Pathophysiology II - Chapter 43

This (ese) structure(s) provide buoyancy and shock-absorbing capacity?

CSF and meninges

From external to internal, what is the name and order of the meninges?

Dura mater, arachnoid mater, pia mater

Dura mater

thick, tough, collagenous, protects soft brain tissue

Arachnoid mater

thin, delicate, semitransparent, weblike, potential space unless pathology is present - CSF flows here

Pia mater

very thin, attached to the brain, follows every contour of sulcus and gyrus

Nervous system is divided into 2 principal systems

Central nervous system (CNS) and peripheral nervous system (PNS)

Central nervous sytem (CNS)

consisting of the brain and spinal cord

Peripheral nervous system (PNS)

with 31 pairs of spinal nerves and 12 pairs of cranial nerves

CNS Primary functions

• receiving and processing sensory information

• creating appropriate responses to be relayed to muscles and glands

CNS is the site of

emotion, memory, cognition, and learning

Blood supply to brain supplied by

2 pairs of arteries

• anterior carotid arteries

• posterior circulation

anterior circulation

internal carotid arteries

posterior circulation

vertebral arteries

Circle of willis

ring of vessels that unites anterior and posterior circulation at the base of the brain

Blood brain barrier (BBB)

specialized tight junctions between cells of the capillary endothelium

Which specialized glial cells make up the blood brain barrier?

Astrocytes

CSF-brain barrier

• cells that line the ventricles provide protection to the brain

Which cells are responsible for the production and maintenance of the cerebrospinal fluid?

ependymal cells

The cerebrum is made of all these structures

• cerebral cortex

• basal ganglia

• limbic cortex

• corpus callosum

Which structure contains midbrain, pons, and medulla

Brainstem

Which lobe contains the visual cortex?

Occipital lobe

True or False: The frontal lobe contains the somatosensory cortex

False - it’s parietal lobe

This lobe contains the auditory and vestibular centers (balance and hearing) and parts of the language center

Temporal lobe

This lobe contains the somatosensory cortex, limbic area is involved in memory and emotion; central regulates visceral and intestinal function

Parietal lobe

This lobe contains motor cortex, involved in complex thought, motivation, and morality

Frontal lobe

Parts of the cerebrum most closely associated with memory and emotion within the parietal lobe

Limbic system

Principal structures of the diencephalon

Thalamus, hypothalamus, and epithalamus

Processes and relays most of the signals traveling to and from the cortex and coordinates motor functions

• involved in the execution of motor function

Thalamus

Within diencephalon, specifically thalamus, what are the higher brain functions

emotion, language, creativity, and complex thought

Basal ganglia

Large masses of gray matter that lie deep within the cerebral hemispheres; involved in initiation, coordination, and execution of movement; control of skeletal muscles

The diencephalon includes the hypothalamic extension to

the pituitary

Thalamus function

involved in the execution of motor functions

• emotion, language, creativity, and complex thought

Hypothalamus function

Regulatory center for the autonomic nervous system (ANS) and along with the pituitary, produces and secretes hormones

Lesions of this structure result in ataxia (impaired balance) and failure of rapid movements

Cerebellum

Cerebellum functions

• Coordinates smooth movement and maintains posture and balance

• Compares the desired motor program with the moment-to-moment execution of the movement and makes instantaneous adjustments to improve the match

The lateral hemispheres of the cerebellum are involved in

planning and programming voluntary movements, especially learned, skilled movements

Which parts of the brain coordinates swallowing, vomiting, and coughing

Pons and Medulla

Brainstem is critical for

transmission of impulses between the brain and spinal cord

Midbrain contains

motor tracts to spinal cord

True or False: The spinal cord is part of the peripheral nervous system

False - it is part of the central nervous system

The spinal cord conveys nervous impulses between

the brain and 31 pairs of spinal nerves that innervate sensory organs and muscle cells of the body

Spinal nerves divide into 2 sections as they make contact with the spinal cord:

Dorsal roots and Ventral roots

Dorsal roots

carry afferent sensory neurons

Ventral roots

carry motor efferent neurons

The point at which sensory neurons enter the cord at which motor neurons exit represent

the separation between CNS and PNS

This division of the nervous system consists of 31 pairs of spinal nerves and 12 pairs of cranial nerves

Peripheral nervous system

PNS serves what functions

afferent sensory function and efferent motor function of the somatic and autonomic systems

Cranial nerves originate in the

brainstem, except for CN I and II which originate in the diencephalon

Each cranial nerve coordinates

motor, sensory, or mixed motor and sensory functions to specific areas of the body

