5- Organization of the Nervous System

what are the 3 main functions of the nervous system

1. receive sens info

2. integrate and process info

3. decide if a motor response will occur

t or f: all sensory stimuli req a motor response

f

whats the major functional unit of the nervous system

a neuron

define dendrite

info receiving area

define cell body/soma

contains organelles for cell metabolism

define axon

info carrying extension of cell membrane

(sometimes has myelin sheath which inc speed)

define pre synaptic terminal

end of axon to transmit info to other cells

what are the 2 major divisions of the nervous system

Central Nervous System and Peripheral Nervous System

what makes up the CNS

brain and spinal cord

what makes up the PNS

autonomic nervous system (sym and parasym)

somatic nervous sys (sensory and motor)

the peripheral nervous system is made up what kind of nerves

spinal and cranial nerves that carry APs

describe afferernt (sensory) axons

carry APs TOWARDS CNS from peripheral sensory receptors

what body parts use somatic afferents

skin and retina

what body parts use visceral afferents

thoracic/abdominal organs, olfactory epithelium and taste buds

describe efferent (motor) axons

carry APs AWAY FROM CNS to synapses

what body parts use somatic efferents

skeletal muscle

what body part uses visceral efferents

cardiac/smooth muscle, endocrine glands

describe how peripheral nerve axons converge to form a single spinal nerve at each intervertebral formina

afferent sensory axons enter SC via DORSAL ROOTS

efferent motor axons enter SC via VENTRAL ROOTS

functional organization of the cns

spinal cord, brainstem, forebrain

describe the spinal cord

it receives sensory input and supplies motor output to trunk/limbs. the input is relayed to the forebrain via brainstem

what part of cns can control muscle stretch reflexes and limb withdrawal from painful stimuli

spinal cord

what makes up the brainstem

medulla, pons, midbrain

what makes up the forebrain

diencephalon, telencephalon

describe the brainstem

sensory input is passed to the forebrain. sens/motor input related to face and head.

describe the forebrain (cerebrum)

most sophisticated info processing and motor output

can bypass brain stem by sending motor output direct to SC

function the medulla (brainstem)

takes info via cranial nerves from external and internal sensory receptors and then sends motor commands to skeletal and smooth muscle

*supports resp/cardio system, tongue movement, taste, swallowing, vocalization

function of pons (brainstem)

CN’s receive sensory info about facial tough and have role in chewing control

-cell bodies of neurons of 2 neuron chain that goes from cerebral cortex to cerebellum

function of midbrain (brainstem)

contains superior/inferior colliculi needed for processing visual and auditory info

CN nuclei controls eye movement, pupil constriction

what does each brainstem region contain

a reticular formation region which modulate consciousness, pain perception, spinal reflexes. movement in general.

what is the diencephalon made up of (forebrain)

thalamus, hypothalamus

function of thalamus

modulator of info from cerebral cortex from sens systems and other brain regions

func of hypothalamus

regulates ANS, controls hormones from pituitary, physio/behavioral aspects of homeostasis

parts of the telencephalon (forebrain)

cerebral cortex, basal ganglia, hippocampus

basal ganglia function

modulate motor func of cerebral cortex

role of cerebral cortex

role in memory/spatial learning

role of hippocampus

-memory/spatial learning

-mediates complex sensory integration like senses and perception

-formulates and executes sequences of voluntary movement

how is the CNS protected

by meninges

Innermost- Pia matter which is on surface of brain and SC

Middle- Arachnoid which looks line spider web and trap CSF cells

Outer- Dura matter which is a thick later of fibroblasts and fuses w bone surface

what is CSF

clear fluid in subarachnoid space, central canal of spinal cord, and ventricular system of the brain. eventually goes to venous system and is replaced many times per day.

function of CSF

cushion brain/SC and equalize pressure

maintain stability for neurons/glia

waste excretion and toxin removal

describe the BBB

its where capillaries in brain and SC have tight junctions (astrocytes) and prevent many molecules from leaving blood and entering brain

-small, uncharged, lipid soluble, non protein bound, O2 and CO2

t or f: glc and AA dont req transport

F- they do!