANSWER-The duct leading to the alveoli
alveolus - ANSWER-A tiny sac which is surrounded by capillaries and makes up the
respiratory zone surface
amphiarthroses - ANSWER-Semi-movable joints, gives small degrees of flexibility and a
lot of support, such as in the vertebrae
anal sphincter - ANSWER-The sphincter which controls the release of feces. Has an
internal sphincter (autonomic) and an external portion (somatic)
anergic - ANSWER-An unresponsive form of a B cell which result when they bind to
plasma-soluble proteins, as a way to stop an autoimmune reaction
angiotensin I - ANSWER-The precursor to angiotensin II, converted by angiotensin-
converting enzyme (ACE) in the lungs
angiotensin II - ANSWER-A hormone which triggers the release of aldosterone, as well
as vasoconstriction which raises blood pressure
angiotensinogen - ANSWER-The precursor to angiotensin I
anterior chamber of the eye - ANSWER-The area just past the cornea filled with
aqueous humor
,anterior pituitary - ANSWER-An endocrine gland controlled by the hypothalamus.
Releases growth hormone, prolactine, TSH, ACTH.
antibody - ANSWER-An immune protein, composed of a constant region and a variable
(antigen binding) region
antigen - ANSWER-The molecule an antibody binds to, important in recognition
aortic semilunar valve - ANSWER-The valve between the left ventricle and the aorta
apical surface - ANSWER-The side of the epithelial cell which faces the GI lumen
appendicular components - ANSWER-All bones not associated with the axial skeleton
appendix - ANSWER-An organ which traps foreign pathogens which enter through
digestion, located at the beginning of the large intestine (cecum)
arteries - ANSWER-Blood vessels which carry blood away from the heart at high
pressure
arterioles - ANSWER-A branching off arteries which are surrounded by thin layers of
smooth muscle. These blood vessels represent the highest cumulative drop in blood
pressure
articular cartilage - ANSWER-A type of hyaline cardilate which lines joints, and makes
the contact between bones very smooth
ascending loop of Henle - ANSWER-Portion of the loop of Henle which has ion active
transporters, and creates the countercurrent gradient needed for concentrating urine
atrioventricular valve - ANSWER-A one-way valve between an atrium and a ventricle
auditory cortex - ANSWER-The center in the temporal lobe which processes auditory
stimulation
auditory hair cell - ANSWER-A mechanoreceptor cell located in the inner ear that
responds to vibrations on a sensitive membrane
autoimmune reaction - ANSWER-Process where immune cells attack normal body cells
or proteins
autonomic nervous system - ANSWER-The portion of the peripheral nervous system
involved in unconscious responses and activities
AV node - ANSWER-The connecting pathway between atria and ventricles, which
causes a slight delay in the transmission of potential from the atria to the ventricles
, axial skeleton - ANSWER-Composed of the skull, vertebrae, and the rib cage
B cell - ANSWER-A type of lymphocyte which matures into a plasma cell and produces
antibodies
B cells - ANSWER-A lymphocyte which produces an antibody on its surface. Binding of
an antigen to this cell's antibody causes proliferation into plasma cells and memory cells
basal nuclei - ANSWER-A portion of the brain located in the cerebrum, and composed
of gray matter, inhibits voluntary movement (along with the cerebellum's excitation of
movement) and facilitates procedural learning
basolateral surface - ANSWER-The endothelium which faces opposite the apical
surface
basophil - ANSWER-A granulocyte which stores and releases histamine, present in the
allergic response
bicarbonate - ANSWER-The principal buffer system in the blood, maintaining a constant
pH of about 7.4, produced by the reaction between carbon dioxide and water
bicuspid valve - ANSWER-The AV valve between the left atrium and left ventricle
bile - ANSWER-A fluid containing acids made from cholesterols and amphipathic salts,
and is used as a vehicle for waste excretion by the liver, as well as the digestion of fats
bilirubin - ANSWER-A breakdown product of heme, which produces the yellow color in
urine
bioplar neuron - ANSWER-A neuron with only one dendrite
bipolar cells - ANSWER-Cells which synapse with rods and cones and transmit
information to ganglia, have only one axon and one dendrite
Bohr effect - ANSWER-The decrease in hemoglobin's affinity caused by low pH (high
H+ conc), increased PCO2, increased temperature, and high altitude. This mechanism
releases oxygen where needed
bolus - ANSWER-A ball of food moving down the GI tract
bone composition - ANSWER-Bone is composed of collagen and hydroxyapatite
bone marrow - ANSWER-The site of synthesis of all cells in the blood from a common
progenitor
