Lab Quiz 2: Study Guide

What is xylene?

A nonpolar substance that separates from polar water and accumulates at the top of a mixture

What happened when KMnO4 was added to the xylene-water mixture?

The polar salt only made the water layer purple, proving two separate layers existed

What is an amphipathic molecule?

A molecule that can bind to both polar and nonpolar molecules (like detergent/soap)

What does osmosis require?

A membrane completely permeable to water and partially permeable or impermeable to solute molecules

What are non-penetrating molecules considered?

Osmotically active

What is osmolality?

When solutions have the same mole value

What happens to RBCs in a hypotonic solution?

Hemolysis (bursting)

What happens to RBCs in a hypertonic solution?

Crenation (shrinking)

What are three isotonic intravenous fluids?

Normal saline (0.9% NaCl), D5W (5% dextrose in water), Ringer's lactate

What is dialysis tubing?

A semipermeable membrane that only allows water to pass

Why did dialysis bags with sucrose gain weight?

Water moved in via osmosis to dilute the sucrose solution

What is the percent change formula?

"[(final - initial)/initial] × 100"

What is the assumed osmolarity of red blood cells?

280 mOsm

What is Fick's Law in relation to dialysis?

The higher the concentration gradient, the bigger the change in weight

Why does higher molecular weight cause slower hemolysis?

Larger molecules diffuse more slowly into the cell

How does polarity affect hemolysis time?

More polar solutions cause slower hemolysis; more nonpolar solutions cause faster hemolysis

What is a nerve?

A bundle of axons in the PNS

What is a tract?

A bundle of axons in the CNS

How many axons are in a frog sciatic nerve?

Approximately 1500 axons (motor and sensory)

What is membrane potential?

Electrical disequilibrium due to uneven distribution of ions across cell membrane

What maintains the resting membrane potential?

The Na/K pump

What is the resting membrane potential for excitable cells?

-70mV

What happens when a nerve is stimulated?

Double-gated sodium channels open and make the cell more positive

What is a compound action potential (CAP)?

Graded (stronger stimulus) --> stronger response Spatial summation - the recruitment of more units (axons) firing together

What is sub-threshold voltage?

Voltage stimulus that generates no response

What is threshold voltage?

The voltage range from minimal response to response prior to maximal

What is maximal voltage?

The max voltage that produces a maximum response (all units recruited)

What is supra-maximal voltage?

Any stimulus higher than maximal (produces same response as maximal)

Are nerves graded or all-or-none?

"All-or-none individually, but CAP is graded due to recruitment"

What type of summation do nerves participate in?

Only spatial summation (not temporal)

How does lidocaine work?

It blocks sodium channels, rendering nerves unable to react to stimulus

What types of summation can muscles demonstrate?

Both spatial and temporal summation

What is treppe?

Muscle response at 2.6 Hz where calcium buildup allows greater response but stimulus returns to zero

What is wave summation?

Muscle response at 6-10 Hz with increased calcium and muscle not reaching baseline

What is tetanus in muscle contraction?

Muscle response at 10-18 Hz where muscle has no time to relax before next contraction

What are the three phases of a muscle twitch?

"Latent period (stimulus to contraction), Contraction period (develop tension), Relaxation period (return to baseline)"

What are twitch muscles also called?

Phasic muscles

What are non-twitch muscles called?

Tonic muscles

What does an EMG record?

measuring electrical activity (action potentials) of nerves and muscles during contraction

What happens to action potential as tension increases?

Action potential increases

Which hand typically shows higher action potentials?

Non-dominant hand (due to less coordinated fiber recruitment)

Is there a difference in action potentials between sexes?

"No, but males generally have higher measurements due to greater muscle mass"

What does the parasympathetic nervous system control?

Rest and Digest functions

What does the sympathetic nervous system control?

Fight or Flight functions

What heart rate is primarily controlled by parasympathetic?

Below 100 bpm

What heart rate is primarily controlled by sympathetic?

Above 120 bpm

What heart rate has equal sympathetic and parasympathetic control?

Between 100-120 bpm

What is the relationship between HR and parasympathetic activity?

