Ch. 8 CNS Flashcards
The CNS is composed of the?
Brain and spinal cord
CNS receives input from?
Sensory neurons
CNS directs activity of ____ ____ that innervate muscles and glands.
Motor neurons
What type of neurons integrate sensory information and help direct the appropriate response to maintain homeostasis and respond to the environment?
Associate neurons
Gray Matter
Unmyelinated nerve cell bodies
–clusters of cell bodies in CNS are nuclei
Dendrites
Axon terminals
White Matter
Myelinated axons
–axon bundles connecting CNS are tracts
Contains very few cell bodies
Brain
Gray matter forms cortex (outer part) and deep nuclei; white matter (myelinated) is deep forming tracts
Adult brain has 100 billion neurons
It receives 15% of total blood flow to the body per minute
Cerebrum, Diencephalon, Midbrain, Hindbrain
Choroid Plexuses
Consists of simple cuboidal to columnar epithelium in close association w/ blood capillaries
Projects into roof of ventricles
Cerebrospinal Fluid (CSF)
Choroid plexuses secrete CSF into ventricles and central canal of cord
- -not part of our circulation
- -no RBCs in CSF
- -composition of CSF is different than that of blood
CSF is made from blood and returned to blood
–turned over rapidly
Cerebrum
Largest portion of the brain - 80% of the mass
Responsible for higher mental functions
Consists of a Right (R) and Left (L) cerebral hemisphere connected internally by the Corpus Callosum
Functional Regions of the Cerebrum
Study diagram in notes (p. 7 in Ch. 8 notes)
You should be able to know the main gyri and sulci, know the location of each lobe, and special areas (Broca’s, Wernicke’s)
Cerebral Cortex
Outer region (cortex) of cerebrum composed of 2-4mm gray matter w/ underlying white matter
Characterized by raised folds called Gyri separated by depressed grooves called Sulci; together called Convolutions
Each hemisphere is divided by deep sulci or fissures into 5 lobes. What are these 5 lobes?
Frontal Parietal Temporal Occipital Insula
Gyri
Raised folds of the brain
Sulci
Depressed grooves of the brain
The Frontal and Parietal lobes are separated by what?
The Central Sulcus
Precentral Gyrus
Frontal Lobe
Responsible for motor control; neurons called upper motor neurons
Postcentral Gyrus
Parietal Lobe
Responsible for Somatesthetic Sensation (coming from receptors in skin, muscles, tendons, and joints); called somatosensory cortex
Tells us where we are in space
Temporal Lobe
Auditory Centers
Interpretation of auditory sensations, storage (memory) of auditory and visual experiences
Occipital Lobe
Vision and coordination of eye movements
Insula Lobe
Encoding of memory and integration of sensory information w/ visceral responses; receives olfactory, gustatory, auditory, and pain information
Frontal Lobe
Voluntary motor control of skeletal muscles, personality, higher intellectual processes, verbal communication
Parietal Lobe
Somatesthetic interpretation, understanding speech and formulating words to express thoughts and emotions, interpretation of textures and shapes
The L side of the brain controls which side of the body?
Right side of body
The R side of the brain controls which side of the body?
Left side of the body
Communication between the 2 halves of the brain occurs through what structure?
Corpus Callosum
Right Hemisphere
Visuospatial tasks, recognizing faces, composing music
Left Hemisphere
Language, speech, writing, calculations
Discuss how Cerebral Lateralization (Dominance) works.
Each side of the precentral gyrus controls movements on the contralateral (opposite) side of the body.
Somatesthetic sensation from each side of the body projects to the contralateral sides of the post central gyrus.
Communication between the 2 sides occurs through the Corpus Callosum.
The Limbic system is the group of brain regions responsible for?
Emotional drives
Areas of the cerebrum included in the limbic system?
Cingulate gyrus, amygdala, hippocampus, septal nuclei, anterior insula
Hypothalamus and Thalamus also included
The Limbic system controls what emotions?
