BIOM 3200 Midterm 1

what does Zona glomerulosa do

produces aldosterone. This hormone affects your body in many ways, by: Causing water retention.

Increasing levels of sodium in your intestines.

\*Central nervous system is the ________________ and the Peripheral nervous system is everything else

brain and spinal cord

**what is neurophysiology?**

the nervous system function is known as the physiology… with neurons being the minimal functional unit

^^nervous system is made up of discrete individual cells^^


1. how does the location of a nerve cell determine its function?

the structure & function of a nerve cell is determined by its location in the body

\-it affects physiology bc they all do the same 2 things: 1. conduct action potential (electrical signal) 2. release chemical signals (neurotransmitters)

therefore location changes what those 2 things do aka move arm or make stomach contact etc.

1. what are the 3 functions of the nervous system

hint: what do motor and sensory nerves do

\

1. %%motor nerves%% = control of movement and some functions (2 way = neuron goes in from muscle to brain then one goes back out to muscle to move it)

\
2. %%sensory nerves%% = detection of external stimuli \*one way communication to the brain

\

3. %%circuitry%% (aka integration of neuronal activity and connections) through %%association neurons%%, thoughts emotions, behaviour

\

what are association/interneurons neurons function

\
\
circuitry and connection

neurons within entirely within the CNS responsible for behaviour, thought, emotions etc

integrate message

1. \*what are the 3 components of a neuron
2. what do each 3 do

1. cell body, dendrite, axon
2. cell body aka axon hillock = condenses information and consolidates the signal .“nutritional center” of the neuron where macromolecules are produced.

dendrites= receive info from sensory receptors or other cells and send it to cell body

axons = drivers electrical signals %%from cell body%% to another neuron or an effector organ (muscle)

aka info heads out

neurons perform the function of rapidly moving information by conducting electrical impulses called ______________ from one physical location to another, then converts that electrical impulse to a chemical signal at a __________

action potential

synapse

the cell body integrates information and the “tail” made up of axons __________ the impulse with the synapse at the end converting it to a chemical signal

conducts

\*sensory/afferent neurons conduct impulses from where to where

from sensory receptors INTO the CNS

peripheral to central

from 5 senses

association or interneurons conduct impulses from where to where

located entirely within the CNS and help integrate CNS functions \*ONE NEURON TO ANOTHERR\*

take message, integrate it and sent it on

\*motor or efferent neurons conduct impulses from where to where

exit \*\*

sensory receptors OUT Of the CNS… to effector organs like muscles or glands)

central to peripheral

\*somatic motor neurons

reflex and voluntary control of skeletal muscles

* *move hand away* \*

\*autonomic motor neurons control what

@@involuntary@@ control of smooth muscle, cardiac muscle and glands

2 lines bc sends to multiple organs sometimes

autonomic motor neurons are further subdivided into sympathetic and parasympathetic … differentiate both

sympathetic = GO

parasympathetic = STOP

\*you put your hand on a stove… what happens next (include what type of nervous system, neuron etc)

PNS - hand on stove, receptor (like nerve ending) sensory/afferent neuron goes to

CNS.. association neuron transfers signal to motor neuron which takes it to efferent/motor neuron

PNS - takes hand away , effector

type of neuron: pseudopolar (unipolar)

sensory, 1 process that splits

type of neuron: bipolar

retinal and cochlear , 2 processes, one is a dendrite, one is an axon

\*type of neuron: multipolar

*most common* \*\*\* motor and association, many dendrites but ==one axon==

type of neuron: anaxonic

some CNS neurons , no obvious axon

\*Schwann cells - form myelin sheaths around PNS neuron axons .. what is the purpose

supporting cells IN PNS

\
form myelin sheath = type of protein

insulate so messages → faster

These gaps in the myelin sheath are known as _____________.__ The successive wrappings of the Schwann cells’ plasma membranes provide insulation around the axon, leaving only the ____________ exposed to produce nerve impulses.

the nodes of Ranvier

Unmyelinated axons are also surrounded by a neurilemma, but they differ from myelinated axons in that they lack the multiple wrappings of Schwann cell plasma membranes that compose the myelin sheath.

