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PHYSIO EXAM 3 - HW

Terms in this set (118)

Aqueous humor forms during capillary filtration in the
ciliary processes [part of ciliary body]
What structure in the eye creates a visual blind spot?
optic disc
Which photoreceptor cells respond to very dim light?
rods
Which portion of the ear is responsible for sound transduction?
cochlea
The malleus, incus and stapes of the middle ear are joined by tiny
synovial joints
Where are equilibrium receptors located?
in semicircular canals & in vestibule of ear
Which of the following is true of receptors for dynamic equilibrium?
receptors for dynamic equilibrium respond to rotational forces
What stimuli does the vestibular apparatus detect?
head position in space
oto-
ear
lyso-
decomposition
tympan-
tympanic membrane
presby-
old age
-opia
having such vision or eye condition
Another name for the middle ear is the
tympanic cavity
Small 'stones' involved in activating static equilibrium receptors are called
otolith
Farsightedness is known as
hyperopia
A component of tears that guards against bacterial infection by breaking bacteria open is
lysozyme
Hearing loss related to normal aging is
presbycusis
You realize that many of your geriatric patients have visual problems that impact their care. Which item is NOT a common cause of decreased visual acuity in the elderly?
abnormal production of vitreous humor
A patient has noticed that his ability to hear has recently decreased. Which item is NOT likely to have caused his problem?
semicircular canals [bc it's for balance]
The amplification of the signal from a water-soluble hormone is achieved through an increase in
cAMP in cytoplasm
Water-soluble hormones affect target cells by binding to
plasma membrane receptors
How do endocrine hormones reach their target cells?
Hormones are transported through blood stream to target cells
What is the role of activated protein kinases?
phosphorylate proteins
Cyclic AMP is degraded by __________.
phosphodiesterase
Which of the following hormones has intracellular receptors?
cortisol
What is the mechanism of action of lipid-soluble hormones?
activation of genes which increases protein synthesis in cell
After a lipid-soluble hormone is bound to its intracellular receptor, what does the hormone complex do?
acts as transcription factor & binds to DNA, activating gene
Which hormone's receptor is always bound to DNA, even when the receptor is empty?
thyroid hormone
What keeps intracellular receptors from binding to DNA before a hormone binds to the receptor?
chaperone proteins [chaperonins]
true or false:

Up-regulation has involves the loss of receptors and prevents the target cells from overreacting to persistently gigh hormone levels
false
Which of the following occurs in situations where different hormones produce the same effects at the same target cell and their combined effects are amplified?
synergism
Hypocalcemia could be caused by
-apoptosis of parathyroid cells

-failure of osteoclasts to respond to PTH

-malfunction of parathormone receptors in kidney tubule cells
What hormone released into the blood by the posterior pituitary would reduce the amount of urine that is formed?
antidiuretic hormone [ADH]
The various hormones secreted by the anterior pituitary that regulate the secretion of hormones from other endocrine organs are called
tropins
Which hormone stimulates mammary glands to produce milk in nursing mothers?
prolactin
Which hormone aids in water resorption?
antidiuretic hormone
What tropic hormone stimulates cortisol from the adrenal gland?
adrenocorticotropic hormone [ACTH]
What is the function of the ventral hypothalamic neurons?
control secretion of thyroid stimulating hormone [TSH]
Insulin-like growth factors are intermediary hormones stimulated by which of the following hormones?
GH
Which of the following hormones is regulated by a neuroendocrine ["letdown"] reflex?
oxytocin
Where is antidiuretic hormone, also known as vasopressin, synthesized?
hypothalamus
What is the most important regulatory factor controlling the circulating levels of thyroid hormone?
negative feedback
Which gland secretes the most important hormone controlling calcium balance in the blood?
parathyroid
What hormone is released by the anterior pituitary to target the adrenal cortex when the body is under stress?
adrenocorticotropic hormone [ACTH]
Which of these conditions would promote aldosterone release from the adrenal glands?
drop in bp is sensed in kidney
Which of the following pairs correctly matches the adrenal gland structure with the class of hormones it produces?
zona glomerulosa - mineralcorticoids
Damage of which of the following brain structures could cause central diabetes insipidus?
hypothalamus
-tropic
attracted specifically to specified organ or tissue
angio-
blood or lymph vessel
Overproduction of urine or ___ is a sign of diabetes mellitus
polyuria
Overeating or ___ is a sign associated with diabetes mellitus
polyphagia
Upon the release of renin, _____ is produced and stimulates vasoconstriction and the release of aldosterone
angiotensin II
FSH and LH are examples of gonadotropic hormones which target the ovaries or testes
gonadotropic
An enzyme that degrades second messengers like cAMP or cGMP is
phosphodiesterase
Your patient has been admitted to the intensive care unit with a severe head injury. As you monitor his urine output, you find that it has fallen sharply. Lab tests indiate that his serum osmolality is lower than normal [i.e., his plasma is too dilute]. What should you suspect?
syndrome of inappropriate antidiuretic hormone [SIADH]
A patient is being treated by her urologist for a fourth episode of kidney stones. Analysis of the stones shows that they are composed of calcium oxalate. The urologist orders an assay of which hormone?
parathyroid hormone PTH
Your patient has been diagnosed with type 1 diabetes mellitus and you are explaining how to administer insulin. Your patient states "I don't want to do this. My brother in law has diabetes and he just takes a pill and watches what he eats." What is your best response?
"Your relative may have type 2 diabetes. People with that condition can make insulin but their cells don't respond to it properly. Your pancreas doesn't manufacture insulin."
The cross bridge cycle starts when
Ca2+ from SR binds to troponin
Single cross bridge cycle steps
1) cross bridge formation

