• Primary Function - To produce movement or behavior

What is the Function of the Somatic Nervous System (SNS)

Def- All spinal cord and cranial nerves carrying sensory information to the CNS from the muscles, joints, and skin

-Is monitored and controlled by CNS

-The cranial nerves by the brain, the spinal nerves by the spinal cord segments

-Also transmits outgoing motor instructions that produce movement

Def - Balances the body's internal organs to rest and digest through the parasympathetic (calming) nervers or fight or flight/vigorous activity through sympathetic (arousing) nervers

Aff - (incoming) refers to sensory info coming into CNS or one of its parts

(ex: sesnory pathways to CNS)

Eff - Info leaving the CNS or one of its parts

(Ex: motor pathways leading from CNS)

Saggital Plane - bisects the brain into right and left halves

Coronal - divides the brain into front (anterior) and back (posterior) regions

Horizontal - divides the brain into upper and lower parts

Meidal- structures toward the brain's midline

Lateral - structures in the brain towards the side

Proximal - near the center

Distal - toward the periphery

Ipsi - same side

Contra - opposite side

Rostral - head end

Caudal - tail end

Dorsal - On or toward the back of an animal in reference to human brai  nuclei, located above.

(Ex a dogs back)

Ventral - on or toward the belly or the side of the animal where the belly is located 

(ex dog)

Meninges - three layers of protective tissue including the dura mater, arachnoid and pia mater 

-Infection here called Meningitis is within the meninges and spinal fluid

Dura Mater - "Hard Mother" - Tough outer layer of fibrous tissue

Arachnoid Layer- "Like a Spider's web - Thin sheet of delicate connective tissue

Pia Mater - "Soft Mother" - Moderately tough layer that clings to the brain's surface

What is the Significance/Location of Cerebral Spinal Fluid (CSF) ?

CSF 

-clear solution of sodium chloride and other salts that fills the ventricles inside the brain and circulates around the brain and spinal cord

-Flows from the lateral ventricle to the third ventriclem through interventricular foramen

-3rd and 4th ventricle connected by the cerebral aqueduct

-Absorption of the CSF into the blood stream takes place through structures called arachnoid villi

Located - Beneath Arachnoid layer and the Pia mater

Function

1) Protection - cushions the brain so that it can move/expand slightly without pressing on the skull

2) Buoyancy

3) Excretion

4) Endocrine medium for brain

- Sulci that are very deep

Longitudinal fissure exists between the cerebral hemishperes and lateral fissure at the side of the brain exists as well

Def - a blockage or break in a cerebral artery that is likely to cause death in the affected region

2 Types of Strokes

1) Blockage

2)Burst Vessel

3 Arteries in Brain

Anterior, Middle and Posterior

Def - Major structure of the forebrain, consisting of two virtually identical hemispheres (left and right) and responsible for most of conscious behavior

Def- Central strux of the brain including the hindbrain, midbrain, thalamus, hypothalamus ,

Function Responsible for most unconscious behavior

Gray - (darker region) is largely composed of cell bodies and capillary blood vessels

function either to collect and modify information or to support this activity

White- (lighter region) an area of the nervous system composed mostly of nerve fibers with fatty covered (myelin) neural axons that form the connections between brain cells

-One of four interconnected areas of the brain that contain cerebrosnpinal fluid 

-Function not entirely understood

-Possible Functions include brain metabolism and excretion

Def canal that runs the length of the spinal cord

PeriAqueductal Gray?

Def - Fiber system connecting the two cerebral hemispheres to provide a route for direct communication between them

Def - area under corpsum callosum that generally controls basic physiological functions like motor, sensory, perceptual and cognitve

Neuron - Carry out brain's major functions, consists of about 80 billion

Glial Cells - Aid and modulate nerons activities, approximately 100 billion

Nucleus - a group of cells forming a cluster in the brain that forms a functional grouping (cakked a ganglion in the PNS)

Fiber a single axon from a neuron

Nerve - A large collection of axons coursing together outside the CNS

Tract - Large collection of axons coursing together within the CNS

1) Spinal Cord 

-Porduces most body movements, houses the cell bodies of motor neurons

-Can act independently of the brain

Segmented Organization -  Spinal refelex is an autamatic movement that is difficult to prevent (ex knee-jerk reflex)

2) Brainstem

-Begins where spinal cord enters the skull

-Produces movement and creates a sensory world

-Receives input/output

Has 3 Regions:

