Mammalian Physiology Exam 1

A given neuron can A. Be either a presynaptic neuron or a postsynaptic neuron B. Receive information from more than one other neuron C. Transmit information to more than one other neuron D. Simultaneously release more than one type of neurotransmitter E. Do all of these things

...

Describe the physical state of a muscle fiber in rigor mortis and the conditions that produce this state. 48 or more hours after the onset of rigor, the muscles will begin to relax. What conditions produce this relaxation?

...

Draw a muscle contractile unit and label the following components: a. Z-line e. Actin b. A-band f. Myosin c. H-zone g. Titan d. I band h. Sarcomere

...

Explain the phenomenon of referred pain.

...

Myasthenia gravis is an autoimmune disease - that is, a disease in which one's immune system gradually attacks a part of one's own body, in this case the receptors for acetylcholine at the neuromuscular junction. Which of the following drugs might be useful in treating this disease? A. A drug that inhibits acetylcholinesterase B. A drug that inhibits release of acetylcholine C. Curare D. Atropine (a muscarinic antagonist) E. All of the choices are correct

...

The Na, K-ATPase in a nerve cell A. Maintains an electrical gradient such that the inside is negative with respect to the outside B. Maintains a concentration gradient for K+ such that diffusion forces favor movement of K+ into the cell C. Maintains an electrical gradient at the equilibrium potential of K+ D. Transports an equal number of sodium and potassium ions E. Both maintains an electrical gradient such that the inside is negative with respect to the outside and transports an equal number of sodium and potassium ions are correct

...

The neural code that signals stimulus strength is A. The size of action potentials B. The frequency of action potentials C. The duration of action potentials D. Both the size of action potentials and the frequency of action potentials E. All of the choices are correct

...

Define sensory receptor.

A cell or portion of a cell that contains structures or chemical molecules sensitive to changes in an energy form in the outside world or internal environment; in response to activation by this energy, the sensory receptor initiates action potentials in that cell or an adjacent one

Define astrocyte.

A form of glial cell that regulates composition of extracellular fluid around neurons and forms part of the blood-brain barrier

Define microglia.

A type of glial cell that acts as a macrophage

Define plasticity.

Ability of neural tissue to change its responsiveness to stimulation because of its past history of activation

Define excitability.

Ability to produce electrical signals

Define electrogenic pump.

Active-transport system that directly separates electrical charge, thereby producing a potential difference

Define synapse.

Anatomically specialized junction between two neurons where electrical activity in one neuron influences excitability of second

Define nerve fiber.

Axon of a neuron

Define central nervous system (CNS).

Brain and spinal cord

Define integrator.

Brain region that compares the actual value of a variable such as body temperature to a set point

Define collateral.

Branch of a neuron axon

Define Goldman-Hodgkin-Katz (GHK) equation.

Calculation for electrochemical equilibrium when a membrane is permeable to more than one ion

Define soma.

Cell body of neuron

Define neuron.

Cell in nervous system specialized to initiate, integrate, and conduct electrical signals

Define stem cell.

Cell that in adult body divides continuously and forms supply of cells for differentiation

Define negative feedback.

Characteristic of control systems in which system's response opposes the original change in the system

Define neurotransmitter.

Chemical messenger used by neurons to communicate with each other or with effectors

Define afterhyperpolarization.

Decrease in membrane potential in neurons at the end of the action potential due to opened voltage-gated K+ channels

Define decremental.

Decreasing in amplitude

Define action potential.

Electrical signal propagated by neurons and muscle cells; an all-or-none depolarization of membrane polarity; has a threshold and refractory period and is conducted without decrement

Define axon terminal.

End of axon; forms synaptic or neuroeffector junction with postjunctional cell

Define axon.

Extension from neuron cell body; propagates action potentials away from cell body; also called a nerve fiber

A muscle fiber is a collection of individual muscle cells. True or False?

False

A receptor potential is synonymous with an action potential.

False

Activation of a muscle cell via the motor neuron leads to the release of calcium from the T tubule. True or False?

False

All production of new neurons in the brain ends at birth. True or False?

False

An example of a somatosensory cell would be a hair cell of the inner ear. True or False?

False

An example of a somatosensory cell would be an olfactory receptor. True or False?

False

Pain receptors travel up the same side of the spinal cord in which they enter, and synapse in the brain stem.

False

Schwann cells are a type of glial cells. True or False?

False

The stria vascularis pumps K+ out of the scala media (cochlear duct) to maintain the low [K+] in the endolymph. True or False?

False

Unfused tetanus results in a decrease in muscle tension when compared to a single twitch. True or False?

False

When coding increasing intensity of a stimulus, a receptor will fire action potentials with increasing intensity. True or False?

False

When light hits a photoreceptor, cGMP is produced, which opens Na+ channels resulting in depolarization of the receptor cell. True or False?

False

Define initial segment.

First portion of axon plus the part of the cell body where axon arises

Define blood-brain barrier.

Group of anatomical barriers and transport systems in brain capillary endothelium that controls kinds of substances entering brain extracellular space from blood and their rates of entry

Define nerve.

Group of many nerve fibers traveling together in peripheral nervous system

Define dendrite.

