module 5 lesson 1.1: nervous system

CNS: brain & spinal cord

PNS: cranial nerves & spinal nerves

-afferent (sensory) pathways: can respond to ___

-efferent (effector/ motor) pathway

PNS: functionally: somatic (voluntary + sensory reception) & autonomic system

Autonomic system: sympathetic & parasympathetic

Tracing the Neural Pathway

1. Dendrite receives stimuli

2. Initiates depolarization at ___

3. Electrical impulse jumps from ___ to ___ on axon

4. At end of axon, reaches axon terminal

5. Terminal releases ___.

CNS: brain & spinal cord

PNS: cranial nerves & spinal nerves

-afferent (sensory) pathways: can respond to internal signals like CO2 & acidity changes for respiratory rate, can sense external stimuli like temp

-efferent (effector/ motor) pathway

PNS: functionally: somatic (voluntary + sensory reception) & autonomic system

Autonomic system: sympathetic & parasympathetic

Tracing the Neural Pathway

1. Dendrite receives stimuli

2. Initiates depolarization at cell body

3. Electrical impulse jumps from node to node on axon

4. At end of axon, reaches axon terminal

5. Terminal releases neurotransmitters.

Initiation of Neural Impulse

single neuron may synapse with 50,000 other neurons

Each secretes a ___

•Hundreds of possible chemicals

•Some ___

•Some ___

•Varying strength

Neuron must interpret all this information and decide ____

Good to know: Once they reach a certain threshold, there will be a change in the electrical balance and cause the message to fire - depolarize

Initiation of Neural Impulse

single neuron may synapse with 50,000 other neurons

Each secretes a neurotransmitter or neuropeptide

•Hundreds of possible chemicals

•Some excitatory

•Some inhibitory: stops a messenger

•Varying strength

Neuron must interpret all this information and decide whether to polarize or depolarize

Good to know: Once they reach a certain threshold, there will be a change in the electrical balance and cause the message to fire

Brain

-Basal ganglia: for ____

-Thalamus: ___

-Hypothalamus: regulates ___

-Cerebellum: __ coordination & motor learning of voluntary actions 

-Brain stem: 

•Midbrain: ___

•Pons: ___

•Medulla: ___

Brain

-Basal ganglia: motor function

-Thalamus: relay station

-Hypothalamus: HR, BP, sleep, etc.

-Cerebellum: motor coordination, motor learning of voluntary actions 

-Brain stem: 

•Midbrain: sensory processing, motor consciousness, sleep

•Pons: relay, sleep, breathing

•Medulla: respiration, heart, GI function, CN 8 - 12

Meninges: 3 membranes surrounding brain and spinal cord

Dura mater: 2 layers

• __ (next to cranium) (epidural space)

• Inner ___ (meningeal layer)

• ___ space between dura mater and next layer, helps regulate spaces between __

Arachnoid membrane

• Follows contours of brain but not sulci

• What space is between arachnoid and next layer? ___

Pia mater

• Delicate, follows sulci and fissures

Meninges: 3 membranes surrounding brain and spinal cord

Dura mater: 2 layers

• Periosteum (next to cranium) (epidural space)

• Inner dura (meningeal layer)

• Subdural space between dura mater and next layer helps regulate spaces between CSF & blood

Arachnoid membrane

• Follows contours of brain but not sulci

• Subarachnoid space between arachnoid and next layer

Pia mater

• Delicate, follows sulci and fissures

CSF and Ventricles

-Similar to plasma

-Circulates in ventricles and subarachnoid space (125 – 150 ml)

-Brain floats in it, prevents ___

•Cushions against jarring and jolting

•Prevents ___

Blood Supply

-Brain receives 20% of cardiac output

-Collateral circulation

•___

•___

•Join in circle of Willis: ____ 

-Venous drainage

•Does not parallel arterial supply

•____ sinuses drain into internal jugular vein

Spinal Cord

• Nerve cell bodies arranged in “horns”

• Nerve pathways ___ in the spinal cord

– Eg. Sensation of the left side of the body enters the left dorsal horn, and crosses to the right ventral horn and travels to right hemisphere

• Sensation

– Spinothalamic tract: responsible for ____

– Posterior columns: (does/ does not) ___ cross sides; responsible for ___

CSF and Ventricles

-Similar to plasma

-Circulates in ventricles and subarachnoid space (125 – 150 ml)

-Brain floats in it, prevents brain from sinking down due to gravity

•Cushions against jarring and jolting

•Prevents pulling on meninges and blood vessels

Blood Supply

-Brain receives 20% of cardiac output

-Collateral circulation

•Internal carotid

•Vertebral arteries

•Join in circle of Willis: internal & vertebral artery come together, helps distribute collateral 

-Venous drainage

•Does not parallel arterial supply

•Venous plexuses and Dural sinuses drain into internal jugular vein

Spinal Cord

• Nerve cell bodies arranged in “horns”

