What diffuses to neighboring cells to exert an effect.
- Panacrine
- Neurotransmitter
- Autocrine
- Hormone
- Panacrine
What is released by a presynaptic cell?
- Panacrine
- Neurotransmitter
- Autocrine
- Hormone
-Neurotransmitter
What binds to receptors on the cell that secreted it?
- Panacrine
- Neurotransmitter
- Autocrine
- Hormone
- Autocrine
What is released from endocrine glands into the bloodstream?
- Panacrine
- Neurotransmitter
- Autocrine
- Hormone
-Hormone
At the normal resting potential of a typical neuron, its Na-K ion exchange pump transports..
- 2 intracellular sodium ions for 1 extracellular potassium ion.
- 3 extracellular sodium ions for 2 intracellular potassium ions.
- 3 intracellular sodium ions for 2 extracellular potassium ions.
- 3 intracellular sodium ions for 1 extracellular potassium ion.
- 1 intracellular sodium ion for 2 extracellular potassium ions.
- 3 intracellular sodium ions for 2 extracellular potassium ions.
Order the main steps of the generation of an action potential.
- Sodium channels are inactivated.
- Voltage-gated potassium channels open and potassium moves out of the cell, initiating repolarization.
- Sodium channels regain their normal properties.
- A graded depolarization brings an area of an excitable membrane to threshold.
- A temporary hyperpolarization occurs.
- Sodium channel activation occurs.
- Sodium ions enter the cell and depolarization occurs.
- A graded depolarization brings an area of an excitable membrane to threshold.
- Sodium channel activation occurs.
- Sodium ions enter the cell and depolarization occurs.
- Sodium channels are inactivated.
- Voltage-gated potassium channels open and potassium moves out of the cell, initiating
- Sodium channels regain their normal properties.
- A temporary hyperpolarization occurs.
Which of the following does not influence the time necessary for a nerve impulse to be transmitted?
- whether or not the impulse begins in the CNS
- length of the axon
- diameter of the axon
- presence or absence of a myelin sheath
- presence or absence of nodes
- whether or not the impulse begins in the CNS
The strength with which a ligand (chemical messenger) will bind with a receptor is referred to as its ________
Affinity
In chemical communication between cells, a ________ cell secretes a chemical messenger that binds to ________ on the ________ cell.
- sensory
- receptors
- target
Slow channels are identified as such because, once the receptor is bound by the ligand, the receptor must directly activate a(n) ________.
- G protein
- enzyme
- ion channel
- hormone response element
- RNA polymerase
G protein
Differences in the rate of activity between fast and slow ligand-gated channels is caused by ________.
- ligand selectivity
- G protein activity gating the slow channel
- G protein activity gating the fast channel
- ligand affinity
- ligands gating both channels to the closed state
- G protein activity gating the slow channel
Which of the following ions can act as a second messenger?
- calcium only
- both sodium and potassium
- both sodium and calcium
- sodium only
- potassium only
- calcium only
In its role as a ________, calcium is observed to bind to ________ that, when complexed, provides for the activation of a protein kinase.
second messenger : calmodulin
The sodium-potassium ion exchange pump..
- transports potassium ions out of the cell during repolarization.
- must reestablish ion concentrations after each action potential.
- transports sodium ions into the cell during depolarization.
- moves sodium and potassium opposite to the direction of their electrochemical gradients.
- depends on a hydrogen gradient for energy.
- moves sodium and potassium opposite to the direction of their electrochemical gradients.
The ion that triggers the release of acetylcholine into the synaptic cleft is..
- sodium.
- chloride.
- calcium.
- potassium.
- magnesium
- calcium.
The function of a second messenger is to ________.
- isolate the response to the inside of a cell
- buffer a cells response to a ligand
- keep calcium involved in these responses
- amplify the response of the first messenger
- facilitate the process of covalent modification of a protein
- amplify the response of the first messenger
In order to terminate a cAMP-mediated response, the enzyme ________ can be activated to degrade cAMP.
- cAMP protein kinase
- cAMP hydrolase
- cAMP hydrogenase
- cAMP phosphodiesterase
- cAMP decarboxylase
- cAMP phosphodiesterase
When associated with G protein, guanylate cyclase will activate the enzyme ________ .
- phospholipase C
- protein kinase C
- phosphodiesterase
- protein kinase A
- protein kinase G
- protein kinase G
Which of the following second messengers, when released by phospholipase C, will directly activate the enzyme protein kinase C?
- diacylglycerol
- inositol biphosphate
- inositol triphosphate
- cGMP
- phosphatidylinositol biphosphate
- diacylglycerol
Which of the following proteins is directly activated by a G protein?
- calmodulin
- phospholipase A2
- adenylate cyclase
- tyrosine kinase
- protein kinase G
- adenylate cyclase
Which of the following describes the signal transduction mechanism for estrogen, a steroid hormone?
- opening or closing of fast ligand-gated channels
- activation of enzyme-linked receptor
- opening of fast ligand-gated channels
- activation of cAMP second messenger system
- altering transcription of mRNA
- altering transcription of mRNA
Which of the following is a second messenger?
- cAMP, calcium, and inositol triphosphate
- cAMP only
- both cAMP and inositol triphosphate
- calcium only
- inositol triphosphate only
- cAMP, calcium, and inositol triphosphate
Opening of sodium channels in the axon membrane causes..
- depolarization.
- hyperpolarization.
- repolarization.
- increased positive charge inside the membrane.
- both A and D
- both A and D
