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M1 Physiology > Test 1 Study Table > Flashcards

Test 1 Study Table Flashcards

1
Q

Compare contraction of smooth vs skeletal muscle

  • voluntary vs involuntary
  • note ligands for receptors
  • role of Calcium
  • main determinant of force
A

Smooth-

  • non-voluntary
  • preganglionic- ACh
  • postganglionic- ACh (parasympathetic), NE (sympathetic)
  • Calcium (depolarizing, lesser role than in sk muscle)
  • MLCK/MLCP- main determinant of force

Skeletal-

  • mostly voluntary (somatic)
  • NMJ- Nicotinic Cholinergic (ACh)
  • Calcium is the main determinant of force
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2
Q

Regulation of muscle contraction in smooth vs skeletal muscle

A

Smooth:

  • Regulation of MLC (K or P) at any given Ca concentration
  • T-type Ca channels help regulate vascular tone
  • Autonomics

Skeletal:

  • contraction force is dependent on intracellular Ca concentration
  • motor units (one neuron & all the fibers it innervates- all the same type)
  • Fiber type
  • Availability of ATP
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3
Q

Describe the steps of the smooth muscle slow wave

A

T type voltage gated Ca channels open —> L type (voltage gated) Ca channels open) —> AP spike —> Ca influx, rise in internal Ca concentration —> Ca dependent K channels open —> slow hyperpolarization —> Voltage gated Ca channels close and internal Ca concentration decreases

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4
Q

Describe histology of smooth muscle

A
  • one nucleus (vs multiple in skeletal)
  • spindle shaped cells
  • smaller in comparison to skeletal
  • caveolae (instead of T tubules) - contain voltage gated Ca channels, increase surface to volume ratio
  • NO: sarcomeres, striations, or T tubules
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5
Q

Both skeletal and smooth muscle have

A
  • thick (myosin) and thin (actin) filaments

- SR (more elaborate in skeletal muscle)

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6
Q

Multi-unit vs single unit smooth muscle

A

Multi-unit: each smooth muscle receives synaptic input from it’s own varicosity. Gives finer control.
- Found in iris smooth muscle, ciliary muscle, and piloerector muscle in the skin (goose bumps)

Unitary (visceral): most common. Contains gap junctions that allow an organ to respond as a unit. Such as propagation of food through intestine, movement of blood through vessels
- Found in intestines, utereus, ureter, small arteries/veins

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7
Q

Smooth muscle contraction

A

Need elevated Ca inside the cell in order to initiate a series of events that will lead to smooth muscle contraction
Ca binds to Calmodulin, creating Ca-Calmodulin complex
Ca-Calmodulin complex binds to and activates MLCK
MLCK phosphorylates myosin at light chains activating it!
- actual contraction occurs when activated (phosphorylated) myosin binds to actin and causes contraction

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8
Q

Smooth muscle relaxation

A

No Ca in the sarcoplams
Ca is pumped out by:
- PMCA, Na/Ca exchanger: from sarcoplasm to ECF
- SERCA: sarcoplasm to sr
MLCK inactive
MLCP removes phosphate from myosin
Dephosphorylation of myosin while it is attached to actin results in a slow detachment - Latch state

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9
Q

Energy sources of muscle: smooth vs skeletal

A

Smooth:

  • mostly aerobic (mitochondria)
  • No creatine phosphate
  • sustained contraction with minimal use of ATP (latch phase)
  • Slow Ca regulation (slow contractions)

Skeletal:

  • Aerobic or anaerobic (depends on type of fiber)
  • Cr-Ph stores phosphate for contractile use
  • Fast contraction and relaxation
  • Force is dependent on SR Ca concentration
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10
Q

Calcium regulation in muscle

A

Smooth- up to 50% from IF

Skeletal- 99% SR

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11
Q

What is responsible for bringing skeletal muscle at the NMJ to threshold potential?

A

Nicotinic cholinergic receptors

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12
Q

An EPSP at a smooth muscle cell depolarizes it to threshold what action happens next?

A

Voltage gated Ca++ channels open

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13
Q

An EPSP at a skeletal muscle cell depolarizes it to threshold what action happens next?

