APEX Brain

The brain is made up of 2 types of cells. What are they?

Neurons and Glial cells

What is the functional unit of the nervous system?

-Primary role?

Neuron - receives and sends information

The cell bodies form what kind of matter?

Grey matter

The axons form what kind of matter?

White matter d/t myelin

Which part of the neuron receives and processes signals?

Dendrites

Which part of the neuron integrates the signal and has the cellular machinery?

Soma

Where is the axon hillock located?

What does the axon do?

-Between soma and axon of a neuron

-Sends signals

What does the presynaptic terminal do?

Releases neurotransmitters

What are the 3 types of neurons found in the CNS?

Multipolar

Pseudounipolar

Bipolar

Most of the CNS neurons are what type?

Multipolar

Where are pseudounipolar neurons found?

Dorsal root ganglion and cranial ganglion

Where are bipolar neurons found?

Retina and ear

You have 2 eyes and 2 ears

Functions of the glial cells (nerve glue) (4)

Support neuronal function by:

-Creating a healthy ionic environment

-Modulate nerve conduction

-Controlling reuptake of neurotransmitters

-Repairing neurons following neuronal injury

4 Types of glial cells

-Astrocytes

-Oligodendrocytes

-Microglia

-Ependymal cells

Which type of glial cell is most abundant?

Astrocytes

Astrocytes function

-Regulation of metabolic environment

-Repair neuron after neuronal injury

Where are ependymal cells located?

-Roof of the 3rd and 4th ventricles and spinal canal

*Involved in CSF production

Which cells form the choroid plexus?

Ependymal cells

Oligodendrocytes function

Form the myelin sheath in the CNS

Which cells form the myelin sheath in the PNS?

Schwann cells (myelinated beans that get skipped- in periphery)

Microglia function

-Act as macrophages and phagocytize neuronal debris

Where do most CNS tumors arise from?

The glia

Label the brain

Pons

Medulla oblongata

Midbrain

Temporal lobe

Hypothalamus

Spinal cord

Cerebellum

Occipital lobe

Parietal lobe

Parietooccipital sulcus

Frontal lobe

Central sulcus

Thalamus

Corpus callosum

Lateral ventricle

The brain can be divided into 4 areas:

-Cerebral hemispheres

-Diencephalon

-Brainstem

-Cerebellum

What connects the hemispheres of the brain?

Corpus callosum

-Located deep in the longitudinal fissure

What are the 4 lobes of each cerebral hemisphere

-What do they contain?

-Frontal - contains motor cortex

-Parietal - contains somatic sensory cortex

-Occipital - contains vision cortex

-Temporal - contains auditory cortex and speech centers

Wernicke's area location and function

Located in temporal lobe

Understanding speech

Broca's area location and function

Located in temporal lobe

Motor control of speech

Cerebral cortex functions

Cognition, sensation, movement

-Structure of the cerebral hemisphere

Hippocampus functions

Memory and learning

-Structure of the cerebral hemisphere

"University campus for memory and learning"

Amygdala functions

Emotion, appetite, responds to pain and stressors

-Structure of the cerebral hemisphere

Basal ganglia functions

Fine control of movement

-Structure of the cerebral hemisphere

"fine control when adding basal to food"

Diencephalon contains...

Thalamus and hypothalamus

Thalamus functions

-Relay station that directs information to various cortical structures

What is the primary neurohumoral organ?

Hypothalamus

neurohumoral - secrets neurotransmitters

4 structures in the brainstem

Midbrain

Pons

Medulla

Reticular activating system

Tracts in the midbrain

Auditory and visual

What, in the brainstem, causes autonomic integration?

Pons and medulla

Reticular activating system function

Controls consciousness, arousal, and sleep

What are the three parts of cerebellum

Archicerebellum

Paleocerebellum

Neocerebellum

Archeocerebellum function

Maintains equilibrium

-Structure of cerebellum

"architecture needs equilibrium"

Paleocerebellum

Regulates muscle tone

-Structure of cerebellum

"Paleo diet muscles"

Neocerebellum

Coordinates voluntary muscle movement

-Structure of cerebellum

What cranial nerve is most likely to be compressed by a pituitary tumor

A. Olfactory

B optic

C Oculomotor

D. Facial

B optic

Number and label cranial nerves

Numbers and Names

Cranial Nerves

On Occasion Our Trusty Truck Acts Funny Very Good Vehicle Any How

What are the functions of each cranial nerve?

Some Say Marry Money But My Brother Says Big Brains Matter Most

Sensory, Motor, Both

Cranial Nerve I

-Nerve name

-Function

-Bedside test

Olfactory

Sensory

Smell

Cranial Nerve II

-Nerve name

-Function

-Bedside test

Optic

Sensory

Vision

Cranial Nerve III

-Nerve name

-Function

-Bedside test

Oculomotor

Motor

Eye movement and pupil constriction

3 - eye lashes so all movement

Cranial Nerve IV

-Nerve name

-Function

-Bedside test

Trochlear

Motor

Eye Movement down and center

Cranial Nerve V

-Nerve name

-Function

-Bedside test

Trigeminal

-VI: ophthalmic

-V2: Maxillary

-V3: Mandibular

Both

Somatic sensation to face

Somatic sensation to anterior 2/3 tongue

Muscles of mastication

Cranial Nerve VI

-Nerve name

-Function

-Bedside test

Abducens

Motor

Eye Movement out to sides

Cranial Nerve VII

-Nerve name (5 branches)

-Function

-Bedside test

Facial (temporal, zygomatic, buccal, mandibular, cervical)

