Exam 2 - Random

Question 1

Evaluation of the MSK Patient - Ankle, Wrist, Hip, Back

Answer 1

Good history and physical exam are so important
Do your own work it is not complete when sent to you
Frequently look alike, don’t let a certain diagnosis take you away
* Ankle
o 5th metatarsal, avulsion fracture
o Present like sprains but need immobility
* Wrist
o FOOSH, scaphoid, distal radial, ulnar styloid, buckle fracture?
* Hip
o Start with OMM, PT, meds, saddle paresthesia in emergency
* Back
o Radiculopathy caused by nerve compression in foramen

Question 2

Cardiac Muscle

Answer 2

• Preload – initial stretch at cardiac myocytes, use EDV to tell how stretched it is, Starlings law more volume more force
• Afterload – resistance to ejection, force overcome to reject blood
• Contractility – same length difference in contraction, same volume with different force
• Cardiac muscle long AP
• Phase 0 lots of Na, 1 is K, 2 is Ca long phase, 3 is K repolarize, 4 is K leak
• Trigger Ca, makes the muscle move, actives RYR by binding troponin C which exposes binding site and allows cross bridging by moving tropomyosin to expose binding site of myosin
• Get rid of calcium via SERCA and ATP, Na/Ca exchanger
• Phospholamban limits SERCA, phosphorylate makes it chill
• Anything that increases Ca or makes troponin more sensitive increases force
• Beta receptor makes cAMP to PKA phosphorylation to make more Ca for more force, contracts harder/faster/quicker
• Main difference is Calcium with skeletal/cardiac

Question 3

Smooth Muscle

Answer 3

• Everywhere, actin/myosin, smooth because sarcomeres are not organized, controlled by calcium
• Multiunit – just like skeletal muscle, can recruit/increase frequency, under nervous control, no spontaneous activity, not electrically coupled
• Unitary
• Gap junctions in hollow organs, allow firing at same time, permits excitation of cells to spread to neighbor, not like cardiac
• Phasic – gut, slow rhthmic
• Tonic – blood vessels/sphincter, continuously contracted
• First mechanism is pharmaco-mechanical coupling – drug binds G protein and induce phospholipase C produce IP3 which causes Ca release
• Second mechanism is depolarization of smooth muscle, Ca goes in through Ca channel and SR can release more Ca
• Smooth muscle has no troponin, need to phosphorylate myosin, Ca activate calmodulin which activates MLCK to phosphorylate myosin and bind to contract
• Relax it by removing Ca (SERCA), or dephosphorylate myosin (MLCP)
  o Norepinephrine – Alpha 1
  o Angiotensin II – angiotensin (A1)
  o Endothelin-1 – Endothelin A
  o Arginine vasopressin – Vasopressin (V1)
  o Acetylcholine – on smooth muscle
  o Constrictors
• Gq->PLC->IP3->SR->Ca->MLCK->myosin->contract
• Gs -> cAMP -> decrease MLCK -> don’t phosphorylate myosin -> relax muscle
  o PDE3 breaks down cAMP, increases MLCK so muscle contracts
  o Epinephrine dilates when it binds to B2
  o NO activates cGMP activates MLCP which gets rid of phosphate and relaxes

Question 4

Autonomic Nervous System

Answer 4

• Homeostasis
• Diameter of pupils, heart pumping, constrict/dilate blood vessels, respiratory, digestion, defecation, urination, erection, ejaculation, birth, sweat, tearing, etc
• Sympathetic – short pre and long post in thoracolumbar, paravertebral ganglion nicotinic acetylcholine, heart/smooth muscle/glands, acetylcholine muscarinic for sweating
• Parasympathetic – cranio/sacral, long pre and short post (on organ), heart/smooth muscle/glands/GI, muscarinic
• Preganglionic are myelinated
• Ach secreted by all preganglionic, nicotinic ganglion, some postganglionic also do muscarinic (long lasting), adrenergic is alpha or beta, acetylcholine for sweating
• Parasympathetic – rest and digest, SLUDGE, transmitter acetylcholine and receptor nicotinic until postganglionic receptor is muscarinic on organ, exceptions not talked about
• AchE chews up Ach
• Adrenal medulla is adrenergic receptors, with epinephrine/norepinephrine
• Goes to Beta before alpha