\*what do satellite cells do

supporting cells IN PNS

\
support neuron cell bodies w/in ganglia of the PNS

wrap around cell body to protect from environment

\*what do oligodendrocytes do

supporting cells IN CNS

just like Schwann cells in PNS aka form myelin sheath around neuron axons

\*what do microglia do

supporting cells IN CNS

migrate through CNS and phagocytose debris

==-macrophage, pick up debris==

\*what do astrocytes do

help regulate external environment of neurons in CNS

==-connect between everything - regulate== **ex: on blood vessel so it communicates w neuron**

Processes terminate in “end feet” at capillaries, others on neurons (axon, cell body, or dendrite) thus they can influence interactions between neurons and blood

\*what do ependymal cells do

\-line ventricles (cavities) of the brain and spinal cord - in CNS

==keep shape in brain and spinal cord==

All axons in the PNS (myelinated and unmyelinated) are surrounded by a continuous living sheath of Schwann cells known as the ___________. The axons of the CNS, by contrast, lack it (Schwann cells are found only in the PNS).

neurilemma

\-good for nerve regeneration x

\*what is the difference between how supporting cells cover a neuron between the PNS and CNS

PNS= bubble gum around stick, wrapped around a single neuron

\
CNS= wrapped around CLUSTER of neurons

what is the most abundant glial supporting cell in the CNS

astrocytes

up to 90% of nervous tissue

what are glial cells

non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system that do not produce electrical impulses.

ASTROCYTES take up K+ from the Extra cellular fluid which diffuses from neurons when they fire… what is the purpose of this

the K+ needs to be reabsorbed to maintain proper ionic environment for neurons

ASTROCYTES can take up neurotransmitter glutamate and transform it to glutamine after they are released by neurons after firing

\
neurotransmitter = carry chemical signals (“messages”) from one neuron (nerve cell) to the next target cell

glutamine can be released back into neurons, which can use it to reform the neurotransmitter glutamate.

ASTROCYTES : the end feet surrounding blood capillaries take glucose up from the blood then do what w it

metabolize it to lactate, then release it for use as an energy source by neurons, which metabolize it aerobically into CO2 and H2O for production of ATP

\
\-neurons need help picking up ex: converted glucose to use for energy and to make neurotransmitters

astrocytes are needed for the formation of synapses in the CNS … what do synapses do

communicate between neurons

astrocytes regulate neurogenesis in the adult brain.. how is this helpful

needed for stem cells to differentiate into both glial cells and neurons

astrocytes help w formation of the BBB and release neurotransmitters like glutamate, ATP, adenosine etc that can do what

stimulate or inhibit activity of neurons

capillaries in brain do not have PORES between adjacent endothelial cells (cells that make up the walls of the capillaries) instead they are joined by…

tight junctions made by astrocytes

\*BBB imposes very strict control of what can move from the blood plasma into the brain .. with **astrocytes** making up the barrier and altering function

what can move through

\
causes trouble w drugs getting through

non polar O2 and CO2 , organic molecules including alcoho and barbiturates

polar molecules

LIPID soluble molecules

who had numerical synesthesia

Daniel Tammet

what was special about Kim Peek

extrodinary memory

absence of corpus calllosum

mega savant

what was Christopher Langan known for

smartest man alive

what happened to Phineas Gage

\-had pole through left eye

\-pierced prefrontal cortex, made him sociopathic and changed behaviour

CNS depressants directly affect brain cells, specifically areas involved in inhibiting behaviours ,, also altered speech, slowed reactions, time fog memory

alcohol gets through

In less 10 seconds, nicotine molecules cross the blood- brain barrier and fit like tiny keys into locks normally activated by acetylcholine neurotransmitter, and increases the levels of several other neurotransmitters ( like ______________ ).

dopamine

Other components in tobacco smoke decrease MAO (monoamine oxidases) activity, the enzyme that is needed to break down _____________

neurotransmitters (dopamine, norepinephrine, and serotonin)

Inhibition of NO through a variety of neurotransmitter receptors including N-methyl-D- aspartate and substance P.

how does rabies affect brain

virus infects brain, causes it to swell, immune cells and antibodies can’t enter the brain

CNS contains brain and spinal cord

PNS contains ___________-

peripheral nerves and ganglia

\*the efferent nervous system of the peripheral nervous system splits into the somatic and autonomic nervous system…

1\. what do each do hint: in/voluntary ? which parts of body

2\. how many neurons are involved in each. draw the autonomic

somatic - send axons to skeletal muscles (voluntary control). conduct impulses along a SINGLE axon from PNS to CNS in spinal cord etc

