Human Physiology Exam 1
In which of the following would the rate of impulse conduction be the greatest?
(A). a myelinated fiber 20 microns in diameter and 75 microns between nodes of Ranvier b. a nonmyelinated fiber 20 microns in diameter c. a myelinated fiber 10 microns in diameter and 75 microns between nodes of Ranvier d. a nonmyelinated fiber 10 microns in diameter e. a myelinated fiber 20 microns in diameter and 40 microns between nodes of Ranvier
Which of the following statements is FALSE?
(A). diffusion is the movement of solute molecules from an area of low solute concentration to an area of high solute concentration b. diffusion is slow over long distances c. the smaller the molecule, the faster the molecule will diffuse d. the larger the surface area, the more molecules can diffuse across per unit time e. all of these statements are true
Facilitated diffusion and active transport differ in that __________.
ATP is necessary for active transport, but not for facilitated diffusion
The following are steps involved in transmission at a cholinergic synapse.
An action potential depolarizes the axon terminal at the presynaptic membrane Calcium ions enter the axon terminal. Acetylcholine is released from storage vesicles by exocytosis. Acetylcholine binds to receptors on the postsynaptic membrane. Chemically regulated ion channels on the postsynaptic membrane are activated
Which of the following statements are true regarding the action potential in a given cell?
Each action potential is identical to any other action potential. An action potential does not diminish in strength as it travels along the cell membrane. As long as a stimulus is above threshold, the strength of the stimulus doesn't matter.
Which of the following is more concentrated inside the cell?
K+
What type of axons have the fastest conduction velocities?
Large diameter myelinated axons
. ________ postganglionic sympathetic neurons secrete ________ onto their target cells.
Most, norepinephrine
Excitatory neurotransmitters of the CNS usually act by opening _________ gates.
Na+
What would happen to the amplitude of the post synaptic potential if the synapse was bathed in a solution that blocks voltage dependent Ca channels?
No post synaptic potential would be recorded
What ion channel is the most important in the generation of the resting membrane potential?
Passive K channel
What happens to membrane permeability when an action potential is initiated in a nerve cell?
The membrane permeability switches from being highly permeable to K ions to being highly permeable to Na ions
Which of the following statements applies to the autonomic nervous system?
The receptor molecules of the ANS may be muscarinic, nicotinic, or adrenergic
If a post synaptic cell at a synapse was depolarized towards -45mV then
There is an increased probability that the postsynaptic cell will be activated
During the afterhyperpolariztion phase of the action potential, which of the following statements is true.
Voltage dependent K channels are open and passive K channels are open
Which of the following statements about the Na+/K+ pump is FALSE?
a. it transports Na+ out of the cell and K+ into the cell b. it is present in neurons c. its activity requires the expenditure of metabolic (cellular) energy (D). it transports Na+ and K+ in a 1:1 ratio
All preganglionic autonomic neurons secrete:
acetylcholine
What is the neurotransmitter released from the presynaptic motor axon at the neuromuscular junction?
acetylcholine
__________ and __________ are the major neurotransmitters released by autonomic nervous
acetylcholine; norepinephrine
The all-or-none phenomenon applies to __________.
action potentials
Saltatory conduction refers to __________.
action potentials "leaping" from one node of Ranvier to the next
When catecholamines (norepinephrine and epinephrine) bind to receptor, _____________________.
alpha 1 receptors cause smooth muscle contraction
A nerve, which causes the smooth muscle of a blood vessel wall to constrict, contains ________ neurons
autonomic
Processes or appendages that are part of neurons include __________.
axons and dendrites
The ion needed to initiate the release of acetylcholine into the synaptic cleft is ___________.
calcium
Which of the following defines the term specificity of protein transport carriers?
carrier transport of a group of closely related molecules
Which type of synapse dominates the nervous system?
chemical
Sweat glands contain
cholinergic receptors.
The thin, branched processes of a neuron whose main function is to receive incoming signals are the __________.
dendrites
Diffusion tends to __________.
eliminate concentration gradients
The absolute refractory period of an action potential __________.
ensures one-way travel down an axon allows a neuron to ignore a second signal sent that closely follows the first prevents summation of action potentials
The tissue that secretes material to the external environment is
epithelial tissue
The watery medium that surrounds a cell is known as __________.
extracellular fluid
Which of the following is a way for solutes in an aqueous solution to move from an area of high solute concentration to an area of low solute concentration?
facilitated diffusion
There are trillions of cells in your body. How many primary types of tissue are there?
four
If a 10% sucrose solution is separated from a 20% sucrose solution by a membrane impermeable to sucrose, in which direction will net movement of water occur?
from the 10% sucrose solution to the 20% sucrose solution
Hyposmotic solutions __________.
have lower concentrations of solutes than hyperosmotic solutions
Water will always move from _________ situations to _________ situations.
hyposmotic, hyperosmotic
Increased parasympathetic stimulation
increases gastric motility
The organ that is vital in the maintenance of Na+ and K+ levels in the blood is the __________.
kidney
In order to signal a stronger stimulus, action potentials become __________.
more frequent
Spatial summation refers to __________.
multiple graded potentials originating from different locations simultaneously.
Saltatory conduction occurs in __________.
myelinated axons
The cells which carry electrical signals are __________.
neurons
All postganglionic neurons bear these receptors:
nicotinic
The afferent and efferent axons together form the _________.
peripheral nervous system
What are the two extracellular fluid compartments in the body?
plasma and interstitial
Which of the following has its cell body in the ganglion?
postganglionic neuron
Which of the following neurons is most likely to be adrenergic?
postganglionic sympathetic
Temporal summation refers to __________.
repeated graded potentials reaching the trigger zone one after the other.
Which of the following pairs of molecular characteristics favors diffusion through the cell membrane?
small, non-polar
EPSPs (excitatory postsynaptic potentials) occur when __________.
sodium channels are opened
The principal cations in our extracellular fluid are __________
sodium, calcium
The division of the autonomic nervous system that prepares the body for intense levels of activity and stress is the __________.
sympathetic division
The basic structural and functional unit of the human body is __________.
the cell
