A gap junction forms when opposing membrane-spanning proteins called __________ on two adjacent cells unite, creating a protein channel that is capable of opening and closing.
An ion widely important in intracellular signaling is
The __________ link membrane receptors to either ion channels or to membrane enzymes located on the cytoplasmic face of the membrane.
The term axonal transport refers to
vesicle transport of proteins and organelles down the axon.
Myelin is formed by
Schwann cells and oligodendrocytes.
A home satellite dish receives signals from a satellite, allowing your television to display TV shows. Which part of a neuron is analogous to the satellite dish?
The rising phase of the action potential is due to
Na+ flow into the cell.
Which of the following is the location where action potentials originate?
In order to signal a stronger stimulus, action potentials become
The all-or-none principle states that
all stimuli great enough to bring the membrane to threshold will produce action potentials of identical magnitude.
When two or more graded potentials arrive at the trigger zone, which of the following could happen?
An excitatory and inhibitory signal can cancel each other out; two excitatory stimuli may be additive, resulting in lower excitability and summation could occur.
The afferent and efferent axons together form the
peripheral nervous system
Exocrine glands, smooth muscles, and cardiac muscles are controlled by the
autonomic nervous system.
Cerebrospinal fluid is produced by the
The brainstem consists of these structures
medulla oblongata, pons, and midbrain
__________ are swellings that contain vesicles filled with neurotransmitter.
The signal molecule __________ elicits the stronger response from alpha receptors.
Which of the following has its cell body in the ganglion?
Which is/are the most common inhibitory neurotransmitter(s) of the CNS?
GABA and glycine
The ion necessary to initiate the release of acetylcholine into the synaptic cleft is
Inhibitory neurotransmitters of the CNS act by opening __________ channels.
Cl- or K+
Smooth muscle cells lack which protein(s)?
The brief period of time between the end of the action potential in the muscle and the beginning of contraction is referred to as
the latent period.
In smooth muscle, what is the small protein chain that regulates contraction and relaxation?
myosin light chain
The primary calcium release channel in smooth muscle sacroplasmic reticulum is
an IP3 receptor channel.
Smooth muscle cells contain stretch-activated calcium channels that open when pressure or other force distorts the cell membrane. This activity is called __________ contractions and are common in __________.
When steroid hormones bind to their receptors,
gene transcription may start or stop.
The majority of hormones in the body are
The pituitary hormone that stimulates milk production by the mammary glands is
A cell's or tissue's response to a hormone primarily depends on __________ and __________.
signal transduction pathways,cell receptors
Hormones are not typically considered to be cytokines because hormones are __________ like cytokines.
synthesized in advance and stored, not
In a simple endocrine reflex, the endocrine cell is the