Sullivan Anatomy Lecture Section 3
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- Name the two control and communication systems of the body and what are the characteristics of each?
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nervous sys- rapid/complex network of cells
endocrine sys- slow/via blood - Helps regulate/maintains homeostatis
- the nervous system
- Name the Functions of the Nervous system:
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MONITORS CHANGE in/out of body (sensation)
PROCESSES AND INTERPRETS sensory input (integration)
EFFECTS RESPONSES (response) - Oranization of NERVOUS SYSTEM in outline form
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2 Divisions:
1. Central Nervous System (CNS)
Brain and Spinal Cord
2. Peripheral Nervous System (PNS)
a. Somatic (SNS)
b. Autonomic (ANS)
* sympathetic
* parasympathetic - Two cell types in neural tissue:
- neurons and neuroglia
- neurons
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Cell body (perikaryon/soma)
* contains nucleus
(amniotic, large nucleolus, chromosomes)
* cytoplasm, mitochondria, Golgi, Nissel granules (ER), microtubules, and microfilaments.
* high metabolic rate
* most cell bodies in CNS
* 2 types of processes - name the two types of processes of neurons
- dendrites and axons
- Features of DENDRITES
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* short, highly branched, unmyelinated RECEPTIVE surfaces of neuron
* carry information TO the cell body - Features of AXONS
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* long, slender process arising from hillock of cell body
* most are myelinated
* carry information AWAY from cell body
* may have collateral branches
* axon endings have synaptic knobs (aka butons)
* many axons surrounded by a phospholipid MYELIN SHEATH
- outside CNS mad from SCHWANN CELLS
- inside CNS made from OLIGODENDROCYTES
* myelinated axons transmit impulses faster
* interruptions in myelin sheath called... nodes of Ranvier - Multiple Sclerosis
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* myelin sheaths lacking on axons
* doesn't form/ degenerates
* interferes with transmission - name the Structural Types Of Neurons
- MultiPolar, Bipolar and Unipolar
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Structural Types of Neurons:
Features of Multipolar -
* 1 axon/many dendrites
* most motor neurons are multipolar -
Structural Types of Neurons:
Features of Bipolar -
* 1 axon/1 dendrite
* parts of eye and ear -
Structural Types of Neurons:
Features of Unipolar -
* 1 process splits a short distance from cell body
* most sensory neurons are unipolar - name the Functional Types of Neurons
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Sensory (afferent) neurons
Motor (efferent) neurons
Association (interneurons) -
Functional Types of Neurons:
Features of Sensory (afferent) neurons -
* tansmit impulses from sensory receptors in skin and internal organs to CNS
* most are unipolar
* cell bodies in sensory ganglia (dorsal root ganglia)
* dendrites may be very long -
Functional Types of Neurons:
Features of Motor (efferent) neurons -
* transmit impulses away from the CNS
* most are multipolar
* cell bodies in CNS (brain/gray matter of cord)
* carry impulse to effector cells (muscle/skin) -
Functional Types of Neurons:
Features of Association (interneurons) -
* transmit between sensory and motor
* most are multipolar
* contained only in CNS
* 99% of all neurons - Neuroglia (in CNS) contains:
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Ependymal cells (ependymocytes)
Astrocytes
Oligodendrocytes
Microglia - Neuroglia (in PNS) contains:
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Schwann Cells (neurolemmocytes)
Satellite cells -
Neuroglia (in CNS):
Features of
Ependymal cells (ependymocytes) -
* cuboidal/ columnar epithelium
* line ventricles of brain and central canal of cord
* along with capillaries and pia mater form choroid plexuses -
Neuroglia (in CNS):
Features of
Astrocytes -
* most numerous neuroglia
* star shaped
* found between neurons and blood vessels
* support, transport nutrients
* blood-brain barrier -
Neuroglia (in CNS):
Features of
Oligodendrocytes -
* similar to astrocytes, but fewer processes
* forms myelin sheaths in brain and cord (CNS) -
Neuroglia (in CNS):
Features of
Microglia -
* small cells wit fewer processes
* support
* phagocytosis of bacteria and debris -
Neuroglia (in PNS):
Features of
Schwann Cells (neurolemmocytes) - * form myelin sheaths in PNS
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Neuroglia (in PNS):
Features of
Satellite cells - * support around neuron cell bodies in gangila in PNS
- Two notible facts re Neuroglia
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* neuroglia are capable of mitosis (unlike neurons)
* tumors of CNS usually of neuroglial origin (gliomas) - Nerves are composed of
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* processes of neurons (axons/dendrites)
* blood/lymph vessels
* connective tissue - Name the Neural Connective Tissues
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Endoneurium
Perineurium
Epineurium - Histology: Endoneurium
- areolar connective tissue sheath around fiber
- Histology: Perineurium
- dense irregular connective tissue around fasciculi
- Histology: Epineurium
- dense irregular connective tissue with collagen fibers around whole nerve
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Nerves and Tracts:
Features of Nerves -
* contain fasciculi wrapped in connective tissue in the PNS
* most nerves contain both sensory and motor fibers (mixed) -
Nerves and Tracts:
Features of Tracts -
* contain fasciculi in the CNS (no connective tissue)
* tracts are either sensory (ascending) or motor (descending) -
Ganglia and Nuclei:
Features of Ganglia - clusters of cell bodies outside the CNS
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Ganglia and Nuclei:
Features of Nuclei - clusters of cell bodies inside the CNS
- Nerve Impulse Transmission
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* mechanism by which neurons carry signals
* nearly all body cells have an electrical difference between the outside and the inside of their cell membranes
* due to this electical potential difference nerve cells (and muscle cells) are excitable. - Neurons can be excited by...
