Chapter 14 Flashcards
What is the brain like at 3-4 weeks of development?
Already 3 distinct divisions of the brain
What are the 5 divisions of the brain seen at 5 weeks of development?
- Telencephalon
- Diencephalon
- Mesencephalon
- Metencephalon
- Myelencephalon
Four principle parts of brain?
- Brain stem
- Cerebellum
- Diencephalon
- Cerebrum (cortex)
Ratio of neurons to neuroglia cells?
10x number of neuroglia cells
3 components of brainstem
Mid brain
Pons
medulla
Brain stem attatchment to spinal cord?
Continuous
Role of brain stem?
Similar role to ANS
What is the cerebellum
Inferior to hemispheres, posterior to brainstem
- Voluntary movement control
What is the diencephalon?
Just above brainstem
Thalamus, hypo thamlamus, and epithalamus (Pineal gland is part of epi)
- Regulates Emotions
What is the Cerebrum?
AKA cortex
- Cognition and intelligence
5 aspects of brain development in 1st year (after birth)
- Hypertrophy (increase in size) of neuroglial cells
- Proliferation (Multiplication) of neuroglial cells
- Increase in number of synapses (existing neurons forming connects)
- Increased dendrite branching (connect to more other neurons)
- Increase in myelination (Lack of myelination reason for lack of motor coordination)
Protective coverings of CNS (Plus spaces)
Epidural Space
Dura Mater
Subdural space
Arachnoid Mater
Subarachnoid Space
Pia Mater
Epidural Space
a space between
the dura mater and the wall of the vertebral canal
Filled with cushion of fat and protective tissue
Dura mater
Toughest meninge layer
Subdural space
Does not exist in skull - DM and AM fused together (But still called a space)
In spine is full of interstitial fluid
Arachnoid Mater
Middle connective tissue layer
- Avascular
Fused with Dura mater in Skull
Subarachnoid Space
Space beneath arachnoid mater containing CSF
Pia Mater
- Inner most delicate tissue that lies right on top of brain tissue
- Very vascular, blood vessels go into brain (jugular vein takes blood out)
4 Major blood vessels bringing blood to brain
Internal carotid (Page 835) (21.19)
- Vertebral arteries (Page 835)
- Circle of Willis (Page 835) (21.19)
- Internal Jugular veins (Page 850) (21.24
Glucose and brain
- Brain requires constant supply of glucose
Brain CAN break down fats for energy as well, but glucose is best
Hypoglycemia
Glucose levels dropping results in fainting
Brain percent of body weight
2%
What amount of the cardiac output does brain use?
20%
Brain and relation to O2 and blood
Requires continuous supply of O2 and blood
- If deprived 1-2 minutes will not generally result in long term problems
- 4-5 minutes is where long term problems will occur, commonly occur months or years later
Cold reduces demands of brain therefore can last longer without O2
BBB
Specific to capillaries and brain tissues
- Capillaries in brain have astrocytes, tight junctions bw cells
- Prevents pathogens from getting into blood and into brain tissue
- Demands differences for medication treatment
- Trauma to head/brain can break the barrier
What sort of things can breach BBB
Proteins, antibodies, viruses, anything water soluble CANNOT
Most lipid soluble (O2,CO2, alcohol, anesthetic) CAN
Extensions of dura mater
Falx cerebi
Falx cerebelli
Tentorium cerebelli
Falx cerebi
Arm of dura mater - Separates L and R hemispheres (Still communicate)
Falx cerebelli
Arms of dura mater Separates Cerebellum into L and R hemispheres
Tentorium cerebelli
Dura mater arms seperates Cerebrum from cerebellum
4 main hollows of brain
Lateral ventricles (1 in each hem)
3rd Ventricle (Inferior to Laterals)
4th Ventricle (Aprox Brain stem location)
Where is CSF found?
