Bio 118 Exam 2

How many neurons to from brain to skeletal muscles?

Two

Upper motor neuron

From cortex to spinal cord

Lower motor neuron

From spinal cord to skeletal muscles

Posterior Porietal Cortex (PPC)

Movements are targeted accurately towards objects in space

Premotor Cortex (PMA)

Organizes motor functions before inititation

Supplementary Motor Cortex (SMA)

Learned sequence of movements

Primary Motor Cortex (M1) (Precenteral gyrus)

Initiates movement

How many neurons to signal the brain?

Three

1st order neuron

From: Receptor in skin/muscle/joint
To: Brain Stem
Function: Detect stimulus and sends it to the CNS

2nd order Neurons

From: Brain stem
To: Thalamus
Functions: relay signal and often undergoes decussation (crosses to teh opposite side of CNS)

Medulla Oblongata

Regulates involuntary function

Thalamus

Information center for all sensory info

Decussation

Crosses to the opposite side of CNS

3rd order neurons

From: Thalamus
To: primary somatosensory cortex
Function: Allows for concious preception of the sensation

Postcentral gyrus

Part of brain where we experience these sensations

If you see brain and spinal cord it indicates

Central Nervous System

Everything outside of the Brain and spinal cord

Peripheral Nervous System

Nerouns travel through ______ to enter the CNS

PNS to Spinal cord

A reflex arc is

A neural pathway that produces a fast response to a stimulus

How does a reflex occur

1) Receptor
2) Sensory neuron/afferent neuron (transfers signal to spinal cord)
3) association Neuron (sometimes skipped) (Inside spinal cord/CNS)
4) Motor neuron/efferent neuron (exit)
5) Effector

Sensory impulses travel through

dorsal spinal cord (Back) (PNS)

Morot (efferent) impulses travel through

ventral spinal cord

Only neuron in CNS is

association neuron (intraneuron)

Descending motor pathways include brain areas that produce

dopamine

Substantia Nigra

Dopamine-producing cells
When we damage teh substantia nigra it will no longer produce enough dopamine
Every decade they lose 5-10% more of the rmax dopamine production
This will effect muscle movements

How does exercise reduce symptoms and the progression of parkinsons disease

It leads to regeneration of damaged nerve tissue
It improves immune response
Stimulates neurogenesis (making new neurons)
It strenghtens synapse strength

Neuron design is

one way flow of information

Dorsal root ganglion

cell body outside the spinal cord that brings information into the spinal cord

Parts of neuron include

Dendrite
Nucleus (Cell body)
Axon
Myelin sheath
Axon terminal

Myelin Sheaths do waht to the speed of the signal

It makes the signal quicker because it jumps from axon to axon - this is called salutary conduction (node to node) F

Flux

The movement of substances between compartments

Passive transport requires

No energy, and high to low

Simple diffusion - small things can get through phospholipid bilayer
Facilitated diffusiuon - protein transport

Active transport

Requires energy

Two gradients that move ions across the membrane are

Electrical and chemical

Active transport uses energy to move ions

against the gradients

Sodium potassium pump

Uses energy from ATP

ATP causes pump to change shape

3 Na+ ions are pumped OUT of the cell

2K+ ions are pumped INTO the cell T

The relative charge of a cell is

The outside is more positively charged then the inside

outside positive, inside negative

Resting membrane potential (-70 mV) are influenced primarily by

Potassium (K+) movement

K+ leak channel

Always open

Would you expect K+ to move inside our out the cell

Electrically - it would move out

chemicall - it would move in

in all, chemical or concentration gradient is prioritized over electrical - answer is out

Depolarization

Making the inside more positive - in this case the inside is negative so moving towards neutrality would be the opposite

Hyperpolarization

Making the inside more negative - opposite reasoning of the depolarization

The leakage of _______ a neuron produces the -70mV resting membrane voltage of a typical neuron

Potassium, K+

A normal cell resting membrane potential is _____ mV. If we activated a pump that moved Cl- ions into the cell to make the membrane potential -75mV it would be called _______

-70mV, hyperpolarization

Which gradient would make potassium move INTO the cell?

