Chapter 14: the Brain& Cranial Nerves Flashcards
Summarize the most important function of human brain (receive information)
To control the movements of the body (determine what you are going to do in the future, impact the world by planned movements )
Three major portions of the brain
Cerebrum , Cerebellum, Brainstem
is 83% of brain volume, cerebra hemisphere
Cerebrum
contains 50% of the neurons; second largest brain region, located in posterior cranial fossa
10% mass of brain
motor control, movement
Cerebellum
is the portion of the brain that remains id the cerebrum and cerebellum are removed, diencephalon, midbrain, pons, and medulla oblongata
Brainstem
deep groove that separates cerebral hemispheres
Longitudinal fissure
think folds that make up the brain
Gyri (gyrus)
shallow grooves in between the folds
Sulci (sulcus)
thick nerve bundle at boot, of longitudinal fissure that connects hemispheres
Corpus callosum
the seat of neuron cell bodies, dendrites, and synapses
Dull white(grayish) color when fresh due to little myelin
forms surface layer CORTEXT over cerebrum and cerebellum (over all fold)
Forms NUCLEI deep within brain
Gray matter
bundles of axons
Lies DEEP TO CORTICAL GRAY MATTER, opposite relationship spinal cord
Pearly white color from Myelin around nerve fibers
Composed of TRACTS, or bundles of axons, that connects one part of the brain to another, and to the spinal cord
White matter
three connective tissue membranes that envelop the brain
Lies between the nervous tissue and bone
they are the DURA MATER, ARACHMOID MATER, and the PIA MATER
Protect the brain and provide structural framework for its arteries and veins
Meninges
in cranial cavity; has two layers
outer PERIOSTEAL
Inner MENINGEAL
Creates DURAL SINUSES
Dura Mater
equivalent to periosteal of cranial bones
Periosteal
Continues into vertebral canal and forms Dural sac around spinal cord
meningeal
pockets of cervical spinal fluid
Dural Sinuses
transparent membrane over brain surface
spider web like
Arachnoid mater
Very think membrane that follows contours of brain, even dipping into sulci
not usually visible without a microscope (so thin you cant observe)
Both involved with circulation, production and reabsorption of the CSF
Pia mater
inflammation of the meninges
serious disease of infancy and childhood
Caused by bacterial and virus invasion of the CNS by way of the nose and throat
Pia mater and Arachnoid are most often affected
Bacterial___
Meningitis
can cause swelling of the brain enlargement of the ventricles, and hemorrhage
comes thru blood, no blood brain barrier
swellings what kills
Bacterial Meningitis
spongy mass of blood capillaries on the floor of each ventricle
Choroid plexus
neuroglia that lines the ventricles and covers choroid plexus
Produces CSF
Ependyma
clear, colorless liquid that fills the ventricles and canals of CNS
Bathes its external surface (purpose)
100 to 160 mL normally present at one time (replaces 4X a day)
Production begins w/ filtration of blood plasma thru the capillaries of the brain
Cerebrospinal fluid (CSF)
Buoyancy
Protection
Chemical stability are functions of what
Big 3
CSF
Allows brain to attain considerable size without being impaired by its own weight
Brainfloats
Buoyancy
Protects the brain from striking the cranium when the head is jolted
Protection
Flow of CSF rinses away metabolic wastes from nervous tissue and homeostatically regulates its chemical environment
Right amount of ions Na, K, Ca
Chemical stability
encourage endothelial cells to move together to prevent infection ; destroy anything they don’t like
Perivascular feet
is also a source of antibodies, macrophages, bacterial toxins, and other harmful agents
blood
strictly regulates what substances can get from the bloodstream into the tissue fluid of the brain
Induce the endothelial cells
Astrocytes contact capillaries
Brain barrier system
reach out and contact capillaries with their perivascular feet
Astrocytes (blood brain barrier)
Induce the ______ cells to form tight junctions that completely seal off gaps between them
endothelial (blood brain barrier)
Blood capillaries throughout the brain tissue
Capillaries of the choroid plexus (of the ventricles)
Two points of entry must be guarded (Blood brain barrier)
to water , glucose, and lipid-soluble substances such as oxygen, carbon dioxide, alcohol, caffeine, nicotine, and anesthetics ( pass thru blood barrier easily)
Obstacle for delivering medications such as antibiotics and cancer drugs (don’t pass thru blood brain barrier )
Blood barrier system is highly permeable
places in the third and fourth ventricles where the barrier is absent
Blood has direct access to the brain ( 3rd & 4th Ventricle)
Enables the brain to monitor and respond to fluctuations in blood glucose, pH, osmolarity, and other variables
Circumventricular organs (CVOs)
Hindbrain – Pons, Cerebellum, and Medulla oblongata
Midbrain – Midbrain
Forebrain – Thalamus, Hypothalamus, and Cerebrum
Brain parts from an embryological perspective
Thalamus, Hypothalamus, and Cerebrum
Forebrain
Midbrain
Midbrain
Pons, Cerebellum, and Medulla oblongata
Hindbrain
Begins at foramen magnum of the skull
Slightly wider than spinal cord
All nerve fibers connecting the brain to the spinal cord pass through the medulla
Contains cardiac, vasomotor, and respiratory centers
Medulla Oblongata
Cardiac center Adjusts rate and force of heart Vasomotor center Adjusts blood vessel diameter Respiratory centers Control rate and depth of breathing Reflex centers (autonomic ally) For coughing, sneezing, gagging, swallowing, vomiting, salivation, sweating, movements of tongue and head
Functions of the Medulla Oblongata
Adjusts rate and force of heart
Cardiac center
Adjusts blood vessel diameter
Vasomotor center
Control rate and depth of breathing
Respiratory centers
For coughing, sneezing, gagging, swallowing, vomiting, salivation, sweating, movements of tongue and head
Reflex centers
Pathways in and out of cerebellum
Contains additional nuclei concerned with sleep, respiration, posture
is the function of
Pons
Short segment of brainstem that connects the hindbrain to the forebrain
Contains continuations of the reticular formation
(middle of everything ; midbrain& forebrain)
Midbrain
Loosely organized web of gray matter that runs vertically through all levels of the brainstem
SOMATIC MOTOR CONTROL
Integrates visual, auditory, and balance and motion stimuli into motor coordination functions of
Group of grey matter that goes thru all parts of brain
Cardiovascular control
Pain modulation(ramping &duliness of pain )
Sleep and consciousness(walking or putting you to sleep)
Habituation(Dulls stimuli higher stimuli )
Reticular Formation
The largest part of the hindbrain and the second largest part of the brain as a whole
Consists of right and left cerebellar hemispheres connected by vermis
Cortex of gray matter with folds (folia) and four deep nuclei in each hemisphere
Contains more than half of all brain neurons—about 100 billion
Cerebellum
Monitors muscle contractions and aids in motor coordination
Planning and scheduling tasks(4th dimension)
Evaluation of sensory input
Spatial perception and comprehension of different views of three-dimensional objects belonging to the same object
Timekeeping center(4th d)
Predicting movement of objects
Ex. Basketball goal
Cerebellum Functions
ovoid mass on each side of the brain perched at the superior end of the brainstem beneath the cerebral hemispheres
Composed of at least 23 nuclei
(cerebral Cortex to the Cerebellum)
Thalamus