\
autonomic - (involuntary, smooth muscle, heart, gland) TWO neurons , 1st cell body in CNS gray matter (preganglionic neuron) synapses with 2nd neuron called a postganglionic neuron, that has an axon that extends from the autonomic ganglion to the effector organ where it synapses w target tissue

which one out of somatic motor neurons or autonomic motor neurons have ganglia

autonomic motor neurons have it

found in the cell bodies of postganglionic autonomic fibers located in paravertebral, prevertebral and terminal ganglia

what are ganglia

Ganglia are clusters of nerve cell bodies found throughout the body. They are part of the peripheral nervous system and carry nerve signals to and from the central nervous system

\*match the following to somatic and autonomic motor neurons:


1. either excitatory or inhibitory
2. excitatory only

1. either excitatory or inhibitory - AUTONOMIC


1. excitatory only - SOMATIC

21\. Following an Action Potential, the following all occur in the postsynaptic neuron (ONE \n INCORRECT): \n A. chemically gated channels open in the postsynaptic neuron dendrites \n B. the presynaptic terminal bouton synapses with the postsynaptic axon \n C. the postsynaptic neuron undergoes inward diffusion of Na+ causing depolarization \n D. localized, decremental conduction of excitatory postsynaptic potential (ESPS) occurs \n E. voltage-gated Na+ and then K+ channels open starting at the axon hilloc

\n B. the presynaptic terminal bouton synapses with the postsynaptic axon

\
should say dendrrite \n

The embryonic brain region called the Prosencephalon develops into these regions (ONE \n INCORRECT): \n A. telencephalon \n B. hypothalamus \n C. suprachiasmatic nucleus (SCN) \n D. frontal cerebral lobe \n E. cerebellum

E. cerebellum

\*type of neuromuscular junction in somatic motor neurons vs autonomic motor neurons

\
hint: think of where the signal is going

somatic - specialized motor end plate The somatic neuromuscular junction is the site of communication between motor neurons and skeletal muscle fibres.

autonomic - all areas of smooth muscle cells contain receptor proteins for neurotransmitter

\*damage to an autonomic nerve makes its target tissue more sensitive than normal to stimulating agents. This phenomenon is called …

denervation hypersensitivity

True or False: somatic motor neurons are fast conducting and autonomic motor neurons are slow conducting … and all fibes involved are myelinated

false! postganglionic fibers in autonomic motor neurons are unmyelinated

\*kinda a hard one… what happens when denervation occurs to somatic and autonomic motor neurons

somatic - paralysis and atrophy to muscles

autonomic - muscle tone and function persist \*but target cells show denervation hypersensivity

how do the sympathetic and parasympathetic divisions of the autonomic nervous system differ

parasympathtic - rest and digest

sympathetic - fight or flight

\
most organs receive input from both

\
particular locations of their preganglionic neuron cell bodies within the CNS, and in the location of their ganglia.

what are the four organs without dual innervation from the sympathetic and parasympathetic nervous system

and what is the nervous system that single-handedly controls them

**only sympathetic**

\-adrenal medullla

\-arrector pili muscles in skin

\-sweat glands

\-most blood vessels

1. \*what are the two main neurotransmitters used in the autonomic nervous system
2. what releases them
3. how do they differ

cholinergic neurons = acetylcholine

adrenergic neurons = norepinephrine

\

3. they both bind diff receptors to mediate target organ response

for parasympathetic and sympathetic outflow, state whether the pre and post ganglionic axons involved are cholinergic or adrenergic and the order of them from the CNS to the effector cell

true or false: acetylcholine is the neurotransmitter for ALL PREganglionic fibers (both sympathetic and parasympathetic)

true

true or false: acetylcholine is the transmitter released most by sympathetic postganglionic fibers at their synapses with effector cells

false

released most by *parasympathetic* postganglionic fibers

the neurotransmitter released most by sympathetic nerve fibers is _____________ so the type of transmission is called _____________

norepinephrine

adrenergic

what is dysautonomia

dysfunction of the autonomic nervous system

can be caused by brain injury, diabetes, genetics, tick bite

what happens after you are bit by a tick

hint: how does it spread

substances in tick saliva disrupt immune response, spirochetes multiply in the skin

immune response causes the bullseye look but *neutrophils dont appear to get rid of infection*

bacteria spread via bloodstream to joints, heart, nervous system

synesthesia vs chromothesia vs synaesthesia

\
who had chromothesia

letters or numbers are perceived as colours

music as colours - MOZART

coloured sounds taste sweet

the cell membrane is just 2 molecules thick, 2 phospholipid molecules thick (phospholipid bilayer)

explain simple passive diffusion and example of what passes through

(there are a few) hint; think ions

1. small uncharged molecules (relatively lipid soluble) can diffuse through the lipid bilayer (eg. steroid hormones)
2. small charged molecules (ions) can pass through water filled pores

these ion channels tho… some are leaky and ions flow in or out as needed
3. voltage-^^gated^^ ion channels

