AP Exam 2

lymphatic, nervous, central

spinal cord

- inferior to brain

- exits cranium via foramen magnum

- descends vertebral canal

spinal cord segments

- 31 total

- 8 cervical

- 12 thoracic

- 5 lumbar

- 5 sacral

- 1 coccygeal

- 1 pair of spinal nerves per segment

- C1- C7 above

- C8- Co1 below

- nerves exit via intervertebral foramina

spinal cord enlargements

- swellings in the spinal cord

- nerves to limbs

- cervical enlargement

- lumbar enlargement

distal end of spinal cord

- known as CONUS MEDULARIS

- between L1 and L2 in adults

- FILIUM TERMINALE anchors end to sacrum

- CAUDA EQUINA is nerves to hip and legs

cross section of spinal cord

- central canal in center

- gray matter( H shaped, cell bodies of motor nerves)

- intermediate horns lateral

- distal horns are posterior (sensory nerves)

- white matter (myelinated axons, tracts are bundles of axons)

- ascending tracts move up the cord

- descending tracts move down the cord

spinal nerve anatomy

- spinal nerves connected to cord via 2 nerve roots

- DORSAL NERVE ROOTS are posterior (sensory nerves)

- DORSAL ROOT GANGLION (bundle of sensory nerve cell bodies in the dorsal root)

- VENTRAL NERVE ROOTS are anterior (motor nerves)

spinal nerve and axons

- SPINAL NERVES = contain sensory and motor nerve fibers)

- INDIVIDUAL AXONS =nerve fibers)

Neuriums

- ENDONEURIUM ( connective tissue covering of axon)

- FASCICLES (inside, bundles of axons)

- PERINEURIUM (connective tissue covering of fascicle) - EPINEURIUM- TOP CONNECTIVE TISSUE LAYER

spinal nerve anatomy

- entire spinal nerve composed of fascicles

- epineurium= (top, connective tissue covering of spinal nerve)

- perinerium = around nerve- -endoneriuem = around axon. dorsal ramus ( posterior branch of spinal cord)

- ventral ramus ( anterior branch of spinal nerve, larger than dorsal)

nerve plexuses

- network of nerves (4 main)

- 1. cervical plexus ( to neck and chest)

- 2. brachial plexus (to arms)

- 3. lumbar plexus (to anterior legs)

- 4. sacral plexus ( to posterior legs and buttocks)

spinal nerve reflex

- quick response to stimuli

- does not involve brain

- 4 or 5 steps

1. sensory receptor- detects environmental change

2. sensory nerve- carries impulse to cns

3. intermediate nerve- within cord and some reflexes do not involve this step

4. motor nerve- cns to periphery

5. effector organ- responds to stimulus (ex: patellar tendon reflex)

types of reflexes

- stretch

- golgi tendon reflex

- withdrawl reflex

- crossed extensor reflex

Stretch reflex

- prevents muscle from stretching too much

- receptors ( intrafusal + extrafusal muscle fibers)

- reciprocal inhibition of antagonist

golgi tendon reflex

- prevents muscle from contracting too much

- protects tendons

- receptor (golgi tendon organ)

- reciprocal excitation of antagonist

crossed extensor reflex

- one leg withdrawn

- one leg extended

meninges

- coverings of the central nervous system

- 3 layers

1. Dura mater- outer layer, dense irregular connective tissue, epidural space above dura mater

2. Arachnoid mater- middle layer, thinner than dura

- subarachnoid space- below arachnoid space, contains CSF

3. pia mater- inner layer, denticulate ligaments connect pia mater to spinal nerves

cerebral spinal fluid

- produced in brain

- covers cns

- protection, nutrition

menigitis

- inflammation / infection of spinal cord

- Streptococcus pneumoniae

- Neisseria meningitidus

- symptoms are headache, stiff neck, seizures

- diagnosis is blood culture and lumbar puncture

- treatment is antibiotics for bacterial infection, rest, fluid, pain medication, and supportive care

lumbar puncture

- also known as spinal tap

- samples cerbral spinal fluid

- needle inserted between L3 and L4 vertebrae

- avoids cord

vaccines for meningitis

- Pneumococcal polysaccharide vaccine

- Adults over 65

- Children over 2 with depressed immune system

Shingles

- Herpes zoster infection

- Chicken pox virus

- Retreats to dorsal root ganglion

- Reactivates in response to illness, stress

- symptoms are pain, redness, blisters; along distribution of sensory nerve (dermatome)

- treatment is shingles vaccine, and antiviral medication

distal end of the spinal cord and structures below

- ends at L1, L2

- called conus medularis

- filium terminale anchors end to sacrum

- cauda equina hangs below conus medularis

nervous system

- fast response to the environment

- fast internal control

- thought

Organization

- central nervous system contains brain and spinal cord

- peripheral nervous system contains all nerve structures out the CNS

- somatic nervous system which is conscious control

- autonomic nervous system which is unconscious functions

nerve types

- sensory nerves (environmental stimulus to cns)