Inversely proportional (if parasympathetic decreases, HR increases)

What is GSR?

Galvanic Skin Response - related to sweat rate

What nervous system exclusively controls GSR?

Sympathetic nervous system

What happens to GSR when sympathetic outflow increases?

GSR increases

What do cold receptors respond to?

A decrease in temperature

Where are touch receptors located?

Everywhere on the body

Where are cold and warm receptors located?

Not everywhere - specific locations

What does two-point discrimination test measure?

The ability to feel two separate pins touching individual sensors

What is the two-point discrimination threshold ranking?

"Fingertip < palm < back of hand < back of neck (smallest to largest threshold)"

What does a larger threshold indicate?

Larger receptive field

What is the receptor density ranking?

"Fingertip > palm > back of hand > back of neck (highest to lowest)"

Where do sensory information from cutaneous receptors project?

Postcentral gyrus of the cerebral cortex

What happens if you put your hand in cold water then room temp water?

Room temperature water feels warm

What does the temperature adaptation experiment prove?

Receptors respond to changes in temperature, not absolute temperature

What receptors adapt rapidly?

Touch and pressure receptors

What receptors adapt slowly?

Temperature and proprioceptors

What receptors never adapt?

Nociceptors (pain receptors)

What is sensory adaptation?

When receptors adapt to a constant stimulus

What is referred pain?

Pain sensed at a location other than its origin

Where is ulnar nerve pain felt?

Palms and fingers

Where do men feel angina?

Shoulder and arm

Where do women feel angina?

Jaw, shoulder, and back

What is angina pectoris?

Left arm and shoulder pain due to heart problem

Can pain exist without actual tissue damage?

"Yes, brain can consciously interpret pain when not there"

What is congenital analgesia?

Inability to feel pain

What is acuity?

Ability to resolve objects clearly

What is the Snellen Eye Chart used for?

Testing visual acuity

What does 20/40 vision mean?

Person reads from 20 feet what a normal person can see from 40 feet

What is the unit for lens strength?

Diopters

What is myopia?

Nearsightedness

What is hyperopia?

Farsightedness

What causes cataracts?

Crystalline proteins changing shape and aggregating into cloudy patches (from UV damage, dehydration, or oxidation)

What is emmetropia?

Normal visual acuity (20/20)

What is astigmatism?

Imperfection in field of view that prevents light from passing equally through all parts of eye

What is accommodation?

The ability of the eye to focus on images at different distances

Why does accommodation worsen with age?

The lens becomes less pliable (harder to change shape)

What does an EEG measure?

electrical brain recording;

Electrical difference between two points on the brain

What does a flat EEG indicate?

+

What happens if there's no difference in electrical activity;

and when that occurs

No electrical difference - the person is dead

What happens to EEG during Jendrassik maneuver?

The EEG gets bigger

What are the five characteristics of reflexes?

"Involuntary, requires adequate stimulus, excites specific receptor, patterned (stereotyped), graded"

What are the five components of a reflex arc?

Receptor --> Sensory (afferent) fiber ---> Integration in CNS ----> Motor (efferent) fiber ---> Effector

What type of reflex is the knee-jerk?

Stretch reflex,

monosynaptic,

simple,

spinal

Is a compound action potential graded or all-or-none?

Graded (because total action potentials are added together)

Is an action potential graded or all-or-none?

All-or-none

What are Renshaw cells?

Cells that normally inhibit reflexes by opening chloride channels

How do Renshaw cells inhibit reflexes?

They open chloride channels, making it harder for action potential to be reached

What stimulates Renshaw cells normally?

The brain

Why does Jendrassik maneuver make reflexes bigger?

Brain gets busy with hand clasp and forgets to stimulate Renshaw cells, causing disinhibition

What is cortical irradiation?

Activity in the outer part of the brain

What type of reflex is the plantar reflex?

Polysynaptic, complicated, cortical reflex

What is the pathway for plantar reflex?

Foot → spine (L5/S1) → brain and back:

via pyramidal motor (corticospinal) tract

What is the Babinski sign?

Flaring of toes

When is Babinski sign normal?

In infants (nervous system still developing)