Week 5 Review Flashcards
Which neurotransmitter is used at the first autonomic nervous system synapse?
acetylcholine
Post-ganglionic autonomic neurotransmitters are diffusely sprinkled from numerous _______ along the axons.
swellings/varicosities
Which neurotransmitter is predominantly used at sympathetic postganglionic synapses? What is the one exception?
norepinephrine, except for sweat glands (ACh - muscarinic M3)
Which neurotransmitter is used at the postganglionic parasympathetic synapse? Which receptor class?
ACh - muscarinic
In which tissues are alpha1 adrenergic receptors found and what is the normal physiologic effect of receptor binding?
smooth muscle (think blood vessels), binding causes vasoconstriction
In which tissues are alpha2 adrenergic receptors found and what is the normal physiologic effect of receptor binding?
alpha2 receptors are found at the nerve terminals/varicosities of preganglionic sympathetic neurons. Receptor binding causes auto-inhibition - stops release of norepinephrine.
In which tissues are beta1 adrenergic receptors found and what is the normal physiologic effect of receptor binding?
heart, kidneys
binding causes increased cardiac output and constriction of afferent arterioles
In which tissues are beta2 adrenergic receptors found and what is the normal physiologic effect of receptor binding?
smooth muscle (think lungs)
binding causes bronchodilation
In which tissues are beta3 adrenergic receptors found and what is the normal physiologic effect of receptor binding?
fat cells and bladder smooth muscle
binding causes lipolysis and bladder muscle relaxation
In which tissues are M3 receptors found and what is the normal physiologic effect of receptor binding?
glands, smooth muscle (bladder, GI), vasculature (endothelial cells)
binding causes contraction of glands and contraction of bladder and GI smooth muscle
in the vasculature, it causes NO release from endothelial cells –> vasodilation
In which tissues are M2 receptors found and what is the normal physiologic effect of receptor binding?
heart, presynaptic nerve terminals
binding causes decreased cardiac output in the heart, and auto-inhibition of ACh release from presynaptic nerves (similar to alpha2)
How are you going to remember the signaling pathways used by autonomic receptors?
QISSS IQ (G-protein types)
a1 = Q a2 = I B1 = S B2 = S B3 = S
M2 = I M3 = Q
Which tissues use ATP as a neurotransmitter? What is the effect of binding?
arterioles, vas defrens, and sweet, bitter, umami gustatory receptors
ATP binding to purinergic receptors –> opening of nonselective cation channel –> Ca2+ entry –> binds to calmodulin –> MLCK activation –> MLCK phosphorylates myosin heads –> cross bridging –> constriction of arterioles and vas defrens
How do M3 receptors in endothelial cells cause vasodilation?
ACh binding –> PLC cleaves PIP2 –> IP3 + DAG –> IP3 releases Ca2+ from SR –> stimulation of NO synthase –> NO stimulates smooth muscle relaxation
Mechanoreceptors in the aortic arch and carotid sinus monitor blood pressure via arterial wall ______.
stretch
If carotid sinus cells sense too much stretch, parasympathetic tone is ________ (increased/decreased).
increased –> decreased cardiac output
Name three histological identifying traits of skeletal muscle.
nuclei are 1) long and 2) squished to the side of the fiber
3) striations
Name three histological identifying traits of cardiac muscle.
1) intercalated discs
2) branched myocytes
3) central, round nuclei
Name three histological identifying traits of smooth muscle.
1) fusiform fibers
2) nonstriated
3) central nuclei
looks like a flowing river
How can you tell the difference between dense regular CT and smooth muscle?
Smooth muscle will be more acidophilic (pink/red) and have more densely-packed nuclei.
CT will have super long, fusiform nuclei of fibroblasts.
What is found in the I band of a sarcomere?
actin filaments
What’s up with the H zone?
In between the thin filaments - only includes thick filaments.
During contraction, which structures in the sarcomere shorten? Select all that apply.
a) A band
b) H zone
c) I band
d) Entire sarcomere
H zone, I band, and entire sarcomere shortens during contraction
Within which connective tissue structure surrounding muscle fibers do motor nerves give off unmyelinated terminal branches?
perimysium
What is a junctional fold?
Invaginations of the sarcolemma at the neuromuscular junction to increase surface area for nACh receptors
What structures are found in an intercalated disc?
Gap junctions, desmosomes.
Which smooth muscle type looks wavy when contracted?
Smooth muscle
Which muscle fiber type has lots of myoglobin and mitochondria, and uses oxphos for energy?
Type I (slow, red)
What energy system is primarily used by type IIb fibers?
glycolysis
Is ATP released along with NE at presynaptic varicosities?
Yeah!
The basis for differences in muscle fiber twitch speed is due to how fast the myosin head can…?
how fast the myosin head can split/hydrolyze ATP
Describe the steps in skeletal muscle contraction.
- ACh binds NAChR.
- Non-selective cation channels open (graded potential).
- Big enough graded potential opens voltage-gated Na+ ion channels, propagating an action potential.
- Voltage gated Ca2+ channels (L-type/DHPR) in the t-tubule open.
