nervous system lecture 6.3 Flashcards
what is the path of CSF starting with the lateral ventricles’ choroid plexus?
lateral ventricles -> interventricular foramen -> third ventricle -> cerebral aqueduct -> fourth ventricle -> lateral and median apertures -> subarachnoid space -> arachnoid villi of dural venous sinuses -> venous blood -> heart/lungs -> arterial blood -> start over
What does the blood-brain barrier consist mainly of?
tight junctions, a thick basement membrane, and astrocytes
What is the reticular activating system (RAS)?
consists of sensory axons that project to the cerebral cortex both directly and through the thalamus
what arises from the walls of metencephalon
pons and cerebellum
what arises from the cavity of the mesencephalon
aqueduct of the midbrain
Which sense has no input in the RAS?
no receptors for smell
What are the three primary brain cavities of a 3-4 week old embryo?
prosencephalon (forebrain)
mesencephalon (midbrain)
rhombencephalon (hindbrain)
reticular activating system functions
active during arousal or waking from sleep
inactivation of RAS produces sleep
damage to RAS causes coma
Where are choroid plexus found?
lateral ventricle, third ventricle, and fourth ventricle
what cranial nerves are associated with the midbrain?
oculomotor/3 and trochlear/4
what arises from the cavity of the telencephalon
lateral ventricles
what do the ventricles of the brain contain?
CSF
Which structure makes CSF?
choroid plexus
what arises from the mesencephalon walls
midbrain
Circumventricular organs location and function
includes a portion of the hypothalamus, the pineal gland, and the pituitary gland
monitor chemical changes in the blood, coordinate homeostatic activities such as blood pressure, thirst, hunger, and fluid balance
functions of the descending reticular activating system
connections to cerebellum and spinal cord
regulates muscle tone, heart rate, blood pressure, and respiratory rate
functional regions of the midbrain
conveys motor impulses from the cerebrum to the cerebellum and spinal cord, sends sensory impulses from the spinal cord to the thalamus, and regulates auditory and visual reflexes
function and location of the pineal gland
located inside the epithalamus
secretes melatonin
habenular nuclei are involved in smelling
what are the functional regions of the medulla oblongata?
heart rate, respiratory rate, vasoconstriction, swallowing, coughing, vomiting, sneezing, and hiccupping.
also contains nuclei associated with sensations of touch, pressure, vibration, conscious proprioception, and are located in the posterior part of the medulla
what are the 5 structural regions of the midbrain?
cerebral peduncles, corpora quadrigemina, substantia nigra, red nuclei, and medial lemniscus
functions of the hypothalamus
control of the ANS
regulation of circadian rhythms and states of consciousness
regulation of emotion and behavioral patterns
control of body temp
regulation of eating and drinking
production of hormones
what arises from the cavity of the diencephalon
third ventricle
functions of the cerebellum
coordination of skeletal muscle contractions and in the maintenance of normal muscle tone, posture, and balance
what is the function of the red nuclei
axons from the cerebellum and cerebral cortex form synapses in the red nuclei which help control muscular movements
what arises from the walls of the diencephalon
thalamus, hypothalamus, and epithalamus
what are the functional regions of the pons?
relays nerve impulses related to voluntary skeletal muscle movements and control of respiration
what are the four major parts of the brain?
cerebrum, diencephalon, brain stem, and cerebellum
what are the functions of the inferior colliculi?
they are part of the auditory pathway and reflex centers for the startle reflex and sudden movements
Which cranial nerves are in the pons?
5-8, trigeminal, abducens, facial, and vestibular branch of vestibulocochlear
How does blood get to the brain?
via the vertebral and carotid arteries and flows back to the heart via the jugular vein
where are the cerebral peduncles and what do they consist of?
the anterior midbrain
contain the axons of the corticospinal, corticobulbar, and corticopontine tracts which conduct nerve impulses from motor areas in the cerebral cortex to the spinal cord, medulla, and pons
What is the function of CSF?
protects brain and spinal cord against chemical and physical injuries. carries oxygen, glucose, and other important substances from the blood to the nervous tissue cells
what is the function of the reticular formation
regulates muscle tone and responsible for maintaining consciousness and awakening from sleep.
Where does CSF continuously circulate through?
the cavities of the brain, the spinal cord, and in the subarachnoid space
What does the rhombencephalon become at 5 weeks?
metencephalon and myelencephalon
How many cranial nerves does the medulla oblongata contain?
4, glossopharyngeal (9), vagus (10), accessory (11), and hypoglossal (12)
What are the three functions of CSF?
mechanical protection-shock absorption
homeostatic function- maintaining pH of the CSF and transporting hormones
circulation- for minor exchange of nutrients and waste products
what is the function of the superior colliculi
reflex centers for certain visual activities. responsible for reflexes that govern head, eyes, and trunk movements in response to visual stimuli
function of the thalamus
contains nuclei that serve as relay stations for all sensory impulses (except smell) to the cerebral cortex
what arises from the myelencephalon cavity
lower part of the fourth ventricle
What is the brain protected by?
cranial bones
cranial meninges- pia, arachnoid, and dura mater (2 layers, periosteal layer and the meningeal layer)
cerebrospinal fluid
What causes hydrocephalus?
excess CSF accumulation in the ventricles caused by a obstruction to the CSF flow or an abnormal CSF production/reabsorption
Where is the tectum located and what does it contain?
posterior part of the midbrain
the superior and inferior colliculi
What does glucose deficiency in the brain cause
confusion, dizziness, convulsions, and loss of consciousness
what arises from the cavity of the metencephalon
upper part of fourth ventricle
What is the function of the blood-brain barrier?
to protect brain cells from harmful substances and pathogens by serving as a selective barrier to prevent passage of many substances from the blood into the brain. The BBB can prevent the entry of therapeutic drugs.
what are the two parts of the neural tube?
cavities and walls
Where is dopamine released from in the midbrain and what is the function?
released from the substantia nigra to the basal nuclei, and these neurons help control subconscious muscle activities. loss of these neurons is associated with Parkinson’s disease
what arises from the walls of the myelencephalon
medulla oblongata
What percentage of the body’s oxygen does the brain use?
20%
what arises from the walls of the telencephalon
cerebrum
what is the diencephalon composed of?
thalamus, hypothalamus, and epithalamus
What is the brain stem composed of?
medulla oblongata
pons
midbrain
What does the prosencephalon become at 5 weeks?
telencephalon and diencephalon
How much CSF does an adult have?
80-150 mL
what are the two structural regions of the medulla oblongata?
pyramids- control voluntary movement of the limb and trunk
inferior olivary nuclei- make adjustment to muscle activity as you learn new motor skills
