PCB3703 Exam 2 (Ahangari)

Nervous system has 3 parts:

Motor, sensory and autonomic

ANS

Automatic processes (breathing and blood pressure) and Innervation of internal organs in abdominal cavity, thoracic cavity and smooth muscle of bloodless cells

Two parts of ANS

Sympathetic and Parasympathetic

Sympathetic system

This system is activated when the body is active and it increases heart rate, increases contractility of myocardium, relaxes m. of bronchi, contracts blood vessels, increases blood flow, increase blood pressure, stimulates sweat glands nand inhibits digestive system

Location of Sympathetic

Spinal cord from T1-L2/L3 (Thoracolumbar) and occurs in: heart, lung, sweat glands and blood vessels

Parasympathetic system

This system is active when you are resting ("Rest and digest") and it decreases heart rate, decreases respiratory system, increases digestive system, increases secretion of gastric hormones

Location of Parasympathetic

Brain stem (CN 3, 7, 9, 10), pelvic splanchnic nerve and sacral portion of spinal cord (S2-S4)

Sympathetic system physiological steps

1. Pre-ganglionic

2. Sympathetic chain

3. Post-ganglionic

4. Internal organ

Norepinephrine on Alpha 1 receptors

*Location: blood vessel, urinary bladder, GI tract

1. Norepinephrine binds to Alpha 1 receptor

2. Activates a protein which normally exists in cytoplasm called g-protein. G protein itself has 3 subunits: alpha, beta and gamma (only need alpha in this case) and alpha has 2 subunits: S (stimulator) and I (inhibitor). Activates G protein alpha S

3. Activates phospholipase-C

4. After, it activated another enzyme IP3

5. Activates S4 (sarcoplasmic reticulum)

6. Releasing of Calcium into cytoplasm from SR

7. Concentration of Ca increases in cytoplasm then it binds to troponin-C (activates microfilaments and causes muscle contraction) Contraction and constriction is purpose

Norepinephrine on Alpha 2 receptors

*Location: GI tract, fat cells, pre-synaptic compartment, etc.

1. Norepinephrine binds to alpha-2 receptor

2. Activates G-protein Alpha I

3. Prevents AC (adenylate cyclase)

4. Decreases intracellular energy (CAMP)

5. Inhibition occurs; relaxation or dilation of smooth muscle

Excess norepinephrin binding to alpha can cause?

Hypertension

Norepinephrine on Beta 1 receptors

*Location: heart in SA node, AV node and myocardium

1. Norepinephrine binds to Beta-1 receptor

2. Activated G-protein alpha S

3. Activates AC

4. Increases CAMP (intracellular energy)

5. Shows its physiological reaction: increases heart rate, contractility of myocardium and conduction velocity (related to SA/AV nodes)

When patient has tachycardia due to exceess norepinephrine, you can use what to decrease heart rate?

Beta-1 blocker (called propranolol)

Norepinephrine on Beta 2 receptors

*Location: urinary bladder sphincter and respiratory system (smooth muscle of bronchi)

1. Norepinephrine binds to Beta-2 receptor

2. Activates G protein alpha s

3. Activates AC

4. Increases CAMP

5. Effect: relaxes smooth muscle

Asthma patients use medications that affect what norepinephrine receptor?

Beta-2 (albuterol)

Differences in sympathetic and parasympathetic

1. The pre-ganglionic fiber of sympathetic system is shorter than parasympathetic

2. The pre-ganglionic fiber of parasympathetic travels toward the wall of internal organs and then has synapse with post-ganglionic fibers inside wall but pre-ganglionic of sympathetic synapses with post-ganglionic fiber inside the sympathetic chain/ganglia

3. The neurotransmitter of pre-ganglionic fiber of sympathetic is ACH and post-ganglionic fiber of sympathetic is norepinephrine but parasympathetic neurotransmitters in both pre-ganglionic and post-ganglionic is ACH

4. Name of receptor for norepinephrine is adrenergic receptor and receptor for ACH is cholinergic receptor (cholinergic has muscarinic and nicotinic receptors)

Adnergic receptor

ACH Sympathetic receptor with multiple types such as alpha and beta

Muscarinic receptor

An ACH parasympathetic receptor (ex: heart)

Nicotinic receptor

An ACH parasympathetic receptor (ex: GI tract)

Cholinergic receptor

ACH parasympathetic receptor with two types

Medulla

Respiratory, vomiting, swallowing, coughing, etc.