All ventricles filled with CSF
- All ventricles produce and collect CSF
What is CSF composed of ?
predominantly water, also O2, glucose, protein, WBCs (Type and number of WBCs varies if person is healthy or not)
Normal amount 80-150mL CSF at a given time
Arachnoid Villus
(fingerlike projections)
- At Locations where CSF is reabsorbed back into blood
- Poke into sinuses
- Choroid Plexuses
(network of capillaries)
- Found along with ependymal cells in all of the ventricles
- Produce CSF
- Superior Sagittal Sinus
(On top of the brain, midline, cavity)
- Number one site of reabsorption of cerebral spinal fluid
3 Ways CSF contributes to homeostasis
Mechanical
- Shock absorbers
b) Chemical
- Tries to keep electrolytic chem environment ideal for APs
c) Circulation
- Provides circulation pathway for nutrients and O2 to pass through
- Runs down central canal (Spinal tube)
- Reabsorbed back into blood
CSF circulation
Choroid plexus (Lat ventricles)
3rd Ventricle
4th Ventricle
Central Canal & Subarachnoid space
How is the CSF removed from brain
Intraventricular foramine
Cerebral aqueduct
Apertures
Ideal CSF absorbtion rate
20mL per hour
How is CSF reabsorbed?
Arachoid villi and superior sagittal sinus
Hydrocephalus
Overproduction of CSF from infection or inflammation (Water in the brain)
Nuclei/us
Clusters of cell bodies inside CNS
Parts of brainstem
Midbrain
Pons
Medulla oblongata
Medulla oblongata
Ascending and descending (Sensory Motor tracts)
Nuclei for CV, HR, BP, Blood vessel, vomiting, swallowing, sneezing etc.)
. Olive (Olivary Nucleus)
Cuneate Nucleus and Gracile Nucleus (R&L)
Nuclei for sensory/motor input/output of cranial nerves VIII, IX, X, XI, XII
Nuclei for taste, hearing and equilibrium sensory pathways
Cuneate Nucleus and Gracile Nucleus
Relay info to and from the thalamus
Thalamus depetermines where info needs to go
Moniter touch, pressure, vibration, proprioception (Body awarenss, movement, joint positions)
Part of Medulla
Important Nuclei of the Pons
Pontine Nuclei
Vestibular Nuclei
Pneumotaxic Area
Apneustic Area
Nuclei for 4 pairs of cranial nerves
Mesencephalon
AKA Midbrain
Extends from Pons to diencephalon
Parts of Midbrain
Cerebral aqueduct passes through
Cerebral Peduncles
Tectum (Posterior)
Substantia Nigra (L & R)
Red Nucleus (L and R)
Cerebral Peduncles (anterior)
Paired bundle of axons in midbrain
Carry cortical spinal tracts (motor impulse to spine)
- Carry Cortical bulbar tracts
- Carry Cortical pontine tracts
Tectum (Posterior) parts (2)
Superior colliculi (2) – reflexes of head, neck and trunk + Scanning/tracking
) Inferior colliculi (2)
- Reflexes for head, neck and trunk for auditory stimuli
- Startle reflex
Posterior part of midbrain
Substantia Nigra (L & R)
Produces NT: Dopamine
- Dopamine controls subconscious motor movements
Part of midbrain
What is Parkinsons and what is the culprit
Underproduction and problem binding of Dopamine
Substantia Nigra
Red Nucleus
Part of the midbrain that Connects the cerebellum and cortex (Voluntary movement control)
Good blood supply
Reticular Formation
a netlike region of interspersed
gray and white matter that extends through brainstem
Contains Motor and sensory neurons
Important in RAS
RAS
Reticular Activation System
- Body’s alarm clock
- More active RAS = more awake
- Less Active RAS = sleepy
Stimulated by all senses but smell
Helps regulate sleep cycle
What sense does not not stimulate the RAS
Smell
What seperates cerebellum from cerebrum
Transverse fissure (And tentorium cerebelli)
Ataxia
- Damage to cerebellum (trauma, tumor, alcohol abuse, motor skills less refined, sppech less fluent)
What is an alcohol test a test of
cerebellar test – alcohol decreases function of cerebellum
Diencephalon
Extends from brain stem to cerebrum
- Includes the thalamus, hypothalamus, epithalamus
- Many rooms/compartments in thalamus
Relay station for info coming in and coming out
Thalamus role
Keeps a person conscious
Hypothalamus four major regions
i) Mammillary Region
- Reflex for olfaction
ii) Tuberal Region
- Connects Pituitary gland to hypothalamus
iii) Supraoptic Region
- Main area that controls Pit gland
iv) Preoptic Region
- Works along with brain stem for autonomic NS control
Hypothalamus funcitnos
ANS control
Hormone Production (Linked to pit gland)
Emotional/behavioural regularion (Along with limbic sys)
Eating/drinking regulation
