Central Nervous System

1. Central Nervous System Part 1 Glial Cells and CSF Brainstem, Cerebellum and Diencephalon

2. Glial Cell Types: Most of the brain is made up of cells that support the nervous tissue CNS PNS Neuron VENTRICLE Astrocyte Ependy- mal cell Oligodendrocyte Fig. 49-6a 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

3. 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

4. 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)

5. Telencephalon Forebrain Diencephalon Mesencephalon Midbrain Metencephalon Fig. 49-9ab Hindbrain Myelencephalon Mesencephalon Metencephalon Midbrain Myelencephalon Hindbrain Diencephalon Spinal cord Forebrain Telencephalon (a) Embryo at 1 month (b) Embryo at 5 weeks

6. Cerebrum (includes cerebral cortex, white matter, basal nuclei) Diencephalon (thalamus, hypothalamus, epithalamus) Midbrain (part of brainstem) Pons (part of brainstem), cerebellum Fig. 49-9c 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

7. 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

8. 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

9. 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;

10. 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

11. Thalamus Hypothalamus Pituitary gland Mammillary bodies Epithalamus Choroid plexus Reticular formation RAS DIENCEPHALON

12. Thalamus: all sensory except smell to the cerebrum expresses emotions with hypothalamus cognition: awareness and acquisition of knowledge

13. 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 

14. 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;

15. 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

16. 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