2) power stroke

3) cross bridge detachment

4) reactivation of myosin head
myofilament with a knob-like head
myosin
myofilament stiffened and stabilized by tropomyosin
actin
the cytoplasm of a skeletal muscle fiber
sarcoplasm
bundle of skeletal muscle fibers enclosed by connective tissue called perimysium
fascicle
membrane of muscle cell
sarcolemma
blocks myosin-binding sites on actin
tropomyosin
long, cylindrical cells
skeletal muscle fibers
contractile unit
sarcomere
made up of several sarcomeres
myofibrils
Location of higher concentration of Ca2+ needed for cross bridge formation and cycling
cytoplasm
Actin status to begin cross bridge formation
actin-binding sites exposed
Molecule(s) bound to the myosin head at the start of the cross bridge cycle
ADP and Pi
Energy state of myosin for beginning cross bridge formation
energized/cocked myosin head
The molecules released just before power stroke
ADP and Pi
Actin behavior during the power stroke
ratchets toward M line
Myosin head energy status during the power stroke
pivots & returns to low energy
the bond between the actin and myosin head weakens as a result of
ATP
Only __________ of the myosin heads are detached from actin at any one time while calcium is present and cycling continues.
one half
_____ is not bound to myosin during the detachment step
ADP
Status of ATP during the myosin head phase?
hydrolyzed to ADP & Pi
Status of the myosin head during the myosin head phase?
returned to energized position
status of actin and myosin during the myosin head phase?
actin and myosin detached
A muscle cell runs out of ATP. Even though these are cyclic reactions, what step of the cross bridge cycle given is most directly inhibited or terminated?
cross bridge detachment
A person dies, and within hours, the skeletal muscles develop a locked contraction known as rigor mortis. Calcium ions leak from the sarcoplasmic reticulum into cytoplasm. From your knowledge of cross bridge cycling, what best explains this rigor?
Cross bridge detachment cannot occur [Detachment requires ATP which is only produced during life]
Excitation-contraction coupling is a series of events that occur after the events of the neuromuscular junction have transpired. The term excitation refers to which step in the process?
propagation of action potentials along sarcolemma
Excitation of the sarcolemma is coupled or linked to the contraction of a skeletal muscle fiber. What specific event initiates the contraction?
Calcium release from SR initiates contraction
A triad is composed of a T-tubule and two adjacent terminal cisternae of the sarcoplasmic reticulum. How are these components connected?
series of proteins that control calcium release
What is bame given to the regularly spaced infoldings of the sarcolemma?
transverse or T tubules
Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers?
calcium ions
What is the relationship between the number of motor neurons recruited and the number of skeletal muscle fibers innervated?
Typically, hundreds of skeletal muscle fibers are innervated by single motor neuron.
Which of the following choices below correctly describes how an action potential generated at the neuromuscular junction is converted to excitation in the muscle fiber?
AP in motor neuron causes ACh to be released into synaptic cleft. Binding of ACh to sarcolemma receptors initiates graded potentials
The action potential propagates along the sarcolemma. As the action potential spreads down the T tubules of the triads, voltage-sensitive tubule proteins change shape. How does the shape change of these proteins lead to contraction?
allows calcium to exit SR & enter cytosol
Which selection correctly describes the role of calcium in coupling?
Calcium binds to troponin, which moves tropomyosin & exposes myosin-binding sites on actin
which selection best describes the initial event in contraction?
Myosin heads bind to newly exposed myosin-binding sites on actin to form cross bridges.
the swollen chamber of an organelle that lies on either side of a T tubule
cistern
A protein that changed shape as a direct result of an action potential
Voltage-sensitive tubule protein
a protein with heads that attach in cross bridging
myosin
A structure that forms a path from the membrane to the cell interior
T-tubule
the protein that binds to calcium
troponin
Which of the following choices best summarizes excitation-contraction coupling?
series of events in which electrical stimulus is conveyed to muscle fiber to enact contraction
Inadequate calcium in the neuromuscular junction would directly affect which of the following processes?
Release of acetylcholine from synaptic vesicles
What structure most directly stimulates a skeletal muscle fiber to contract?
motor neuron
Membranous sac located in the axon terminal that contains neurotransmitter
synaptic vesicle
A type of chemically-gated ion channel located on the junctional folds of the muscle fiber
acetylcholine receptor
The space between the axon terminal and junctional folds
synaptic cleft
Neurotransmitter that stimulates skeletal muscle contraction
acetylcholine
Enzyme located in the synaptic cleft that breaks down acetylcholine
acetylcholinesterase
A type of voltage-gated ion channel located on the axon terminal
calcium channel
A type of voltage-gated ion channel located on the sarcolemma of the muscle fiber
sodium channel
Myasthenia gravis is a disease resulting from an autoimmune attack on the ACh receptors of the motor end plate. Binding of antibodies to the ACh receptors results in generalized muscle weakness that progresses as more ACh receptors are destroyed. Which of the following medications would help alleviate the muscle weakness?
drug that binds to & inactivates acetylcholinesterase [neostigmine]
sarco-
flesh
tropo-
turning
A missing protein in Duschenne 19s muscular dystrophy
Dystrophin
During an exercise where muscles do not shorten, ____ contractions have occured
isometric
____ has an affinity for myosin binding sites in the absence of calcium
tropomyosin
The two proteins directly involved in muscle contraction are broadly called
myofilaments
If troponin is a component of both cardiac and skeletal muscle, why is an elevated plasma troponin level useful in diagnosing myocardial damage?
subunits of troponin in cardiac muscle are unique to heart muscle.
Botulism and myasthenia gravis are conditions that cause muscle weakness. Which of these statements is NOT true?
Both conditions are caused by inability of body to produce adequate acetylcholine.
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