- interneurons ( within cns)

- motor neurons (cns to effector organs)

Cells of the nervous system

- neurons= transmit info

- glial cells= helper cells of the nervous system ( astrocytes, oligodendrites, schwann cells)

Neuron structure

- dendrites= receive info

-cell body= cell control, nucleus, ribosomes

- axons= send info (one per cell)

Astrocytes

- support cells

- blood brain barrier meaning barrier between capillaries and nervous system

Oligodendrites

- produce myelin in cns

- cover axons and speed nerve conduction

schwann cells

- produce myelin in the pns

- myelin composed of cell membranes and white matter

ependymal cells

- line internal cavities in cns

nerve impulse

- electrochemical

- movement of ions in/out of cell

- involves changes in electrical potential

- charge difference between 2 locations

resting potential

-electrical potential on either side of the membranes on the neurons

- no nerve impulse at this time

- more negative inside (-70mV)

- inside cell is potassium (K+) and phosphate and proteins

- outside cell is sodium (Na+) and chloride (Cl-)

channels in membranes

- made of proteins

- each channel specialized for certain ion

- chemically gated (respond to chemical)

- voltage gated (respond to electrical)

sections of membranes

- 1. receptive = recieve stimuli from dendrities, cell body

- 2. initial= begining of axon

- 3. transmissive = end of axon

action potential steps

1. chemical channels for Na+ open

2. Na diffuses into cell

3. inside cell becomes more positive

4. voltage gated channels triggered

5. inside cell goes to +30mV (depolarization)

end of action potential steps

1. K channels open

2. K diffsuses out

3. inside cell becomes more negative (repolarization)

refractory period

- time when difficult to generate additonal action potential

- absolute= during current action potential

- relative = for short period after action potential

reestablishment of Na/K distribution

Na now inside

K now outside•

Sodium potassium pump reestablishes originalion distribution

pumps na out and k in

movement of action potential along membrane

- Ions move laterally along membrane

- na channels triggered

myelin and nerve conduction

- Myelin is composed of the membranes of glial cells

- Covers axons in sections

- Small gaps between sections known as nodes of Ranvier

- Action potential jumps from gap to gap ( saltatory conduction)

synapses

- junctions between nerve and second cell

1. presynaptic cell (axon of neuron, sends info to second cell

2. synaptic cleft ( space between cells)

3. Postsynaptic cell ( can be nerve cell)

chemical synapses

- majority of synapses

- chemical communication between cells

synpatic functioning

A. at presynaptic cell

step 1. nerve impulse reaches end of axon

step 2. calcium influx into axon triggered

step 3. neurotransmitters released from axon

B. neurotransmitters diffuse across synaptic cleft

C. postsynaptic cell contains receptors for neurotransmitters

D. neurotransmitters deactivated ( breakdown of enzymes and reuptake)

Postsynaptic potentials

1. excitatory post synaptic potential (allows na ions in)

2. inhibitory post synaptic potential (allows k ion out)

neurotransmitters

1. acetylcholine

2. noepinephrine + epinephrine

3. dopamine

4. serotonin

5. endorphins + enkephalins -FUNCTION IS TO CARRY SIGNALS

Acetylcholine

- in cns and pns

-autonomic ns

- neuromuscular junctions (MUSCLE CONTRACTION)

Norepinephrine + epinephrine

- adrenaline

- cns and autonomic ns

-stimulants

dopamine

- in cns

- pathways that modify movement

- responsible for addiction

serotonin

- cns + pns

- mood, appetite, sleep, digestive functions

endorphins and enkephalins

- cns

- pain relief and euphoria

- opioid receptors

electrical synapses

- work through gap junctions (intercalated discs between cardiac muscle cells)

- action potential moves between cells

- faster and efficient

Multiple Scerosis (MS)

- demyelinating disease (IN CNS)

- autoimmune in nature

- macrophages attack myelin

- diagnosis includes symptoms and medical imaging

- spasms, weakness, exaggerated reflexes

- treatment is corticosteriods and plasma exchange

Guillian-Barre Syndrome (GBS)

- demyelinating disease ( IN PNS)

- autoimmune

- diagnosis is spinal tap (CSF sample) and nerve conduction studies

- symptoms include muscle weakness, numbness, tingling, starts in hands/feet

-treatment is plasmapheresis to remove antibodies

- prognosis is death in 5%, 60 full recovery, 80 partial recovery

lymphatic system

- contains lymph capillaires

- collect lymph (water, electrolytes, lymphocytes

- prevents fluid buildup in tissues

- contain one way valves

lymphatic ducts in the lymphatic system

- largest lymphatic vessels

- right duct goes to subclavian vein

- thoracic duct goes to left subclavian vein

lymph nodes

- connective tissue and lymphocytes

- filter lymph

- swell in response to infection and cancer (lymphadenopathy)

lymph node structure

- germinal centers that have b cells and macrophages

- mantle zones that are around germinal centers and contain T lymphocytes

tonsils

- Lymphatic tissue

- 1. pharyngeal tonsils in nasopharynx

- 2. palatine tonsils in posterior boundry of oral cavity

- 3. Lingual tonsils at the base of the tongue

Thymus

- anterior and superior to heart

- largest in infancy

- decreases size into adulthood

- maturation of T lymphocytes takes place here

Spleen

- in posterior left abdomen

- functions: removal of abnormal blood cells, iron storage, and provides exposure of antigens to immune system

