Chapter 14 Part 1 Flashcards
the adult brain is dominated in size by ____
the cereburm
the cerebrum can be divided into…….
large, paired cerebral hemispheres
what is “neural cortex”
the layer of gray matter covering most of the brain’s surface
what is the cerebral cortex?
the superficial layer of the NEURAL CORTEX
What is the name for the elevated ridges formed by the cerebral cortex?
gyri
what is the function of the gyri?
to increase surface area
the gyri are separated by ___or _______
shallow depressions called SULCI or by deeper grooves called FISSURES
What is the most notable function of the cerebrum?
conscious thoughts, sensations, intellect, memory, and complex movements
what is the second largest part of the brain that is partially hidden by the cerebral hemispheres?
cerebellum
is the cerebellum also covered in gray matter?
yes – called the cerebellar cortex
what is the function of the cerebellum?
adjusts ongoing movements by comparing arriving sensations with what has been previously experienced.
allows you to perform the same movements over and over
what is the “floor” of the diencephalon?
the hypothalamus
the walls of the diencephalon are composed of….
the left thalamus and the right thalamus
which part of the diencephalon has processing centers for sensory information?
the thalamus
which part of the diencephalon has centers controlling emotions, autonomic functions, and hormone production?
the hypothalamus
the hypothalamus is connected to the _____ by a narrow stalk called the infundibulum
pituitary gland
the pituitary gland is a component of which system?
the endocrine system
what is responsible for the integration of the nervous and endocrine systems?
the hypothalamus and pituitary gland
what is the structural and functional link between the cerebral hemispheres and parts of the brain stem?
the diencephalon
the brain stem includes…..
midbrain
pons
medulla oblongata
(in that order top to bottom)
what connects the cerebellum to the brain stem?
the pons
what is the function of the midbrain?
to process visual and auditory information and ot control reflexes triggered by these stimuli
the spinal cord connects to the brain at what structure?
the medulla oblongata
which part of the brain helps to maintain consciousness?
the midbrain
which part of the brain relays sensory information to the cerebellum and thalamus AND has subconscious somatic and visceral motor centers?
the pons
which part of the brain has autonomic centers for the regulation of visceral function? (cardiovascular, respiratory, and digestive system activities)
medulla oblongata
embryology:
the CNS begins as…..
a hollow cylinder known as the neural tube.
neural tube has a fluid-filled internal cavity known as the neurocoel
what creates the primary brain vesicles?
the enlargement of the cephalic portion of the neural tube
cells of _____ line the ventricles of the brain
ependyma
each cerebral hemisphere contains a large…. separated by…….
cerebral hemisphere, separated by the septum pellucidum
the diencephalon is the _______ ventricle
3rd
each lateral ventricle communicates with the diencephalon through an………..
interventricular foramen
what ventricle is the midbrain?
the cerebral aqueduct
the 4th ventricle is……
the pons, medulla oblongata, and cerebellum
what passageway connects the 3rd ventricle with the 4th ventricle?
the cerebral aqueduct (midbrain)
the 4th ventricle becomes continuous with what as it goes down?
the central canal of the spinal cord
what are the ventricles filled with?
cerebrospinal fluid (CSF)
the CSF continually circulates from the _ and ____ into the ______
from the ventricles and central canal into the subarachnoid space of the cranial meninges
name 3 protections that the brain has from MECHANICAL forces
skull (cranial bones)
cranial meninges
CSF
name the biochemical protection for the brain
BBB - isolates the brain from general circulation
name the layers of cranial meninges.
are they continuous with the spinal meninges?
from superficial to deep:
dura mater
arachnoid mater
pia mater
dura matter has an outer and inner fibrous layer
YES they’re continuous with the spinal meninges, but the cranial meninges have distint anatomical and functional characteristics
which cranial meninge sticks to the surface of the brain, is anchored by astrocytes, and extends into every fold, and accompanies the branches of the cerebral blood vessels as they penetrate the surface of the brain to reach internal structures
the pia mater
the dura mater has an outer ___ layer and an inner _______ layer
outer endosteal
inner meningeal
which cranial meninge covers the brain but does NOT follow the brain’s underlying folds?
the arachnoid mater
compare the various protections of the brain to a car getting into an accident
car = cranial bones. not enough protection.
dural folds act like seat belts that hold the brain in position
CSF in the subarachnoid space acts like a bumper by cushioning against shocks and jolts
what is cranial trauma?
a head injury resulting from impact with another object
each year in the US, about ____ cases of cranial trauma occur, but only 1 in ___ results in serious brain damage
8 million,
1 in 8 results in serious brain damage
true or false:
the cranial meninges and csf are so effective in protecting the brain
true
what completely surrounds and bathes the exposed surfaces of the CNS?
