Human Anatomy Exam 3

CNS

central nervous system; brain and spinal cord

PNS

the sensory and motor neurons that connect the CNS to the rest of the body

somatic receptor

Sensory receptors in the skin, muscle, and joints; respond to pain, temp, proprioception (sense of knowing the position of your body without looking)

visceral receptor

Sensory receptors in the internal organs (blood vessels, stomach, heart, lungs); respond to stretch, pressure, oxygen levels, pH

somatic effector

skeletal muscle that produces voluntary movement

visceral effector

cardiac and smooth muscle fibers, glands that produce involuntary movements

afferent pathway

flow from receptor to control center

efferent pathway

flow from control center to effector

neuron

a nerve cell; the basic building block of the nervous system; workhouse of nervous tissue

cell body of neuron

contains nucleus and organelles; golgi, RER, mitochondria

dendrites

Branchlike parts of a neuron that are specialized to receive information.

axon

the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands

axon terminal

The endpoint of a neuron where neurotransmitters are stored

synaptic vesicles

Membrane-bounded compartments in which synthesized neurotransmitters are kept.

neurotransmitters

chemical messengers that cross the synaptic gaps between neurons

myelin sheath

covers the axon of some neurons and helps speed neural impulses

neurofibril nodes of ranvier

gaps between segments of myelin sheath

they allow the action potential to jump from node to node

synapse

the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron

presynaptic neuron

conducts impulses toward the synapse; has neurotransmitters

postsynaptic neuron

transmits impulses away from the synapse; has neurotransmitter receptors

synaptic cleft

The narrow gap that separates the presynaptic neuron from the postsynaptic cell.

action potential

a neural impulse; a brief electrical charge that travels down an axon

depolarization

The process during the action potential when sodium is rushing into the cell causing the interior to become more positive; action potential spreads along axon

somatic

conscious control

visceral

part of autonomic nervous system; sympathetic: in control when in fight/flight/fright; parasympathetic: in control in nonstressful situations

local potentials

excitatory and inhibitory potentials

multipolar (motor) neuron

has numerous processes (dendrites) extending from the cell body and a single axon, allowing it to receive many inputs and send signals to effectors

unipolar (sensory) neuron

only one process from the cell body that splits into a central process and a peripheral process(sensory neurons)

neuroglia

all cells of nervous tissue, expect neurons. cells that perform various supportive and protective roles for the neurons

oligodendrocytes (CNS)

forms myelin sheath in CNS

schwann cells

form myelin sheath in PNS

microglia (CNS)

Act as phagocytes, eating damaged cells and bacteria, act as the brains immune system

ependymal cells (CNS)

line the cavities of the brain (ventricles) and spinal cord (central canal) and produce cerebral spinal fluid

astrocytes (CNS)

star-shaped; processes wrap around blood vessels and form the blood brain barrier

grey matter

unmyelinated axons that appear grey because they are not wrapped in fatty myelin; unmyelinated axons carry sensations such as pain

white matter

groups of myelinated axons in the CNS

nerves

bundle of axons in PNS

tracts

bundles of axons in the CNS

neural tube

a groove formed in the top layer of differentiated cells in the embryo that eventually becomes the brain and spinal cord; The tips of the neural folds fuse with each other to form it

primary vesicles

Prosencephalon (forebrain)

Mesencephalon (midbrain)

Rhombencephalon (hindbrain)

secondary vesicles

telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon

skull

frontal, parietal, temporal, and occipital bones all protect brain

vertebral column

protects spinal cord

pia mater

thin, delicate inner membrane of the meninges; ends at L2

arachnoid mater

middle layer of the meninges; ends at S2

dura mater

thick, outermost layer of the meninges surrounding and protecting the brain and spinal cord; has periosteal (closer to bone) and meningeal layers which are usually fused and if they aren't the form the dural venous sinus which contain venous blood; ends at S2

arachnoid villus

get cerebral spinal fluid from subarchanoid space into the dural venous sinus

arachnoid trabeculae

extensions of the arachnoid that occur within the subarachnoid space

subarachnoid space

gap between pia and arachnoid

rostral neural tube

brain

caudal neural tube

spinal cord

telencephalon becomes

cerebral hemispheres and has lateral ventricle in each

lateral ventricle shape

backwards C with posterior projection

cavity in diencephalon

3rd ventricle--between left and right thalamus

interventricular foramen

connects 3rd ventricle and lateral ventricles

cavity in mesencephalon

cerebral aqueduct (connects 3rd and 4th ventricles)

