EXAM 2: BIO&252 (Chapter 14: Part 1)

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  1. Brain Stem
    • Medulla
    • Pons
    • Midbrain (mesencephalon)
  2. Cerebellum
    2 hemispheres
  3. Diencephalon
    • Thalamus
    • Hypothalamus (infundibulum connects to pituitary)
    • Epithalamus (pineal gland, choroid plexus)
  4. Cerebrum (cerebellar cortex)
    Two cerebral hemispheres each contain:

    • Parietal Lobe
    • Frontal Lobe
    • Temporal Lobe
    • Occipital Lobe
  5. Embryology of the Brain
    Neural tube with neurocoel = a hollow tube

    • Develops brain vesicles:
    • 1. Prosencephalon ("forebrain")
    • 2. Mesencephalon ("midbrain")
    • 3. Rhombencephalon ("hindbrain")

    Primary vesicles develop into secondary vesicles.
  6. Secondary Brain Vesicles
    • 1. Prosencephalon becomes:
    •    A. Telencephalon = cerebrum
    •    B. Diencephalon
    • 2. Mesencephalon = midbrain
    • 3. Rhombencephalon becomes:
    •    A. Metencephalon = cerebellum and pons
    •    B. Myelencephalon = medulla (oblongata)
  7. Ventricles
    • Fluid filled chambers within the brain
    •    Neurocoel develops into the ventricles
    • Lined with ependymal cells
    • Filled with CSF
    •    Produced by choroid plexuses in all ventricles
  8. Dura Mater
    • Endosteal Layer: Thicker part, fused with periosteum
    • Meningeal Layer: Thinner part, next to the arachnoid membrane

    • Forms dural folds:
    •    Stabilize and support brain
    •    Contain dural (venous) sinuses
    •    Between endosteal and meningeal layers
    •    Contain venous blood (and CSF)
  9. Dural Folds
    • A. Falx Cerebri
    •    Between cerebral hemispheres
    •    Superior and inferior sagittal sinuses

    • B. Tentorium Cerebelli
    •    Between cerebrum and cerebellum
    •    Transverse sinus

    • C. Falx Cerebelli
    •    Between cerebellar hemispheres
  10. Arachnoid Membrane
    • Subarachnoid space contains CSF
    • Membrane does not follow into sulci
  11. Pia Mater
    • Closely adheres to brain surface
    • Follows sulci
  12. Cerebrospinal Fluid (CSF) Functions
    • Formed by choroid plexuses
    •    Cushions brain
    •    Supports brain (brain floats in CSF)
    •       Actual mass about 1400 grams
    •       Effective weight in CSF about 25 grams
    •    Transports nutrients, wastes, chemicals
    •    Turnover rate = about 4x-5x per day

    NOTE: Except in the choroid plexuses, there is a free exchange of fluids and solutes between CSF and the extracellular fluid of the brain.

    Leaky capillaries will allow solutes to be transferred. Ependymal cells are connected to one another by tight junctions. H+ is using Active Transport.
  13. CSF Formation by Choroid Plexuses
    • 1. "Leaky" (permeable) capillaries covered by ependymal cells.
    • 2. Ependymal Cells joined by tight junctions.
    •    Secrete CSF from fluid filtered by leaky capillaries
    •    Remove wastes from CSF

    • Composition of CSF is different from blood
    •    No blood cells
    •    Much less protein
    •    Lower pH
  14. CSF Circulation
    • Later Ventricles →
    • Interventricular Foramen (of Monro)→
    • Third Ventricle→
    • Cerebral Aqueduct→
    • Fourth Ventricle→
    • Central canal of spinal cord or lateral and median aperatures →
    • Subarachnoid Space→
    • Arachnoid Villi/Granulations→
    • Superior Sagittal Sinus → Venous return to the heart
  15. Blood Supply to the Brain
    • Arterial Supply: Internal carotid and vertebral arteries
    • Venous Return: Dural sinuses → internal jugular (most)
    • Vasomotion: Neurons rely on glucose - blood supply must be continuous (no energy or oxygen reserves)

    ↑Metabolism → ↑CO2 → ↑[H+] → ↑vasodilation → ↑blood flow
  16. Blood-Brain Barrier (1)
    • 1. Brain capillary endothelial cells have tight junctions
    •    Restricts diffusion of non-lipid materials
    •    Water and ions move through cells via channels
    •    Large, water-soluble materials may be transported into brain ECF

    • 2. Astrocytes
    •    Psuedopods cover capillaries
    •       Regulate capillary permeability, blood flow
  17. Blood-Brain Barrier (2)
    • NO blood-brain barrier:
    • 1. Part of the hypothalamus
    • 2. Posterior Pituitary
    • 3. Pineal Gland
    • (ALL of these have Endocrine Functions)

    • 4. Choroid Plexuses
    •    Have choroid-blood barrier
  18. Medulla
    • 1. Ascending and descending tracts
    • 2. Autonomic nuclei: visceral control (part of reticular formation)
    •    Receive inputs from cranial nerves, cprtex, brain stem
    •    A. Cardiovascular Centers
    •       Cardiac Center
    •       Vasomotor Center
    •    B. Respiratory Rythmicity Center
    •       Sets basic breathing rhythm
    • 3. Sensory and Motor Nuclei
    •    Cranial nerves Vlll (with pons), lX-Xll
    • 4. Relay Centers
    •    A. Nucleus gracilis and nucleus cuneatus
    •       Somatic sensory relays to the thalamus
    •    B. Olivary Nuclei
    •       Relay proprioception info to cerebellum
    • 5. Pyramids
    •    Decussation of the pyramids
    •    Voluntary motor fibers cross over here
  19. Pons
    Contains nuclei and tracts that carry or erlay sensory and motor information.

