Download ANPS 019 Black 10-28

OVERVIEW OF THE CENTRAL NERVOUS SYSTEM
This lecture will introduce you to the terms we will discuss throughout the rest of the semester
ORGANIZEATION OF THE CNS
How neurons and glia arranged?
How does the CNS get its adult shape?
How do we tell one part from another?
What does each part of the brain do?
Glial cells are smaller than neurons
Many neurons synapsing on many neurons
CNS: brain and spinal cord
PNS:
-special sensory
-somatic: from muscles, joints, skin
-visceral: info form gut
-motor: spinal nerves to innervate neurons involved in gut functions
Intercrosses brain:
Sensory: crosses up
Motor: crosses down
Receptors can be far from synapse
Brain neuron that projects to lumbar spinal cord is about 3 meters long
Spinal motor neuron that projects to muscle that moves the big toes s about 2 meters long
Sensory neuron that carries sensation from the toes to the brain is about 5 meters long
HUMAN BRAIN
Common: cerebrum, cerebellum, brain stem
Differences: increasing amounts of fold---intelligence
Weighs about 3 pounds
-folds: more brain info into head
HOW DOES THE CNS GET ITS ADULT SHAPE?
EMBRYONIC DEVELOPMENT OF THE NERVOUS SYSTEM
*understanding the embryology helps the understand both anatomy and function of the brain
THE NERVOUS SYSTEM BEGEINS FROMING AROUND EMBRYONIC DAY 19 WHEN THE CELL LAYER CALED
ECTODERM BEINGS TO FOLD
Within a week, the neural plate closes to form the neural tube which extends the length of the embryo
Neural plateneural tube
Neural tube: becomes cell of CNS
Cells of the neural tube become CNS cells
Cells of the neural crest become PNS cells
Neural Crest: PNS structures
Sensory ganglia (e.g, dorsal root ganglia)
Autonomic (sympathetic and parasympathetic) ganglia
Schwann Cells
Adrenal Medulla
Digestive system
Neural tube close begins in the middle of the embryo and proceeds in both directions
Neural tube defects can occur when the neural tube fails to close in development
Spina Bifida:
Failure of caudal neural tube closure
Anencephaly: (no head)
Failure of rostral neural tube closure
Folic Acid deficiency (70% of cases)
High Glucose Levels
Retinoic Acid excess (Vitamin A)
Neural tube events occur early in development, often before a woman realizes she is pregnant
THE NEURAL TUBE CHANGES SHAPE AS IT GROWS
By week 4, 3 primary brain vesicles form
Forebrain or prosencephalon
Midbrain or mesencephalon
Hindbrain or Rhombencephalon
Unchanged neural tube (spinal cord)
By week 5, 5 primary brain vesicles form
*huge amount of spinal proliferation
MUCH OF CNS DEVELOPMENT OCCURS POSTNATALLY
CNS develops a lot before and afterbirth
SUMMARY OF BRAIN DEVELOPMENT
**CHART ON THIS SLIDE IS VERY IMPORTANT AND SHOULD KNOW IT
VENTRICLES: holes left from closing of neural tubes
The fluid filled (CSF, cerebrospinal fluid) spaces within the brain resulting from neural tube closure
Delivers nutrients and removes wastes!
HOW DO WE TELL ONE PART FROM ANOTHER?
WHAT DOES EACH PART OF THE BRAIN DO?
CEREBRUM
Largest part of brain
Controls higher mental functions:
-intellect
-reason
-learning
-memory
-planning
-emotion
CEREBRUM
Divided into left and right hemispheres by the longitudinal fissure
Sometimes called the interhemispheric fissures
Subdivided into lobes with specialized functions
1. Frontal: personality
2. Parietal: sensory info
3. Temporal: hearing, points towards limbic function
4. Occipital: vision
CEREBRUM: Cerebral Cortex
Folds increase surface area
Fissure: deep depression
Left hemisphere: speech/critical thinking
Right hemisphere: interpretation/face artistic
-contains synapses/neurons
THE ORGANIZATION OF THE BRAIN IS GRAY-WHITE-GRAY
Gray cortex = neuron cell bodies + synapses
White matter = axons
Gray nuclei = groups of neurons with a common function
CEREBRUM: THE LIMBIC SYSTEM
Mostly located deep in the temporal lobe
Learning/memory and emotion
Hippocampus (temporal lobe)
-Learning/memory
Amygdala
-emotion (especially fear)
Nucleus accumbens
-reward/addiction
-driven by dopamine neurotransmitter
CEREBRUM: THE BASAL GANGLIA
Involved in fine tuning motor activities
Especially starting and stopping motor activities
-substania nigra: death of neurons making dopamine results in Parkinson’s disease
DIENCEPHALON
4 COMPONENTS
Located under cerebrum
Links cerebrum and brainstem
Major components:
Thalamus-sensory relay
Hypothalamus-homeostasis
Pituitary bland-regulates hormone production
Pineal gland-daily rhythms
DIENCEPHALON: THALAMUS
Deep nucleus (switchboard)
Smell goes straight through cortex
Relays sensory info to cortex
Relays motor info between cerebellum and cerebral cortex
DIENCEPHAMON: HYPOTHALAMUS AND PITUTARY GLAND
Homeostasis: underneath thalamus
Hypothalamus
“homeostasis”
-autonomic function
-hormone production
-emotion
Pituitary Gland
-major endocrine gland
DIENCEPHALON
Pineal Gland:
Produces hormone Melatonin:
-regulates sleep/wake “cycle”
Circadian (daily) rhythms
CEREBELLUM
Second largest part of the brain
Coordinates body movements
2 hemispheres (just like the cerebrum)
Covered with cerebellar cortex (just like the cerebrum)
-balance and coordination: ability to do motor functions smoothly
THE BRAINSTEM:
Controls the daily functions that keep you alive
Most cranial nerves attach to brainstem
Processes information between spinal cord and cerebrum/cerebellum
Tracts that carry information going up to a leaving the cerebral cortex run through the brainstem
Includes:
-midbrain
-pons
-medulla oblongata
THE BRAINSTEM: MIDBRAIN
Also called mesencephalon
Superior colliculi – controls eye movements (light tracking)
Inferior colliculi – play a role in sounds localization (sound tracking)
Sunstantia nigra –neurons die in Parkinson’s disease
BRAINSTEM: PONS
Also called mesencephalon
Connects cerebellum to brainstem
Controls sensory and motor function for the face
-motor neurons send through here
BRAINSTEM: MEDULLA OBLONGATA
Also called myelencephalon
Regulates autonomic functions vital to life
-heart rate, blood pressure, breathing and digestion
Contains pacemakers
SPINAL CORD
Gray matter: inside
White matter: outside
Controls sensory and motor function for the body and viscera
SPINAL CORD
There is not gray cortex in the spinal cord. The spinal cord consists of a butterfly-shaped internal gray
matter surrounded by white matter. Due to fixation of the tissue, the grey matter appears white and the
white matter appears brown in this photograph