CSF (cerebrospinal fluid)
name 3 functions of the CSF
-cushion delicate neural structures
-support the brain (brain is suspended inside the cranium and floats in the CSF. weighs around 3 pounds in air, but only around 50g (1.8 oz) when supported by CSF
-transport nutrients, chemical messengers, and waste products
where is CSF produced?
at the choroid plexus
true or false:
the ependymal lining is freely permeable everywhere
false – permeable everywhere BUT at the choroid plexus where CSF is made
since the ependymal lining is freely permeable everywhere else, the CSF is constantly in chemical communication with the interstitial fluid that surrounds the cells (neurons and neuroglia) of the CNS
a __ __ can provide useful clinical information about CSF injury, infection, or disease
spinal tap – collects CSF fluid from the spinal canal
explain the difference in composition between CSF and blood plasma
blood plasma contains high concentrations of soluble proteins, but CSF does not.
other conc’s are different too – ions, amino acids, lipids, waste products, etc
the ENTIRE VOLUME OF THE CSF is replaced every….
explain how you got this number
8 hours
choroid plexus produces CSF at a rate of 500mL/day, and theres only 150mL of CSF at a time
500/150 = 3
3x=24
x=8 hours
explain what the CSF circulates through
the choroid plexus, the ventricles, and fills the central canal of the spinal cord
where is CSF absorbed into venous circulation?
at arachnoid granulations – clusters of arachnoid villi
a problem with the reabsorption of the CSF in infancy causes what condition?
hydrocephalus “water on the brain”
this makes the infant have an enormously expanded skull
in ADULTS, if there is an issue with the circulation or reabsorption of CSF, what happens?
distortion and damage of the brain
true or false:
the brain has limited circulatory supply
FALSE - the brain has extensive circulatory supply
arterial blood reaches the brain through…..
venous blood LEAVES the brain through….
arterial blood GOES TO THE BRAIN via the vertebral arteries and carotid arteries
most of the venous blood leaves the brain through the internal jugular veins
a head injury that damages the cerebral blood vessels will cause what?
bleeding into the dura mater.
this blood compresses and distorts the soft tissue in the brain – very serious
what are cerebrovascular diseases?
cardiovascular disorders that interfere with normal blood supply to the brain
what does CVA stand for and what is it
cerebrovascular accident
STROKE
a blood supply to a portion of the brain is shut off. affected neurons begin to die within minutes
neural tissue in the CNS is isolated from general circulation by the….
BBB blood brain barrier
the blood brain barrier is formed by…
tight junctions of capillary endothelial cells that PREVENT the diffusion of materials between adjacent endothelial cells
only lipid soluble molecules can diffuse across the membranes of the endothelial cells and into the interstitial fluid of the brain and spinal cord
the restricted permeability of the endothelial lining of the brain capillaries is in some way dependent on chemicals secreted by…..
EXPLAIN
astrocytes
the astrocytes processess wrap around the endothelial cells and releases chemicals that control the permeability of the endothelium to various susbstances
if astrocytes are damaged or stop stimulating the endothelial cells, what happens?
the blood brain barrier disappears
does the choroid plexus have a BBB? explain
NO. the choroid plexus is not part of the neural tissue of the brain, so there are no astrocytes in contact with the epithelial cells there.
HOWEVER, substances do not have free access to the CNS through the choroid plexus either.
Specialized endymal cells at the choroid plexus create a Blood-CSF barrier.
The cells also have tight junctions and surround the capillaries of the choroid plexus
neurons have a constant need for _____
glucose
name 4 EXCEPTIONS where the BBB is NOT intact within the CNS
-portions of the hypothalamus, the capillary endothelium is extremely permeable. exposes hypothalamic nuclei to circulating hormones and permits diffusion of hypothalamic hormones into circulation
-capillaries in the posterior lobe of the pituitary gland (continuous with the floor of the hypothalamus) are HIGHLY PERMEABLE. here, antidiuretic hormone and oxytocin are released into circulation
-capillaries in the PINEAL gland are very permeable. (located on superior posterior surface of diencephalon). allows pineal secretions into general circulation (part of endocrine system)
-as mentioned, capillaries in the choroid plexus are extremely permeable with no BBB, but there’s a blood-CSF barrier
is tetracycline used to treat meningitis or other CNS infections?
no – this drug is excluded from the brain. physcians have to keep in mind the limitations of the BBB and blood-CSF barrier
can sulfisoxazole and sulfadiazine be used to treat CNS infections?
yes