\*\*integral membrane proteins can act as transporters

active transport requires ATP. explain the Na+/K+ ATPase pump

why is it important

moves Na+ out of the cell

moves K+ into the cell

ATP turns to ADP to do this

\*establishes electrochemical gradient

\
The sodium-potassium pump carries out a form of active transport FOR MAKING ACTION POTENTIAL MOVEEEE

why are ion channels especially important in the nervous system

they help produce electrical impulses that transmit info rapidly

\---- voltage gated ion channels open and change the membrane potential of the cell and that’s how electrical signals are conducted in neurons

All cells in the body have a potential difference – or voltage – across the membrane. This is called the resting membrane potential….

what is it for neurons

\-70 mV on the INSIDE of the cell

what are the locations of Na+ and K+ at the start of action potentials

Na+ starts outside (then rushes in)

K+ starts inside (then rushes out)

the primary function of nerve cells is to receive, conduct and transmit signals in the form of :

action potentials.. which go along the nerves, taking signals from one place to another place

what is an action potential

why do they need to be reamplified along the way and HOW

1. momentary discharges %%(depolarizations)%% of the resting membrane potential caused by a rapid influx of Na+ caused by the opening of sodium ion channels

%%= make positive%%

\

2. they have to travel a long way w/o weakening, so we use voltage-gated ion channels

what are the three steps of ion gating in axons

1. electrical event must be strong enough to trigger the axonal membrane beyond its threshold, if it is it initiates the action potential (aka channel has to get positive enough from sodium coming in) ----voltage gates sodium channels open from stimulus and Na+ rushes into cell and makes it very positive (depolarization).. if its strong enough there is an action potential


1. Na+ channel closes and the permeability of Na+ decreases
2. Action potential trickles into the next channel down axon, now making it depolarized and triggers another action potential by surpassing threshod

Meanwhie old channel cell has to repolarize, which is done by letting K+ diffuse out of the cell to restore the original resting membrane potential Sodium channels of refractory area are inactivated, that’s why action potential can’t flow backwards

\
**K+ is only pumped out of the cell once the action potential is reached** \*\*\*\*\*\* @@__*When the depolarization reaches about -55 mV a neuron will fire an action potential. **__@@

\*\*the Na+ and K+ pumps are constantly working to in the plasma membrane, they pump out the Na+ that entered the axon during an action potential and pump in the K+ that left

\
\

the size of all action potentials is the same bc once the depolarization reaches that -55 mV threshold, it will always fire an action potential

\
*all or none principle*

1. compare how action potentials flow in non-myelinated axons vs myelinated


2. what does this allow

hint: saltatory conduction

**non-myelinated axons**= the action potential passes smoothly along the axon, and all parts of the membrane are depolarized

**myelinated axons**= action potential jumps between non-insulted nodes by saltatory conduction

allows more rapid movement of the action potentials, and needs less energy to restore the membrane after the action potential has been transmitted \*\*dont need to go through every Na channel

\----- refractory period still exists in these neurons

axons end close to another cell so once the action potential reaches the end of the axon, they stimulate the next cell.. how tho

presynaptic nerve ending releases neurotransmitters that stimulate action potentials in the post synaptic cell

they hop across 10nm space between

in the CNS, the 2nd cell is also a neuron

what is it in the PNS

could be a neuron, or en effector cell within a muscle of gland

what are the steps of the synapse triggerring the next cell

1. action potential reach axon terminals
2. voltage-gated Ca2+ channels open
3. Ca2+ binds to sensor protein in cytoplasm
4. Ca2+ protein complex stimulated fusion and exocytosis of neurotransmitter

on the post synaptic side, the neurotransmitter binds to its receptor on thee dendrite… this causes ion channels on the postsynaptic dendrite membrane to open .. how are the gates different than axon ones

note that these gates are chemically regulated (ie. not voltage - regulated as in the axons

this stimulates the cell to make an action potential

what are the steps of the action potential in the presynaptic neuron in the axon terminal

action potentials conducted by axon (travel through) and reached axon terminal

voltage gated Ca2+ channels open and Ca2+ flows in

release of excitatory neurotransmitter bc of Ca2+ influc

what are the steps of the action potential in the postsynaptic neuron in the next neuron

