Chapter 7 Nervous System Flashcards Preview

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Flashcards in Chapter 7 Nervous System Deck (91):
1

Nervous System


Sensory input

integration

motor output

2


Sensory input


monitor changes occuring inside and outside the body

gather information

3


Integration


process and interpret sensory input

decide if action is needed

4


motor output


respond to integrated stimuli

activate muscles or glands

voluntary and involuntary

5


Organization of Nervous System


Central Nervous system

Peripheral Nervous System

6


Central Nervous System


brain and spinal cord

7


peripheral nervous system


nerves outside the brain and spinal cord

cranial and spinal nerves

8


Nerve functional classification


sensory (afferent) division

Motor (efferent) division

9


Sensory nerves


nerve fibers that carry information to the CNS
and the central canal

10


motor nerves


nerve fibers taht carry impulses away from the CNS

1  Somatic nervous system:  voluntary, skeletal muscle

2: Autonomic nervous system: involuntary, smooth and cardiac muscle and glands

11


Nervous tissue
 structure


consists of neurons and neuroglia

12


neurons


structural and functional unit of the nervous system and conduct nerve impulses

13


neuroglia


supports cells that provide physical support, insulation and nutrients to neurons

14


Support cells


astrocytes

microlia

ependymal cells

oligodendrocytes

satellite cells

schwann cells

15


Astrocytes


abundant star chaped cells

form barrier between capillaries and neurons

control chemical environment of brain

16


microglia


phagocytose bacterial cells anc cellular debris in the CNS

Remove debris

17


ependymal cells


line cavities of the brain and spinal cord

circulate cerebrospinal fluid

18


oligodendrocytes


wrap around nerve fibers (axons) in the CNS

poroduce myelin sheaths

19


satellite cells


protect neuron bodies in ganglia of the peripheral nervous system

 

20


schwann cells


form myelin sheath around axons in the PNS

21


Neurons


Nerve cells

specialized to transimt nerve impulses

22


Neuron regions


cell body

Dendrites

Axon

23


Cell body


nucleus

large nucleolus

nissl substance

specialized rough ER

Neurofibrils maintain shape

24


Dendrites

short highly branched cytoplasmic extensions

conduct signals toward the cell body

25


axon


1 per neuron

arises from the axon hillock

may have many branches (collaterals)

trigger zone region that initiates action potential (impulse)

conduct impulse away from cell body to axon termials

terminals contain vessels with neurotransmitters

 

 

26


axon terminals


separated by gap from next neuron

1 synaptic cleft: fluid filled gap between adjacent neurons

2 synapse: junction between nerves

27


unmylenated axon


schwan cells surrounds region of several axons but does not form myelin sheath

28


myelinated axon


in PNS schwann cells wrap around peripheral axons in jelly roll fashion

layers of cell membrane create myelin sheath, whitish fatty material

neurilmma: portion of schwann cell that contains most of the cytoplasm and nucleus (outer surface)

in CNS aligodendrocytes form the myelin sheath (no neurolemma)

Nodes of ranvier: gaps in myelin sheath

29


Locatoin of neuronal cell bodies


most are located in CNS

1  gray matter: cell bodies and unmyelinated fibers

2 Nucleus: cluster of cell bodies within the white matter of CNS

 

30


Ganglion


collectoin of cell bodies outside the CNS or in the PNS

31


Functional classification of neurons


Sensory (afferent)

Motor (efferent)