Pons

Pneumotaxic center

Midbrain

Urinary system

Hypothalmus

Contains many nuclei (hypothalamic nuclei) that contains certain neurons that control many things such as: appetite, body temp, sleep, learning, memory, sexual behavior, emotional behavior, sympathetic, parasympathetic, endocrine (most important) and brain stem

Effects of ANS on heart

o Sympathetic: Beta-1 positive chronotropic (heart rate) and beta-1 positive Dromotropic (contractility of myocardium and conduction velocity)

o Parasympathetic: Decreases chronotropic and Dromotropic

Effects of ANS on lungs

o Sympathetic: Constriction, decreases secretion and dilation

o Parasympathetic: Constrictor, dilates vessels and increases secretion

Effects of ANS on GI tract

o Sympathetic: Relaxes smooth muscle of GI tract/decreases peristalsis, constricts sphincter of stomach or gallbladder, decreases gastric hormones

o Parasympathetic: Activates peristalsis, relaxes sphincters and increases gastric hormone secretion

Effects of ANS on liver

o Sympathetic :Gluconeogenesis by B-receptor

o Parasympathetic: Glycogenesis

Effects of ANS on Gallbladder

o Sympathetic: Beta-2 receptor relaxation of sphincter

o Parasympathetic: Constriction of sphincter

Effects of ANS on Pancreas

o Sympathetic: Alpha 1 inhibits insulin, Beta 2 activates insulin, Alpha inhibits exocrine (pancreatic enzyme secretion

o Parasympathetic: Activates exocrine secretion

Effects of ANS on Adrenal Medulla

Sympathetic: Activates secretion (innervated by pre-ganglionic fiber of sympathetic only)

Effects of ANS on Urinary bladder

o Sympathetic: Alpha receptor for contraction of sphincter muscle and Beta receptor for relaxation for detrusor muscle (controls filling/urge to go)

o Parasympathetic: Relaxation of urinary sphincter and contracts detrusor muscle (controls emptying of urine)

Effects of ANS on Uterus

****Only by sympathetic

o Pregnant: Alpha-1 receptor that contracts uterus

o Non-pregnant is Beta receptor for relaxation of uterus

Effects of ANS on Genitals

o Sympathetic: Ejaculation and Emission (emission is internal circulation of semen)

o Parasympathetic: Erection (vasodilation) and Ejaculation

Sensory systems (2nd part of CNS)

2nd part of CNS and uses different types of receptors

Mechanoreceptors

Pacinian corpuscles, joints, stretch receptors, hair cells in auditory and vestibular, baroreceptors in carotid sinus

Photoreceptors

Detect light; rods and cones in retina

Chemoreceptors

Detect chemical changes in environment such as: Olfactory, taste, osmoreceptor (found in wall of large blood vessels such as aorta) and carotid body O2 receptors

Nociceptors

Detect extremes of temperature and pain (ex: substance P and glutamate)

Baroreceptors

Blood receptor that detects changes in blood pressure

Fiber types

1. Type A (fastest)

2. Type B

3. Type C (C is slowest and for pain)

General sensory pathway

1. Sensory receptors are located in peripheral organs such as skin

2. After stimulation of sensory receptors in peripheral, then it activates 1st group of neurons These neurons travel from peripheral to either spinal cord or brain stem

3. First group of neurons have synapse with second group of neurons in either spinal cord or brain stem

4. The second group of neurons travel to contralateral thalamus (ex: from left hand to right thalamus)

5. Then synapse with 3rd group of neurons in contralateral thalamus

6. 3rd group goes to cerebral cortex (brain) and synapse with 4th group of neurons

Dorsal sensory system

Fine touch pressure, two point discrimination and vibration

Anterolateral sensory system

Temp, pain, light touch

Head trauma occurred on right side due to car accident. What sensory disorder can occur?

Problems with side of brain due to contralateral thalmus

Referred pain for myocardial infarction

They have pain radiation to left shoulder, arm, forearm, last two fingers (fourth and fifth) and neck

Referred pain for gallstone

Can cause epigastric line pain especially on right/right backside (pain could also be from right kidney problems because pain is similar; to find difference you have to look at amount of urine, color of urine, etc.)