    • 1. Ascending, descending, transverse fiber tracts
    • 2. Sensory and motor nuclei
    •    Cranial nerves V, Vl, Vll, and Vlll (with medulla)
    • 3. Respiration Nuclei
    •    Apneustic and pneumotaxic centers
    •    Modify basic rhythm set by medulla
    • 4. Nuclei and tracts associated with cerebellum
    •    Process and relay info to/from cerebellum
  20. Cerebellum
    • "Little Brain"
    • Coordinates learned and reflexive patterns of musculary activity at the subconscious level.
    • Communicates with brain stem, cerebrum, spinal cord via cerebellar peduncles
    • Modifies motor outputs of brain stem centers and motor pathways

    • Compares intended with actual movements and makes necessary adjustments
    •    Subconscious (automatic)
    •    Facilitates coordinated movements
    •    Adjusts posture, muscle tone, balance
  21. Cerebellum receives input from...
    • Proprioceptors
    • Equilibrium sensors
    • Visual receptors
    • Touch recpetors
    • Auditory receptors

    • Purkinje fibers important:
    •    Reveive up to 200,000 inputs per cell
  22. Midbrain (Mesencephalon)
    Regulates auditory and visual reflexes and controls alertness

    • Contains:
    • 1. Cerebral peduncles
    • 2. Cerebral aqueduct
    • 3. Tectum ("roof" of cerebral aqueduct)
    •    Superior and Inferior Colliculus
    • 4. Substantia nigra + red nucleus = tegmentum
    • 5. Part of reticular activating system
    • 6. Cranial nerve nuclei (lll and lV)
  23. Cerebral Peduncle
    • Midbrain (Mesencephalon)
    • "Little Feet"
    • Motor and sensory fiber tracts
  24. Tectum
    • Midbrain (Mesencephalon)
    • "Roof" of the cerebral aqueduct
    • Corpora quadrigemina (part of tectum)
    •    A. Superior Colliculus
    •       Visual reflexes: eye tracking, reflexive head and neck movements
    •    B. Inferior Colliculus
    •       Auditory reflexes: reflexive head, neck, and trunk movements
  25. Tegmentum
    Anterior to Aqueduct

    • 1. Substantia Nigra ("black substance")
    •    Regulates activity of basal nuclei
    •    Involved in muscle tone (discussed later with basal nuclei)
    • 2. Red Nucleus
    •    Muscle tone, subconscious movements of arms
    • 3. Reticular Formation of RAS
    •    General level of arousal, muscle tone
  26. Midbrain Cranial Nerve Nuclei
    • A. Oculomotor Nerve C.N. lll
    •    Eye movement, proprioception
    •       All extrinsic eye muscles except superior oblique and lateral rectus
    •    Lens shape (ciliary muscles)
    •    Pupil diameter (iris)
    • B. Trochlear Nerve
    •    Eye movement, proprioception
    •       Superior oblique (extrinsic eye) muscle
  27. Diencephalon
    Integrates sensory information with motor output at the subconscious level.

    • Thalamus
    • Hypothalamus
    • Epithalamus
  28. Thalamus
    • "Inner Chamber"
    • Major sensory relay area
    • Except for smell, relays all sensory signals to specific area of cortex for conscious perception

    • Crosses the 3rd ventricle as:
    •    Intermediate Mass = massa intermedia = interthalamic adhesion = middle commissure

    • Allows a crude appreciation of:
    •    Pain, temperature, and pressure
    •    Sensation not localized to a particular area

    • Part of the limbic system
    •    Influences emotional states
  29. Posterior Thalamic Nuclei to Know
    • A. Lateral Geniculate: Visual relay center
    •    Optic tract → thalamus → occipital lobe
    • B. Medial Geniculate: Auditory relay center
    •    Auditory receptors → thalamus → temporal lobe


    KNOW THESE!
  30. Hypothalamic Functions
    • 1. Subconscious control of skeletal muscles associated with emotions
    •    Ex. facial expressions, body positions
    • 2. Control of autonomic nervous system
    •    Influences centers in pons and medulla
    •    Ex. heart rate, BP, respiration
    • 3. Secretion of hormones
    •    Oxytocin
    •    Antidiuretic hormones
    •    Both stored in posterior pituitary
    • 4. Coordinates nervous and endocrine systems
    •    Releases regulatory hormones that control release of anterior pituitary hormones
    • 5. Influences emotions, behavioral drives
    •     Feeding, righting, pleasure, thirst
    • 6. Coordinates voluntary and autonomic functions
    •    Think about a stressful situation = Increase of heart rate and BP before the stress begins
    • 7. Body temp regulation
    •    Cold = vasoconstrict, shiver, etc.
    •    Hot = vasodilate, sweat, etc.
Author:
tgherasim
ID:
315218
Card Set:
EXAM 2: BIO&252 (Chapter 14: Part 1)
Updated:
2016-02-07 00:15:36
Tags:
anatomy
Folders:
BIO&252
Description:
brain
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