BOdy Temp contrl
Circadian rythy/arousal control (24 hr awake sleep cycle)
- Makes tired when dark, awake when light
2 Components of Epithalamus
Pineal Gland and Habenular Nuclei
Role of Pineal Gland
- Secretes melatonin (main hormone responsible for sleepy feeling vs awake feeling)
- Light correlates with melatonin release (Daylight savings affects awakeness)
Role of Habenular Nuclei
- Links emotion to olfaction (Positive or negative to smell)
- 80% of taste linked to smell
Circumventricular Organs (CVO’s)
Receptor structures that primary measure pH levels
- Signals hypothalamus
- Wherever there are CVOs there is NO BBB
5 Lobes of Cerebrum
Frontal, Parietal, temporal, occipital, Insula
Cerebrum responsible for
Intelligence, cognition, personality
Corpus Callosum
- Myelinated white tracts which connect R to L hemispheres
- Large area in the center of the brain
- Sensory and motor back and forth
Most well known fissure
Longitudinal Fissure
Gyrus
- Each bump or ridge in brain
- Typically gyrus’s in opposite sides of brain handle similar kinds of information
Central Sulcus
(Front to back, motor (in front) sensory in back)
Cerebral White matter made up of
Myelinated axons and tracts
Types of myelinated tracts
Association tracts
- Gyrus to Gyrus (Same hem)
Commissural Tracts
- Gyrus to Gyrus (opp. hem.)
Projection Tracts
- Cerebrum decending to other part of CNS (Thalamus usually and then elsewhere)
Basal Ganglia/nuclei (3) + lumped roles
Basal Nuclei if in CNS
- Globus pallidus
- Putamen
- Caudate nucleus
In general, they are all involved in voluntary motor control
- Info on when to initiate movement (Anticipation) and when to terminate a movement.
- Distributed in each hemisphere (Clusters of grey matter
Limbic System
Emotional region of the brain
- Important for memories
Hippocampus
Amygdala
encircles upper part of brain stem
Hippocampus
Part of the limbic system responsible for
- Linking memories to smell
- Important for memories
Amydala
Part of limbic system responsible for:
Rage, anger, fear, affection
- Antisocial behaviours (serial killer)
Detatchment syndrome
Lack of affetion in childhood resulting in amydala issues
Problems associated with amydala
Parkinson’s(midbrain more) , Schizophrenia, OCD, Anxiety (Limbic basal nuclei challenes)
What divides anterior from posterior brain
Central Sulcus
What type of neurons are typically associated with anterior brain vs posterior?
Front is motor
Back is sensory
Primary somatosensory areas
Touch, tickle, pressure, itch
Primary visual area Injuries
Impact ransfers to opposite side of brain
- Concussion resulting in double vision
Primary auditory area
Temporal lobe close to ears
Primary gustatory area
- Taste, receive most of incoming sensory information and typically allow for discrimination (identification of sensation)
Primary olfactory area
- Smell, , receive most of incoming sensory information and typically allow for discrimination (identification of sensation)
Motor Primary motor area
(front of cerebral cortex) – anterior to central sulci
- Large expanse of area
- Areas that need more control require large areas of cortex controlling them (discreet muscle requires more neurological control)
Broca’s area
Frontal Lobe
Linked to correct speaking (allows for articulation)
Aphasia
- Condition where damage occurs to Wernicke’s or brokers OR both
Resulting in speaking disability
Wernicke’s association area
Used in Word choice
Non- Fluent aphasia
Damage to brokers area (mind knows what it wants to say but you cannot articulate and vocalize)
Fluent aphasia
Damage primarily Wernicke’s area (Say a whole bunch of words that don’t make sense)
Association areas anterior to motor area
- Assistant to primary areas
- Mainly with the motor area
- Give clarity to motor areas so correct decision can be made
Somatosensory area
- Allow to determine the texture of two objects
- Refine sensory input
Visual association area
- Help visual area to evaluate and analyze type of picture
How does facial recognition occur
- Mainly temporal lobe inferior that works along with visual to recognize someone’s face when you see them
Left brain more linked to
to math, chemistry, physics – logical thinking and reasoning
- More developed left brain would pick up sign language faster than someone on the right side
RIght brain more linked to
Creativity, music, art etc.
