Chapter 15 - Brain and Cranial Nerves Flashcards
Gray Matter
- outer part (cortex) of cerebrum and of cerebellum, as well as deep nuclei
- neurosomas, dendrites, and synaspes
White Matter
- deep in brain
- bundles of mylinated axons
Ventricles
chambers filled with CSF and lined by ependymal cells
- lateral ventricles (connected by interventricular foramen)
- third ventricles (connected to fourth by cerebral aqueduct)
- fourth venttricle (central canal)
Cerebrospinal Fluid (CSF)
clear, colorless liquid = plasma that is filtered and modified by ependymal cells
- produced by choroid plexus within ventricles
- flows within ventricles, canals, and subarachnoid space around CNS
- absorbed by arachnoid granulations into blood of superior sagittal sinus
Functions of CSF
- Buoyancy
- Protection
- Chemical Stability
Brain Blood Supply
- brain is 2% of body weight
- receives 15% of blood
- receives 20% of oxygen and glucose
Blood-Brain Barrier
- isolation from general circulation
- seals capillaries in brain tissue (astrocytes)
- tight junctions between endothelial cells
Blood-CSF Barrier
- seals choroid plexus within brain ventricles (ependymal cells)
- tight junctions between ependymal cells
Medulla Oblongata
Several important nuclei:
- Cardiac center
- regulated rate and force of heartbeat
- Vasomotor center
- regulates blood pressure
- Respiratory center
- breathing, speech, coughing, sneezing, salivation, swallowing, gagging, and vomiting
Pons
- facial sensation and expression
- control of chewing, respiration, and sleep
- many tracts and relay centers
Midbrain
- nuclei that process visual and auditory information and control reflexes triggered by them
- cerebral aqueduct passes through
- centers that control consciousness
Reticular Formation
- web of gray matter that runs through all levels of brainstem
- regulates vital autonomic functions
1. Somatic motor control
2. Cardiovascular control
3. Pain modulation
4. Sleep and consciousness
5. Habituation
Cerebellum
- autonomic processing center
- adjusts postural muscles (balance and equilibrium)
- fine tunes & programs movements (e.g. riding a bike)
- Cortex of folia - gray matter
- Purkinje cells (receive input)
- deep nuclei (coordinate and control body movements)
- Arbor vitae - white matter
- connects cortex and nuclei w/ peduncles
Diencephalon
- part of forebrain
- three divisions that surround third ventricle
- Thalamus
- Hypothalamus
- Epithalamus
- integrates sensory information with motor output
Thalamus
- gateway to the cortex
- involved in sensation, movement, memory, and emotion
Hypothalamus
- relay signals from limbic to thalamus
- major control center of the autonomic nervous system and endocrine system
- Functions:
- Hormone secretion (ADH & OXT)
- Autonomic effectors
- Thermoregulation
- Sleep and circadian rhythms
- Emotional & behavioral drives
Epithalamus
- thin rood over third ventricle
- pineal gland (endocrine) - melatonin
- habenula - relay from limbic system to midbrain
Frontal Lobe
- cognition
- speech
- motor control
Parietal Lobe
interprets signals of general senses and taste
Occipital Lobe
principle visual center
Temporal Lobe
- hearing
- smell
- learning
- memory
Insula
- taste
- visceral sensation
- language
Association tracts
connect regions within same hemisphere
Commissural tracts
cross between two hemispheres (corpus callosum is largest)
Projection tracts
travel vertically to carry information between cerebrum and rest of body
Cerebral Cortex
- surface of the hemispheres
- 40% of mass of brain
- stellate cells
- short dendrites, no axon
- local processing of sensory info
- pyramidal cells
- output neurons of cerebrum (only neurons that exit the cortex)
- “neocortex” - six layers, recently evolved = highest development in mammals
Limbic System
- nuclei and tracts “functional grouping”
- important function for:
- emotion
- motivation
- memory
- multiple gratification and aversion centers
Vision = _______ lobe
occipital
Hearing = ________ lobe
temporal
Equilibrium = _______ & several _________ _______
cerebellum, brainstem nuclei
Taste = _______ lobe
parietal
Smell = _______ & _______ lobes
temporal, frontal
Broca Area
speech and language
Wernicke Area
recognition of written and spoken language
Postcentral gyrus
receives sensory information
Precentral gyrus
primary motor cortex
