cAMP is formed
When adenylyl cyclase is activated
When stimulated by a pWhen stimulated by a particular hormone, there is a marked increase in the activity of G proteins in the membrane. The hormone is probably
The most complex endocrine responses involve the
a second messenger appears in the cytoplasm.
When a catecholamine or peptide hormone binds to receptors on the surface of a cell
the presence or absence of appropriate receptors.
A cell's ability to respond to a particular hormone is determined by
are composed of amino acids.
E) all of the above
The endocrine system
gene transcription may start or stop.
When steroid hormones bind to their receptors,
release their secretions into the blood.
The backup energy source for muscles is
the amount of overlap of thick and thin filaments must be sufficient to allow cross-bridge formation.
Within a single fiber, the tension developed during a twitch can vary because
derivatives of amino acids.
Hormones known as catecholamines are
A single contraction-relaxation cycle in a skeletal muscle fiber is known as
The condition that results when a muscle is no longer able to generate or sustain the expected power output is called
the length of the sarcomeres prior to contraction.
Within a single fiber, the tension developed during a twitch depends on
one neuron and the muscle fibers it controls.
A motor unit consists of
Metabolism of __________ is the fastest way for cells to increase their supply of ATP in order to meet the ATP demands of heavy exercise.
Muscles require __________ constantly; they can only store enough of it for about eight twitches.
the inorganic phosphate and ADP are released from the myosin.
The power stroke begins when
generate force, heat, motion
The body depends on muscles to
The contraction cycle is triggered by the rise in __________ concentration from the SR.
the chemical and electrical events that trigger the mechanical events in a muscle fiber.
Excitation-contraction coupling refers to
__________ is made of multiple globular molecules polymerized to form long chains or filaments.
The myosin head detaches from actin.
As ATP binds to the myosin head at the beginning of a muscle contraction cycle,
Skeletal muscles are said to be striated because of a repeating pattern of light and dark bands. One repeating unit of the entire pattern of bands is called a(n)
When the myosin heads are loosely bound to the actin filaments, the __________ span the space between the parallel thick and thin filaments.
The thick filament of the myofibril is composed of numerous __________ molecules.
It is easily fatigued
Which statement about cardiac muscle is false?
The pituitary hormone that stimulates milk production by the mammary glands is
rapidly conduct action potentials to the interior of the muscle fiber.
The purpose of transverse tubules is to
Peptide hormones in the bloodstream are always bound to carrier proteins.
Each of the following statements concerning peptide hormones is true except one. Identify the exception.
The hypothalamus contains centers for __________.
1. temperature regulation
2. behavioral drives
3. coordination of reproductive hormones
4. fight-or-flight response
E) all of the above
Pheochromocytomas are tumors of the adrenal medulla that cause hypersecretion of catecholamines. What symptoms would you associate with a person who suffers from this condition?
a folded area of muscle cell membrane with ACh receptors clustered at the top of each fold.
The motor end plate is
A) stretch B) length
D) A and B
Muscle spindles monitor __________ in skeletal muscles.
What types of structures produce hormones? _________
The inner portion of the adrenal gland is called the __________.
The enzyme of clinical importance that becomes elevated in the event of damage to either skeletal or cardiac muscle tissue is __________.
A signal molecule that is secreted into the external environment, instead of into the blood, is called an __________.
Chemical signals released into the blood by neurons are called __________.
At a(n) __________ synapse, a neurotransmitter is released to affect the postsynaptic cell.
relative refractory period
The period of time during which an excitable membrane can respond again, but only if the stimulus is greater than the initial stimulus is the __________.
When an organ or gland shrinks due to lack of use, that condition is referred to as __________.
The term for two hormones that have additive effects is __________.
Cholinergic receptors respond to the neurotransmitter __________.
T/F Cutaneous receptors include both mechanoreceptors and thermoreceptors.
T/F Receptors that produce action potentials continuously, for as long as they are sitmulated, are called phasic receptors.
T/F Whereas a taste bud may have receptors for different tastes, each sensory neuron is devoted to a single taste only.
T/F There are five recognized categories of olfactory receptors.
T/F The cochlea is not a part of the vestibular apparatus.
T/F The utricle responds to horizontal acceleration and the saccule responds to verticle acceleration.
T/F The malleus is the middle ossicle.
T/F Volume discrimination depends on the number of hair cells stimulated by pressure waves.
T/F Pitch discrimination depends on the region of the basilar membrane affected by a frequency of sound.
T/F Accommodation is the ability of the iris to control the amount of light that enters the eye.
T/F Myopia results from an eyeball that is too short
T/F Types of polar hormones include polypeptides, proteins, and glycoproteins.
T/F Thyroid hormones, thyroxine and triiodothyronine, are nonpolar and can cross plasma membranes.
T/F During embryonic development, the anterior pituitary gland forms from the brain while the posterior pituitary forms from different embryonic tissue.
T/F Hormones releases by the anterior pituitary gland are transported there by axons of the hypothalamo-hypophyseal tract.
T/F Cushing's syndrome and Addison's disease may result from abnormal levels of corticosteriod secretion.
T/F Under prolonged stress, the general adaptation syndrome maintains high blood cortisol levels in opposition to negative feedback control.
T/F Over secretion of parathyroid hormone increases basal metabolic rate and may cause weight lose.
T/F After a meal, insulin secretion causes blood glucose level to decline.
T/F Individuals with type 2 diabetes mellitus may produce more insulin than normal.
T/F Melatonin secretion is greatest at night.
T/F The connective tissue that surrounds a fasiculus within a muscle is called epimysium.
T/F I bands contain only thin filaments.
T/F The strength of a muscle contraction depends on the strength of the contractions of all of the individual muscle fibers.
T/F ATP is required to release a myosin head from a thin filament.
T/F Sarcomere length less than 2.0 micrometers generates less tension most likely due to decreased overlap between thin and thick filaments.
T/F Muscle tension that is optimum for muscle contraction is maintained by monosynaptic muscle stretch reflexes.
T/F The sarcoplasmic reticulum stores the ATP required to fuel muscle fiber contraction.
T/F The main function of a transverse tubule is to allow the conduction of an action potential deep into a muscle fiber.
T/F Relaxation of a muscle fiber following contraction is a passive process and uses no ATP.
T/F High intensity exercise can increase muscle size by promoting an increase in muscle fiber size.
T/F Each cardiac muscle fiber must by stimulated independently to produce contraction.
T/F Smooth muscle cells are not striated because they lack thick and thin filaments.
T/F Each cell of a multiunit smooth muscle must by stimulated to contract independently.