Test 2 (Nervous System)

Front 1

What are nerves?

Back 1

• Nerves are the master coordinating system of the body

• All thoughts, actions and sensations are reflected in their activity

• Conscious and unconscious life functions are regulated by nervous tissue

Front 2

Basic Functions of the Nervous System

Back 2

1. Sensory (input) - sense changes both internal and external
2. Integrative (what does it mean) - to interpret these changes
3. Motor (do something) - react to changes

Front 3

Parts of the Nervous System

Back 3

• Central Nervous System

- (Chara Never Sleeps)

- Brain and Spinal Cord

• Peripheral Nervous System

- (Papyrus Never Stops)

- Cranial and spinal nerves

- Afferent system (incoming sensory)

- Efferent system (Outbound motor)

Hint 3

Front 4

CNS vs. PNS

Back 4

Front 5

Central Nervous System

Back 5

Front 6

Two Types of Nervous Tissue Cells

Back 6

Neurons

Neuroglia (Glial Cells)

Front 7

Neurons

Back 7

• Functional Units of the Nervous System
  

• Three distinct portions

1. Cell body
2. Axon
3. Dendrites
   

Front 8

Neuron - Cell Body

Back 8

• Contains the nucleus surrounded by cytoplasm with typical organelles
  

• Many extensions from cell body called Dendrites (little trees)

• Single long extension called Axon

Front 9

Neuron - Dendrites

Back 9

• Typically short, tapering and highly branched
  

• dendrites receive information from another neuron, or body structure such as muscle, gland or surface

Front 10

Neuron - Axon

Back 10

• Long, thin, cylindrical projections
  

• conduct impulses towards another neuron, muscle or gland

• end of axon made of terminals with end bulbs

Front 11

Nerves

Back 11

• A nerve is a bundle of axons and associated connective tissue & blood vessels with specific function and direction.
  

Front 12

Synapse

Back 12

• The site where 2 neurons or neuron and an effector (acting producing) cell communicate
  

• End bulbs store chemicals called neurotransmitter

Front 13

Neurotransmitters

Back 13

• Chemical that transmits information from nerve cell to nerve cell
  

• Odours, tastes, motions stimuli for some neurons

• Acetylcholine is the neurotransmitter for muscle cells

Front 14

Functions and Characteristics of Nervous Tissue

Back 14

Neurons:

• Respond to various electrical and chemical stimuli

• Convert stimuli into nerve impulses (action potentials)

• Conduct impulses to other neurons, muscle fibers or glands

Front 15

Neuroglia

Back 15

• "nerve glue"
  

• Astrocytes - provides nutrients, maintain environment

• Microglia - Protects CNS from disease, Phagocytes

• Oligodendrocytes - forms myelin sheath for CNS neurons

• Ependymal Cells - forms cerebrospinal fluid

• Schwann Cells - forms myelin sheath of PNS neurons

Front 16

Anatomy of an Axon

Back 16

• Axons are often covered in "insulation" to speed transmission and maintain integrity of pathway
  

• Myelin Sheath is the phospholipid layer of insulating material surrounding axon

• Myelin produced by Schwann Cells

Front 17

Importance of Myelin

Back 17

• Insulation that keeps nerves separate from one another

• Similar to covering of an electrical wire

• Helps fine tine transmission

• Myelin begins to form pre-natally, and continues to adolescence

• Maturation of myelin sheaths responsible for enhanced coordination in maturing young

• Diseases of neurons can destroy myelin and disrupt nerve transmission

Front 18

Neuron Function

Back 18

• Nerves are said to "fire: when an impulse is conducted from one end of a neuron to the other.
  

• When a nerve does fire several stages are involved:

1. Resting state
2. Depolarization
3. Repolarization

Front 19

Resting State

Back 19

• When a nerve is not being stimulated
  

• Energy is required to maintain this state

• Molecules on the neuron cell membrane are responsible for maintenance

• Called the Sodium potassium pump

Front 20

Sodium Potassium Pump

Back 20

• Pumps sodium ions (Na+) out of the neuron
  

• Also pumps potassium ions (K+) in to the neuron

• Na+ is not able to freely diffuse across cell membranes

Front 21

Resting Membrane Potential

Back 21

• S-P pump maintain a difference in electrical charge across the cell membrane
  

• This "difference" in charges is called Resting Membrane Potential

Front 22

Depolarization

Back 22

• The "firing" of the neuron
  

• Results in a loss of the difference in electrical charges

Front 23

Action Potential

Back 23

• The big shift from negative to positive charge is called the: Action Potential

Front 24

Repolarization

Back 24

• Period of recovery in which the ions are reorganized
  
• Cell is re-polarized, but backwards
• NaK pump has to get back to work

Front 25

Biophysics

Back 25

• Threshold
  

• The Wave

• All or None principle

• Refractory period

Front 26

Threshold

Back 26

• Not every stimulus is capable of making the neuron fire
  

• Neuron has a minimum level of stimulation

• Called the Threshold

Front 27

Wave of Depolarization

Back 27

• Threshold stimulus causes a wave of sodium channels to open along the entire neuron
  

