Transcript Central Nervous System

Central Nervous System
Part 1
Glial Cells and CSF
Brainstem, Cerebellum and
Diencephalon
Fig. 49-6a
Glial Cell Types: Most of the brain is made up of cells that support
the nervous tissue
CNS
VENTRICLE
Ependymal
cell
PNS
Neuron
Astrocyte
Oligodendrocyte
Schwann cells
Microglial
cell
Capillary
(a) Glia in vertebrates
Oligodendrocytes: produces myelin sheath
Astrocytes: maintains environment for nerve impulses, blood brain barrier,
provides nutrients, picks up excess NT
Microglial Cell: WBC of the brain
Ependymal Cells: lines ventricles and makes CSF
Protection: Skull, Meninges and CSF:
~ 150 mL CSF in ventricles and
subarachnoid space
• Dura mater, arachnoid , pia
mater
• CSF Circulation: lateral >
interventricular foramen >
3rd > cerebral aqueduct >
4th
• Superior sagital sinus and
arachnoid villi
• Capillaries are different: tight
junctions combine ET cells
choroid plexsus:
specialized capillary
network projecting from
the pia mater into the
ventricles of the brain
forming cerebral spinal
fluid (70% of CSF)
99% water, (glucose, aa,
salt, less density and
protein than plasma)
Fig. 49-9ab
Telencephalon
Forebrain
Diencephalon
Mesencephalon
Midbrain
Metencephalon
Hindbrain
Myelencephalon
Mesencephalon
Metencephalon
Midbrain
Hindbrain
Forebrain
(a) Embryo at 1 month
Diencephalon
Myelencephalon
Spinal cord
Telencephalon
(b) Embryo at 5 weeks
Fig. 49-9c
Cerebrum (includes cerebral cortex, white matter,
basal nuclei)
Diencephalon (thalamus, hypothalamus, epithalamus)
Midbrain (part of brainstem)
Pons (part of brainstem), cerebellum
Medulla oblongata (part of brainstem)
Diencephalon:
Cerebrum
Hypothalamus
Thalamus
Pineal gland
(part of epithalamus)
Brainstem:
Midbrain
Pons
Pituitary
gland
Medulla
oblongata
Spinal cord
Cerebellum
Central canal
(c) Adult
BRAINSTEM: medulla, pons and midbrain
Medulla oblongata w/ pyramidal tracts,
• * CV & Vasomotor center VITAL CENTERS
•top of the spine, two bulges of white matter = pyramids (pyramid
tracts)
•All ascending sensory and descending motor tracts
VITAL CENTERS (CV and Vasomotor center)
Cardiovascular center (rate/force of heart) diameter =
vasodilation
Respiratory center: adjust basic rhythm of breathing
Reflex: vomit, cough, sneeze, swallow
Reticular formation: gray matter from spine to thalamus
Keeps cerebrum conscious and alert
Reflex centers: cardiac, vomit, sneeze, vasomotor, cough,
respiratory, swallow
12 pairs of cranial nerves
Pons w/ Reticular formation is a relay pathway between the motor cortex and
the cerebellum also functions as a *pneumotaxic center *houses cranial nerves:
trigeminal, abducens, and facial.
Respiration center
Reflex w cranial nerves 5-8, eye, chewing, facial expression, taste, equilibrium
Midbrain w/ cerebral peduncles
corpora quadrigemina: Righting reflexes
Superior colliculi: visual reflex center
Inferior colliculi: auditory reflex center
Substantia nigra: pigmented
neurons in motor fxn and produces
the precursor for the
neurotransmitter DOPAMINE
Red nuclei (pink)important for acting as
a relay between motor cortex and
muscles of the limbs for limb flexion;
III. CEREBELLUM
Arbor vitae: coordination of skeletal muscle movements
Some cognitive function in predicting motor movements
Fine coordination: 3 main function
Smooth not jerky, steady not trembling
Muscle tone and posture
Flocculonodular lobe= equilibrium and posture
Hemispheres separated by falx cerebelli
Cereballar cortex – gray
But mainly white matter underneath : arbor vitae
30 million purkinje cells in cerebellar cortex integrate infor
motor activity to keep informed about body position
axons carry infor to nuclei for relay to brainstem
DIENCEPHALON
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Thalamus
Hypothalamus
Pituitary gland
Mammillary bodies
Epithalamus
Choroid plexus
Reticular formation
RAS
Thalamus: all
sensory except
smell to the
cerebrum
expresses emotions
with hypothalamus
cognition:
awareness and
acquisition of
knowledge
Hypothalamus w/ VITAL
CENTERS:
•maintain and regulate
HOMEOSTASIS
•sleep and wake patterns
controls Endocrine system
•link the endocrine and
nervous systems
•secretes variety of hormones
that regulate pituitary
secretes oxytocin and
antidiuretic hormone
•osmotic balance (thirst)
•thermoregulation
•appetite
•sexual behavior and
emotional aspect of sensory
Pituitary gland: master
gland of the body
secretes:
• posterior lobe: secretes
oxytocin and antidiuretic
hormone; anterior lobe:
•ACTH affects adrenal
cortex; TSH affect thyroid
and thyroxin; FSH,LH
affects ovary and testes;
•Prolactin affects
mammary glands; GH for
bone growth;
Mammillary
bodies:
activate feeding
reflexes such as
swallowing and
licking the lips and
may be involved in
relaying olfactory
messages
Epithalamus
pineal gland: produces
melatonin for biological
clock
RAS *(reticular activating system): nuclei axons connect
hypothalamus, thalamus, cerebellum and spinal cord to send
sensory information to keep the cortex alert and conscious ALSO
acts as a filter for sensory input to the cortex…filters out 99% of
sensory input as unimportant. Has to be inhibited in order to sleep