Chapter 2 and 7 - Anatomy of the NS Flashcards
Neuron
The basic functional unit of the nervous system
Nerve
A bundle of axons in the peripheral nervous system
Tract
A bundle of axons in the central nervous system
Ganglion
A group of cell bodies in the peripheral nervous system
Nucleus
A group of cell bodies in the central nervous system
Neuroanatomical Directions
Brain:
Dorsal - up
Ventral - down
Anterior - front
Posterior - back
Spine:
Anterior - up
Posterior - down
Ventral - front
Dorsal - back
Others:
Medial – towards the middle
Lateral – towards the side
Proximal – close to the body
Distal – further away from body
Contralateral – opposite side
Ipsilateral – same side
Sections of the Brain
Horizontal – a slice parallel to the ground
Frontal (coronal) – slicing bread or salami
Sagittal – a midsagittal section separates the left and right halves
2 Parts of the Nervous System
Central nervous system
Peripheral nervous system
Anatomy - Central Nervous System (CNS)
Brain (in the skull)
Spinal Cord (in the spine)
Anatomy - Peripheral Nervous System (PNS)
Located outside of the skull and spine
Serves to bring information into the
CNS and carry signals out of the CNS
The CNS is covered by…
three meninges and encased in bone (skull or spinal cord)
- Dura mater - tough outer membrane
- Arachnoid membrane - weblike
- Pia mater - adheres to CNS surface
Cerebrospinal fluid (CSF)
- Fluid serves as cushion
Cerebrospinal Fluid
Acts as cushion for CNS
Found in:
1. Subarachnoid space → between arachnoid membrane and pia mater
- Ventricles → Series of hollow interconnected chambers, filled with CSF
- 4 ventricles: 2 lateral, 3rd and 4th
- Cerebral aqueduct
2 Parts of the Peripheral Nervous System
- Somatic Nervous System:
- interacts with external environment
(Afferent nerves (sensory to CNS))
(Efferent nerves (motor from CNS)) - info from sense organs to CNS
- voluntary muscles control
- Autonomic Nervous System
- regulates body’s internal environment
(Afferent nerves (sensory from internal organs to CNS))
(Efferent nerves – 2 kinds) - controls heart, intestines, etc
- involuntary muscles
Autonomic Nervous System
Sympathetic and parasympathetic nerves generally have opposite effects
Sympathetic - fight or flight
Parasympathetic - rest and relaxation
Both outputs we don’t control
Cranial Nerves
I - Olfactory nerve - olfactory
II - Optic - vision
III - Oculomotor - eye movements, control of pupil, lens and tears
IV - Trochlear - eye movements
V - Trigeminal - facial sensations, chewing
VI - Abducens - eye movements
VII - Facial - facial movements, salivary glands, taste
VIII - Vestibulo-cochlear nerve - acoustic branch, vestibular branch
IX - Glossopharyngeal - throat muscles, salivary glands, taste
X - Vagus - control and sensation of internal thoracic and abdominal viscera such as bronchioles, heart and stomach
XI - Spinal accessory - head and neck muscles
XII - Hypoglossal - tongue muscles
“on old Olympus’s towering top a Finn and German viewed some hops”
Development of the Human Brain
From the ectoderm of our embryotic cells, we develop a neural tube
The 5 Major Divisions of the Human Brain
- Telencephalon
- Diencephalon
- Mesencephalon
- Metencephalon
- Myencephalon
Major Divisions of the Brain, Continued
Forebrain - Telencephalon, Diencephalon
Midbrain - Mesencephalon
Hindbrain - Metencephalon, Myelencephalon
Hindbrain Divisions - Myelencephalon
Medulla
- life support functions
- damage
Reticular formation
- gate keeper, can admit or block sensory info
- many general anesthetics work here
- damage
Hindbrain Divisions - Metencephalon
Pons
- bridge
- ventral surface
- main connection b/w cortex and cerebellum
- role in sleep, dreaming, eye movements, vestibular sense
Cerebellum
- little brain
Midbrain Divisions - Mesencephalon
Tectum - dorsal surface
Tegmentum - ventral
Tectum
“Roof”
Superior colliculus - vision
Inferior colliculus - audition
Visual reflexes and reactions to moving stimuli
Tegmentum
3 colourful structures:
Periaqueductal gray - analgesia
Substantia nigra - sensorimotor
Red nucleus - sensorimotor
Forebrain Divisions - Diencephalon
Thalamus
Hypothalamus
Thalamus
Switchboard
Senses (except olfaction) stop here before going to appropriate area of cortex
LGN - vision
MGN - audition
VPN – touch, taste
Hypothalamus
Located just below thalamus
Homeostatic control motivated behaviors
HOW?