• Called a Wave of Depolarization

• A nerve impulse is actually the wave of depolarization traveling along the neuron

• Also called conduction of the action potential

Front 28

All or None Principle

Back 28

• When a neuron "fires"
  

• It does so to the full extent of its ability

• Therefore a neuron fires "to the max" or not at all

Front 29

Refractory Period

Back 29

• A neuron will not fire if a stimulus arrives before it has returned to its resting state
  

• This time of inability to respond is called The Refractory Period

• Absolute Refractory Period
• Absolutely no go

• Relative Refractory Period
• Strong stimulus at tail end

Front 30

Speed of Transmission

Back 30

• Signals can travel along a myelinated neuron at speeds of up to 100m per second (350 kph)
  

• Transmission along unmyelinated neurons is slower due to interference and leakage of electrical signal

Front 31

Two Categories of Neurotransmitters

Back 31

• Excitatory
  

• Causes depolarization of next neuron or target by helping approach threshold
• Most body neurotransmitters are excitatory

• Inhibitory

• Causes next neuron or target to get even higher - hyperpolarize threshold, preventing firing
• Tranquilizers work this way

Front 32

The Brain

Back 32

• The principle parts of the brain are:
  

• Cerebrum
• Cerebellum
• Diencephalon
• Brain stem

Front 33

Cerebrum

Back 33

• Higher order thought, consciousness
  
• Initiates voluntary movement, expresses conscious behaviours
• Damage to Cerebrum

• May cause abnormal movements, seizures, abnormal behaviours, hallucinations, loss of voluntary movement, inability to learn.

Front 34

Cerebellum

Back 34

• Smooths and coordinates muscle movements
  

• Compares intended movements to what is actually happening

• Damage to cerebellum from genetic, viral or bacterial causes results in hypermetria

• Alcohol affects cerebellum

Front 35

Diencephalon

Back 35

• Consists of the thalamus, hypothalamus and pituitary
  

• Hypothalamus region also
• Regulates temperature, hunger &thirst, rage and anger responses

Front 36

Brain "Stem"

Back 36

• Medulla Oblongata
  

• Pons

• Midbrain

• Damage to brainstem can result in death from respiratory failur or CV collapse

Front 37

The Brain - Protection

Back 37

• The brain is protected by cranial bones, cranial meninges, and cerebrospinal fluid
  

• Meninges are 3 layers of connective tissue" dura mater, arachnoid and pia mater

• Epidural anesthetics are injected around dura mater and bone in spinal area = decreased sensation without affecting brain functions

• Inflammation of meninges = meningitis

Front 38

Brain Blood Supply

Back 38

• Blood supply to brain is essential
  

• If blood supply is interrupted for a short time, unconsciousness results

• More than four minutes permanently damages neurons

• Lysosomes break down, release their contents and self-destruct the brain cells. (stroke, brain injury)

Front 39

Blood Brain Barrier

Back 39

• Separates nervous tissue itself from capillaries in the brain
  

• Walls of brain capillaries have no fenestrations or openings like other capillaries

• Glial cell membranes also assist in creating cellular barrier

• The Blood Brain Barrier serves to let only glucose, oxygen, CO2 and some ions through.

Front 40

OOOTTAFVGVAH

Back 40

Oh - Olfactory

Oh - Optic

Oh - Oculomotor

To - Trochlear

Touch - Trigeminal

And - Abducent

Feel - Facial

Very - Vestibulocochlear

Green - Glossopharyngeal

Vegetables - Vagus

A - Accessory

H - Hypoglossal

(Oh Oh Oh, To Touch And Feel Very Green Vegetables AH)

Front 41

Comparison of Somatic and Autonomic Nervous Systems

Back 41

• Autonomic and Somatic nervous systems together comprise the Peripheral nervous system
  

• Autonomic implies self-governing

• Usually operates without conscious control of the brain

Front 42

Autonomic Nervous System

Back 42

• Autonomic input is through sensory neurons which monitor internal conditions, such as blood CO2 level, degree of stretching of internal organs or blood vessels
  

• The ANS regulates the activities of smooth muscle, cardiac muscle, and glands

Front 43

Sympathetic vs. Parasympathetic Divisions

Back 43

• Parasympathetic division is principally concerned with activities that conserve energy.
  

• Sympathetic division is concerned with activities that expend energy

Example:

• Sympathetic division increases heart rate and inhibits digestive processes

• Parasympathetic division enhances digestive processes and slows down heart rate

Front 44

Spinal Cord

Back 44

Gray Matter vs. White Matter

• White matter refers to groupings of myelinated axons organized into sensory or motor tracts

• Gray matter is a collection of unmyelinated nerve structures

Front 45

Spinal Cord

Back 45

• Spinal cord conducts information via ascending and descending tracts.

