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