Unit 2

Central Nervous System

Brain and spinal cord

Peripheral Nervous System

nerves (not brain and spinal cord)

Surface area to volume ratio

- increase means more efficiency with greater exchange of materials

Gyri

- bumps on brain

Sulci

- gaps between the bumps on brain

Frontal lobe

- voluntary movements
- Speech production
- high level executive functions
- Reasoning + problem solving
- Happiness

Motor cortex

- small sliver on posterior end of frontal lobe
- controls voluntary movement

Parietal Lobe

- processes somatosensory info
- integrates info
- body sensations
- taste

Somatic Sensory Cortex

- Anterior to parietal love
- processes info from peripheral nervous system

Occipital Lobe

- visual perception (color, form, and motion)

Temporal Lobe

- process auditory info
- encode memory
- language understanding

Cerebellum

- balance and motor functions

Brain stem

- automatic functions: breathing and blood pressure
- midbrain (most superior)
- pons (bulge)
- medulla oblongata (stem)

Lymbic System

- hypothalamus, thalamus, olfactory bulb, amygdala, hippocampus
- behavioral and emotional response to outward and inward stimuli
- thirst and hunger, happiness, smell

Dendrites

- recieve info from other neurons
- send them to cell body

Axon

- take info away from the cell body

Axon terminal

- end of axon
- send messages from the neuron to another body

Myelin Sheath

- Insulator around schwann cells that optimize transfer of electrical impulse along the neuron

Nodes of Ranvier

- gap between myelin sheath
- helps to maximize transfer of electrical impulse along the axon

Synapse

- Space between two neurons where neurotransmitters go between

Neurotransmitter

- Chemical substance that transfers electrical signals between neurons

Multipolar

- 1 axon + many dendrites
- mostly the CNS and efferent PNS

Bipolar

- 1 axon + 1 dendrite
- retina of eye and the olfactory system

Unipolar

- one structure extending from cell body
- mostly in invertebrates + efferent division of PNS of mammals

Broca

-area in inferior posterior portion of frontal lobe
- responsible for speech production

Wernickes

- area superior posterior portion of temporal lobe
- responsible for language understanding

Motor Neuron

- Efferent
- sends messages from brain to spinal cord to the muscles and organs

Sensory Neuron

- Afferent
- messages from receptions to the brain or spinal cord

Association/Interneuron

- from sensory neuron to motor neuron
- mostly in CNS

Afferent

Towards the CNS

Efferrent

Away from the CNS

Pseudonipolar

- single structure extending from soma
- later branches into two instinct structures

Charges of Cell at resting potential

- positive exterior with more Na+
- negative interior with more K+

Charges at action potential

- Negative exterior
- positive interior

Na+/K+ pump

- active transport
- goes against concentration gradient
- 3 Na+ and 2 K+

What causes the beginning of an action potential?

- opening of Na+ channels
- Na+ will naturally move inside of cell w/ the concentration gradient.
- Called depolarization

Repolarization

- outside becomes more positive than the cell cause k+ move out through the K+ channels that are now open
- returns to correct charge but not correct ions
- sodium potassium pump switches the ions to reestablish resting potential.

What happens to an action potential at the end of an axon?

- calcium ions (Ca2+) move into cell through voltage gated ion channels
- neurotransmitters in presynaptic neuron are released by vesicles which were triggered to fuse with the cell membrane because of the Ca2+
- the neurotransmitters are caught by specific ligand gated receptors on the postsynaptic cell
- this causes specific ion channels to open and begins depolarization in the receiving cells

Voltage Graph

- must pass threshold of -55 mV to start action potential
- voltage spikes to 40 mV during depolarization (the action potential)
- voltage decreases during repolarization
- voltage dips below the resting state during hyperpolarization
- voltage returns to resting state (-70 mV) after Na+/K+ pump fixes the substance concentrations

Reflex

- brain not involved only reaches spinal cord

Reaction

- brain is involved

Central Sulcus

The sulcus that divides the motor and sensory cortex

Multiple Schlerosis

- autoimmune
- muscle weakness, loss of balance, and missing sensory info
- body attacks myelin on the neuron

Huntington’s

- genetic
- motor, behavioral, and psychological
- autosomal dominant
- effects lymbic system

ALS

- affects nerve cells: motor neurons, brain stem, spinal cord, motor cortex, and anterior spinocerebellar tract.
- specifically voluntary movement
- Hereditary and sporadic

Epilepsy

- rapid misfiring of neurons

Alzeihmers

- Affects entorhinal cortex, hippocampus, cerebral cortex
- Amyloid and Tau build up in the brain and tangles
- stops the production of acetylcholine

Parkinson’s

- CNS disease that affects movement
- Affected Basal Ganglia
- Dopamine creation is affected

Lymbic system functions

Hypothalamus: thirst and hunger
Hippocampus: memory
Amygdala: happiness & emotion