A) Hindbrain 

          Cerebellum 

Cerebellum Consists of 3 Sections:

1) Reticular Formation

2/3) Pons and Medulla

B) Midbrain

C) Diencephalon

a) Thalamus (has one on each hemisphere)

b) Hypothalamus (also one in each hemishphere)

3) Forebrain (contains 3 structures)

a) Neocortex

b) Basal Ganglia

c) Limbic system (includes hippocampus, amyglada and cingulate cortex)

Brainstem 

-Begins where spinal cord enters the skull

-Produces movement and creates a sensory world

-Receives input/output

Has 3 Regions:

A) Hindbrain - evolutionary oldest part of the brain, especially important in motor functions (ex dancing).

Consists of:

          Cerebellum 

one of the largest structures in the human brain, larger areas of this in animals indicates increases in physical speed and dexterity

Cerebellum Consists of 3 Sections:

1) Reticular Formation

A netlike mixture of neurons (gray matter) and nerve fibers (white matter) that gives this structure the mottled apearnce from which its name derives. Nucelei are localized along its length into small patches, each with a special function in stimulating the forebrain such as in awakening from sleep

2/3) Pons and Medulla

Contain substructures that control many vital movements of the body. anuclei within the pons receive input from the cerebellum and actually form a bridge from it to the rest of the brain. Medulla is lovated at the rostral tip of the spinal cord and functions to regulate breathing and the cardiovascular system

B) Midbrain

-Contains the Tectum (roof of midbrain)

Superior Colliculus (above) - visual processing 

Inferior Colliculus (below) - auditory processes

-Contains Tegmentum (floor of midbrain)

-responsible for eye/limb movements, species-specific behaviors, and perception of pain

-Also contains red nucleus (controls limb movements) and the substantia negra (important in initiating movements, destruction causes Parkinson's Disease) which is cionnected to the forebrain. 

C) Diencephalon

Integrates sesnory and motor information on its way to the cerbral cortex

a) Thalamus (has one on each hemisphere)

Gateway for channeling sensory information to the cortex, receives input from all sensory systems and sends output to cerebral cortex (forebrain)

b) Hypothalamus (also one in each hemishphere)

Hormone function (through connections with the pituitary gland), feeding, sexual behavior, sleeping, temperature regulation, emotional behavior, contains at least 22 different nuclei

3) Forebrain 

(contains 3 structures)

a) Neocortex

-Tissue that is visible when we view the brain from the outside

Unique to mammals

-What makes us "human"

-Regulates various mental activitites

(e.g. perception, planning, goal directed movement)

-Connected to virtually all other parts of the brain as opposed to other structures

-Has 6 layers of cells (microsopic)

(1-3 Integrative functions, 4 sensory input (afferent), 5-6 output to other parts of the brain

-Evolutionary older cortex has 3 layers

b) Basal Ganglia

-Lie within the fiorebrain just below the white matter of the cortex

Does NOT produce voluntary movement

-Applies brakes to voluntary movement, in a sense controlling it that way

-Control of voluntary movement - receives input from cortex

c) Limbic system (includes hippocampus, amyglada and cingulate cortex)

-Group of structures between the neocortex and brain stem

-Regulates emotions, sexual behavior, memory and spatial navigation

-Amyglada is typically involved in fear regulation/coordination and lack of one can result in little/no fear in an animal

-Hippocampus area is associated specifically with memory and spatial memory, loss of fibers here is related to Alzheimer's

-Located in the forebrain

-System itself is evolutionary ancient, not very developed in humans but is in many other animals

The order of this system is as follows:

1) Olfactory Bulb

2) Pyriform Cortex

(where most info from olfactory bulb is sent to)

3) Thalamus

4) Neocortex (or frontal cortex) 

What is the Law of Bell and Magendi?

- ANS connects the central and somatic nervous systems to unconsciously regulate bodily organ function

Ganglia - collections of neural cells

Auntonomic Ganglia - A group of neurons located outside the CNS

Preganglionic Neurons- run from the CNS to the autonomic ganglia

Postganglionic Neurons- run from the autonomic ganglia to targets in the body

What are the two main divisions in the ANS?

-Postganglionic sympathetic and parasympathetic neurons use different transmitters:

a) Postganglionic sympathetic neurons produce norehinephrine (AKA noradrenaline) 

(Increases hear rate)

b) Postganglionic parasympathetic neurons produce acetylcholine

(decreases heart rate)