Medical Physiology Midterm
How many net ATP molecules are produced during glycolysis?
2
Plasma makes up approximately ___% of total body water volume
7-10%
What kind of neurotransmitter is serotonin?
A catecholamine neurotransmitter
What is protein conformation dependent upon?
A combination of covalent and non covalent bonds within the protein
A protein is found in blood that is produced by the pancreas and acts on receptors of cells in the liver. What type of physiological regulator is it most likely to be?
A hormone
Alzheimer's disease is thought to involve primarily:
A loss of cholinergic neurons
SHP-1
A physical inhibitor which terminates or prevents activity of intracellular signaling molecules
With regard to the action of hormones and neurotransmitters on cellular receptors, which of these describes "amplification"?
A single first-messenger molecule activates multiple second-messenger molecules, each of which activate thousands of enzymes
Which of the following situations best represents a homeostatic mechanism?
After eating a large batch of salty popcorn, levels of salt in the urine increase.
Examples of secondary protein structures include which of the following options?
Alpha helix and beta pleated sheets
During protein metabolism one toxic metabolite that is produced is detoxified into urea. The metabolite is which of the following options?
Ammonia
Tay-Sachs disease is characterized by
An abnormal accumulation of a glycolipid in the myelin sheath
Which is a series of reactions by which fatty acid catabolism occurs?
Beta oxidation
About 3-5% of school-aged children are diagnosed with ADHD. This neurobehavioral problem is anatomically linked primarily to which area of dysfunction in the brain?
Both basal nuclei and pituitary gland
Opening channels for which of the following ions can trigger exocytosis?
Calcium
Which of the following solutes enters the cell through channel-mediated diffusion?
Calcium (Ca2+)
How is autocrine regulation best described?
Chemical regulators affect the same cells that produce them
The synthesis of acetylcholine involves an enzyme called ____, which is present within the cytosol and is responsible for converting ____ into acetylcholine
Choline acetyl transferase : acetyl CoA + choline
GABA activates its receptor to increase the flow of which ions into the cell?
Cl-
How might an individual avoid the negative consequences of Type I Glycogen Storage Disease (von Gierke's disease)?
Consume multiple small meals throughout the day to avoid drops in blood glucose
Accommodation for near vision requires
Contraction of the ciliary muscles
_______ acts as an inhibitor of the electron transport chain and results in death of the organism exposed to it
Cyanide
NSAIDs target which signaling molecule to produce analgesia?
Cyclooxygenase (COX)
Receptor down regulation results in ____
Desensitization of the target cell
Receptor down regulation results in which of the following options?
Desensitization of the target cell
Which of the following second messengers when released by phospholipase C will directly activate the enzyme protein kinase C?
Diacylglycerol (DAG)
Glial cells that produce the cerebrospinal fluid are called ______
Ependymal cells
By what transport mechanism does glucose enter most cells?
Facilitated diffusion
Activation of which G protein results in a decrease in cAMP production?
Gi
Carbohydrates are stored in the liver and muscles in the form of what?
Glycogen
Identify the effectors in this homeostatic reflex: Eating a salt-rich meal increases blood volume and pressure, stretching blood vessel walls. Nerve signals sent to the brainstem stimulate changes in hormonal and neural signaling. The heart rate is slowed, blood vessel walls are relaxed, and the kidneys increase urinary salt. The blood pressure returns to normal.
Heart, kidneys, and blood vessels
Physiology is the study of
How organisms function
A change in a cell's membrane potential from rest such that it becomes more negative is referred to as a _______
Hyperpolarization
If the amount of sodium in the blood decreases, what would a negative feedback control mechanism be expected to do?
Increase the amount of sodium in the blood
Which is true about mediated transport of substances across cell membranes?
It involves a specific membrane protein that functions as a carrier molecule
What best describes the extracellular matrix?
