MCB32: Midterm 2

Where are the following membrane proteins located? 1. Voltage-gated Na+ channels 2. Voltage-gated Ca+2 channels 3. Ionotropic glutamate receptor 4. K+ leak channel 5. Na/K pump 6. Glutamate transporter 7. Na+ leak channel 8. Voltage-gated K+ channels

1. Voltage-gated Na+ channels --> axon 2. Voltage-gated Ca+2 channels --> presynaptic axon terminal 3. Ionotropic glutamate receptor --> dendrites or cell body 4. K+ leak channel --> EVERYWHERE 5. Na/K pump --> EVERYWHERE 6. Glutamate transporter --> presynaptic axon terminal 7. Na+ leak channel --> EVERYWHERE 8. Voltage-gated K+ channels --> axon

Which of the following is NOT physically located in the central nervous system? A) Dendrites of sensory neuron B) Dendrites of efferent neuron C) Axon terminal of afferent neuron D) Axon terminal of interneuron E) Cell body of efferent neuron

A) Dendrites of sensory neuron

Where do you think you would find a progesterone receptor? (Progesterone is a steroid) A) Inside cells of the hypothalamus B) On the membrane of cells in the gonads C) On the membrane of cells in the anterior pituitary D) On the membrane of cells in the hypothalamus

A) Inside cells of the hypothalamus

Which direction will Ca+2 go if the cell becomes more permeable to Ca+2? (Vm = -70 mV, ECa = 122 mV) A) Into the cell B) Out of the cell C) Equal amount going in as going out D) No movement across membrane

A) Into the cell

Which of the following substances do you think could get through the blood brain barrier? (There is more than one correct answer) A) Glucose B) Oxygen C) Red blood cells D) Glycogen E) Cortisol

A) glucose- membrane transport and pumps B) oxygen- simple diffusion E) cortisol- simple diffusion

Which of the following structures of an autonomic neuron is NOT located within the ganglion? A) the cell body of preganglionic neurons B) the axon terminal of preganglionic neurons C) the synapse between pre- and postganglionic neurons D) the cell body of postganglionic neurons E) the dendrites of postganglionic neurons

A) the cell body of preganglionic neurons

Metabotropic receptor-induced gating of ion channels requires more time to occur because of which of the following? A) their gating is linked to a G protein B) the channels are slower to open C) intracellular calcium must increase before those channels will open D) ion channels linked to metabotropic receptors must move to the membrane before gating

A) their gating is linked to a G protein

What will happen if a ligand-gated ion channel opens that is permeable to all cations (Na+, K+ and Ca+2)? A)Postsynaptic cell depolarizes B)Postsynaptic cell hyperpolarizes C)No change in membrane potential

A)Postsynaptic cell depolarizes

When does ovulation (egg release) occur during the menstrual cycle? A) Start of menstruation (period) B) Around 14 days after the start of menstruation C) At the end of menstruation D) Around 7 days after the start of menstruation

B) Around 14 days after the start of menstruation

In the dendrites, there are neurotransmitter receptors that are either ligand-gated ion channels or G-protein coupled receptors (GPCR). Choose the correct statement about these receptors. A) Ligand-gated ion channels are not selective for particular ions (all ions can go through) B) Ligand-gated channels lead to a faster response than GPCRs. C) GPCRs are enzymes that phosphorylate other enzymes inside the cell D) GPCRs are ion channels

B) Ligand-gated channels lead to a faster response than GPCRs.

Which lobe is the primary somatosensory cortex in? A) Occipital B) Parietal C) Temporal D) Frontal E) Hippocampal

B) Parietal

1 ms after voltage-gated Na+ channels open, they inactivate for several milliseconds. What is the consequence of inactivation? A) Na+ will flow out of the neuron while the channels are inactivated B) The neuron cannot fire another action potential until the voltage-gated Na+ channels are reset back to the resting state C) The neuron will rely on K+ going into the cell to initiate another action potential D) The equilibrium potential for Na+ will change and become more negative

B) The neuron cannot fire another action potential until the voltage-gated Na+ channels are reset back to the resting state

Sensory neurons are ____________ neurons and their cell bodies are in the _____________. A) afferent; ventral root B) afferent; dorsal root ganglion C) efferent; spinal cord D) efferent; brain

B) afferent; dorsal root ganglion

Which of the following statements is FALSE? A) Graded potentials can sum over time but action potentials cannot. B) Graded potentials do not have refractory periods, but action potentials do. C) Graded potentials and action potentials are all-or-none. D) Graded potentials and action potentials are caused by ions moving through channels. E) Graded potentials and action potentials can change the membrane potential of adjacent areas of the membrane.

C) Graded potentials and action potentials are all-or-none

4) Why is epinephrine considered to be a neurohormone? A) It is released from the axon of a postganglionic neuron B) It is released by an endocrine cell in the adrenal gland C) It is released by a modified postganglionic neuron and travels in the blood D) It is released by the same cells that release norepinephrine

C) It is released by a modified postganglionic neuron and travels in the blood

Think back to what you learned about intercellular signaling... The receptors for neurotransmitters are found A) On the membrane of the axon B) Inside the neuron (intracellular receptor) C) On the membrane of the dendrites D) In the nodes of Ranvier

C) On the membrane of the dendrites

1) What are sensory receptors that respond to tissue-damaging stimuli or stimuli that have the potential to damage tissue called? A) thermoreceptors B) proprioceptors C) nociceptors D) mechanoreceptors E) stretch receptors

C) nociceptors

1) Which of the following statements about sodium is FALSE? A) There is a chemical force driving sodium ions into the cell. B) At the resting membrane potential, there is an electrical force driving sodium ions into the cell. C) At the sodium equilibrium potential, there is an electrical force driving sodium ions out of the cell. D) At the potassium equilibrium potential, there is an electrical force driving sodium ions out of the cell. E) At the sodium equilibrium potential, the electrochemical force for sodium movement across the plasma membrane is zero.