A

Voltage gated Na channels open

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14
Q

Autonomic receptors

A

Postganglionic neuron cell body- nicotinic neuronal cholinergic receptor (Nn)

Target cell-
Sympathetic- alpha & beta adrenergic
PSNS- M1, M2, M3 muscarinic

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15
Q

Adrenergic R’s: pathway, function

A

Alpha1- PLC pathway. Increases smooth muscle contraction
Alpha2- Gi —> inhibit AC —> dec cAMP —> favors smooth muscle contraction (can block gastric secretion and insulin release)
Beta- Gs —> stimulate AC —> inc cAMP —> PKA —> inhibits MLCK —> smooth muscle relaxation

Beta 1- heart. Increase HR & increase cardiac contractility
Beta 2- smooth muscle relaxation
Beta 3- lipolysis in adipose tissue

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16
Q

Muscarinic Receptor

A

M1- ganglionic slow EPSP in CNS
M2- Decrease HR (IPSP)
*** M3- smooth muscle contraction, GI secretion, Endothelial NO secretion
- overstimulation causes asthma

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17
Q

Proteosome system

A

Proteins marked for degradation by proteosome when lighted to Ub

DUB enzyme, less protein enters a proteasome and effectively not all of the marked proteins get destroyed

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18
Q

_______ is involved in signal transduction

A

Phosphatidylinositol

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19
Q

What influences fluidity of a plasma membrane?

A

Cholesterol and degree of saturation

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20
Q

Fick’s law

A

Diffusion rate = -PA (Ci - Co)

P= permeability

  • membrane resistance
  • membrane thickness
  • size and solubility of the molecule
  • Temperature

A= surface area

Ci-Co = concentration gradient across the membrane

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21
Q

Facilitated diffusion exhibits ___________________ and requires _______________

A
  • saturation
  • specificity
  • competition

A Protein channel

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22
Q

Transmembrane ion channels

A

Antiport:
Na/H
3Na/Ca

Symport:
Na/K/2Cl
Na/Cl
Na/HCO3
Na/PO4
Na/amino acids
23
Q

Receptor mediated endocytosis

A 
Ligand binds receptor
Formation of a coated pit with clathrin 
Formation of a coated vesicle 
Vesicle uncoating
Uncoated vesicle fuses with lysosomes
Recycle clathrin & endocytose product
24
Q

2,4-Dinitrophenol (DNP)

A

Uncoupled oxidative phosphorylation by ruining the hydrogen gradient at the mitochondrial membrane resulting in production of heat with no ATP produced
- used to be a diet pill

25
Q

Sodium Azide

A

Inhibits cytochrome C oxidase (complex IV) by binding to the heme cofactor
- similar to cyanide poisoning

Affects organs undergoing high rates of respiration

26
Q

Body water compartments

A 
TBW (total body water) is 60% of BW (body weight)
40% intracellular
20% extracellular
- 4% plasma
- 16% interstitial fluid 
ECF= 1/3 TBW or 20% BW
ICF= 2/3 TBW or 40% BW
27
Q

Plasma osmolality

A

Plasma osmolality = 2 Na + glucose + urea

28
Q

Plasma toxicity

A

Plasma toxicity = 2 Na + glucose

29
Q

Regulatory volume increase

A

A cell is in hypertonic solution, after the cell shrinks in size
It will undergo RVI
- activate Na/H exchanger —> Cl-HCO3 exchanger (H out, bicarbonate in)
- activate Na/K pump
- activate Na/K/2Cl cotransporter
- Chronic response- generation of idiogenic osmoles (example sorbitol)

30
Q

Regulatory volume decrease

A

When a cell is in a hypotonic solution, after swelling, it will undergo RVD
- activate K/Cl symport

31
Q

Oncotic pressure

A

The osmotic pressure generated by the presence of protein (albumin) in blood vessels keeping fluid in vessels and out of interstitial fluid

32
Q

Give 3 possible problems in fluid regulation

A

Hypoalbumenia- secondary to liver disease/damage, or malnutrition

CHF- increased hydrostatic pressure

Impaired lymphatic drainage

33
Q

CFR equation

A 
CFR= hydrostatic - oncotic 
CFR= Kf (Pc-Pisf) - sigma (onc c- onc isf)
34
Q

Hydrostatic pressure

A

The pressure exerted by a fluid at equilibrium at a given point within the fluid, due to the force of gravity. Pushes fluid out of the vessel

35
Q

Transcellular

A

Utilizes proteins and channels which are restricted to either the basolateral or apical surface