It surrounds cells; it contains proteins, polysaccharides, and minerals; it provides a scaffold for cell attachment; it transmits chemical messengers to cells.
Na+-K+ ATPase pump characteristics
It transports Na+ out of cells and K+ into cells; it binds to, and hydrolyzes, ATP; its activity requires the expenditure of metabolic energy; it is constantly active in all cells
The _____ is the source of most of the cellular energy
Mitochondria
Calcium binding to calmodulin initiates the intracellular signaling cascade leading to phosphorylation of what protein in what type of muscle?
Myosin in smooth muscle only
Sympathetic responses generally are widespread because _____
NE and epinephrine are secreted into the blood as part of the sympathetic response
Acetylcholine acts at which receptors?
Nicotinic
When a muscle has been repeatedly contracting at a moderate intensity for an extended period of time (more than a few minutes), what is the primary source of ATP?
Oxidative phosphorylation
Specificity is an important characteristic of intercellular communication, how does it occur?
Protein receptors for chemical messengers are only expressed in specific target cells
Which mechanisms serve as a causative factor of fatigue?
Repeated action potentials along the same neuron can lead to ACh depletion; the crossbridges can become depleted of ATP; glycolysis fibers produce lactic acid which inhibits enzyme activity
Which of the following signaling molecules is an example of a phosphatase?
SHP-1
The ____ is a saclike membranous network that surrounds each myofibril and is the site of intracellular storage of calcium ions
Sarcoplasmic reticulum
What type of hearing loss is characterized by a problem with the organ of corti or the auditory nerve?
Sensorineural hearing loss
The portion of the peripheral nervous system that is composed of nerve fibers that inner age skeletal muscle is called the:
Somatic motor nervous system
Which of the following is the correct sequence for a regulatory reflex arc?
Stimulus, receptor, afferent pathway, integrating center, efferent pathway, effector
Activation of the _____ system leads to the release of _____ which acts at ____ on the ____ muscle of the _____ to cause _____ of the pupil
Sympathetic nervous; NE; a1 receptor; radial; circular; iris, dilation
Phosphorylation is a necessary component of any enzyme activation (T/F)
T
Which of the following chemical messengers is NOT derived from an amino acid?
Testosterone
In its active form, a G protein will have ______
The alpha subunit separates from the beta and gamma subunits
What prevents the development of a tetanic contraction and summation of contractions in cardiac muscle?
The long (250 msec) absolute refractory period
Which situation describes a feedforward mechanism?
The smell of food on a plate triggers the vomit reflex
At very low concentrations, epinephrine causes an artery to dilate. At higher concentrations epinephrine causes the same artery to constrict. How can these different effects be explained?
There are two types of epinephrine receptors with different affinities for epinephrine that use two different second-messenger systems
What is the clinical effect of local anesthetics such as procaine and lidocaine?
These drugs block voltage-gated sodium ion channels which stimulates action potentials
What best describes the signaling mechanism of receptor guanyl cyclases?
They are enzyme-linked receptors that synthesize the second messenger cGMP
What describes the signaling mechanism of receptor guanylyl cyclases
They are enzyme-linked receptors that synthesize the second messenger cGMP
What is true about metabolic myopathies?
They can lead to kidney failure, myopathies can generate a condition called rhabdomyolysis, and they can be due to alterations in the body's ability to handle the storage and/or metabolism of sugars or fats/lipids
What is the main function of cellular tight junctions?
They form barriers that restrict the passage of materials through the extracellular space between cells
What accurately describes afferent neurons?
They transmit information from the periphery to the CNS
Why do solutions for injection or infusion into people with low blood volume normally contain 150 mM NaCl.
This is an isotonic solution and NaCl will keep the added volume in the extracellular fluid compartment.
What is the general purpose of positive feedback mechanisms?
To bring about a rapid change in the body
Rhodopsin is a g-protein coupled receptor. Which G-protein does it couple with?