Segment of the body innervated by a spinal nerve is called

a dermatome

All spinal nerves merge into a large group called a plexus EXCEPT

Thoracic nerves

True or False: Autonomic nervous system is composed of neurons in the PNS that mediate automatic or involuntary functions

False - it contains neurons in the CNS and PNS

ANS has sensory afferents and motor efferent that primarily innervate

visceral organs and blood vessels

Neurons that emerge from the spinal cord

preganglionic

Neurons traveling to the target cell

postganglionic

Effect of SNS and PSNS on target organs is nearly always

antagonistic

• if one contracts smooth muscle, the other relaxes it

• if one stimulates glandular release, the other inhibits it

• if one speeds up a process, the other one slows it down

Which divisions of the nervous system secrete acetylcholine?

Somatic nervous system, PSNS, and preganglionic neurons of the SNS

Postganglionic neurons of the SNS secrete which neurotransmitter?

Norepinephrine, except for sweat glands and some skeletal muscles (acetylcholine receptors)

Postganglionic neurons of the PSNS secrete which neurotransmitter?

acetylcholine

Acetylcholine receptor on the effector cells of the SNS secrete which neurotransmitter?

muscarinic receptor

True or False: Inhibitory neurotransmitters create inhibitory postsynaptic potentials (IPSPs) caused by opening of channels that allow potassium influx or chloride efflux

False - Chloride influx and potassium efflux

Excitatory neurotransmitters create excitatory postsynaptic potentials (EPSPs) resulting from

opening of channels that allow sodium influx

Neurons

generate and transmit nerve impulses

Glial cells

provide support functions to neurons

• glial cells outnumber neurons - 10:1

Dendrites

receive signals and transmit them to the cell body

Axon

generates and conducts action potentials

Neurons may be

inhibitory or excitatory

4 types of neuroglia

• oligodendrocytes

• astrocytes

• microglia

• ependymal cells

ologodendrocytes

form myelin sheath that wraps around nerve axons

astrocytes

maintain integrity of BBB, regulate ionic balance of the interstitial fluid, and transfer nutrients from capillaries to neurons

microglia

provide phagocytic functions

ependymal cells

produce CSF and maintain CSF-brain barrier

Voltage-gated potassium channels assist with

repolarization - potassium flows out of cell

Nodes of ranvier

allow impulse to hop quickly from node to node

True or False: Peripheral neurons may be regenerate if the injury is not severe

True

These structures send action potential to the spinal cord through the dorsal root which are later intercepted by thalamus and relayed to the somatosensory cortex

Sensory receptors

Complete the following statement: Motor function is transmitted from the ______ down the ______ crosses over down the ______ to control motor function on the ______ side of the body

primary motor cortex; cortico-spinal tract; spinal cord; the other side of the body

Motor Activity preprogrammed into neuronal connections in the spinal cord without going to the brain

Spinal reflex

Protective mechanism that allows withdrawal of a body part from a physical threat while maintaining balance

Withdrawal reflex

Amine neurotransmitters are in

limbic system, hypothalamus, and basal ganglia

Amines example

noradrenaline, dopamine (DA), serotonin

Amines function

Regulate thought, process, and mood

Amino acids include what mechanisms

excitatory and inhibitory mechanisms

Amino acids example

glutamate (excitatory) and GABA (inhibitory)

Amino acids glutamate is involved

in memory

Neuronal circuits

patterns of neuronal synaptic connections

• divergence

• convergence

Divergence

used to send sensory input to a large number of receiving neurons

Convergence

mechanism of processing and integration of input

Failure of nervous system to develop

anencephaly or myelomeningocele

Excessive neuronal degeneration in adulthood

Alzheimer disease or senile dementia

Severely injured CNS neurons generally

do not regenerate

damaged axons

break up and then disappear

axonal injury is

common event even in mild concussion

Sensory function begins with what activation of specialized dendritic processes at the ends of sensory afferents that project to the spinal cord?

sensory receptors

After sensory receptors, secondary neurons in the cord

are activated and carry the signals up the cord to the brain

Thalamus sensory function

relays signals to various brain areas, including the somatosensory cortex in the parietal lobe

Stimulation of receptors by mechanical stretch, temperature, or chemicals alters

membrane permeability resulting in receptor potentials

Sensory information from both sides of the somatosensory tracts are transmitted from

the thalamus to the same areas of the somatosensory cortex

Spinal reflexes include

motor activity preprogrammed into neuronal connections in the spinal cord

• allows sensory information to cause a reaction in the spinal cord without going to the brain