• Ascending tracts carry sensory information up the spinal cord toward the brain

• Descending tracts conduct motor impulses from the brain down to the spinal cord and to the spinal nerves

Front 46

Reflexes

Back 46

• Reflexes are the body's principal mechanisms for responding to certain changes in the internal and external environments
  

• A reflex is a quick, involuntary response to a stimulus that passes through the reflex arc.

• A reflex arc is the shortest route that can be taken by an impulse from a receptor to an effector.

• Basic components are:
• receptor
• sensory neuron
• integrating centre
• motor neuron
• effector

Front 47

Withdrawal Reflex "Flexor" reflex

Back 47

• Protects us by causing immediate withdrawal of a limb from a source of injury, even before sensing pain.
  

Front 48

Corneal Reflex

Back 48

• Basic and common indicator of depth of anesthesia
  

• As anesthetic depth increases, pons of brain becomes less responsive and corneal reflex also becomes less responsive

Front 49

PLR

Back 49

• Does not measure vision
  

• Measures retinal response, CN2 integrity, diencephalon and CN3

Front 50

The General Senses

Back 50

• Visceral Sensation
  
• Touch
• Temperature
• Pain
• Proprioception

Front 51

Visceral Sensations

Back 51

• Hollow organs:
  

• Stretch causes Pain (cramps)
• Except the urinary bladder

Front 52

Touch (Tactile sense)

Back 52

• Provides a "window" for CNS to be aware of contact
  

• Constant pressure fades to subconscious
• Aware of sever or abrupt contact
• pressure receptors throughout integument

Front 53

Temperature Sense

Back 53

• Monitoring system for body's temperature control
  
• Prevents hypo and hyper thermia

• Receptors are Superficial or Deep

• Superficial (in the skin) - detects rise or fall of temperature

• Deep - monitoring of blood temperature. receptors in hypothalamus

Front 54

Corrective Actions

Back 54

• Alter blood flow
  
• Sweating
• Piloerection
• Shivering
• Thyroid hormone
• Seek heat or cold

Front 55

Nociception

Back 55

1. Transduction - stim converted to impulse at sensory nerve ending
   
2. Transmission - nerve fiber to spine
3. Modulation - Change degree of pain in spine
4. Perception - Spine to brain

Front 56

Proprioception

Back 56

• Awareness of body position and movement
  

• Receptors in muscles, tendons and joints

• Important for posture and movement

Front 57

5 Special Senses

Back 57

• Taste
  
• Smell
• Hearing
• Equilibrium
• Vision

Front 58

Gustation (Taste)

Back 58

• Gustatory receptor cells are called taste buds
  

• Interact with sense of smell

• Substance to be tasted must be in a solution of saliva

• If animal can't smell, they won't want to eat

Front 59

Olfaction (Smell)

Back 59

• Receptors in mucous membranes of nasal cavity

• Most highly evolved in dogs
• cats - 19 M receptors
• dogs - 147 M receptors
• Human - 5 M receptors

• Olfactory cells mixed with supporting cells

Front 60

Hearing

Back 60

• A dog can hear sounds 250 meters away
  

• Dogs have twice as many muscles for moving their ears as people

• The ear consists of three anatomical subdivisions: The external ear- comprised of the pinna, external auditory canal, and the eardrum
• middle ear- Small air-filled cavity, connected to pharynx by Eustachian Tube
• and the internal ear - Comprised of a series of canals. Outer bony labyrinth and an inner membranous labyrinth that fits into the bony labyrinth

Front 61

Equilibrium

Back 61

• When dizzy or head spins, your equilibrium was affected
  

• Includes information from inner ear, eyes and somatic proprioceptors

• Brain gets impulses about rotary motion

Front 62

Vision

Back 62

• Eye Words"
  
• Ocular
• Opthalm

• Vision is associated with a single layer of photoreceptors

Front 63

Anatomy of the Eye

Back 63

• The eye is constructed of 3 layers
  

• Outer fibrous layer,
• Sclera and cornea

• Middle vascular layer,
• Choroid, iris, ciliary body

• Inner nervous layer
• Retina

Front 64

Rods & Cones

Back 64

• Photoreceptors cells are either rods or cones
  

• There are many more rods than cones present in most species including humans

• Rods detects shades of gray and light

• Cones stimulated in brighter light, detect colours

Front 65

Image Formation

Back 65

• Refraction of Light
• Bending rays upon entering eye and traveling through transparent substances such as cornea, aqueous humor, lens, vitreous humor

• Accommodation
• Change in shape of lens in relation to angle of light rays

• Constriction of Pupil
• Autonomic response causes contraction of circular muscle of iris

• Convergence
• Ability of eye to focus on one object

• Inverted Image Formation
• Refraction causes images to be inverted (upside down)

Front 66

Extraocular Structures

Back 66

• Conjunctive

• eyelids

• tear production & drainage system

• Extraocular muscles