4th ventricle

partial contributions from metencephalon and myelencephalon; leads into central canal of spinal cord; CSF can get out of 4th ventricle and go to the subarachnoid space through lateral openings

choroid plexus

produces CSF; where ependymal cells in the brain are paired with capillaries and they filter blood and produce CSF

forebrain

cerebrum, thalamus, hypothalamus

cerebrum

largest, L and R hemispheres --derived from telencephalon; surface is all grey matter (cell bodies and dendrites)

diencephalon

thalamus and hypothalamus; important in motor and sensory pathways and ANS

brainstem

midbrain, pons, medulla oblongata; contains nuclei of cranial nerves--these control vital functions (cardiovascular activity, respiratory control)

midbrain

derived from mesencephalon

pons

derived from metencephalon

medulla oblongata

derived from myelencephalon

cerebellum

derived from metencephalon; separated from pons by 4ht ventricle; occupies most of posterior cranial fossa; function: balance and movement

gyrus (gyri)

ridges/bumps on brain

sulcus (sulci)

grooves in brain

nucleus

a cluster of cell bodies of neurons in the CNS

tract

a cluster of axons in the CNS

fissure

deep sulcus

longitudinal fissure

separates cerebral hemispheres

transverse fissure

separates cerebrum from cerebellum

cerebral cortex

The intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body's ultimate control and information-processing center.

white matter of brain

deep to cerebral cortex; has myelinated axons

cerebral nuclei

cluster of cerebral cell bdoes

thalamus

made up of unmyelinated cell bodies; 3rd ventricle is between left and right thalamus; made up of nuclei that have different functions-relates to regions of the cerebrum

frontal lobe

The lobe at the front of the brain associated with movement, speech, and impulsive behavior; left side contains brocas area

parietal lobe

portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position; has Wernicke's area

central sulcus

separates frontal and parietal lobes

precentral gyrus

motor cortex; GSE pathways begin here

postcentral gyrus

sensory cortex; GSA pathways end here

occipital lobe

A region of the cerebral cortex that processes visual information

temporal lobe

A region of the cerebral cortex responsible for hearing and language; long term memory

lateral sulcus

Separates temporal lobe from parietal and frontal lobes

primary motor cortex

the section of the frontal lobe responsible for voluntary movement

motor homunculus

broad areas of primary motor cortex devoted to controlling movements of different body regions; amount of space a portion of the body makes up relates to how much motor control is needed for that part of the body

primary somatosensory cortex

the region of the anterior parietal lobe whose primary input is from the somatosensory system

sensory homunculus

Demonstrates that the area of the cortex dedicated to the sensations of various body parts is proportional to how sensitive that part of the body is.

primary visual cortex

the region of the posterior occipital lobe whose primary input is from the visual system

primary auditory cortex

the region of the superior temporal lobe whose primary input is from the auditory system

cerebral white matter

myelinated fibers and their tracts

responsible for communication

commissural fibers

horizontal fibers that connect gray matter of two hemispheres

corpus callosum

the large band of neural fibers connecting the two brain hemispheres and carrying messages between them

association fibers

connect different parts of the same hemisphere

projection fibers

tracts between the cerebrum and other parts of the brain and spinal cord

basal nuclei

islands of gray matter buried within the white matter

limbic system

A doughnut-shaped system of neural structures at the border of the brainstem and cerebral hemispheres; associated with emotions such as fear and aggression and drives such as those for food and sex. Includes the hippocampus, amygdala, and hypothalamus.

hypothalamus

nuclei control thirst, hunger, rage, sexual, parts of autonomic nervous system; 2 but only one is needed to function

cranial nerves

midbrain: III, IV

pons: V, VI, VII, VIII

medulla: IX, X, XI, XII

-cranial nerves I and II don't have cell bodies in the brainstem

-don't have to be mixed like spinal nerves

-can be motor: cell body in brainstem and axon effector goes to muscle in the head

-GVE (parasympathetic); start in brainstem and stop to synapse onto a second neuron that goes to the smooth muscle or glands of the head (have ganglion in the middle of their pathway)