Taste bud regions

Anterior: Sweet

Lateral: Sour

Anterolateral: Salty

Posterior: Bitter

Compounds needed for different tastes

Salty: NaCl

Sour: Hydrogen

Bitter: GPCR from g-protein

Sweet: GCPR from g-protein

Innervation of tongue

CN 7 by chorda tympani (anterior 2/3), CN 9 (posterior 1/3 of tongue) and CN 10 (base of tongue)

Bell palsy

Paralyzed facial nerve & has 5 branches (viral infection can affect chorda tympani branch of facial nerve and affect taste

Ageusia

You may lose your sense of taste if the facial nerve is damaged.

Hypogeusia

Decreased taste sensitivity

Hypergeusia

Increased taste sensitivity

Sore tongue

It is usually caused by some form of trauma, such as biting your tongue, or eating piping-hot or highly acidic food or drink. Can also be caused by disorders such as diabetes, anemia, vitamin deficieny and certain skin disorders

Glossodynia

A condition characterized by a burning sensation on the tongue

Benign migratory glossitis (geographic tongue)

This condition is characterized by irregular and inflamed patches on the tongue surface that often have white borders. The tongue may be generally swollen, red and sore. The cause of benign migratory glossitis is unknown.

Tumor on tongue

Cause inflammation of tongue and can be benign or malignant

Chemoreceptor stimulation

1. After stimulation of chemoreceptors in nasal cavity leads to stimulation of first group of neurons (mitral cells) which take the information about sensory or odor to olfactory bulb

2. Olfactory bulb neurons depolarize by activation of sodium channels then the first group of neurons have synapse with second group of neurons and travel to the olfactory tract and from there they travel to center of olfactory (location of olfactory center is at base of olfactory tract)

Olfactory system

Anosmia

Lack of olfaction, or a loss of the sense of smell

Caused by: neurological issues, damageto olfactory tract (such as head trauma), psychological or damage to sensory receptor

Phantosmia

Phenomenon of smelling odors that aren't really present

Dysosmia

When things smell differently than they should

Layers of eye

Sclera, choroid and retina

Sclera

Connective tissue for protection of eye from external trauma

Choroid

Layer of eye full of blood vessel and gives nutrient to eyes and filled with pigment cells from iris with ciliary bodies w/ ciliary muscles and secretes fluid which drains into posterior chamber then anterior chamber. Also contains Canal of Schlemm

Canal of Schlemm

Foramen opening that the intraocular fluid passes through and releases into venous system

Glaucoma

Caused by obstruction of Canal of Schlemm (could be genetic, tumor, trauma, infection, etc.) and closes canal

Untreated glaucoma can cause

Blindness

Layers of Retina

Layer 1: Pigment cells

Layer 2: Photoreceptor (rods and cones)

Layer 3: Bipolar cells

Layer 4: Horizontal cells

Layer 5: Amacrine cells for circuits with the bipolar cells

Layer 6: Ganglion cells and axons from ganglion cells form optic nerve

Where does visual stimuli finally end up in brain?

Area 17, 18 and 19 (primary visual area) in occipital lobe

Excess fluid in anterior and posterior chamber

Can destroy retina, optic nerve and lens

Optic disc

"Blind spot" because there are no rods or cones (lacks photoreceptor)

Rods vs. Cones

Rods are very sensitive to light and cones cells detect wavelength of light which detects colors (internal structure of rod is similar to cones)