• Nerve pathways cross in the spinal cord

– Eg. Sensation of the left side of the body enters the left dorsal horn, and crosses to the right ventral horn and travels to right hemisphere

• Sensation

– Spinothalamic tract: pain, temperature, crude (hard) and light touch

– Posterior columns: does not cross sides; position, vibration, finely localized touch

Nerve Impulse

Pre-Synaptic Neuron Transmission of Impulse

… → … → …

Release Neurotransmitter

Bind to Post-Synaptic Cell

Cell Change Actions

• Muscle ___

• Glands ___

• Another neuron fires ___

Neurotransmitters 

• Produced + released by ____

• Release of Transmitter

– Small number released

– ___ a concentration gradient

• Receptor Binding (reversible/ irreversible) ____

• Termination of Transmission

– Reuptake: ____

– Enzymatic Degradation: _____

Ways we can interfere

Alter ___ conduction: local anesthetics

Alter ___ : more/ less neurotransmitters

Affect ____: block or enhance the job of specific neurotransmitter

Agonist

• Same effect as natural process

Antagonist

• Reduces or opposite receptor deactivation

Nerve Impulse

Pre-Synaptic Neuron Transmission of Impulse

Dendrite→ Axon→ Axon Terminal

Release Neurotransmitter

Bind to Post-Synaptic Cell

Cell Change Actions

• Muscle relaxes or contracts

• Glands secreted or stopped

• Another neurons fire more or less

Neurotransmitters 

• Produced + released by neurons (vesicles)

• Release of Transmitter

– Small number released

– Down a concentration gradient

• Receptor Binding (reversible)

• Termination of Transmission

– Reuptake: some neurotransmitters get absorbed by reuptake transporters back into neuron

– Enzymatic Degradation: breaking down neurotransmitters & therefore stopping the next impulse from being sent

Ways we can interfere

Alter axonal conduction: local anesthetics

Alter synaptic transmission: more/ less neurotransmitters

Affect receptors: block or enhance the job of specific neurotransmitter

Agonist

• Same effect as natural process

Antagonist

• Reduces or opposite receptor deactivation

Receptor types and selectivity

Drug Selectivity: consider ___

→ Does drug bind to only A1 receptors or does it bind to B1 and B2 receptors?

→ we want something to be selective bc it has ____

→ minimizes ___

Physiologic Selectivity: consider ___

→B1 receptors control heart, conductivity, and contract as well as renin release from kidney

Receptor types and selectivity

Drug Selectivity: selectivity of drug for effected receptor

→Does drug bind to only A1 receptors or does it bind to B1 and B2 receptors?

→ we want something to be selective bc it has specific action on specific site

→ minimizes side effects in non target tissues

Physiologic Selectivity: does the receptor do more than one thing?

→B1 receptors control heart, conductivity, and contract as well as renin release from kidney

Peripheral: Neurotransmitters + Receptors

• Acetylcholine

• Epinephrine

• Norepinephrine

• Dopamine (kind of): 

– Naturally- no

– Drug Excessive dose-yes

Symp: Adrenergic Receptors

• mediate ____

→___

→___

Para: Cholinergic Receptors

• mediate ___

• ___

• ___

Peripheral: Neurotransmitters + Receptors

• Acetylcholine

• Epinephrine

• Norepinephrine

• Dopamine (kind of): 

– Naturally- no

– Drug Excessive dose-yes

Symp: Adrenergic Receptors

• mediate response to Epi/Norepi

→Alpha-1, Alpha-2

→Beta-1, Beta-2

Para: Cholinergic Receptors

• mediate response to ACh

• Nicotinic: Skeletal muscle contraction

• Muscarinic: increased gland secretion, smooth muscle contraction, slow HR

Transmitter	Alpha-1	Alpha-2	Beta-1	Beta-2	Dopamine
epinephrine	X	X	X	X
norepinephrine	X	X	X
dopamine	X		X		X

.

Autonomic Functions

Regulation of the heart

Regulation of Glands

• Salivary

• Gastric

• Sweat

• Bronchial

Regulation of Smooth Muscle

• includes ____

• GI tract

Sympathetic function

Cardiovascular system

• Increase ___

Body temperature

Stress: Fight or Flight

• Blood: ___

• Bronchi: constriction or dialatin?

• Pupils: constriction or dilation?

