Exam 3 - Lower Brain Flashcards
(163 cards)
The major parts of the brain are:
Brain stem
Cerebellum
Diencephalon
Cerebrum
Brain stem is Continuous with the spinal cord Consists of:
Medulla oblongata
Pons
Midbrain
Posterior to the brain stem
Cerebellum
ser-e-BEL-um = little brain
Superior to the brain stem
Comprises mainly:
Thalamus
Hypothalamus
Diencephalon
dī-en-SEF-a-lon
di = through, encephalon = brain
Diencephalon is Superior to the brain stem and Comprises mainly:
Thalamus
Hypothalamus
It is the largest part of the brain
The cerebrum is supported on the diencephalon and brain stem
It is the largest part of the brain
se-RĒ-brum = brain
The cranial meninges are continuous with the spinal meninges of the same name, and have the same basic structure:
Dura mater (outer) Arachnoid mater (middle) Pia mater (inner)
The cranial dura mater has two layers, whereas the spinal dura mater has only one
The cranial dura mater consists of:
An external periosteal layer formed by the periosteum covering the internal surface of the cranium
An internal meningeal layer that is continuous with the dura mater covering the spinal cord
The two layers are fused together except where they separate to enclose the dural venous sinuses that drain blood from the brain into the internal jugular vein
YUP
An _______ formed by the periosteum covering the internal surface of the cranium
external periosteal layer
An ________ that is continuous with the dura mater covering the spinal cord
internal meningeal layer
Extensions of the dura mater separate parts of the brain:
Falx cerebri separates the two hemispheres (sides) of the cerebrum
Falx cerebelli separates the two hemispheres of the cerebellum
Tentorium cerebelli separates the cerebrum from the cerebellum
_____ separates the two hemispheres (sides) of the cerebrum
Falx cerebri
_____ separates the two hemispheres of the cerebellum
Falx cerebelli
_____ separates the cerebrum from the cerebellum
Tentorium cerebelli
Although the adult brain is only about 2% of the total body weight, it consumes about 20% of the oxygen and glucose when the body is at rest
Neurons synthesize ATP almost exclusively from glucose
Virtually no glucose is stored in the brain
The brain therefore requires a virtually uninterrupted flow of blood to it, and that blood must have sufficient glucose
Neuronal respiration
A blood-brain barrier (BBB) protects brain cells from harmful substances and pathogens by preventing many such substances from entering the brain
The BBB can be broken down or disrupted by trauma, certain toxins, and inflammation
Some parts of the brain lack the blood-brain barrier:
The pineal gland, pituitary gland, and hypothalamus (median eminence of hypothalamus) secrete hormones directly into the bloodstream. The area postrema (of the fourth ventricle in the medulla) senses toxins in the blood, that the blood-brain barrier protects other parts of the brain from; it controls vomiting
Blood-brain barrier
Cerebrospinal fluid (CSF) is a clear, colorless liquid that . . .
Protects the brain and spinal cord against chemical and physical injuries
Carries oxygen, glucose, and other needed chemicals from the blood to neurons and neuroglia
Continuously circulates through cavities in the brain and spinal cord, and around the brain and spinal cord in the subarachnoid space (between the arachnoid mater and the pia mater)
Ventricles are four CSF-filled cavities within the brain
The lateral ventricles together comprise the…
A thin membrane called the _____ separates the lateral ventricles
The third ventricle is a narrow cavity surrounded by the right and left halves of the ____
The fourth ventricle is between the _____
first and second ventricle
septum pellucidum
thalamus
brain stem and the cerebellum
CSF contribution to homeostasis:
______, by serving as a shock-absorbing medium that protects the tissue of the brain and spinal cord from physical jolts; CSF also buoys the brain, causing it to “float” in the cranial cavity
______, by providing an optimal ionic composition chemical environment for accurate neuronal signaling
______, through acting as a medium for exchange of nutrients and waste products between the blood and nervous tissue
Mechanical protection
Chemical protection
Circulation
CSF contribution to homeostasis:
Mechanical protection
Chemical protection
Circulation
Production of CSF:
1) CSF is produced by the….
2) These are networks of capillaries covered by ____ that form CSF from….
3) The ependymal cells are joined by tight junctions, thereby preventing materials from leaking between the cells, and forcing materials that might potentially enter the CSF to be subjected to…
1) …choroid plexuses in the walls of the ventricles
2) ependymal cells; blood plasma by filtration (and some secretion)
3) ependymal cell selectivity
CSF circulation - brain:
1) CSF is formed in the choroid plexuses of each ____
2) It flows into the third ventricle through two small openings called ____
3) The roof of the ____ produces more CSF
4) CSF then flows through the ____ and into the fourth ventricle
5) A choroid plexus in the ____ produces more CSF
CSF circulation - brain:
1) lateral ventricle
2) interventricular foramina
3) third ventricle
4) cerebral aqueduct
5) fourth ventricle
CSF circulation – spinal cord:
From the fourth ventricle, CSF enters the subarachnoid space through three openings in the roof of the fourth ventricle:
a median aperture, and two lateral apertures (a pair—one on each side)
CSF circulation – spinal cord:
Since the subarachnoid spaces of the brain and spinal cord are continuous, CSF also enters the….
It then circulates in the ___ of the spinal cord and the ____ of the brain and spinal cord
spinal subarachnoid space.
central canal and subarachnoid spaces