- Ryanodine receptors in the SR open (mechanically linked to the L-type receptor), Ca2+ flows out of the SR.
- Ca2+ binds troponin C.
- Tropomyosin moves to expose myosin binding site on actin.
- Myosin + ADP + Pi binds to actin
- Pi is released and the power stroke happens.
- ADP is displaced by ATP and the cross-bridge is broken.
- ATP is hydrolyzed to ADP + Pi to start cycle again.
What is the difference between initiation of cardiac muscle contraction and skeletal muscle contraction?
The main difference is that the L-type/DHPR is NOT mechanically linked to the Ryanodine receptor in the SR. Ca2+ release from the SR via the Ryanodine receptor is chemically-gated by Ca2+ entry through the SR (calcium-induced calcium release, CICR)
Describe the steps in smooth muscle contraction.
- Ligand binds to GPCR alpha q.
- PLC hydrolyzes PIP2 –> IP3 + DAG.
- IP3 binds IP3R on SR, Ca2+ is released.
- Ca2+ binds calmodulin and activates it.
- Calmodulin activates myosin light chain kinase.
- MLCK phosphorylates myosin heads.
- Cross-bridge cycle happens.
OR
Action potential via gap junction causes Ca2+ entry and CICR, Ca2+ binds to calmodulin, etc.
Which fiber type uses a mix of aerobic and anaerobic metabolism?
Fast type IIa
For how long in a working muscle to ATP stores and creatine phosphate provide energy?
Stored ATP last for 3-5 seconds.
Creatine phosphate regenerates ATP for 30 seconds.
In a muscle, after approximately 45 seconds of work, ________ metabolism peaks. After that, ________ metabolism increases and accounts for 75% of the energy load after around 90 seconds of work.
anaerobic peaks at 45 seconds, aerobic metabolism is at 75% of energy load at 90 seconds
What is the preferred energy source and metabolic pathway of cardiac muscle?
Fatty acids, aerobic metabolism
What is the preferred metabolic pathway for smooth muscle?
aerobic metabolism
True or false:
Force of contraction in skeletal muscle is dependent on the amount of myosin and actin overlap.
true
________ contraction occurs when afterload is too great for the muscle to shorten even though cross-bring cycling continues.
Isometric
What is isotonic contraction?
When a muscle shortens at a constant tension.
Myasthenia gravis is an autoimmune disorder that attacks __________ at the neuromuscular junction.
nicotinic ACh receptors
The breakdown and release of myoglobin into the blood, causing kidney damage, is characteristic of what disease?
Rhabdomyolysis
Malignant hyperthermia is an autosomal ________ mutation of the _______ _______. When given inhaled anesthetics, the ________ ______ is stimulated to release dangerously high levels of Ca2+, causing muscle contraction, ATP depletion, and an increase in temperature.
autosomal dominant
mutation of the ryanodine receptor
inhaled anesthetics trigger the ryanodine receptor to release Ca2+
Which rib attaches at the sternal angle?
2nd
At what spinal level is the sternal angle? Name 4 important anatomical considerations at this spinal level.
T4/5.
- limit of the superior portion of the pericardium
- aortic arch is located at this level
- brachiocephalic veins join to form the SVC
- bifurcation of the trachea
What bony landmark marks the axial division between the superior and inferior mediastinum?
sternal angle
Which intercostal muscles are used during inspiration?
External intercostals
When performing a thoracocentesis, where in the intercostal space should you place the needle? Why?
Just above a rib to avoid the neurovascular bundle in the groove on the inferior edge of the rib.
Intercostal nerves arise from the ______ primary rami.
ventral
From what arteries do the superior epigastric arteries arise?
internal thoracic
Superior epigastric arteries anastomose with the inferior epigastric arteries, which are branches off of the ______ ______ arteries.
external iliac arteries
Spinal nerves from which level supply the dermatome at the pubic symphysis?
L1
Name the spinal nerves that correspond to the dermatomes at the following landmarks:
nipple
xyphoid process
epigastric area
umbilicus
nipple: T4
xyphoid process: T5
epigastric area: T7
umbilicus: T10
________ is characterized by a rubbing, crackling noise upon auscultation of the lungs caused by inflammation of the pleura.
Pleurisy
In general, how much lower is the parietal pleura than the inferior extent of the lungs?
two ribs lower
Which drug on our list is used to treat BPH? What else does it treat?
Prazosin (alpha1 antagonist) blocks smooth muscle contraction in the prostate to un-squish the prostatic urethra and increase urine flow. It also dilates blood vessels to treat hypertension.
What are Merkel’s discs? What do they sense? Do they adapt?
Thin discs around nerve endings that sense pressure in skin and joints. They are slow-adapting.
What do Meissner’s corpuscles sense? Do they adapt?
They sense fine touch, and kind-of adapt (faster than Merkel’s, slower than Pacinian)
What do Pacinian corpuscles do? Do they adapt?
Sense vibration (>50 Hz), fast adapting.
Ruffini’s endings sense _____.
stretch (of skin)
Which nerve endings sense pain and temperature?
free nerve endings
How do photoreceptors work?