• Mobilization of stored energy: glucose, fatty acids

Autonomic Functions

Regulation of the heart

Regulation of Glands

• Salivary

• Gastric

• Sweat

• Bronchial

Regulation of Smooth Muscle

• Bronchi, blood vessels, urogenital

• GI tract

Sympathetic function

Cardiovascular system

• Increase HR and BP

Body temperature

Stress: Fight or Flight

• Move blood from skin and viscera to muscles

• Dilation of bronchi

• Dilation of pupils (for better vision)

• Mobilization of stored energy: glucose, fatty acids

Adrenergic response

Alpha 1:

•Eyes: ___

•Blood vessels: ___

•Ureter: ___

Alpha 2:

•Insulin: ___

•Which neurotransmitter? ____

•Modulates ___

Beta 1:

•Heart: ____

•Kidney: ___

Beta 2:

•Involves the following systems: ___

Adrenergic Agonist- AlphaPhenylephrine

Why	• ___ • Constriction of ___ • Pupil ___ (constriction/ dilation?) Acts primarily on ___ to stimulate ___ response
MOA	• bind primarily to ___; stimulate within SNS
Side Effects	• Neuro: ___ • HEENT: ___ • CV: ___, don’t give to patients with ___ • GI: NV • GU: decreased urine output
Pharmacokinetics	• Widely distributed, M: L, E: urine

Adrenergic response

Alpha 1:

•Eyes: iris dilate

•Blood vessels: vasoconstrict, increase BP

•Ureter: closes sphincter

Alpha 2:

•Insulin: beta cells release insulin

•Acetylcholine

•Modulates norepinephrine

Beta 1:

•Heart: increase myocardial activity

•Kidney: increased renin (to maintain BP/ fluid volume)

Beta 2:

•Bronchial tree, muscle, liver- smooth muscle dilation

Adrenergic Agonist- AlphaPhenylephrine

Why	• Orthostatic hypotension • Constriction of topical vessels in nose • Pupil dilation Acts primarily on A1 receptors to stimulate sympathetic response
MOA	• bind primarily to alpha receptors; stimulate within SNS
Side Effects	• Neuro: anxiety, restlessness, depression, fatigue • HEENT: blurred vision • CV: EKG changes, arrhythmias, BP changes (don't give to patients with high BP) • GI: NV • GU: decreased urine output
Pharmacokinetics	• Widely distributed, M: L, E: urine

Parasympathetic actions

Eyes: __ (constrict/ dilate?) allow to focus,

Tears, salivary: secretion

Bronchial tree: increased ___, broncho (constriction/ dilation?)

Enzymes: ___

Gastric: ___

Heart: fast or slow? ___

GI: release gastric juices, and increased motility through guts

Bladder: contracts or relaxes?

Parasympathetic actions

Eyes: allow to focus, constrict (meiosis vs mydriasis)

Tears, salivary: secretion

Bronchial tree: increased sputum, bronchoconstriction

Enzymes: more secreted

Gastric: increased gastric secretion + motility

Heart: slowing down heart

GI: release gastric juices, and increased motility through guts

Bladder: contractions to help go to the bathroom

Cholinergic response

Cholinergic Nerves: for ___ & includes:

• ___

• ___

• ___

• ___ in CNS

Muscarinic Receptors

• stimulated by ___

• Found in: ___

• Stimulated: ____

Nicotinic Receptors

• Found in: ___

• Stimulated: ____

Cholinergic response

Cholinergic Nerves: ACh synthesis, storage, + release

• all preganglionic in ANS (SNS + PNS)

• All postganglionic in PNS, few in SNS

• Skeletal muscle nerves

• Cholinergic Nerves in CNS

Muscarinic Receptors

• stimulated by muscarine

• Found: visceral effector organs, sweat glands, some vascular smooth muscle

• Stimulated: pupil constriction, increased GI motility, salivation, bladder constriction, decreased HR

Nicotinic Receptors

• Found: CNS, adrenal medulla, autonomic ganglia, NMKS junction

• Stimulated: muscle contraction, autonomic response, release of NE and EPI from adrenal medulla

Direct acting cholinergic agonist - Bethanechol (Urecholine)

Why	• ____
MOA	•Acts like ___ •At ___
Side Effects	•HEENT: __ salivation •CV: ___ & (don’t give to patients with ___) •GI: ___ •GU: urinary frequency

Direct acting cholinergic agonist-Bethanechol (Urecholine)

Why	•Increase tone of detrusor muscle of bladder + relax bladder sphincter
MOA	•Acts like Ach •At cholinergic receptors sites in the PNS to mimic Ach and PSNS
Side Effects	•HEENT: increased salivation •CV: bradycardia, heart block, hypoTN, flushing, sweating (don’t give to patients with low BP or HR) •GI: NV, cramps, diarrhea, involuntary defecation •GU: urinary frequency

Anticholinergic - Benztropine

MOA	•___. •___ •___
Side effects	•Blurred vision •Dryness of mucus membranes •Increase pulse palpitations, dysrhythmias •Constipation •Urinary retention •Restlessness, confusion, depression, hallucinations, •photophobia
Contraindications	•___ •___

Anticholinergic - Benztropine

MOA	•Block the cholinergic receptors in the CNS, thereby suppressing acetylcholine activity. •Reduce the effect of acetylcholinesterase than there will be more Ach •Increase amount of ACh at receptor site
Side effects	•Blurred vision •Dryness of mucus membranes •Increase pulse palpitations, dysrhythmias •Constipation •Urinary retention •Restlessness, confusion, depression, hallucinations, •photophobia
Contraindications	•Glaucoma •Chronic lung disease: develop dry, thick mucous secretions