Highly branched extension of neuron cell body; receives synaptic input from other neurons

Define cell body.

In cells with long extensions, the part that contains the nucleus

Define myelin.

Insulating material covering axons of many neurons; consists of layers of myelin-forming cell plasma membrane wrapped around axon

Define process.

Long extension from neuron cell body

Define excitable membrane.

Membrane capable of producing action potentials

Define ligand-gated channels.

Membrane channel operated by the binding of specific molecules to channel proteins

Define mechanically gated channels.

Membrane ion channel that is opened or closed by deformation or stretch of the plasma membrane

Define graded potential.

Membrane potential change of variable amplitude and duration that is conducted decrementally; as no threshold or refractory period

Define kinesin.

Motor protein that uses the energy from ATP to transport attached cellular cargo along microtubules

Define dynein.

Motor protein that uses the energy from ATP to transport attached cellular cargo molecules along microtubules

Define retrograde.

Movement of a substance or action potential backward along a neuron, from axon terminals toward the cell body and dendrites

Define anterograde.

Movement of a substance or action potential in the forward direction from a neuron's dendrites and/or cell body toward the axon terminal

Define current.

Movement of electrical charge; in biological systems, this is achieved by ion movement

Define peripheral nervous system (PNS).

Nerve fibers extending from CNS

Define efferent neuron.

Neuron that carries information away from CNS

Define afferent neuron.

Neuron that carries information from sensory receptors at its peripheral endings to CNS; cell body lies outside CNS

Define presynaptic neuron.

Neuron that conducts action potentials toward a synapse

Define postsynaptic neuron.

Neuron that conducts information away from a synapse

Define interneuron.

Neuron whose cell body and axon lie entirely in CNS

Define Schwann cell.

Nonneural cell that forms myelin sheath in peripheral nervous system

Define glial cell.

Nonneuronal cell in CNS; helps regulate extracellular environment of CNS; also called neuroglia

Define axon hillock.

Part of the axon nearest the cell body where the action potential begins

Define all-or-none.

Pertaining to event that occurs maximally or not at all

Define inactivation gate.

Portion of the voltage-gated sodium or potassium channel that closes the channel

Define leak K+ channels.

Potassium channels that are open when a membrane is at rest

Define axonal transport.

Process involving intracellular filaments by which materials are moved from one end of axon to other

Define apoptosis.

Programmed cell death that typically occurs during differentiation and development

Define neurotrophic factor.

Protein that stimulates growth and differentiation of some neurons

Define node of Ranvier.

Space between adjacent myelin-forming cells along myelinated axon where axonal plasma membrane is exposed to extracellular fluid; also called neurofibril node

Define varicosity.

Swollen region of axon; contains neurotransmitter-filled vesicles; analogous to presynaptic ending

Define action potential propagation.

The movement of an action potential along an axon; in myelinated axons, it occurs via saltatory conduction

Define absolute refractory period.

Time during which an excitable membrane cannot generate an action potential in response to any stimulus

Define growth cone.

Tip of a developing axon

Define hyperpolarized.

To change membrane potential so cell interior becomes more negative than its resting state

Define depolarize.

To change membrane potential value toward zero so that cell interior becomes less negative than resting level

A motor unit includes all of the muscle cells that connect with a given motor neuron. True or False?

True

A somatosensory receptive field includes an individual receptor and all of its receptor endings. True or False?

True

A term used to describe the type of stimulus energy is modality. True or False?

True

Afferent transmission from the periphery enters the dorsal side of the spinal cord, while efferent transmission from the CNS to the periphery leaves the ventral side of the spinal cord.

True

Any given neuron can be both presynaptic and postsynaptic. True or False?

True

Any given oligodendrocytes can surround several different neurons with its plasma membrane. True or False?

True

Contraction of skeletal muscle is independent of the presence of extracellular Ca++. True or False?

True

Glial cells are the most abundant cells in the brain. True or False?

True

Hair cells near the helicotrema are responsible for the sensation of low frequency sounds. True or False?

True

LTP is a cellular event that is often used to explain learning, and is rooted with the idea that repeated use of a synapse increases its "strength".

True

Olfactory receptors are chemoreceptor cells that require the ligand to be soluble in water. True or False?

True

One example of descending CNS activity would be in the modulation of pain afferent sensation. True or False?

True

While sitting in your chair taking this quiz, your perception of seated pressure on the chair is lost. This is due to rapidly adapting "on-off" receptors. True or False?

True

Define ependymal cell.

Type of glial cell that lines internal cavities of the brain and produces cerebrospinal fluid

Define oligodendrocyte.

Type of glial cell; responsible for myelin formation in CNS

Define equilibrium potential.

Voltage gradient across a membrane that is equal in force but opposite in direction to concentration force affecting a given ion species

Any cell that can fire an action potential has an ____________ membrane.

excitable

The phagocyte of the CNS is the ____________.

microglial cell

The fatty membranous sheath that covers many neurons is ____________.

myelin

The ____________ helps set up the resting membrane potential and requires energy to do this.

sodium potassium ATPase pump

The chemical ____________ produced by puffer fish blocks voltage-gated Na channels and prevents action potentials.

tetradotoxin