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Northeastern University Physician Assistant Program > Cellular Biology > Flashcards

Cellular Biology Flashcards

1
Q

What is the Nucleus?

A

DNA Storage - The control center of the cell which sends messages to grow, mature, replicate or die

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2
Q

What is the Mitochondria?

A

The powerhouse of the cell; responsible for energy production within the cell.

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3
Q

What is the Smooth Endoplasmic Reticulum?

A
  • Lipid production
  • Phospholipids and cholesterol
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4
Q

What is the Rough Endoplasmic Reticulum?

A
  • Embedded with Ribosomes
  • Protein synthesis
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5
Q

What is the Endoplasmic Reticulum?

A
  1. Provides maximum surface area for physiological function.
  2. Divides cytoplasm into compartments and allows different chemical reactions to take place.
  3. Protein and fat synthesis
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6
Q

What is the Golgi Apparatus

A

Protein Modification - processes substances from the ER to form lysosomes, secretory proteins and other cytoplasmic components.

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7
Q

What is a Ribosome?

A

Composed of rRNA and protein; site of protein synthesis; free w/I cytosol and bound to RER

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8
Q

What is a Lysosome?

A

Protein Destruction - intracellular digestive system disposing of damaged cellular structures, food particles and unwanted material such as bacteria.

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9
Q

Describe the composition of intracellular fluid and the three most common ions?

A

Fluid located within the cell membrane which contains water, electrolytes, lipids and carbs. Potassium, magnesium, and phosphate are the three most common electrolytes

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10
Q

Describe the function of extracellular fluid?

A

Created and maintained by circulatory function.

Provides micro and macro nutrients

Removes cell waste by carrying toxins to the liver, CO2 to the lungs and Urea to the kidneys

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11
Q

What is the structure and composition of the cell (plasma) membrane?

A

It is a thin, pliable, elastic structure composed almost entirely of proteins and lipids.

55% Protein
25% Phospholopids
13% Cholesterol
4% other lipids
3% Carbhydrates

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12
Q

What is the function of the cell membrane?

A
  • semi-permeable
  • allows some molecules to diffuse across the lipid bilayer.
  • specialized proteins in the cell membrane regulate the concentration of specific molecules inside the cell.
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13
Q

What is the function of second messenger mechanisms?

A
  1. Membrane receptor binds a molecule in the ECF
  2. Activates inrtacellular enzyme
  3. Causes change to the physiology within the cell
  4. Cellular response
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14
Q

What Ions are found in the Extracellular Fluid (ECF)?

A
  1. Sodium (Na) 142
  2. Calcium (Ca) 2.4
  3. Chlorine (Cl) 103
  4. Bicarb 28
  5. Glucose 90
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15
Q

What Ions are found in the Intracellular Fluid (ICF)?

A
  1. Potassium (K) 140
  2. Magnesium (Mg) 4
  3. Phosphate 10
  4. Amino Acids 200
  5. Protein 16g
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16
Q

Describe Transcription.

A

The process through which DNA replicates into RNA. mRNA carries the code to the ribosome for translation; tRNA transports Amino Acids to Ribosome, and rRNA completes the AA chain which folds into a new protein.

17
Q

What is Mitosis?

A

The process of cellular division through two phases; interphase and mPhase (Mitosis).

Interphase prepares the cell for division through:

  • G1 - (Cellular content duplicate minus Chromosomes),
  • Synthesis (Chromosomes Duplicated and DNA Replicated)
  • G2 (Cell grows, prepares for Mitosis and checks for errors).

mPhase - Mitotsis - Cell divides into two daughter cells through Prophase, Metaphase, Anaphase, Telophase and Cytokinesis.

18
Q

What is Oxidative Stress?

A

Free Radicals have an unstable electron, which causes them to attack healthy cells trying to steal electrons. Once started, the process continues until stopped, which causes oxidative stress causing cellular breakdown.

19
Q

What is Reactive Oxygen Species?

A

Chemically reactive molecules containing oxygen - Peroxide, Superoxide and hydroxyl radical

20
Q

What is Diffusion?

A

The kinetic movement of molecules or ions through a membrane without interaction with carrier proteins in the membrane.

21
Q

What is Facilitated Diffusion?

A

Facilitated diffusion requires interaction of a carrier protein. The carrier protein aids passage of molecules through the membrane by binding with them and moving them through.

