BIOL1040 Lecture Notes - Lecture 3: Digestion, Carl Wernicke, Aplysia

38 views10 pages

periwinklecat943

30 Jun 2018

School

Department

Biology

Course

BIOL1040

Professor

All

For unlimited access to Class Notes, a Class+ subscription is required.

Module 3: Nervous

Systems

Lecture 1

Information processing - nervous systems

Sensory input, integration, motor output

Dendrites pull in information towards the cell

Axon hillock, where the action potential can be made

Electrical events - various ions going in and out of the cell

Structural diversity of vertebrate neurons

There is some diversity, slightly different characteristics…

sensory neurons have dendrites intersect with the axon, and the cell body is along the axon

Interneurons… really variable dendritic tree.. Very dense dendrites.. Bigger the dendritic

tree, the more information its pulling in to determine the signal down that neuron… more

info pulled in than sensory and motor

Motor neuron.. Most typical.. One axon going down to a muscle cell

A nerve consists of many neurons…

Individual cells… packaged into nerves to protect and supply with blood and taking away waste…

protective

Glia - supporting cells

Glia - from greek for glue… glue that holds everything together

Vital for structural integrity and normal function

10-50 times more glia than neurons in the mammalian brain… large part of the cell

Different types of glia cells

1.Astrocytes

2.Oligodendrocytes & schwann cells

1.Astrocytes (star structure)

CNS

Structural support

Regulate extracellular concentration of ions and neurotransmitters (important)

Blood-brain barrier

Blood brain barrier pic:

Can squeeze through the endothelial cells.. Not good in the brain.. So there are really tight

junctions between the cells in the barrier… they get stuck in the blood vessels… glial cells go

around the blood cells, they need to go through the astrocytes and endothelial cells to get it out…

can be bad if trying to treat something like meningitis.

find more resources at oneclass.com

Unlock document

This preview shows pages 1-3 of the document.
Unlock all 10 pages and 3 million more documents.

Already have an account? Log in

1.Oligodendrocytes and schwann cells same cells.. Different names for where they are

Form myelin sheaths around axons reasons they look white… not all axons have them.. But

most do

Lipid membranes: electrical insulator (see next section)

What happens when this insulator is defective? Multiple sclerosis.. Lose the sheet

In all cells…

There are gradients of ions across the cell membrane

The resting membrane potential is negative

There are gradients of ions across the membrane

Na+/K+-ATPase

Pumps 3 x Na+ out of the cell

Pumps 2 x K+ into the cell

Against the concentration gradient

Uses energy from atp

Resting membrane potential is negative

The inside of the membrane is negative relative to the outside

Electrogenic

10 fold concentration gradient

No open Na channels at rest

Open K channels at rest… they can get out but the electrical gradient leaves it mostly

inside (roughly -70mV at rest… equilibrium)

The resting membrane is negative

Because

oNa+/K+-ATPase pumps 3 Na+ out and 2K+ in

oThe membrane at rest has many open K+ channels and few open Na+ or Cl- channels

oBuildup of -ve charge in neuron: limited by electrical gradient vs. chemical gradient

of K+

oEquilibrium potential in neuron: approx -70 mV

oProcess not dependent on voltage-gated ion channels - which are required for

action potentials

Lecture 2

All cells have a membrane potential

Ionic gradients are important in all cells

Rapid changes in membrane potential in excitable cells:

Membrane potential

Membrane potential: voltage of inside of membrane relative to outside - equilibrium

Hyperpolarisation: inside of membrane becomes more negative

oOpening of voltage-gated k+ channels

oK+ out

Depolarisation: inside of membrane becomes more positive

oOpening of voltage-gated Na+ channels

oNa+ in

find more resources at oneclass.com

Unlock document

This preview shows pages 1-3 of the document.
Unlock all 10 pages and 3 million more documents.

