Physiology Test 1 - BU MAMS

Set Point

value around which the normal range fluctuates

Homeostasis

term used to describe the concept of constancy of the internal environment; proposed by Claude Bernard in the 19th century, cioned by Walter Cannon in 1932

60%

What percent of total body composition does water represent?

Interstitial Fluid, Plasma

two components of extracellular fluid

60:40:20

ratio of total body water : intracellular fluid : extracellular fluid compared to body weight

80:20

ratio of interstitial fluid : plasma compared to extracellular fluid weight

Plasma + RBC Volume

formula for blood volume (BV)

Hematocrit (%)

What is the following formula solving for? RBC Volume / BV * 100

35-50%

physiological range of hematocrit in adults

140:12

extracellular : intracellular concentration for sodium (ion)

4:150

extracellular : intracellular concentration for potassium (ion)

2.5:10^-4

extracellular : intracellular concentration for chloride (ion)

24:10

extracellular : intracellular concentration for bicarbonate (ion)

16:60 (16 in plasma, <1 in interstitial fluid)

extracellular : intracellular concentration for proteins- (ion)

300 mOsm/L

osmolarity for most body fluids

J = PA(C1-C2)

Fick’s Law of Diffusion for biological membranes

Equilibrium

When does the hydrostatic pressure difference accurately measure the osmotic pressure difference between two solutions?

MEPP (Miniature End-Plate Potential)

Post-synaptic response to spontaneous release of one vesicle, with no stimulation

EPP: End-Plate Potential

Summation of many MEPPs (many vesicles) in response to an action potential

Quantal Content

Number of MEPPs per EPP

Membrane Potential (Electric Potential Difference, mV)

Difference between the inside and outside of a cell

Millions, 10,000s

Throughput difference for channels versus transporters

1. Channel Diameter

2. Charged/Polar Surfaces on Walls

3. Number of Water Molecules (associated w/ ion)

Determinants for selectivity of channels

True

True or false: transporters can become saturated

Secondary Active Transport

Type of transport that relies on the electrochemical gradient across a plasma membrane as its energy source; movement of an ion down its gradient is coupled with the transport of another molecule

Examples:

• Sodium-Dependent Glucose Transport (Cotransport)

• Sodium-H+ Exchanged (Counter-Transport)

MDR1, MRP2

Subset of primary active transporters (ABC transporters) that are present in renal tubular cells and hepatocytes that are involved in excretion of anions

Pressure = CRT

Formula for osmotic pressure

Nonpenetrating/Effective Solutes

Substances that cannot cross the plasma membrane

Reflection Coefficient

Dimensionless number that describes the ease with which a solute crosses a membrane

Formula: Πeff/Πideal

V = IR

Ohm’s Law

Decreased

High Conductance = [Increased/Decreased] Resistance

E = 61/Z log(deltaC)

Nernst Equation

-96 mV

E(K)

66 mV

E(Na)

-70 mV

Vm (Membrane Potential)

Outward, Inward

For a cation, a positive driving force results in [outward/inward] flux and a negative driving force results in [outward/inward] flux

Chlorine (Cl-)

In many excitable cells, the resting membrane potential is close to the equilibrium potential of which ion due to the absence of these ions’ pumps?

T = Rm*Cm

Time Constant Formula

Sqrt (Membrane Resistance/Internal Resistance)

Length Constant Formula

I = g * Driving Force

Flux Formula

Tetrodotoxin (TTX)

What toxin blocks voltage-gated Na+ channels?

Tetraethyl Ammonium (TEA)

What toxin blocks voltage-gated K+ channels?

Sodium Channels

Which of the two voltage-gated channels behave as having two gates?

Increasing Membrane Resistance

How does myelination increase conduction velocity?

Saltatory Conduction

Action potentials only at the nodes of Ranvier

Interstitial Fluid

The “internal environment” specifically refers to which body fluid?

42 L

Total body water is approximately how many liters for a 70-kg person?

Synapse

Basic structure of communication between adjacent cells/neurons responsible for transmitting signals to downstream partners

Dendrites

Structure responsible for receiving information from synapses/stimulus and propagating postsynaptic potentials

Axon Hillock

Structure where action potentials are initiated in response to the integration of passive postsynaptic potentials that depolarize a cell above its threshold

Gap Junction

Structures that allow current (electrical communication) to flow from a presynaptic neuron into a postsynaptic neuron

Properties:

• No signal amplification

• Limited modulation of signal strength

• Transmission signal dependent on morphology

Calcium

Synaptic transmission is dependent on what extracellular ion?