Mechanism for Rod cells

1. Absorbs light

2. Stimulation of rhodospin

3. Converted in 11-cis retinal

4. Converted into all trans-retinal

5. Activation of metarhodospin

6. Activation of g-protein alpha subunit

7. Activation of phosphodiesterase enzyme

8. Decrease in cGMP

9. Closure of Na channels (prevents inhibitory neurotransmitters from releasing)

10. Passes to bipolar cells

11. Passes to horizontal cells

12. Passes to amacrine cells

13. Ganglion cells receive light signal

14. Ganglion cell releases stimulatory neurotransmitter

15. Stimulates optic nerve

16. Optic nerve carries info about light to CNS

Optic pathway in nasal field

1. Signals in nasal field

2. Goes to temporal portion of retina of that eye

3. Goes to optic chiasm

4. Reaches ipsilateral optic tract

5. First group of neurons reach thalamus nucleus (lateral geniculate)

6. Synapse with next group of neurons

7. Next group of neurons travel on geniculo-calcarine tract to occipital lobe of brain to Area 17, 18 and 19

Optic pathway in temporal field

1. The signals from temporal field

2. Focuses on nasal portion of retina of that eye

3. Passes through optic chiasm

4. Reaches contralateral optic tract

5. First group of neurons reach thalamus nucleus (lateral geniculate)

6. Synapse with next group of neurons

7. Next group of neurons travel on geniculo-calcarine tract to occipital lobe of brain to Area 17, 18 and 19

If there is any cut or damage to left optic nerve

Blindness of left eye occurs (affects both fields)

Partial damage of left optic nerve causes

Left nasal field blindness

If optic chiasm is cut or damaged it affects

Left temporal field and right temporal field

Complete damage of optic tract affects

Left nasal field and right temporal field

If Geniculo-calcarine tract is cut or damaged, it affects

Partially affects left nasal field and right temporal field (usually 50% because it receives signals from different neurons)

Color blindness

Caused by any damage to cones

Night blindness

Deficiency of Vitamin A

Visual agnosia

Inability of brain to make sense/use of normal stimuli. (cannot recognize faces or objects)

Emmetropia

Normal vision. Light focuses on the retina

Hypertropia

Farsighted. Light focuses behind the retina and is corrected with a convex lens

Myopia

Nearsighted. Light focuses in front of the retina and is corrected with a biconcave lens

Astigmatism

Curvature of the lens is not uniform and is corrected with a cylindric lens

External ear

Has auricle, auditory tube, tympanic membrane

Middle ear

Found behind tympanic membrane and contains three bones (ossicles) called malleus (connected to tympanic membrane), incus and stapes (connected to small

Inner ear

Found ehind oval window) and has 2 parts: Cochlea (for hearing) and vestibular system w/ 3 semicircular canals (maintains body equilibrium)

Organ of Corti

Found inside the cochlea of the ear and contains 3 parts: Scala vestibule, scala tympani and scala media

Scala media

Contains hair cells (cilia). At the base of these is a membrane called basilar membrane and a sensory cochlear afferent fiber which detects any change in hair cells as a signal and takes it to CNS. On top of hair cells is the tectorial membrane. Contains endolymph

Scala tympani and scala vestibule

Parts of the organ of Corti that contain perilymph

Auditory transduction in organ of Corti

1. Sound waves travel through the air which is converted into pressure waves into fluid (perilymph and endolymph)

2. Sound waves pushes back tympanic membrane and leads to vibration or movement of 3 bones in middle ear

3. Last bone in ossicles is stapes which is connected to the oval window which pushes back the oval window which leads to circulation of perilymph in scala vestibule then scala tympani. Scala tympani is connected to the round window

4. When the fluid or perilymph reaches the oval window, leads to vibration of basilar membrane causing vibration of cilia hair cells against tectorial membrane prevents potassium conductance

5. Leads to releasing of stimulatory neurotransmitter into synaptic cleft and stimulation of sensory afferent fibers (post-synaptic)

6. Stimulation of afferent fiber/cochlear nerve and the nerve takes the information to the CNS

Bending of hair cells (cilia) in one direction inside the cochlea

Prevents potassium conductance causing hyperpolarization

Bending of hair cells in different directions inside the cochlea

Causes depolarization

Main center for auditory

Temporal lobe, superior temporal gyrus, Area 41 and 42 for T1 and T2

Auditory pathways

1. nucleus (spiral nucleus/cochlear nucleus) which has synapse with next group of neurons

2. This group travels to medulla oblongata which has 2 nuclei: dorsal and ventral nuclei of cochlear nerve and synapse with next group of neurons

3. After synapse, some fibers travel ipsilateral and some travel to contralateral

4. It passes through pons (pathway is called lateral lemniscus)

5. After pons, it reaches midbrain and passes through inferior colliculus

6. After passing inferior colliculus, it reaches the medial geniculate nucleus in the thalamus

7. After medial geniculate synapse, next neurons travel to the superior temporal gyrus (Area 41 and 42 for T1 and primary auditory area for T2)