Through the release of hormones from pituitary gland
(dangles beneath hypothalamus)
Cerebral Cortex
Surrounds the cerebral hemispheres, convolutions serve to increase surface area
Made up of:
- sulci (small grooves)
- fissures (large grooves)
- gyri (bulges or bumps)
Longitudinal fissure –
a groove that separates right and left hemispheres
Major Fissures of Cerebral Hemispheres
Lateral fissure
Central fissure
Longitudinal fissure
Lobes of the Brain
Frontal lobe
Central sulcus
Parietal lobe
Occipital lobe
Sylvian fissure
Temporal lobe
Cerebellum
Broadman Areas
Defined by their cytoarchitecture
- structure of their cells
Neurons
Functional unit of the NS
Specialized for the reception, conduction and transmission of electrochemical signals
Many sizes and shapes
External Anatomy of a Neuron
Cell membrane
Dendrites
Axon hillock
Axon
Myelin
Nodes of Ranvier
Cell body
Buttons
Synapses
Cell Membrane
The semipermeable membrane that encloses the neuron
Dendrites
The short process emanating from the cell body, which receives most of the synaptic contacts from other neurons
Axon Hillock
The cone-shaped region at the junction between the axon and the cell body
Axon
The long, narrow process that projects from the cell body
Cell Body
The metabolic center of the neuron, also called the SOMA
Myelin
The fatty insulation around many axons
Nodes of Ranvier
The gaps between sections of myelin
Bottons
The buttonlike endings of the axon branches, which release chemicals into synapses
Synapses
The gaps between adjacent neurons across which chemical signals are transmitted
The Antenae of the Neuron
Dendrites - collect incoming signals from other neurons
Incoming signals are comboined and processed; if strong enough, they are passed forward through the soma
Dendritic Morphology (shape)
Neurons can be classified by the nature of their dendrites
Dendritic branching
Dendritic spines
Parts of the Neural Soma (cell body)
Cytoplasm
Gogli apparatus
Membrane
Mitochondria
Myelin sheath
Microtubules
Lysosome
Dendritic spines
Smooth endoplasmic reticulum
Rough endoplasmic reticulum
Dendrite
DNA Expression
DNA ➡️ RNA ➡️ Protein
Replication (DNA duplicates) ➡️ Transcription (RNA synthesis) ➡️
Translation (protein synthesis)
Regulating DNA Expression
Promoters - sequence of DNA that increases the likelihood of genetic expression
Transcription Factors - protiens that regulate the polymerase
Stop Sequence - sequence of DNA that stops transcription
Axon Collaterals
Parallel (branching) paths that the axon from a single neuron may take
Axon Transport
Some material needed at the end of the axon are too big to be built there
They are built in the cell body and transported
(the transport protein is KINESIN)
Axoplasmic Transport - occurs from the soma to the button
At The Button - Synapse
The junction between the axon buttons/terminal of one sell, and the body/dendrites of another is called SYNAPSE
What happens at the axon terminal?
Exocytosis
The Support Structures of the Neuron
Microtubules
Neurofilament
Microfilaments
Microtubules
Long pipes running down the axon
Regulated by “microtubule associated proteins”
Neurofilament
Consists of wound rope-like subunits
Very strong
Microfilaments
Most densely found in the “neurites”
Plays a role in changing shapes of a sell (actin)
Glial Cells
Support and nourish neurons
Recent evidence for glial communication and modulatory effects of glia on neuronal communication
4 Classes of Glial Cells
Oligodendrocytes:
- extensions rich in myelin create myelin sheaths in CNS
Schwann Cells:
- similar to function of oligodendrocytes but in PNS, csn guide axonal regeneration
Astrocytes:
- large glia, start-shaped, many functions
Microglia:
- involved in response to injury or disease