SNARE Complex

Structure that causes the fusion of vesicles with the membrane and release of neurotransmitter; calcium influx into the pre-synaptic terminal causes this

Botulinum Toxin

Proteases that inhibit neurotransmitter release by cleaving the SNARE protein in the NMJ

150, 1-4

Difference in number of transmitter-filled vesicles released in the neuromuscular junction vs CNS

Diffusion, Degradation, Reuptake

How are neurotransmitters removed from the synaptic cleft?

Ionotropic Receptors

Class of receptor/postsynaptic response where the receptor is the channel and binding of one neurotransmitter opens one channel

Metabotropic Receptors

Class of receptor/postsynaptic response where channels open indirectly through a pathway; longer response time and allows for amplification

Acetylcholine

Neurotransmitter found in the neuromuscular junction; responsible for muscle activation and cerebral cortex activity

GABA

Neurotransmitter found in inhibitory synapses

Glutamate

Neurotransmitter found in excitatory synapses in the CNS

Glycine

Neurotransmitter found in major inhibitory neurotransmitters in the spinal cord

Motor Unit

Name of unit for one motor neuron and many muscle fibers

Somatic, Autonomic

Two types of nervous systems in peripheral nervous system

Sympathetic, Parasympathetic, Enteric

Three subdivisions of autonomic nervous system

Preganglionic Neuron, Neuron (Adrenal Medulla), Postganglionic Neuron

Pathway for autonomic nervous system

Sympathetic

The following traits are characteristic of which division of the autonomic nervous system?

• Thoracolumbar

• Short pre, long post

• Widespread

Parasympathetic

The following traits are characteristic of which division of the autonomic nervous system?

• Craniosacral

• Long pre, short post

• Localized

Acetylcholine

All preganglionic neurons release which neurotransmitter?

Acetylcholine

Parasympathetic neurons generally release which neurotransmitter?

Norepinephrine (Epinephrine)

Sympathetic neurons generally release which neurotransmitter?

Nicotinic (Skeletal), Muscarinic (Smooth/Cardiac)

Two main types of receptors for acetylcholine

Atropine

What are muscarinic receptors blocked by?

Curare

What are nicotinic receptors on skeletal muscle blocked by?

Hexamethonium

What are nicotinic receptors on autonomic ganglia blocked by?

Alpha, Beta

Two types of receptors for norepinephrine

Varicosities (“En Passant” Synapses)

Regions of swellings located along the length of an axon from where NE (in general) is released in the sympathetic nervous system

Re-uptake, Diffusion, Extra-neuronal Uptake

Three mechanisms by which NE action terminates

Horner Syndrome

What is the name of the disease with the following symptoms?

• Ptosis (eyelid drooping on one side)

• Miosis (pupil constricted on affected side)

• Anhidrosis (decreased sweating on affected side)

Actin, Myosin

Contractile Proteins

Smooth Muscle

Non-striated muscles

Actin, Tropomyosin, Troponin

Components of thin filament

400 Angstroms, 7

At about how many angstroms and how many actin molecules does tropomyosin/troponin appear?

Myosin Head, Light Chain, Alpha-Helical Coil

Components of thick filament (myosin)

MADPPi to M+ADP+Pi

Rate-limiting step for myosin ATPase activity

Rigor Mortis

The state that follows death due to its depletion of cellular ATP resulting from circulatory failure

TnI, TnC, TnT

Three components of troponin, a key regulatory protein influencing the contractile state of muscle

A-I Junctions

Where do t-tubules appear?

Isometric Contractions

Type of contraction where muscle develops force, but does not change length

Isotonic Contractions

Type of contraction where muscle shortens under a constant load and tension equals the weight of the load during constant velocity shortening

Titin

Which elastic protein is largely responsible for passive tension?

Latent Period

The time delay between the stimulus and the first-recorded tension increase; it represents the time required to depolarize the cell membrane and activate the contractile apparatus

Mechanical Summation

When a second stimulus is applied before relaxation is complete, exceeding the tension of the first

Tetanic Contraction (Fused Tetanus)

Sustained tension that occurs with a sufficiently rapid series of action potentials

Series Elastic Component

The elastic elements that yield to the applied, active force

Rest Length (L0 or Lmax)

Optimal length at which maximum isometric, active tension can develop due to the fact that there will be the largest overlap between thick and thin filaments

Touch, Proprioception, Temperature, Nociception

Four distinct classes of sensation upon stimulation of body tissues

Hair Follicle Capsules

Rapidly adapting receptor ending used for light contact

Meissner Corpuscles

Rapidly adapting receptor ending used for high acuity tactile, small receptive fields

Merkel Disks

Slowly adapting receptor ending used for high acuity tactile, small receptive fields