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* stimulation of sensory receptors
* other neurons - How does a NERVE IMPULSE happen?
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when a neuron is stimulated the electrical difference across the cell membrane is altered
This alteration is propagated along the length of the neuron as a NERVE IMPULSE - what are Neurotransmitters
- * chemicals that transmit impulse across a synapse from a presynaptic neuron to postsynaptic neuron
- define synapse
- the space between two neurons
- where are neurotransmitters stored?
- in synaptic vesicles in axon endings of presynaptic neuron
- Name some neurotransmitters in the body
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1. acetylcholine
2. epinephrine
3. norepinephrine
4. dopamine
5. endorphins/enkephalins
6. serotonin
7. gamma aminobutyric acid (GABA) - define meninges
- 3 layers of connective tissue protecting the brain and cord of the CNS
- name the meninges
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1. dura mater
2. arachnoid mater
3. pia mater -
CNS MENINGES:
Features of DURA MATER -
* tough mother
* dense irregular connective tissue
* outermost layer
* double layered (2 ply)
* space between layers create blood DURAL SINUSES
* dura terminates at level of 2nd sacral vertebra -
CNS MENINGES:
Features of ARACHNOID MATER -
* delicate, avascular, connective tissue with collagen/elastic fibers
* between pia/dura maters
* subarachnoid space (space under arachnoid) is filled with CSF
* folds in arachnoid mater called villi function as 1 way passage to allow CSF to diffuse from subarachnoid space into blood in dural sinuses -
CNS MENINGES:
Features of PIA MATER -
* soft mother
* thin, transparent, areolar connective tissue
* innermost, delicate, vascular
* follows contours of brain
* with capillaries and ependymal cells forms choroid plexes (secrete CSF) - name the two layers to DURA MATER
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outer = periosteal dura
inner = meningeal dura - Cerebrospinal fluid (CSF)
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* similar to plasma
* formed by an ultrafiltration process from choroid plexes in roofs of ventricles
* circulates in brain (ventricles) and outside of brain (subarachnoid space)
* reabsorbed into arachnoid villi and then returned to venous circulation - Notibles re Cerebrospinal fluid (CSF)
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* CNS contains 150 ml CSF
* 500 ml CSF produced/reabsorbed each day
* clear, colorless fluid similar to plasma (except more Na+, Cl-, no protein)
* CSF functions to cushion and protect the brain
* CSF carries nutrients and metaabolic wastes to/from nervous tissue
* CNS "floats" in CSF - CSF Cerebrospinal Fluid is contained in...
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* Ventricles
lateral (1 and 2)
third
fourth
* spinal cavity
* subarachnoid space - between the lateral and third ventricle?
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Interventricular foramen
Foramen of Monro - between the third and fourth ventricle?
- cerebral aqueduct
- Connecting the fourth ventricle to the subarachnoid space?
- lateral aperture and median aperture
- Ventricle connected to the central canal of cord?
- Fourth ventricle
- epinim of lateral aperture
- Foramen of Luschka
- Epinim of median aperture
- foramen of magendie
- epinim of cerebral aqueduct
- Aquaduct of silvius
- Life as a CSF
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formed in CHOROID PLEXES
flows from ventricles 1 & 2
through interventricular foramina
ventricle 3
cerebral aqueduct
ventricle 4
down central canal of cord, up median and lateral apertures
subarachnoid space
arachnoid villi
dural sinuses
inter jugular vein (venous circulation) - BRAIN 3rd week of development...