22
Q

What is Active Transport?

A

Movement against a concentration gradient, which involves a carrier protein moving a substance all the way through a membrane.

Primary - Energy comes form ATP breakdown

Secondary - Energy was stored in the concentration gradient

23
Q

What is Osmotic Pressure?

A

Osmotic pressure is the exact amount of pressure required to stop osmosis across a semipermeable membrane

24
Q

What is Oncotic Pressure?

A

Osmotic pressure caused by proteins - dependent on the number of particles, not the size.

25
Q

What is hydrostatic Pressure?

A

The force exerted by a column of fluid on the walls of the container (think of the human body)

26
Q

What is Tonicity?

A

Tonicity is a measure of the effective osmotic pressure gradient; the water potential of two solutions separated by a semipermeable cell membrane.

27
Q

What is Resting Membrane Potential?

A

Resting Membrane Potential is the electric potential of the cell, which is a result of ions moving in and out.

28
Q

What are the stages of depolarization?

A

The muscle receives nerve stimulous suddenly becomes permeable to sodium ions. Once the threshold has been met, sodium gated ion channels open allowing rapid diffusion of positively charged Na+ ions into the cell. The normal polarized membrane rapidly gains a positive charge until sodium levels reach +35 at which time Na+ Ion channels close.

29
Q

What are the stages of repolarization?

A

Within a few 10,000ths of a second after the membrane becomes highly permeable to sodium ions, the sodium channels begin to close (+35) and the potassium channels open to a greater degree than normal. Then, rapid diffusion of potassium ions to the exterior establishes the normal negative resting membrane potential, which is repolarization.

30
Q

How does action potential propagate from a nerve to a muscle?

A

Acetylcholine is released from the axon terminal of the nerve cell at the neuromuscular junction and binds to acetylcholine receptors on the muscle cell. This binding allows the cell membrane to become more permeable to sodium. As sodium enters the cell, the cell reaches its threshold level of -70 mV and begins to depolarize. Due to the fact that muscle cells can be thick, t-tubules which are invaginations of the sarcolemma help to propagate the action potential to many myofibrils within the cell allowing for simultaneous depolarization throughout the cell.

31
Q

Explain the pathophysiology associated with the blockage of neuromuscular junctions?

A

The neuromuscular junction (NMJ) is a synaptic connection between the terminal end of a motor nerve and a muscle (skeletal/ smooth/ cardiac). It is the site for the transmission of action potential from nerve to the muscle.

32
Q

Compare and contrast slow and fast oxidative and glycolytic muscle.

A

Contraction Speed: Slow - Fast - Fast

Myosin ATPase Activity: Slow - Fast - Fast

Major Pathway for ATP synthesis: Aerobic Respiration - Aerobic Respiration - Glycolysis

Rate of Fatigue: Slow - Intermediate - Fast

Mitochondria: Many - Many - Few

Color: Red - Red to Pink - White

33
Q

Describe the functional anatomy and physiology of skeletal muscle contraction.

A
  • RMP of -90mv; duration is 5x longer than nerve APs and1/13th the velocity
  • contractions require nervous signal input, the NMJ and the release of Ach
  • able to contract 30% of length;
  • energy required to maintain contraction; contraction stops when nerve impulse stops
  • all contractions are voluntary and rather quick
  • skeletal muscle has a greater store of calcium in its sarcoplasmic reticulum
34
Q

Describe the functional anatomy and physiology of smooth muscle contraction.

A
  • contraction activated via nervous, hormonal or other ligand signal
  • requires extracellular calcium and no troponin – binds to calmodulin
  • mostly prolonged, involuntary tonic contractions
  • able to contract 80% of length (sphincter; movement through intestines)
  • low energy requirement to maintain contractile state (latch phenomenon)
  • unitary muscle responds to sudden ‘stress-relaxation’ response
  • maximum contraction force greater than skeletal.
35
Q

Compare and contrast action potential generation in different muscle types.

A

Skeletal: activated via Ach release from a nervous signal only

Smooth: can be activated by the following signals/stimuli: nervous / hormonal / Ligand / Stretch of a hollow organ

Cardiac: Na+ influx for depolarization, short repolarization via exfil of K+, plateau phase Ca++ influx, repolarization through K+ exfil, Resting

Northeastern University Physician Assistant Program (12 decks)

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