Transducin
The correct order of middle ear structures from lateral to medial is:
Tympanic membrane, malleus, incus, stapes, oval window
Glutamate is detected by which taste modality?
Umami
How does alcohol (ethanol) affect the central nervous system?
Very high doses of ethanol are sometimes fatal, due to suppression of brainstem centers responsible for regulating the cardiovascular and respiratory systems; ethanol and GABA agonists such as alprazolam and diazepam all act via the same receptor; ethanol stimulates GABA synapses and simultaneously inhibits excitatory glutamate synapses
What is the main function of the rods in the eye?
Vision in dim light
If all other conditions remain the same and the concentration of a non penetrating solute increases inside a cell, which is most likely to occur?
Water will tend to enter the cell because the interior has an increased osmolarity.
Norepinephrine binds with an _____ receptor to activate a ____ protein which results in the inactivation of _______
a2; Gi; adenylate cyclase
The contractile portion of the thin filament is composed of what protein?
actin
Desmosomes
anchor adjacent cells together firmly in areas that are subject to stretch
What type of glial cell is necessary for normal development of the blood-brain barrier?
astrocytes
What type of receptor detects blood pressure?
baroreceptor
Epithelial cell barrier compartments in the order of the typical Na+ concentrations, from highest to lowest
blood side, lumen side, intracellular
The central nervous system includes the:
brain and spinal cord
The molecule target of caffeine is _____
cAMP phosphodiesterase
In smooth muscle, calcium triggers contraction by binding to what protein?
calmodulin
In active transport, the affinity of a given binding site for the molecule to be transported _______ as the site goes from facing one side of the membrane to facing the other side
changes
Which organ system is responsible for transporting cells and dissolved material, including nutrients, wastes, and gases?
circulatory system
The transport of two molecules across the cell membrane in the same direction is called ______, while the movement of two molecules in opposite directions is called _______
cotransport; countertransport
Distinguishing the pitch of sounds is possible because:
different frequencies of sounds stimulate different regions of the basilar membrane in the cochlear duct
Why does breathing continue to be rapid and deep for a time after heavy exercise?
extra oxygen is needed to eliminate lactic acid and restore muscle creatine phosphate and glucose concentrations
Protein channels that link the cytosol of adjacent cells are called ___ junctions
gap
Direct communication between cells in contact with one another where the messenger does not leave the cell to enter the extracellular fluid is accomplished through ______
gap junctions
A combination of a sugar with a protein is a ____
glycoprotein
The myosin head is converted into the high-energy state by _____
hydrolysis of ATP
Enzymes function in chemical reactions to ___________
lower the energy of activation needed to start the reaction
What two enzymes catalyze the breakdown of catecholamines?
monoamine oxidase and catechol-O-methyltransferase
What are the 4 general categories of cells that make up the human body?
muscle, epithelial, neuron, connective tissue
Potentially damaging stimuli that result in pain are selectively detected by_____
nociceptors
In the cytochrome oxidase system, the final acceptor of a pair of electrons is ______.
oxygen
Extracellular fluid volume - interstitial fluid volume =
plasma volume
What enzyme is activated by cAMP?
protein kinase A
Metabolic pathways are regulated by a(n) ____ enzyme
rate-limiting
Increases in the amount of cytoplasmic calcium required to initiate a muscle contraction are mediated by the coupling between a ________ on the T tubule and a ________ on the membrane of the sarcoplasmic reticulum.
ryanodine receptor ; Dihydropyridine receptor
Two receptors, A and B, can bind the same chemical signaling molecules but the concentration of those molecules required to reach 50% saturation is twice as great for receptor B. Therefore, the receptors have the same ____, but different _____.
specificity, affinity
Describing a physiological variable as "homeostatic" means _____
that it is in a state of dynamic constancy that is regulated to remain near a stable set point value
What is the protein component of the thin filament that binds to calcium thereby initiating skeletal muscle contraction?
troponin