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3 vesicle brain
1. FOREBRAIN - prosencephalon
(cerebrum, thalamus & hypothalamus)
2. MIDBRAIN - mesencephalon
(cerebral peduncles & corpora quadrigemina)
3. HINDBRAIN - rhombencephalon
(pons, medulla oblongata & cerebellum) - BRAIN 5th week of development
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5 vesicle brain
FOREBRAIN - prosencephalon splits to form:
1. telencephalon...cerebrum
2. diencephalon...thalamus & hypothalamus
3. MIDBRAIN - mesencephalon
(cerebral peduncles & corpora quadrigemina)
HINDBRAIN - rhombencephalon splits to form:
4. metencephalon...pons/cerebellum
5. myelencephalon...medulla oblongata - Features of the CEREBRUM
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* 2 hemispheres
* convolutions (gyri/sulci)
* longitudinal fissure between hemispheres
* falx cerebri (dipping down of meningi to attach to the crysta galli
* lateral ventricles
* white matter/gray matter (couple mm on surface)
* basal ganglia
* cental sulcus (frontal/parietal)
* lateral sulcus (frontal/temporal) - Name the 4 lobes of the CEREBRUM
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Frontal
Parietal
Temporal
Occipital - Cerebral cortex notibles
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* "conscious mind"
* aware of ourselves/sensation
* initiate and control voluntary movement, communicate, remember and understand - Functional areas of Cerebral Cortex
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Primary Motor Cortex
Primary Sensory Cortex
Visual Cortex
Auditory and Olfactory Cortices
Association areas and Integrative centers -
Functional areas of CEREBRAL CORTEX:
Primary Motor Cortex -
* FRONTAL LOBE (precentral gyrus)
* origin of pyramidal tracts
* conscious control of skeletal muscles -
Functional areas of CEREBRAL CORTEX:
Primary Sensory Cortex -
* PARIETAL LOBE (postcentral gyrus)
* conscious perception of touch, pressure, vibration, pain, temperature and taste -
Functional areas of CEREBRAL CORTEX:
Visual Cortex -
* OCCIPITAL LOBE
* conscious perception of visual stimuli -
Functional areas of CEREBRAL CORTEX:
Auditory and Olfactory Cortices -
* TEMPORAL LOBE
* conscious perception of hearing and smell -
Functional areas of CEREBRAL CORTEX:
Association areas and Integrative centers -
* ALL LOBES
* connected to sensory and motor regions
* integration and processing of sensory data
* coordinate and initiation of motor activities
* includes Premotor area (ant. to precentral gyrus)
responsible for learned motor activities
* integrative centers are hemisphere specific - Features of Tracts
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* association tracts
* arcuate fibers
* commissural tracts
* projection tracts -
Tracts:
Association tracts - move information around in one hemisphere
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Tracts:
Arcuate fibers - short assoc tracts that run from on gyrus to anogher
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Tracts:
Commissural Tracts - connect the 2 hemispheres
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Tracts:
Projectio Tracts - connect cerebrum to other parts of brain or CNS
- Basal Ganglia features
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* nuclei
* (little groups of cell bodies that are) deep in white matter of cerebrum
* clusters of gray matter
* cell bodies of extrapyramidal tracts
* function for subconscious control of skeletal muscle tone and coordination of learned movement patterns - name some of the BASAL GANGLIA
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1. caudate nucleus
2. lentiform nucleus
3. globus pallidus
4. putamen
5. amygdaloid body - Functions of BASAL GANGLIA
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* function as complex neural calculators that work with the cerebral cortex in controling movements
* regulate intensity of movements - LIMBIC SYSTEM features
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* a group of tracts and nuclei that form a ring (limbus) around the brainstem
* "our emotional brain"
* establishes emotional/behavioral drives
* link conscious/intellectual function with unconscious autonomic function
* facilitate short term memory
* a functional grouping of structures
* amygdaloid body acts as integration center - Reticular Formation (RAS)
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* reticular activating system
* network of fibers in medulla, pons, and midbrain
* interconnects nuclei
* activates/arouses cerebral cortex
* maintains wakefulness/alertness - THALAMUS
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* part of diencephalon
* between cerebral hemispheres
* surrounds 3rd ventricle
* largely gray matter (nuclei)
* relay station for sensory and motor pathways
* relays all sensory impulses except olfactory to cerebrum or brainstem - HYPOTHALAMUS
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* diencephalon
* below thalamus
* lower sidewalls/floor of 3rd ventricle
* several important functions
* LINK between nervous-endocrine systems
1. produces releasing/inhibiting factors (anterior pituitary)
2. produces 2 hormones:
oxytocin and antidiuretic hormone "ADH" (secreted from posterior pituitary)
* controls of autonomic function (heartrate, blood pressure, respiration and digestive functions)
* helps control body temperature
* helps regulate hunger, thirst, sleep-wakefullness - Epithalamus
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* roof of diencephalon
* includes pineal gland (secretes melatonin)
* melatonin
* diurnal rhythms - Cerebral Peduncles
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* ventral midbrain
* bundles of pyramidal motor fibers descending from primary motor cortex
* budles of sensory fibers ascending to thalamic nuclei
* oculomotor nerve (III) emerges - Corpora Quadrigemina
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* dorsal midbrain
* 4 rounded elevations (sensory nuclei)
* trochlear nerve (IV) emerges just below (the only cranial nerve emerging dorsally - name the Corpora Quadrigemina and their functions
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Superior Colliculi (2) - relay visual stimuli from thalamus
Inferior Colliculi (2) - relay auditory stimuli from medulla - PONS features and functions
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* rounded bridge on underside of brainstem
* nuclei / tracts
* connects cerebellum with cerebrum and brainstem
* tracts relay to/from other parts of CNS
* nuclei for modifying respiratory rhythmicity
* nuclei for cranial nerves V, VI, VII, VIII - Medulla Oblongata features and functions
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* most inferior part of the brain
* continuation of cord above foramen magnum
* pyramids on ventral surface are tracts from primary motor area/lateral corticospinal tracts decussate at medulla. (cross over to other side, so motor areas on 1 side of cortex control muscles on other side of body).
