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