Aggression Fear Hunger/Satiety Sex drive Goal-directed behaviors
Limbic System: Aggression
Areas in amygdala and hypothalamus
Limbic System: Fear
Amygdala and hypothalamus
Limbic System: Hunger/Satiety
Hypothalamus
Limbic System: Sex drive
The whole system
Limbic System: Goal-directed behaviors
Hypothalamus and other regions
The Diencephalon includes?
Epithalamus Thalamus Hypothalamus part of Pituitary Gland Third ventricle
The Diencephalon is located in the? What is it surrounded by?
Forebrain
Surrounded by cerebral hemispheres
The hypothalamus is important in?
Maintaining homeostasis and regulating the autonomic system.
The hypothalamus contains centers for?
- Hunger/satiety and thirst
- Regulation of body temp
- Regulation of sleep and wakefulness
- Sexual arousal and performance
- Emotions of fear, anger, pain, and pleasure
- Control of endocrine system
- Controls hormone secretion from pituitary gland
Posterior Pituitary Gland
ADH and Oxytocin (transported along the hypothalami-hypophyseal tract) where they are stored until needed
Hypothalami-Hypophyseal Tract
How the hypothalamus communicates to the posterior pituitary
The pituitary is __ gland with __ part(s).
1 gland, 2 parts
ADH
Anti-diuretic hormone
Regulates urine concentration
Oxytocin
Acts on mammary glands
Anterior Pituitary
Hormones and inhibiting hormones produced by the hypothalamus are transported here via the circulation (portal vessels) to regulate the secretion of pituitary hormones
The hindbrain is known as the?
Rhombencephalon
The hindbrain is composed of?
Metencephalon (pons and cerebrum) and Myelencephalon (medulla oblongata)
Metencephalon
Pons and Cerebrum
Helps compose Hindbrain
Myelencephalon
Medulla Oblongata
Helps compose Hindbrain
What does the Pons house?
Sensory and motor tracts heading from/to the spinal cord, and respiratory centers
Cerebellum
2nd largest brain structure; gray matter outside, white matter inside
The cerebellum receives input from?
Proprioceptors, which sense joint angle, muscle length and tension
senses body position
The cerebellum works with?
Basal nuclei and motor cortex to coordinate movement
The cerebellum is needed for?
Motor learning and the proper timing and force required to move limbs in a specific task
motor control
Myelencephalon
Made up of Medulla Oblongata
All ascending and descending tracts between brain and spinal cord pass through medulla
Contains nuclei required for regulation of breathing and cardiovascular response = vital centers
- -remember, in CNS nuclei are clusters of cell bodies
- -gray (unmyelinated)
Myelencephalon: Vasomotor Center
Controls blood vessel diameter
Myelencephalon: Cardiac Control Center
Controls HR
Myelencephalon: Respiratory Center
Works w/ areas in the Pons to control breathing
Spinal Cord
Composed of white matter surrounding a gray matter core
–cell bodies w/in gray matter (unmyelinated)
Spinal Cord: Gray Matter
Arranged w/ a left and right dorsal horn and a left and right ventral horn
Spinal Cord: White Matter
Composed of ascending and descending fiber tracts
–tracts in CNS are where bundled [myelinated] axons are (allows info to run up and down spinal cord)
Dorsal Root
Carries sensory information
Ventral Root
Motor neurons exit through ventral root to muscles/glands
Ascending Tracts
Convey sensory info from receptors in skin, muscles, joints, and organs to brain
Crossover of tracts (decussation) may occur in the spinal cord or in the medulla. This means that the origin of the input and brain area are Contralateral.
Descending Tracts
Two Major Groups:
- Corticospinal or Pyramidal: descend directly w/o synaptic interruption from the cerebral cortex to the spinal cord
- -no synapse - Extrapyramidal Tracts: originate in brain stem and are controlled by motor circuits of various brain regions
- -you are not required to know the specific brain regions
Are Cranial Nerves part of the CNS or PNS?
PNS
Cranial Nerves
Arise directly from nuclei in brain
12 pairs
Most are mixed nerves w/ both sensory and motor neurons (somatic and parasympathetic)
Those associated w/ vision, olfaction, and hearing are sensory only and have their cell bodies in ganglia located near the sensory organ