Spleen structure

- Hilus is the attachment of spleenic artery and vein

- Capsule is the connective tissue covering

- Pulp is the cellular interior ( red= red blood cells, white= lymphocytes

Mucosa-associated lymphoid tissue (MALT)

- protects mucous membrances from infection

-ex: peyers patches in small intestine

Lymphocytes

- found in lymphatic system

- in blood

- responds to anitgens (infections)

- production in bone marrow

Immunogen

an antigen (infection) already responsed to

T cells

- 80% of lymphocytes

- cytotoxic t cells that attack antigens directly

- helper cells that stimulate other lymphocytes ( can be destroyed by HIV)

- suppressor t cells that turn off (inhibit) immune system

B cells

- lymphocyte

- produce specific antibodys

- differentiate into plasma cells

NK cells

- natural killer cells

- attack cells and antigens directly

- less specific than cytotoxic t cells

Immunities

- innate immunity (born with)

- not specfic to any disease

- adaptive immunity

- develops after exposure, specific disease

Physical barriers to disease

- skin

- mucous membranes (respiratory, digestive)

- tears (contains enzyme, washing action)

Disease protection

- macrophages that are attracted to areas of infection by chemicals (chemotaxis)

NK cells

- immunological survelliance

- responds to any foreign antigen

- releases perforins

- recognizes tumor and viral antigens

Interferons

- proteins

- activated by lymphocytes, macrophages, and viral infected cells

- activates production of antiviral proteins

- basically warning cells

compliment system

- proteins

- compliment antibody action

chain reaction activated

- cytolysis= destroys target cell membranes

- stimulates inflammation

inflammation

- localizes response to injury

- activated basophils become mast cells

- releases histamine and heparin (clots blood)

- signs are redness, swelling, heat, pain

chemotaxis

- stimulates movement of cells to the area of injury

Fever

- controlled by hypothalamus

- response to pyrogens

- decreases microbial growth

- increases tissue repair

specific resistance

- specific response to specific antigen

- T lymphocytes

Cell mediated immunity

- T cells must first recognize antigen

- cells are activated when protein receptor binds to antigen

- needs 2 protein receptors to activate T cell

Major Histocompatibility Complex (MHC)

- produced by B cells and macrophages

- proteins that are used to present antigens to T cells

- MHC1 (produced at all times) and MHC2 (only produced in response to foreign antigen)

cytotoxic T cells

- ruptures cell membrances

- secrete poisnous lymphotoxins

- activates fatal genes in target cell

Memory T cells

- produced in response to activated T cells

- remain in body after infection

- response is now quicker and stronger

Suppressor T cells

- have delayed activation

- reduce extent of response

Helper T cells

- produce cytokines

- proteins

- attract macrophages

- stimulate nk cells

Antibody mediated immunity

- b cell mediated

- antigen bonds to b cell receptors

- b cells produce plasma cells which will produce the antibodies

Antibody actions

1. Neutralizing antigen.

2. Immobilizing bacteria.

3. Agglutinating and precipitating antigen.

4. Activating complement

5. Enhancing phagocytosis.

Antibody structure

- immunoglobulins

- 4 protein chains

- ends variable to bind to different antigens

Types of antibodies

1. IgG, most common and functions

2. IgM, first anitbodies produced

3. IgA, sweat, tears, saliva, breast milk

4. IgD,

5. IgE

Immune responses

1. primary- on 1st exposure to antigen (slow+weak)

2. secondary- subsquent exposure (faster, stronger)

Vaccines

- patient exposed to safe antigen

- primary response is memory cells develop

- secondary response to pathogen

- needs to be specific

- stimulates lymphocytes to that anitgen ONLY

Organ trasnplants

- donor and recipent must have MHC to reduce response

- immunosuppressive drugs to reduce rejection

Tumor necrosis factor (TNF)

- produced mainly by macrophages + cytotoxic cells

- acts as a cytokine

- kills tumor cells

Autoimmune diseases

- immune system damages its own tissues

- juvenile diabetes

- rheumatoid arthritis

- MS

- lupus

AIDS

- caused by human immunodefiency virus (HIV)

- attacks T helper cells

- infection through bodily fluids (sexual and iv drug abuse)

- Treatment is drug cocktails of choice