36
Q

Paracellular

A

Utilizes electrochemical gradient and occurs through tight junctions
Positive charge created by certain channels pushes Ca and Mg towards paracellular transport
Not in the distal aspects of nephron

37
Q

Kidney transport

A

Basolateral:

  • Na-K ATPase (3Na to blood, 2K into cell maintains gradient)
  • Cl channel (Cl into blood)

Apical:

  • Na/K/2Cl symporter (into cell)
  • K channel (into lumen)
  • Ca, Mg, and H2O paracellular

K+ pushes Mg and Ca back into the blood via paracellular transport

Diuretics block leaky channels so water flows into lumen (to ion inc concentration). Pee out water

38
Q

Sweat gland

A

Acinus (deep)- water and Cl channel. Na paracellular

Duct: CFTR and ENac channel so less salty sweat

39
Q

Cystic fibrosis

A

Mutation in CFTR gene
Homozygous- more salty sweat

Heterozygous- less salty sweat

40
Q

Aldosterone

A

Diffuses through the cell membrane where once it forms a complex with a dimerized receptor in the cytoplasm, then enters the nucleus where it acts as a TF to stimulate cellular components to assist in positive water balance

Receptor intracellular bound to HSP
- aldosterone binds mineralocorticoid R —> TF in nucleus —> positive water balance

1- Increase Na/K ATPase
2- Increase Na leak channel
3- decease permeability of tight junctions

41
Q

Dyneien and kinesin

A

Microtubule axoplasmic transport

  • Retrograde transport - Dynein
  • Orthograde transport- Kinesin
42
Q

Normal Ca levels and result of abnormal levels

A

8.5-10.5

Extracellular Ca opens Na channel

Hypocalcemia- increased opening of Na channel —> tetany

Hypercalcemia- decreased opening of Na channel —> weakness

43
Q

Significance of Cytochrome p450

A

Different genetic expressions of CYP can result in different drug metabolism

Therapeutic doses of a drug may be toxic or not effective depending on CPY genetics of the individual

44
Q

Role of Glutamate

A

Release from UMN (CNS) to stimulate LMN (PNS)

ACh then released from LMN

45
Q

Demyelinating disease

A

Leads to leakage/opening of K channels, slowing AP

46
Q

Relative susceptibility of mammalian nerve fibers to conduction block

A

C- slowest and smallest (sensory) most susceptible to local anesthetics

A- motor fibers, most myelinated largest. Least susceptible to local anesthetics

47
Q

Name 3 inhibitory neurotransmitters

A

GABA
Glycine
Substance p

48
Q

GABA a vs GABA b

A

GABA-A: ionotropic results in opening of Cl anion channel. Brings membrane to Chloride equilibrium potential -89. Produces fast IPSP.

GABA-B: metabotropic. Results in opening of K channels via GPCR. Brings membrane closer to K eq potenital -95

49
Q

Myasthenia Gravis

A

Autoimmune disease
Antibodies bind and eventually reduce the number of ACh receptors
Increased muscle weakness as day progresses
Tx- Pyridostigmine (AChE inhibitor)

50
Q

Lambert Eaton

A

Autoimmune disease
Against voltage gated Ca channels
Sx- weakness in limbs, not in ocular muscles
EMG compound motor action potentials (CMAP) - repetitive stimulation increases contraction

Tx- Pyridostigmine

51
Q

Neuromodulators

A

Proteins that can increase or decrease effect of neurotransmitters

Can change- response to nt, synthesis of nt, amount of nt released in response to a stimuli

Cannot change- rate of AP firing, conduction of nerve impulses

Ex. Adenosine, beta-endorphin, substance p

52
Q

Malignant hyperthermia

A

Autosomal dominant defect in RYR
- risk with depolarizing agent Succinylcholine
Over secretion of Ca —> sustained muscle contraction and generation of excess body heat
Tx- Dantrolene (RYR antagonist)

53
Q

Fiber types

A

Type 1- slow twitch
Type 2A- fast twitch oxidative
Type 2B- fast twitch glycolysis

Fatigue rate: increases from 1 to 2B

54
Q

Intracellular and extracellular concentration of Na, K, Ca, Cl

A

Na- 12, 145
K- 155, 4.5
Cl- 4.2, 116
Ca- 0.0001, 1

M1 Physiology (2 decks)

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