D) At the potassium equilibrium potential, there is an electrical force driving sodium ions out of the cell. Potassium equilibrium potential is ~90mV; thus more sodium ions (due to electrical force) would go INTO the cell.

There are a number of diseases that cause demyelination of axons (like multiple sclerosis). What defect would you expect in someone with demyelinated ventral root neurons? A) Leaky blood brain barrier B) Impaired vision C) Inability to sense pain D) Impaired/slow limb movement

D) Impaired/slow limb movement

If the resting membrane potential is equal to chloride's equilibrium potential, in which direction will chloride ions move if chloride channels open while the cell is at resting membrane potential? A) inward B) outward C) No ions will move through the channel. D) Ions will move equally in both directions. E) 3 chloride ions will move out for every 2 chloride ions that move in.

D) Ions will move equally in both directions.

Think back to what you learned about intercellular signaling... Neurotransmitters are all ________________ and are released from neurons by __________________. A) Lipophilic; simple diffusion B) Lipophobic; simple diffusion C) Lipophilic; exocytosis D) Lipophobic; exocytosis

D) Lipophobic; exocytosis

The postganglionic neurons cause complex changes in the target organs/tissues, not just graded potentials. What type of receptors are likely on the target cells? A) Enzyme-linked receptor B) Ionotropic receptor C) Intracellular receptor D) Metabotropic receptor E) GPCRs

D) Metabotropic receptor E) GPCRs

Which of the following statements about end-plate potentials (the graded potential in the muscle) is FALSE? A) They are graded potentials. B) They are always depolarizations. C) They are almost always of sufficient magnitude to generate an action potential. D) They are a result of acetylcholine binding to muscarinic cholinergic receptors. E) They are terminated by removal of acetylcholine from the synaptic cleft.

D) They are a result of acetylcholine binding to muscarinic cholinergic receptors.

2) If, under resting conditions, the membrane is much more permeable to sodium than potassium, what would happen to the resting membrane potential? A) be altered very little B) become more negative C) approach potassium's equilibrium potential D) approach sodium's equilibrium potential E) approach chloride's equilibrium potential

D) approach sodium's equilibrium potential

The opening of a cation channel (like nAChR) that allows both Na+ and K+ to move through will cause the membrane to ________ because of the ________. A) hyperpolarize : greater K+ electrochemical gradient as compared with Na+ B) hyperpolarize : greater Na+ electrochemical gradient as compared with K+ C) depolarize : greater K+ electrochemical gradient as compared with Na+ D) depolarize : greater Na+ electrochemical gradient as compared with K+ E) not change : same electrochemical gradient for K+ and Na+

D) depolarize : greater Na+ electrochemical gradient as compared with K+

Touch activates mechanoreceptors. What is the likely response in mechanoreceptors during a touch stimulus? A) K+ channel opens B) Ca+2 channel closes C) Increased glucose transporters to membrane D) Increased gene expression E) Na+ channel opens

E) Na+ channel opens

Which of the following does NOT have nicotinic cholinergic receptors? A) skeletal muscle cells B) parasympathetic postganglionic neuron dendrites C) sympathetic postganglionic neuron dendrites D) effector organs for the parasympathetic nervous system E) chromaffin cells

D) effector organs for the parasympathetic nervous system so skeletal muscle cells have nicotinic cholinergic receptors

Which of the following statements is true? A) Cortisol is an enzyme that helps breakdown proteins B) Cortisol is an enzyme that helps breakdown glucose C) Cortisol receptors are enzymes that catalyze protein synthesis D) Cortisol is a membrane transporter for glucose E) Enzymes involved in breaking down proteins get activated/expressed when cortisol binds the cortisol receptor in muscles

E) Enzymes involved in breaking down proteins get activated/expressed when cortisol binds the cortisol receptor in muscles (Hormones are not enzymes!)

True/false: If a cell is getting a lot of excitatory stimulation from other cells, it will fire an action potential with a larger amplitude than normal.

FALSE; All or nothing

How long is the VgNaCh open for? How long is absolute refractory? Relative refractory?

Open for 1ms. Absolute- 2ms, relative 5-15ms

Which of these pairings between brain structure and function is incorrect? A) Thalamus - relay station for sensory B) Medulla oblongata - regulate breathing rate C) Cerebellum - regulation of homeostasis D) Ventricle - holds cerebrospinal fluid E) Midbrain - orienting head to sounds

c) Cerebellum - regulation of homeostasis

Which of the following would most likely cause this graded potential? (concave) A)GABA receptor agonist B)GABA receptor antagonist C)Glutamate receptor agonist D)Release of glutamate into synaptic cleft

concave = hyperpolarization (away from threshold); this means it should be inhibiting an excitatory neurotransmitter (like glutamate) or inhibiting an excitatory receptor none available, so answer is A) GABA receptor agonist (promoting an inhibitory)

3) Beta blockers inhibit beta-adrenergic receptors and are sometimes used by athletes who compete in archery and shooting. Why do you think these athletes in particular use beta blockers?

less sympathetic signalling --> lower heart rate--> small movements reduced