1. the neurotransmitter bind to receptor proteins on next cell…. ==neurotransmitter receptors are, for the most part, ligand-gated ion channels, that open in response to being bound by the neurotransmitter they are specific for.==
2. Activation of postsynaptic receptors leads to the opening or closing of ligand gated channels in the cell membrane. (chemically)
3. inward diffusion of Na+ causes depolarization (EPSP = excitatory postsynaptic potential aka depolarization in the postsynaptic neuron…… because the membrane potential moves toward the threshold required for action potentials)
4. localized, decremental conduction of EPSP… less and less effective propagation of an impulse due to a progressive decrease in membrane potential

at axon hillock : 5. opens voltage-gated Na+ channels then K+ channels.. aka moving action potential


6. at AXON - conduction of action potential

how to record membrane potentials

patch clamp recording technique - record electrical currrent in spinal neuron grown in cell culture using microelectrode

\
*voltage for a certain area of the cell membrane over time so it changes in one place*

myotonia are ?

what are they caused by

\
hint; fainting sheep

neuromuscular disorders characterized by delayed relaxation of skeletal muscle after voluntary contraction or electrical stimulation

\*problem in muscle

can be caused by mutations in muscle Cl- channel

channel gates do not open properly

repolarization delayed, several Action Potentials fire instead of just one

describe information flow from dendrites to axon

1. dendrites collect electrical signals
2. cell body integrates incoming signals and generates outgoing signal to axon


1. axon passes electrical signals to dendrites of another cell or to an effector cell

the CNS is composed of gray matter and white matter … what do each contain

gray matter - contains neuron @@cell bodies and dendrites@@, found in the cortex (surface layer) of the brain and deeper w/in the brain in aggregations known as nuclei

white matter -consists of @@axon@@ tracts (myelin sheaths produce white color) that underlie the cortex, and that surround the nuclei.

neurotrophin =Any of a family of autocrine regulators secreted by neurons and neuroglial cells that promote axon growth and other effects. Nerve growth factor (NGF) is an example.

what does NGF do

NGF is required for the maintenance of sympathetic ganglia, and neurotrophins are required for mature sensory neurons to regenerate after injury

Neurotrophins regulate the survival and differentiation of adult neural stem cells in parts of brain for memory and learning

explain the P.A.D.S in terms of protection of the skull… P.S these same meningeal layers protect the spinal cord!

P - Pia matter (innermost membrane, clings to surface of brain/spinal cord, follows every fold

A - arachnoid mater (spider/webby)

D - dura mater (tough mother and 2 layers)

S - skull and scalp

in addition to the skull and meninges, the brain is protected by two fluid cushions that give some protection for the brain against head traumas….

what are the two cavities and

where are they located

\
P.S the cavities are filled w cerebrospinal fluid

outer cavity - superior sagittal sinus (SSS) sits right under dura mater

inner cavity - subarachnoid space - space between arachnoid and pia mater

what does the cerebrospinal fluid found in brain cavities and spinal cord do

provides protection and is similar to blood plasma

CSF tap can be used to examine for signs of disease

there are 31 pairs of spinal nerves split into 6 sections

\-each nerve is a mixed nerve composed of sensory and motor fibers, packed together but they are separated near the attachment of the nerve to the spinal cord

cranial

cervical

thoracic

lumbar

sacral

coccygeal

the spinal cord extends from the brain stem to the pelvic region, ending right before the end of the vertebral column…. how do spinal nerves enter or leave the spinal cord

they enter and leave in between the vertebrae

explain the link between the spinal cord and peripheral nervous system

interneurons also communicate w one another along the length of the spinal cord

an afferent sensory stimulus can be translated up or down the spina cord by the interneurons (afferent = peripheral to CNS)

\
interneurons are the ones in between - they connect spinal motor and sensory neurons \*exclusive to CNS

how to tell lower motor neuron damage when doing a myotatic stretch reflex eg: knee-jerk reflex

with lower motor neuron damage - the reflex will be diminished

how to tell upper rmotor neuron damage when doing a myotatic stretch reflex eg: knee-jerk reflex

with upper motor neuron damage, reflex will be exaggerated