BIO271H1 Lecture 4: Lecture 4 Notes.docx

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beigeeel272

6 Mar 2012

School

UTSG

Department

Biology

Course

BIO271H1

Professor

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Document Summary

Two main types of mechanoreceptor proteins: enac (epithelial na channels, trp channels. These channels are linked to the extracellular matrix. Mechanical stimuli cause the exracellular anchors to move relative to the cytoskeleton, pulling on the chane and causing a conformational change that opens or closes the channel (changing the rmp) Tactile r"s are isolated sensory cells embedded in the skin. Some are free nerve endsing and other are associated with accesosroy structures. Merkel"s disks are free nerve endings associated with an enlarged epidermal cell. Slowly adapting tonic receptors most sensitive to indentation of the skin: fire ap through duration of stimulus, localization time and for how long it lasts because it wont adapt. Small receptive field is beneficial because we can localize where the input was coming from: discriminate particular location. Nerve endings that are wrapped around the base of a hair follicle. Rapidly adapting phasic receptors; most sensitive to changes in movement.

Related Questions

which of the following is not true after a G protein-type receptor binds its ligand?

a) The receptor binds to a G protein complex.

b) The cell may be stimulated to open ion channels in the plasma membrane.

c) The cell may be stimulated to activate one or more intracellular signal pathways.

d) The cell may be stimulated to activating enzymes associated with the plasma membrane.

e) All of the preceding are events that result or may result upon ligand binding to the receptor.

Sensory systems

1.All sensory input arrives at the central nervous system in the same form, as ____________ propagated by afferent neurons. Perception of the type and intensity of a stimulus depends on which part of the brain the impulse projects to and the firing frequency the sensory neuron.

A.action potentials B.receptor potentials C.reflexes D.frequency localizations E.thresholds

2.The simplest sensory receptors are __________ that respond to mechanical distortion,changes in temperature, or specific chemicals.

A.nociceptors B.free nerve endings C.gated channels D.photoreceptors. E.ganglia

3.When membrane proteins on an olfactory neuron are stimulated by the binding of a specific chemical, what is the immediate result?

A.membrane depolarization B.membrane repolarization C.active ion transport D.membrane hyperpolarization E.neurotransmitter release

5.The lateral line system provides ________ with a sense of "distant touch," enabling these animals to sense objects that reflect pressure waves and low-frequency vibrations.

A.adult amphibians B.reptiles C.birds D.mammals E.fish

6.Which correctly represents the sequence of steps involved to convey sensory information to the CNS?

A.stimulation and ion flow through the synaptic cleft B.neurotransmitter release and interpretation
C.neurotransmitter release and ion flow through the synaptic cleft D.stimulation, transduction, transmission, and interpretation E.stimulation, transmission, and neurotransmitter release

7.Which of the following stimuli do vertebrates NOT have a specialized receptor for?

A.hearing B.taste C.smell D.humidity E.vision

8.Which of the following is NOT an example of a mechanoreceptor?

A.Meissner's corpuscles B.Ruffini endings C.Merkel cells D.red corpuscles E.Pacinian corpuscles

9.What are the receptors called that transmit impulses that are perceived by the brain as pain?
A. baroreceptors B. chemoreceptors C. nociceptors
D. thermoreceptors E. propioceptors

10. Which of the following do humans NOT have taste buds specialized to sense?

A. salty B. sour. C. sweet. D. vitamins E. bitter

1. Why are sensory receptors good translators (i.e., what do they do)?

a What are the four types of sensory receptors and give an example for each?

b. How does lateral inhibition enhance the perception of a stimulus?

c ) Why is spatial preservation so important in the somatosensory system?

d) Hair cells transduce sound waves into action potentials via mechanoreception. They communicate intensity of sound (loudness) because they fire more action potentials when the stimulus is louder; however, they are not able to transduce information regarding the location of the sound in the environment. How is location of sound determined in the brain?

e) Describe the receptive field for a hair cell (hint, what makes a given hair cell fire an action potential?). What is the main characteristic of the basilar membrane that determines the specific receptive field for an individual hair cell?

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BIO271H1 Lecture 4: Lecture 4 Notes.docx

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