Interneurons

32


sensoru neuron function


most unipolar some bipolar

cell bodies in ganglia

carry impulses from sensory receptors to the CNS

receptor-specialized dendritic ending

cutaneous sensr organs

proprioceptors-dectect stretch or tension

33


motor neuron function


multipolar neurons

cell body within the CNS

carry implulses from teh CNS to viscera, muscles and glands

34


interneurons function


found in pathways within the CNS

multipolar

some cell bodies in nuclei of CNS

connect neurons

35


Structural classification of Neurons


multipolar:  many extensions from the cell body

bipolar:  one axon and one dendrite

unipolar: short single process leaving the cell body

36


functional properties of neurons


irritability: ability to respond to stimuli

conductivity: ability to transmit an impluse

37


Cell membrane potential


potential difference across cell membrane

plasma membrane is polarized at rest

fewer + ions are inside the cell than outside

resting potential caries with cell type-40 to -90 mV

38


Membrane potential cause


distributino of ions across plasma membrane

1  Na+ high outside cell, low inside

2 K+ low outside cell, high inside

negatively charged molecules: DNA, RNA, proteins

membrane permeable to Na+ and K+

Na+/K+ pump (2 Na+ out, 2 K+ in)

39


Membrane potential changes


depolarization

repolarization

40


membrane depolarization


membrane potential bnecomes less negative

Na+ channels open

K+ channels close

Na+ enters cell

41


Membrane repolarization


membrane potential returns to resting membrane potential (RMP)

K+ channel opens

Na+ channel closes

K+ leaves cell

42


Nerve impulses

Action potentials


rapid sequence of depolarization and repolarization

 

43


Nerve impulse threshhold potential


membrane potential at which an action potential is genterated

stimuli from other neurons sum to bring membrane to threshold

44


nerve impulse propagation


if the action potential starts it is propagated over the entire axon

if not enough it begins ar trigger zone and ends at axon terminals

45


Nerve impulse

myelinated axons


action potentials occur only at nodes of ranvier

saltatory conduction: AP appears to jump from node to node

Fast 120m/sec

46


Nerve impulse

unmyelinated axon


action potential travels along the entire plasma membrane

slow .5 m/sec

47


Synapse


neurons not in direct contact

separated by small gap : synaptic cleft

48


synapse structure


axon terminal of presynaptic neuron

synaptic vesicles filled with neurotransmitter

synaptic cleft

receptors on postsynaptic membrane

49


synapse signal transmission


impulses not directly able to cross to another nerve

action potential causes vesicle to move to membrane

neurotransmitter is released from axon terminal

neurotransmitter diffuses across synaptic cleft

neurotransmitter binds to protein receptors on dendrite of next neuron, post synaptic neuron

to stop a signal the neurotransmitter is broken down

50


Relexes


rapid predictable and involuntary response to stimuli

simplest neural pathway (reflex arc)

51


reflex pathway


Sensory receptor-sensory neuron-interneuron-motor-neuron-effector

52


Reflex types and regulation


somatic reflexes: effectors are skeletal muscles

autonomic reflexes:

                             smooth muscle regulation

heart and BP regulation

regulation of glands

digestive system regulation

53


Brain anatomy


3 lbs

contains about 100 billion multipolare neurons

4 major sections

cerebrum, diencephalon, brain stem, cerebellum

54


Cerebrum


2 cerebral hemispheres

paird left and right superior part of brain

connected internally by corpus callosum

includes more than half of brain mass

surface is made of ridges (gyri) and grooves (sulci)

55


Lobes of cerebrum


fissures divide the cerebrum into lobes

frontal lobe

parietal lobe

occipital lobe

temporal lobe

56


Frontal lobe


primary motor area:

voluntary control of skeletal muscle

sends impulses to skeletal muscles

Borca's area:

motor speech

involved in our ability to speak

problem solving and language comprehension

57


parietal lobe


somatic sensory area

receives and interprets impulses from the bodies sensory receptors

speech and language region

58


Occipital lobe


visoin center

59


Temporal lobe


olifaction (smell

Hearing

60


Cerebrum layers


gray matter:  outer layer in cerebral cortex composed mostly of neuron cell bodies

white matter:  fiber tracts deep to the gray matter

tract: bundle of fibers (axons) within the CNS

Basal nuclei: regions of gray matter burried within the white matter

61


Diencephalon


sits on top of the brain stem

enclosed by cerebral hemispheres

main parts:  Thalamus and Hypothalamus

62


Thalamus


surrounds third ventricle

relay staton for sensory impulses

transfers impulses to the correct part of cortex for localization and interpretation