Both

Facial movement

Eyelid closing

Taste anterior 2/3 of tongue

*Two zebras bit my carrot

*Two zits by my clavicle

Cranial Nerve VIII

-Nerve name

-Function

-Bedside test

Vestibulocochlear

Sensory

Hearing and balance

Cranial Nerve IX

-Nerve name

-Function

-Bedside test

Glossopharyngeal

Both

Somatic sensation and taste to posterior 1/3 tongue

Cranial Nerve X

-Nerve name

-Function

-Bedside test

Vagus

Both

Swallowing

Cranial Nerve XI

-Nerve name

-Function

-Bedside test

Spinal accessory

Motor

Shoulder shrug

Cranial Nerve XII

-Nerve name

-Function

-Bedside test

Hypoglossal

Motor

Tongue movement

Cranial Nerve Eye functions

Where do cranial nerves arise from?

Brain and brainstem

-12 cranial nerves

Cranial nerves are part of the central or peripheral nervous system?

-Which one is the exception?

-Peripheral nervous system

-Optic Nerve (II) is part of the central nervous system and is surrounded by dura

What is tic doulureaux?

What nerve is affected?

Trigeminal neuralgia CN 5

Excruciating neuropathic pain in the face

What nerves control eye movement

CN 3, 4, 6

Mnemonic for five branches of the facial nerve (CN7)

Two Zebras Bit My Carrot

Bell's palsy results from injury to...

the facial nerve (7)

-causes ipsilateral facial paralysis

Parasympathetic output is carried by which cranial nerves?

III, VII, IX, and X

Which nerve is responsible for 75% of all parasympathetic activity?

Vagus

What does the blood brain barrier separate?

What restricts passage of large molecules and ions within the BBB?

-Separates CSF from plasma

-Tight junctions restrict passage of large molecules and ions (does not have carrier proteins)

When is the BBB dysfunctional?

Sites of tumor, injury, infection, or ischemia

& poorly developed in the neonate

Cerebrospinal fluid functions (3)

-Cushions the brain

-Provides buoyancy

-Delivers optimal conditions for neurologic function

Cerebrospinal fluid locations (3)

-Ventricles (left lateral, right lateral, third, and fourth)

-Cisterns around the brain

-Subarachnoid space in brain and spinal cord

Where is the BBB not present? (5)

Chemoreceptor trigger zone (CTZ)

Posterior pituitary gland

Pineal gland

Choroid plexus

Parts of the hypothalamus

"Diencephalon"

The BBB is poorly developed in...

neonates

CSF volume

150mL

Specific gravity of CSF

1.002-1.009

What produces CSF and where is it located?

-Produced by ependymal cells of choroid plexus in cerebral ventricles

-Choroid plexus is located in all 4 cerebral ventricles

Where is CSF reabsorbed

Arachnoid villi in the superior sagittal sinus. Reabsorption is dependent on pressure gradient between CSF and venous circulation

CSF pressure

5-15mmHg

Flow of CSF

Lateral ventricles

Foramen of Monro

3rd ventricle

Aqueduct of Sylvius

4th ventricle

Foramen of Luschka and Magendie

Subarachnoid Space

Superior sagittal sinus/arachnoid villi

"Love My 3 Silly 4 Lorn Magpies"

Production rate of CSF

30mL/hr

Relative tonicity of CSF compared to plasma

Isotonic

(CSF is isotonic with plasma, it is not an ultrafiltrate of plasma and has its own chemical composition)

-Osmolarity the same 295 mOsm/L

Site of absorption of CSF

Reabsorbed into venous circulation via arachnoid villi in the superior sagittal sinus

CSF reabsorption is dependent on the pressure gradient between ___ and ___

CSF and venous circulation

Potassium in CSF compared to plasma

2.8 in CSF vs. 4.5 in plasma

"Guess lower - everything is lower except CO2 in the brain"

Which electrolytes are similar between CSF and plasma?

Sodium

Bicarb

Chloride (119 in CSF vs 102 in plasma)

PaCO2 (47 in CSF vs 40)

Glucose content in CSF vs. plasma

60 in CSF vs. 90 in plasma

*all used up

Protein in CSF vs. plasma

35 in CSF vs. 7000 in plasma

pH of CSF

7.33

(PaCO2 47 in CSF)

What is hydrocephalus

Excessive accuulation of CSF in the brain which can increase ICP

What are the 2 types of hydrocephalus

Obstructive hydrocephalus- obstruction to CSF flow in the ventricular system (most common)

Communicating hydrocephalus- decreased CSF absorption by arachnoid villi (ICH) or overproduction of CSF

Surgical management for either type of hydrocephalus

Depends on cause

Could either be a catheter in cerebral ventricles to drain CSF or placing a ventriculoperitoneal shunt (brain to heart) or ventriculoperitoneal shunt (brain to belly)

Global cerebral blood flow

45-55mL/100g tissue/min

Percentage of cardiac output going to global cerebral blood flow

15%

Cerebral autoregulation definition

-Formula for cerebral blood flow

The brains ability to maintain a constant cerebral blood flow over a wide range of mean arterial blood pressures

CBF = Cerebral perfusion pressure/Cerebral vascular resistance

-Benefit: ensures steady supply of O2 even with blood pressure fluctuations

Cortical CBF

75-80mL/100g/min

Subcortical CBF

20mL/100g/min

At what level of CBF is there evidence of ischemia?

20mL/100g/min

At what level of CBF is there complete cortical suppression?

15mL/100g/min

At what level of CBF is there membrane failure and cell death?

<15mL/100g/min