* ALL ascending and ALL descending tracts pass thru medulla (some synapse)
* nuclei of cranial nerves VIII, IX, X, XI, XII
* contains nuclei and centers for regulation of vital autonomic functions - Vital Autonomic Centers
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* Cardiac center
increase/decrease heart rate
* Vasomotor center
constrict/dialate blood vessels
raise/lower blood pressure
* Respiratory center
functions with pons to regulate rate, depth, and rythm of breathing - Cerebellum
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* 2nd largest part of the brain
* behind cerebrum
* surface convolutions... folia
* 2 cerebellar hemispheres (vermis between)
* hemispheres consist of anterior/posterior lobes
* flocculonodular lobes lie anterior and inferior to hemispheres
* 3 pairs of cerebellar peduncles (tracts connect cerebellum to brainstem, cerebrum and spinal cord) - Functions of cerebellum...
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Anterior/posterior lobes
* involved in planning, execution and coordination of limb and trunk movements
Flocculonodular lobes
* maintain balance and control eye movements -
Cerebellum:
Name the peduncles and functions -
Inferior cerebellar peduncles
* link cerebellum to medulla and spinal cord
Middle cerebellar peduncles
* link cerebellum to pons
Superior cerebellar peduncles
* link cerebrellum to midbrain, thalamus and cerebrum - two notable physical features re Cerebellum
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* white matter of cerebellum is treelike pattern ... ARBOR VITAE
* TENTORIUM CEREBELLI... meningeal projection between cerebrum and cerebellum that contains TRANSVERSE SINUS - SPINAL CORD Features
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* 18 in in length
* CNS below medulla
* passes thru vertebral canal of vertebrae
* extends from forament magnum to level of 1st or 2nd lumbar vertebra - SPINAL CORD Functions
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* conduct impulses to/from brain
* process spinal reflexes - matter in Spinal Cord
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Gray matter (butterfly)
* cell bodies (neurons/glia)
White matter (around butterfly)
* tracts (myelinated/unmyelinated axons) -
Spinal Cord:
White matter
How many columns?
AKA for columns?
Name columns -
Three Columns.... funiculi
Anterior funiculus
Lateral funiculus
Posterior funiculus -
Spinal Cord:
White matter
Re Columns -
Funiculi contain tracts (fasciculi)
* Ascending tracts (sensory)
- carry information to brain
* Descending tracts (motor)
- carry information from brain -
Spinal Cord:
White matter
Ascending Tracts -
fasciculus gracilis
* carry fine touch, pressure & proprioception from lower half of body
fasciculus cuneatus
* carry fine touch, pressure and proprioception from upper half of body
lateral spinothalamic tracts
* carry pain, temperature
ventral (anterior) spinothalamic tracts
* carry crude touch and pressure
dorsal (posterior spinocerebellar tracts
ventral (anterior) spinocerebellar tracts
* carry unconscious proprioception from uscles to cerebellum -
Spinal Cord:
White matter
Descending Tracts function - * carry motor information from brain to skeletal muscles
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Spinal Cord:
White matter
Descending Tracts -
Pyramidal tracts
* originate from cells in precentral gyrus
* carry motor stimuli for fine skeletal muscle movements
corticobulbar tracts
* motor control over skeletal muscles
lateral corticospinal tracts
* decussate in medulla
* motor control over skeletal muscles
ventral corticospinal tracts
* motor control over skeletal muscles
Extrapyramidal tracts
* originate in cerebral cortex
* medial pathway
vestibulospinal tracts
tectospinal tracts
reticulospinal tracts
* lateral pathway
rubrospinal tracts - Medial pathway
- subconscious regulation of balance, tone, eye, head, neck, arm position in response to visual and auditory stimuli. Regulation of reflex activity
- lateral pathway
- subconscious regulation of arm muscle tone and movement