- Photon hits receptor
- cis-retinal –> trans-retinal
- trans-retinal activates rhodopsin (rhodopsin –> metarhodopsin II)
- Metarhodopsin II activates Gs protein
- Gs activates phosphodiesterase
- Phosphodiesterase cleaves cGMP –> GMP
- cGMP-gated Na+ and Ca2+ channels close –> hyperpolarization
- Hyperpolarization prevents release of glutamate
- No glutamate neurotransmitter –> no action potential –> vision!
Gustatory receptors for which tastes act through GPCRs? What is the signaling pathway?
Sweet, bitter, umami. Gq –> PLC –> IP3 and DAG –> Ca2+ release –> ATP released as a neurotransmitter to bind on afferent sensory neurons
Which neurotransmitter is used by sour and salty gustatory receptors?
serotonin
Hair cells are bathed in a ____-rich fluid. When the hair cells are bent, it causes opening of ____ channels –> depolarization, influx of Ca2+ –> release of the neurotransmitter _______.
K+ rich fluid. Bending opens a K+ channel –> depolarization and influx of Ca2+ –> release of glutamate.
When there is mechanical damage to cells, proteases are released that cleave stuff to make _______, which binds to free nerve endings, stimulating the release of ________, which then binds to mast cells, stimulating release of ________.
bradykinin –> substance P –> histamine
What is the significance of a positive Babinski sign?
Possible upper motor neuron lesion.
Which nerve supplies sensation to the skin of the scrotum/labium majus?
Ilioinguinal nerve (L1)
Which nerve provides motor innervation for the cremaster muscle?
Genital branch of the genitofemoral nerve
The inferior epigastric arteries can be found between the rectus abdominis muscle and the ________ _______ within the ________ umbilical folds.
between rectus abdominis and transversalis fascia within the lateral umbilical folds
Where is the pampiniform plexus located and what is its function?
Located in the spermatic cord, function is to cool blood in the testicular artery
Name the layers of the testis/spermatic cord and their corresponding abdominal wall layers.
Superficial to deep:
skin - skin
Dartos fascia - superficial fascia (membranous layer/Scarpa’s)
External spermatic fascia - deep fascia of external oblique
Cremaster fascia/muscle - deep fascia and muscle of internal oblique
Internal spermatic fascia - transversalis fascia
tunica vaginalis - parietal peritoneum
note the transversus abdominis muscle does not contribute to anything in the scrotum
Where is the femoral artery located with respect to the inguinal ligament?
Femoral artery is deep to the middle of the inguinal ligament
Where is the deep inguinal ring located with respect to the femoral artery? From what did the deep inguinal ring arise?
Deep inguinal ring is just superior to the middle of the inguinal ligament, superficial to the femoral artery.
It arose from the transversalis fascia.
Describe where a direct inguinal hernia occurs with respect to the rectus abominis muscle, the inguinal ligament, and inferior epitastric vessels.
Direct inguinal hernia occurs lateral to the rectus abdominis, medial to the inferior epigastric arteries, and superior to the inguinal ligament (this area is called the inguinal/Hasselbach’s triangle)
Where does an indirect hernia happen with respect to the inferior epigastric vessels? What path does it take to exit the abdominal wall?
Lateral to the inferior epigastric vessels, through the deep inguinal ring, through the inguinal canal, and out the superficial inguinal ring into the scrotum.
Describe the contents of the subinguinal space. Which one of these is not found in the femoral sheath?
NAVEL (lateral to medial)
nerve, artery, vein, empty, lymphatics
the nerve is not in the femoral sheath
To place a line in the femoral vein, one should palpate the femoral artery, and place the line _______ to the artery.
the femoral vein is medial to the femoral artery
What is the term for an accumulation of fluid in the tunica vaginalis?
Hydocele
Your male patient notes a “heavy feeling” in his scotum, along with a dull ache. On PE you find a bag of worms. What is your Dx?
varicocele
What is the name of the condition characterized by failure of testicular descent, which causes sterility and an increased risk of testicular cancer?
cryptorchidism
Your patient comes to you and tells you that they have a mutated CIC-1 channel. You notice that they have hypertrophied muscles. What is your diagnosis?
myotonia congenita - mutated CIC-1 chloride channel slows repolarization, causing prolonged contraction and hypertrophy.
How does intense exercise increase the risk for paralysis in someone that has hyperkalemic periodic paralysis?
Intense exercise can increase extracellular [K+] slightly because of all the action potentials that have involved K+ efflux from cells. This causes the resting membrane potential to become less negative, and therefore more Na+ channel inactivation gates are closed, exacerbating the inability to generate another action potential.
Which gene is mutated in hyperkalemic periodic paralysis? What is the mechanism by which this defective protein causes disease?
SCN4A gene that encodes for the Na+ channel. The channel doesn’t close after an action potential is generated to allow for membrane repolarization.
Malignant hyperthermia is characterized by a mutated _________ receptor. Inhaled anesthetics can trigger this receptor to release Ca2+ from muscle SR, causing constant muscle contraction, depletion of _____, and release of a lot of heat.
mutated ryanodine receptor
depletion of ATP, release of heat!
What are the three stress biomarkers?
- Catecholamine levels
- Telomere length
- Cortisol levels