63


Hypothalamus


located under the thalamus

important autonomic nervous system center

helps regulate body temp

controls water balance

regulates metablolism

important part of the limbic system (emotions)

pituitary gland attached

64


Brain stem


attaches to spinal cord

3 parts

Midbrain

Pons

medulla oblongata

65


midbrain


mostly composed of tracts of nerve fibers

reflex center for vision and hearing

66


pons


mostly composed of fiber tracts

modifies activity of respiratory centers in the medulla

67


medulla oblongata


lowest part of brain stem

merges into spinal cord

includes important fiber tracts

contains important control centers

heart rate control, BP regulatoin, respiratory centers sets rate and depth of breathing, swallowing and vomiting

68


Cerebellum


cooridinates skeletal muscle activity

helps maintain posture, balance and equilibrium

69


CNS protection


scalp and skin

skull and vertebral column

meninges

cerebrospinal fluid

blood brain barrier

70


meninges


3 connective tissue membranes covering brain and spinal cord

dura mater

arachnoid mater

pis mater

71


dura mater


double layered external covering

periosteum: attached to inner surface of skull

Meningeal layer: out covering of brain

folds inward in several areas

72


arachnoid mater


middle layer

web like

73


Pia mater


clings to surface of brain and spinal cord

contains superficial blood vessels

74


subarachnoid space


space between acrachnoid and pia mater

filled with cerebrospinal fluid

75


Epidural space


space bewtreen meninges surrounding spinal cord and bonds of vertebral canal

filled with adipose and loos connective tissue

76


cerebrospinal fluid


similar to blood plasma composition

formed by the choroid plexus, reabsorbed by arachnoid villi

watery cushion to protect brain

ciculated in subarachnoid space, ventricles and central canal of spinal cord

77


Ventricles


4 interconnected cavities with in the brain filled with CSF

CSF flows through

78


Hyrocephalus


CSF accumulates and exerts pressure on the brain if not allowed to drain

newborns

79


Blood brain barrier


includes the least permeable capillaries of the body

excludes many potentially harmful substances

useless against:

fats and fat soluable molecules

respiratory gases (CO2 and O2)

alcohol

Nicotine

Anesthesia

80


Spinal Cord


slender column of nerve fibers (tracts) and neurons

center for spinal reflexes

81


Spinal cord surface anatomy


extends from the foramen magnum of skull to the first or second lumbar vertebra

31 pairs of spinal nerves arise from spinal cord

Cauda equina

anterior median fissure

posterior median sulcus

82


Spinal cord internal anatomy

gray matter is mostly cell bodies

Dorsal (posterior) horns

Anterior (ventral) horns

Gray commissure surround the central canal

central canal is filled with CSF

83


Spinal cord exterior


White mater-fiber tracts

ascending tracts carry sensory information to brain

descending tracts conduct motor impulses from brain to motor neurons

pathways between brain and spinal cord

84


Spinal nerves


leave at each level of vertebra

dorsal roots: sensory fibers

sensory neurons found in dorsal root ganglia

ventral roots: motor fibers

motor neurons are found in the anterior horn

spinal nerve forms where posterior and anterior roots merge

85


Peripheral Nervous System

PNS


Nerves and ganglia outside the CNS

cranial nerve arises from brain

spinal nerves arise from spinal cord

86


nerve


bundle of neuron fibers

87


nerve structure


neuron fibers bundled by connective tissue

endoneurium surrounds each fiber

groups are bound into fascicles by perineurium

fascicles are bound together by epineurium

88


Autonomic Nervous System


portion of PNS that function automatically

2 neurons in series from CNS to effector

regulates activites of cardiac, smooth muscle and glands

 

89


autonomic nervouse subdivisions


Sympathetic nervous system

Parasympathetic nervous system

90


Sympathetic Nervous System


extraordinary situations-fight or flight

exercise, excitement, emergency and embarrassment

91


Parasympathetic Nervous System


housekeeping activites (rest and repose)

digestoin, defacation and diereses