Chapter 14 Questions based on objectives Flashcards
What are the 4 major parts of the brain?
- Brain stem
- Cerebellum
- Diencephalon
- Cerebrum
What is the brain stem?
continuous with spinal cord and consists of medulla oblongata, pons, and midbrain.
Where is the cerebellum?
posterior to the brain stem
What is the Diencephalon, and what does it consist of?
Superior to the brain stem.
It consists of the thalamus, hypothalamus, and epithalamus.
What is the cerebrum?
the largest part of the brain. Supported by diencephalon and brain stem.
What surrounds and protects the brain?
The cranial cavity bones and the cranial meninges
The cranial meninges are continuous with the spinal meninges and consist of what 3 parts?
the outer dura mater
the middle arachnoid mater
the inner pia mater
How is the dura mater in the brain different than those of the spinal cord?
The cranial dura mater has two layers; the spinal dura mater has only one.
What are the two layers of the dura mater called?
periosteal layer (which is external) and the meningeal layer (which is internal)
Is the periosteal layer of the dura mater internal or external?
which is external
Is the meningeal layer of the dura mater internal or external?
Internal
What is the function of the dural venous sinuses (endothelial-lined venous channels)
drain venous blood from the brain and deliver it into the internal jugular veins
Blood vessels that enter brain tissue pass along the surface of the brain and do what?
They penetrate inward they are sheathed by a loose-fitting sleeve of pia mater
What are the three extensions of the dura mater that separate parts of the brain?
(1) The falx cerebri
(2) The falx cerebelli
(3) The tentorium cerebelli
How does the falx cerebri separate parts of the brain?
Separates the two hemispheres (sides) of the cerebrum.
The brain represents only ___% of the total body weight.
2%
How much oxygen and glucose are used in the brain even when at rest?
It Consumes about 20% of the oxygen and glucose used by the body, even when resting.
Blood flows to the brain mainly via the _________and vertebral_______
internal carotid
and
vertebral arteries
___________consists mainly of tight junctions that seal together the endothelial cells of brain blood capillaries and a thick basement membrane that surrounds the capillaries.
blood-brain barrier (BBB)
What is Cerebrospinal fluid (CSF)
It is a clear, colourless liquid composed primarily of water that protects the brain and spinal cord from chemical and physical injuries.
__________are cavities within the brain that are filled with cerebrospinal fluid.
Ventricles
What are the four CSF-filled cavities within the brain?
2 lateral ventricles
third ventricle
fourth ventricle
What Protects the brain from chemical and physical injuries and nourishes neurons and neuroglia
Cerebrospinal Fluid
What are the three functions of the Cerebrospinal Fluid?
- Mechanical protection
- Homeostatic function
- Circulation
What is the Mechanical protection of the Cerebrospinal Fluid?
CSF acts as shock absorber the protects delicate brain tissue
What is the Homeostatic function of the Cerebrospinal Fluid?
the pH of CSF affects ventilation and cerebral blood flow. CSF also transports
polypeptide hormones secreted by hypothalamic neurons that act in the brain
What is the Circulation function of the Cerebrospinal Fluid?
CSF acts as an exchange medium for nutrients and wastes between blood and adjacent nervous tissue
Where is the majority of CSF produced?
Choroid Plexuses
What are the Choroid Plexuses?
networks of blood capillaries in the walls of the ventricles
___________ cells joined by tight junctions cover the capillaries of the choroid plexuses
Ependymal cells
Selected substances (mostly water) from the __________ filtered from the capillaries are secreted by the ependymal cells to produce the cerebrospinal fluid.
Blood plasma
CSF made in choroid plexuses of each lateral ventricle flows in the third ventricle through two narrow openings called ____________ ________
Interventricular foramina
CSF flows to the fourth ventricle through the aqueduct of the ___________
midbrain (cerebral aqueduct)
CSF enters the subarachnoid space through 3 openings in the roof of the fourth ventricle: What are the three openings?
1 median aperture
2 lateral apertures
What do arachnoid villi have to do with CSF?
CSF gradually reabsorbed in the blood through arachnoid villi, finger-like extensions of arachnoid matter that project in dural venous sinuses.
CSF __________ and ____________ are the same, so pressure and volume are constant.
formation
&
absorption
What is the brain stem?
The brain stem is the part of the brain between the spinal cord and the diencephalon
What are the three parts of the brain stem?
Consists of 3 parts: medulla oblongata, pons, and midbrain.
Where is the medulla oblongata?
Inferior part of the brain stem
Where does the medulla oblongata begin and end?
It begins at the foramen magnum and extends to the inferior border of the pons.
What type of matter is the medulla?
White matter
What does the white matter in the medulla contain?
Contains all sensory (ascending) tracts and motor (descending) tracts that go from the spinal cord to the brain
What are pyramids?
Are white matter bulges or protrusions formed by the large corticospinal tracts from the cerebrum to the spinal cord, controlling the voluntary movement of the limbs and trunk
What is the decussation of pyramids in the medulla?
Just superior to the junction of the medulla with the spinal cord, 90% of the axons in the left pyramid cross to the right side, and 90% of the axons in the right pyramid cross to the left side.
_______________centre in the medulla is a collection of neuronal bodies (called nuclei) that regulates the rate and force of heartbeat and diameter of blood vessels.
Cardiovascular
___________ _______________ centre (another nucleus) adjusts the basic rhythm of breathing.
Medullary respiratory
Besides regulating heartbeat, blood vessel diameter, and the normal breathing rhythm, nuclei in the medulla also control reflexes for what 5 other reflexes?
vomiting, swallowing, sneezing, coughing, and hiccupping
Vestibulocochlear (VIII) nerves convey what type of impulses?
These nerves convey impulses related to hearing.
These nerves convey impulses related to balance and equilibrium.
Glossopharyngeal (IX) nerves relay what type of information?
relay sensory and motor impulses related to taste, swallowing, and salivation via the glossopharyngeal nerves.
What do the Vagus (X) nerves receive?
Nuclei in the medulla receive sensory impulses from and provide motor impulses to the pharynx, larynx, and many thoracic and abdominal viscera via the vagus nerves.
Accessory (XI) nerves are part of what nerve?
Vagus (X)
Accessory (XI) nerves (cranial portion) are the origin of nerve impulses that control?
swallowing via the vagus nerves (a cranial portion of the accessory nerves)
Hypoglossal (XII) nerves are the origin for nerve impulses where?
That controls tongue movement during speech and swallowing via the hypoglossal nerves.
The medulla also contains nuclei that are components of sensory pathways. For what three components?
Gustation (taste), audition (hearing), and equilibrium (balance).
Where is the Pons located?
Superior to the medulla and anterior to the cerebellum.
What is the function of the pons?
It connects the right and left sides of the cerebellum by bundles of axons
Within pons are nuclei called _____ ________ ______, which, along with the medullary respiratory centre, helps control breathing.
pontine respiratory group,
Where are the Trigeminal (V) nerves located in the brain?
Pons