4 types of brian waves
Alpha, beta, theta, delta
How are brainwaves measured?
Electrodes measure APs in brain
What are alpha waves?
(8-13 cycles per second normal) for adult who is awake with eyes closed (not asleep)
Beta waves
- Beta waves: (14-30 cycles per second): dominant brain wave when receiving lots of sensory input – many APS firing around
Theta waves
(4-7 Cycles per second): dominant brain wave when under severe emotional distress
Delta waves
(1-5 Cycles per second): dominant in adult during deep sleep and newborns and infants when they’re awake.
What is PTSD in relation to brain waves?
Brain wave pattern changed from what would be the ideal
What is does distortion on the brain mean
Pressure
What is transection
Puncture or damage to brian
- Usually translates into change in O2 supply and number of free radi
Contusion
Bruising (microscopic blood vessels are leaking)
- blood vessels of pia matter
- Blood may get into subarachnoid space
- Unconsciousness is longer
- Reflexes ara slower
- BP may drop due to bleeding
Laceration of brain
- Tearing/puncture of brain
- Knife wound, gunshot
- Pia mater and larger blood vessels damaged
- Cerebral hematoma (blood collection and swelling of brain)
- If bleeding is severe and is not addressed it will pool and increase pressure on brain
12 cranial nerves
- Olfactory Nerve (I)
sensory nerve of smell
nasal mucosa to olfactory bulbs
through cribiform plate of ethmoid bone - Optic Nerve (II)
sensory nerve of vision
forms optic chiasm - Oculomotor Nerve (III)
motor nerve of extrinsic eye muscles - Trochlear Nerve (IV)
motor to superior oblique - Trigeminal Nerve(V)
sensory to face, motor to mouth
ophthalmic, maxillary and mandibular divisions - Abducens Nerve (VI)
motor to lateral rectus - Facial Nerve (VII)
sensory and motor face to face
temporal, zygomatic, bucal, mandibular, cervical branches - Vestibulocochlear Nerve (VIII)
sensory from ear
hearing and equilibrium - Glossopharyngeal Nerve (IX)
sensory and motor to tongue and pharynx - Vagus Nerve (X)
sensory and motor to many organs
extends beyond head and neck - Accessory Nerve (XI)
motor to neck
cranial and spinal roots - Hypoglossal Nerve (XII)
motor to tongue
How does aging affect the brain?
AP potentioal velocity decreases with aging
Less efficient
Reflexes are slower
It takes older adults longer to take in info and respond
Drive slower bc everything is coming so fast
CVA
- Cerebral vascular accident (Stroke)
- Some region of brain dies off
- I.e. intercranial bleed
- Decussation (motor and sensory pathways cross over in medulla in brain) results in opposite side effected by stroke
TIA
(Transient Ischemic Attack)
- Minutes to 24 hrs someone has symptoms of stroke
- Then things return back to normal
- Generally a stroke is more likely to occur within the next five years
Alzheimer’s
Type of dementia
- Early onset is becoming more prevalent
- Remember experiences with greater emotion
- Struggle with forming new memories
ADHD
- Identified as a different style of learning
- IQ is not less
- Different way of processing emotion
- Riddelliine was the old prescription
Part of brain housing respiratory and cardiovascular control centers?
Medulla
What are pyramids in the medulla?
Bulges of white on anterior surface
Decussation of pyramids?
90% of motor tracts controlling skeletal muscles from medulla cross to opposite side of body
What and where are cerebral peduncles
Midbrain
White fibers connecting upper and lower brain areas
Superior colliculi
Reflex center in midbrain controlling eye, head and neck movement with visual stimulization
Inferior colliculi
Part of midbrain containing Relfexcenter for head and trunk movement in response to auditory stimulus
What works with the medulla to control respiration?
Pons
Cerebral Cortex
Outer grey matter of cerebellum
Cerebral peduncles
wo stalks that attach the cerebrum to the brainstem
