Chapter 1 - The Nervous System Flashcards
K+/Na+: which cation has a high concentration outside a neuron?
Na+
What is the purpose of a neuron’s ATPase pump?
It generates the asymmetrical concentration gradient of Na+ and K+ across the cell membrane. It pumps Na+ out and K+ in.
What cation movement generates an action potential?
a rush of Na+ ions entering the cell once a threshold potential has been reached
What are the ion channels in an axon called?
ionophores
What is hyperpolarization?
As K+ rushes out of the neuron during repolarization, the membrane potential passes its original resting state.
What is saltatory conduction?
An action potential on myelinated nerves seems to jump from node to node.
How does ATP affect the binding of actin and myosin?
It reduce’s myosin head affinity for actin.
What role does the pituitary gland play?
It is the master endocrine gland, receiving information from the hypothalamus.
Where do sympathetic nerves originate?
from the thoracic and lumbar portions of the spinal cord
Where do somatic nerves synapse?
directly on skeletal muscle
What are first-order sensory neurons?
They carry information from the receptive field to the spinal cord.
What is troponin?
a multi-subunit binding protein that interacts with actin, tropomyosin, and Ca2+
Which cerebral lobe is associated with touch and stretch sensation?
parietal
What hormones does the adrenal medulla release?
epinephrine and norepinephrine
Where and how do exocrine glands secrete substances?
into the lumen by way of a duct
Under aerobic conditions when glucose is oxidized to CO2 and H2O, how much ATP is formed?
36 molecules ATP
As a receptor potential increases above a threshold, what happens to the action potential of the neuron?
It will increase in frequency, not in amplitude.
An active neuron has greater permeability to Na+ or K+?
Na+
What is the purpose of histamines?
They cause an increase in blood flow to regions that have been affected by allergy, infection, or injury.
What is the purpose of erector muscles?
They straighten the hair shaft.
What is the protein that coils around actin?
tropomyosin
What do mast cells secrete?
histamines
Where is acetylcholine synthesized?
in the cytosol of a neuron
When muscle is in a relaxed state, what is bound to the myosin heads?
ATP
Where is reticulin found?
in the spleen and lymph nodes
Where are the ganglia in the parasympathetic division?
near or in the organs they innervate
How does calcium leave the cytosol of a muscle cell?
Ca2+ - ATPase pump
Under anaerobic conditions when glucose is metabolized to lactate, how much ATP is formed?
2 molecules ATP
How does the size of a motor unit affect the strength of contraction?
The smaller the motor unit, the smaller the strength of contraction.
What is the power stroke?
The myosin heads bind to actin, releasing ADP and Pi, causing a conformational change that cocks the heads to 45º, pulling the actin away from the Z-line.
What is a ganglion?
grouping of nerve cell bodies
What makes bone flexible?
collagen
The autonomic nervous system can be divided into what two systems?
sympathetic and parasympathetic
What is the contractile unit of a muscle?
sarcomere
Through exercise, do muscle cells multiply or grow larger?
They just grow larger, gaining actin and myosin.
What are the areas called between myelinated areas?
nodes of Ranvier
What comprises the A-band?
myosin
Which cerebral lobe is associated with hearing and memory?
temporal
What are the glial cells called in the peripheral nervous system?
Schwann cells
What role does the hypothalamus play?
It deals with visceral activities (autonomic nervous system).
Somatic sensory input from the right side of the body will be represented by which part of the brain?
somatosensory cortex of the left cerebral hemisphere
Large/small cross-section neurons: which conduct action potentials faster?
large cross-sections
What are the glial cells called in the central nervous system?
oligodendrocytes
What cells deposits myelin on an axon
glial cells
Nodes of Ranvier have many of which ion channel?
Na+
What structural proteins do fibroblasts secrete?
- collagen - reticulin - elastin