Electrical

How do ligand-gated chnnels work?

Ligand is a type of a protein that binds to the channel which will cause it to change shape

Voltage gated Na channel

Closed: outside is positive, inside negative
Open: Outside is negative, inside is positive
Inactive: refactory period
Protein tethered to channel that will plug it so that flow is always one way
Quick to open and close

Threshold:

When the charge changes enough to change channel shape

Voltage gated K+ channel

Slow to open, slow to close

Independet variable

Changes

Dependent variable

Stays the same but changes due to the independent variable

Which way will the sodium ions move if the channels opened?

Inside, concentration is low inside cell so chemically it would move in. Charge is also negative inside cell so it would be electrically want to move in as well. Ac

Acetycholine is

a neurotransmitter/ligand that binds to a ligand gated sodium channel to open it

If Acetycholine binds to a ligand gated sodium channel what will rush in

Sodium

Spatial summation

Multiple signals in multiple places

Temporal summation

Multiple signals in one place

Action potential review

1. Graded depolarization brings an area of excitable membrane to threshold.

2. Voltage-gated Na⁺ channels open.

3. Na⁺ ions flood into the cell.

4. Transmembrane potential goes from −70 mV to +30 mV.

5. Voltage-gated Na⁺ channels close AND voltage-gated K⁺ channels open.

6. Repolarization begins.

   1. Voltage-gated K⁺ channels close.

Cornea

Transparent layer of stratified squances epithelium that refracts light, continues with the sclera (white of eye)

Iris

Pigmented layer of eye that has muscles that control the pupil (opening when light passes)

Retina

Sensory layer of the eye that contains a pigmented section to absorb light and a neural layer containing photoreceptors

Fovea

Area of greatest vsiual acuity that contains only cones

Lens

Concentric layers of cells with internal lens filters that contain proteins called crystallines and are covered by a dense fibrous capusle

Optic disc

Area where the optic nerve leaves the eye, blind spot of the eye where there are no photoreceptors

Optic nerve

Brings info from eye to brain

Focal point of light in the eye

Fovea

Myopia

nearsighted - cant see far

Hyperopia

Far sighted - cant see near

Photoreceptors

Cell in the retina detecting light and converts it into electrical signals that the brain interprets as vision

Cones

detects color

Rods

Detects brightness

Cones peak in the

Fovea

Rods are

absent in fovea but peak outside it and decrease with distance

Humans and animals have cones that

detect different wavelenghts of light

Difference in cones for color blindness

Protarope (no red cones) Detrope (no green cones)

cGMP is produced in the

Dark

Give the order for why we don’t see in the dark

cGMP is produce and opens ligand gated Na channel
membrane potential goes to -40
rod reacts to this and releases glutumate (inhibitor)
Glutumate inhibits the bipolar cell from releasing anything
Due to lack of release from bipolar cell, ganglioin cell is not stimulated
Thus, brain is sent no signals

Rod cells only release glutumate in the

Dark

Light passes through

The cornea, then ens, then retina

Rod cells can react in

any condition

Lens are made of

epithelial cells

The order of processing visual information is

Lens → retina > optic nerve → thalamus → occiptal lobe

The receptors that the eye uses are

photoreceptors

The thalamus is an

Information center/reciever

The process of moving across the brain/CNS is

decussation

What are the three type of muscles

Skeletal muscles - voluntary, usually attached to skeleton
smooth muscles - involuntary, usually covering wall of internal organs
Cardiac muscles - involuntary, only covering walls of heart

What does myo stand for

Muscle

Tendon

A strong fiberous collagen tissue that attaches the muscle to the bone

Fascia

Encloses a muscle or organ

Fascicle

bundle of muscle fibers surrounded by connective tissue

muscle fiber or myocyte

muscle cell —- contains nuclei

myofibril

long thread like organelles

myofilaments

actin and myosin