Already have an account? Log in

Graded potentials

Hyperpolarisation

oCan be a big or little decrease from the stimulus

depolarisation

oEg. Letting sodium ions into the cell

If you hit the threshold, an action potential is reached

Action potentials

All or nothing: when threshold is reached

Magnitude is independent of the strength of the original stimulus

Fast: 1-2 milliseconds and high frequency



Voltage-gated Na+ and K+ channels

Same: Allow ions to move across, opened by a depolarising event

Different: speed at which the Na opens is much faster than K, 2 conformations of K channel,

voltage gated Na channels (found in neurons), 3 conformations… inactivated makes it quicker to

allow the Na through or block it, theres a peptide tail in the structure of the channel, moves across

and blocks off the channel

Na+ channels (Navs)

K+ channels (Kvs)

Depolarisation if THRESHOLD is reached:

A stimulus causes a few Na+ channels to open

Na+ rushes in

Repolarisation

K+ channels open

K+ rushes out

Na+ channels inactivated and then start to close

Resting state

Voltage-gated ion channels are closed

Undershoot

Small hyperpolarisation

Also need Na+/K+ ATPase to restore Na+ and K+ concentrations

Refractory period (RP)

Voltage-gated Na+ channels inactivated during repolarisation

During absolute RP (ARP), no AP can be generated all or none response

oNa+ channels open then inactivated

During relative RP (RRP), AP only if apply large stimulus can get another action potential

oBecause some Na+ channels closed again

Limits firing frequency

The action potential can only travel in one direction, cant start moving backwards

Mechanism of action of local anaesthetics

Depolarisation if threshold is reached:

olots of Na+ channels open

oLots of Na+ rushes in

find more resources at oneclass.com

Unlock document

This preview shows pages 1-3 of the document.
Unlock all 10 pages and 3 million more documents.

Already have an account? Log in

Document Summary

Axon hillock, where the action potential can be made. Electrical events - various ions going in and out of the cell. There is some diversity, slightly different characteristics sensory neurons have dendrites intersect with the axon, and the cell body is along the axon. Bigger the dendritic tree, the more information its pulling in to determine the signal down that neuron more info pulled in than sensory and motor. Most typical one axon going down to a muscle cell. Individual cells packaged into nerves to protect and supply with blood and taking away waste protective. Glia - from greek for glue glue that holds everything together. Vital for structural integrity and normal function. 10-50 times more glia than neurons in the mammalian brain large part of the cell. Regulate extracellular concentration of ions and neurotransmitters (important) Can squeeze through the endothelial cells not good in the brain

Related Questions

Nerve cells that conduct messages are called (1) ____. (2) _____ cells, which support and nurture the activities of neurons, make up less than half the volume of the nervous system. (3) _______ neurons respond to specific kinds of environmental stimuli, (4) ______ connect different neurons in the spinal cord and brain, and (5) ______ neurons are linked with muscles or glands. All neurons have a (6) _______ ________ that contains the nucleus and the metabolic means to carry out protein synthesis. (7) _______ are short, slender extensions of the (6), and together these two neuronal parts are the neuronsâ âinput zoneâ for receiving (8) _____. The (9) _____ is a single long, cylindrical extension away form the (10) ______; in motor neurons, the (11) ______ has finely branched (12) ________ that terminate on muscle or gland cells and are âoutput zones,â where messages are sent on to other cells. A neuron at rest establishes unequal electric charges across its plasma membrane, and a(n) (13) ____ ____ is maintained. Another name for (13) is the (14) _____ _____ _____; it represents an ability for the membrane to be disturbed. Weak disturbances of the neuronal membrane might set off only slight changes across a small patch, but strong disturbances can cause a(n) (15) _______ ______, which is an abrupt, short-lived reversal in the polarity of charge across the plasma membrane of the neuron. For a fraction of a second, the cytoplasmic side of a bit of membrane becomes positive with respect to the outside. The (16) ______ that travels along the neural membrane is nothing more than short-lived changes in the membrane potential. A. Neurons H. Sensory B. Motor I. Endings C. Interneurons J. Disturbance D. Cell body K. Signals (stimuli) E. Axon L. Voltage differential F. Dendrites M. Resting membrane potential G. Neuroglial N. Action potential

azureelk922

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

BIOL1040 Lecture Notes - Lecture 3: Digestion, Carl Wernicke, Aplysia

Document Summary

Get access

Related Documents

BIOL1040 Lecture Notes - Lecture 1: Information Processing, Oligodendrocyte, Sensory Neuron

[01:146:295] - Final Exam Guide - Everything you need to know! (36 pages long)

HMB320H1 Study Guide - Midterm Guide: Golgi'S Method, Axon Hillock, Peripheral Nervous System

Related Questions