BIPN 100 Lecture Notes - Lecture 18: Impedance Matching, Resting Potential, Pacemaker Potential

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browngnu790

28 Jun 2018

School

UCSD

Department

Biology/Animal Physiol & Neurosc

Course

BIPN 100

Professor

Catalina Reyes Gonzales

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BIPN100 Lecture 18 Notes 5/14/18

- pacemaker cells have different action potential: don’t have

resting membrane potential. Instead, they have a pacemaker

potential that continually increases

o4) at pacemaker potential, funny current channels (If)

activate: Na+ goes in and K+ goes out (more Na+ moves)

oT-type calcium channels (transient, quickly activate and

deactivate) activate, allowing calcium into the cell,

making cell less negative

o0) increase in potential reaches threshold, activating L-

type calcium channels (voltage-gated calcium channels

that activate for longer time) which allows calcium into

the cell. Depolarization is much slower than in cardiac contractile cells because calcium

channels are slower at activating than sodium channels

o2) voltage-gated calcium channels deactivate (no calcium plateau)

o3) voltage-gated potassium channels finally activated, allowing K+ out of the cell, and

repolarization occurs. Once it reaches -60mV, potassium channels close

o4) If channels open again, restarting cycle

othe cycle is what gives the heart the autorhythmic characteristic

oANS or hormones can modulate the pace at which the heart depolarizes

- can increase frequency in which heart contracts by doing the following:

oincrease phase 4 slope, reaching AP more quickly

oincrease resting membrane potential, to reach the threshold more quickly

- pacemaker cells: heart beats

oSA node: 80-100 bpm

Found in right atrium

Pacemaker of the heart; depolarizes fastest

oAV node: 45 bpm

oBundle of his: 30 bpm

oIf SA node is damaged, AV node takes over at slower rate

- Electrical conduction in myocardial cells

ocells of SA node have pacemaker action potentials.

These electric signals are sent to contractile cells, which

have action potentials that contain the calcium plateau

owhen pacemaker potential starts, electric signal moves

through cells through gap junctions in intercalated

disks, so heart contractile cells depolarize and contract

simultaneously

oAV bundle branches into left and right bundles of his, which branch into the Purkinje

fibers

- Electrical conduction system of the heart

oSA node

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Related Questions

Which of the following statements is TRUE regarding sea anemones?

	None of the answer options is correct.
	Spongesânot sea anemonesâpossess what is considered to be the âsimplestâ nervous system found in animals.
	Because sea anemones are âsimpleâ organisms, these animals only possess motor neurons; sensory neurons or interneurons are never found in sea anemones.
	Although sea anemones possess ânet-likeâ nervous systems, these animals have brains located at their bases (near where they would attach to rocks).
	Although sea anemones lack definitive brains, they do possess ganglia that serve a similar function to the paired ganglia of flatworms.

Some people have low levels of calcium circulating in the blood, a condition known as hypocalcemia. While for many this disorder has little to no effect, for some it can be life-threatening. How could low levels of calcium harm an individual?

	Low levels of calcium would not have any effect on synaptic transmission.
	Low levels of calcium would cause sustained depolarization of the presynaptic cell.
	Low levels of calcium would result in fewer signals sent between the pre- and postsynaptic cell.

Cephalization is: the

	All of these choices are correct.
	development of a brain within the head of an animal.
	concentration of sensory organs within the head end of an animal.
	development of a âhead endâ in an organism.

Which of the following are TRUE about the resting membrane potential? (Select all that apply.)

	It results from voltage-gated sodium channels remaining open for long periods of time.
	It results from K⁺ ions diffusing out of the cell.
	It results from the sodium-potassium pump moving more Na⁺ ions out of the cell than K⁺ ions into the cell.

Afferent and efferent neurons differ in:

	their size.
	the directionality of the information they send.
	their pattern of myelination.

A neuron that responds to the environment is a(n):

	interneuron.
	homeostatic neuron.
	motor neuron.
	sensory neuron.

Which of the following is NOT the role of an interneuron?

	stimulating a muscle to contract
	conveying information from the internal environment of an animal
	relaying information from sensory to motor neurons
	maintaining homeostasis

Where are postsynaptic cell receptor proteins synthesized?

	the Golgi apparatus
	the lysosome
	the cytoplasm
	the rough endoplasmic reticulum

Inhibition of the flexor muscle during the knee-extension reflex is an example of:

	homeostasis.
	reciprocal inhibition.
	negative feedback.
	All of these choices are correct.

10.

What type of cells produce myelin for sensory neurons?

	pyramidal neurons
	glial cells
	melanocytes
	astrocytes

BIPN 100 Lecture Notes - Lecture 18: Impedance Matching, Resting Potential, Pacemaker Potential

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