Cell Physiology Flashcards by Deleted Deleted

Most abundant component of the protoplasm.

Water (70-80%); (Other components: proteins (10-20%), lipids (1-2%), ions, carbohydrates)

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Contains DNA, Histones & Chromosomes; has nucleolus.

Nucleus

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Powerhouse of the cell.

Mitochondria

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Involved in detoxification, lipid synthesis, lipid-soluble substances –> water-soluble substances

Agranular/Smooth Endoplasmic Reticulum (SER)

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For synthesis of proteins bound for cell membrane, lysosomes, outside of the cell

Rough Endoplasmic Reticulum

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For synthesis of proteins bound for cytoplasm and mitochondria

Free-floating ribosomes

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Reason for the negative charge of DNA

Phosphate

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Reason for the positive charge of histones

Lysine and Arginine

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For packaging, molecular tagging, and synthesis of hyaluronic acid and chondroitin sulfate

Golgi apparatus

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Contains proenzymes, neurotransmitters, and replenishes cell membrane components

Secretory vesicles

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For regression of tissues and autolysis; suicide bags of the cells; destroys FBs

Lysosomes

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Degrades membrane-associated proteins; not membrane-bound

Proteasomes

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Contains oxidases, catalases; for detoxification

Peroxisomes

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What is the function of the nucleolus?

Site of transcriptin and processing of rRNA

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What is unique about the mitochondria?

Contains mitochondrial DNA that is maternally-derived and does not follow the genetic code

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Mitochondria-exclusive pathways.

Beta oxidation, Kreb’s Cycle

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The RER and SER is abundant in which organ?

Liver

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What are the subunits of the ribosomes?

Prokaryotes: 30s, 50s; Eukaryotes: 40s, 60s

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Specialized SER in the skeletal muscle

Sarcoplasmic reticulum

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Specialized SER in the neuron

Nissl substance

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Only substance modified int he RER and not the Golgi apparatus

Collagen

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What is added to lysosome-bound proteins by the Golgi apparatus?

Mannose-6-phosphate

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Lysosomes and peroxisomes come from which organells?

Lysosome: Golgi Apparatus; Peroxisome: SER

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Wear-and-tear pigment that accumulates in lysosomes

Lipofuschin

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Microtubules: motor protein causing transport of substances from center of the cell to the periphery (anterograde axonal transport)

Kinesin

Microtubules: motor protein causing transport of substances from periphery of the cell to the center (retrograde axonal transport)

Dynein

Microtubules are derived from what?

Tubulin dimers

Disease with Dynein missing in cilia and flagella

Kartagener's syndrome: situs inversus, bronchiectasis, infertility

What is the explanation for the situs inversus in Kartagener's syndrome?

Defective primary cilia (directs the organs to their proper locations during embryogenesis)

Movement exhibited by WBCs, fibroblasts, germinal cells of skin, fertilized embryo

Amoeboid movement

Movement found only in the respiratory airways and fallopian tubes; whip-like movements

Ciliary movement

Much longer and moves in quasi-sinusoidal/rotatory waves

Flagellar movement

Disk-shaped; for firm intercellular adhesions; found in epithelium

Macula adherens (desmosomes)

Ring-shaped; increases surface are for contact; found in intercalated disks of cardiac muscles

Zonula adherens (fascia adherens)

Reticular pattern; divides cell into apical and basolateral side; 2 types: leaky (PCT, jejunum) and tight (BBB)

Zonula occludens (tight junctions)

For intercellular communication; found in cardiac and unitary smooth muscles

Gap junctions

Functional unit of the gap junction

Connexons

Movement of substances through the apical and basolateral side

Transcellular transport

Movement of substances between cells through tight junctions

Paracellular transport

Most abundant component of the cell membrane

Proteins (55%) (Other components: phospholipids (25%), cholesterol (13%), other lipids (4%), carbohydrates (3%)

Mainly determines membrane fluidity and permeability to water-soluble structure

Cholesterol

Describe integral proteins

tight attachment using hydrophobic interactions; spans entire cell membrane

Describe peripheral proteins

loose attachment using electrostatic interactions; found in inner leaflet or outer leaflet

GLUT transporters in brain & RBC, liver & pancreas, muscles and adipose

GLUT 1,3: brain and RBC; GLUT 2: liver and pancreas; GLUT 4: muscles and adipose

Type of cell membrane transporter used by water

Aquaporins

Two types of ATP-dependent transporter

ATPase Ion transporters: Na-K-ATPase pump; ATP-Binding Cassette (ABC) transporter: Multidrug Resistance Protein

Which disease involves a mutation in a gene of chromosome 7 that encodes for an ABC transporter called CFTR?

Cystic Fibrosis (CFTR: Cystic Fibrosis Transmembrane conductance Regulator)

Substance that facilitates endocytosis by helping form coated vesicles

Clathrin

Secretion of hormones and neurotransmitters from intracellular vesicles by exocytosis is mediated by:

SNARE proteins

How much water is lost in sweat at rest and in exercise?

100mL and 5000mL respectively

Percentage of TBW, ICF, ECF.

60% TBW, 40% ICF, 20% ECF (15% interstitial, 5% plasma)

What is the principle of macroscopic electroneutrality?

In each compartment, total number of cations should equal total number of anions

What is the basis for the saying "where sodium goes, water follows"?

90% of the solutes in the ECF is Na+ making it a reasonable indicator of osmolarity

What are the various indicator molecules?

TBW: Deuterium oxide, antipyrine; ECF: Inulin, mannitol; Plasma: 124I-labeled albumin

Difference of osmolality and osmolarity

OsmolaLity: per kg of water, independent of temp OsmolaRity: per liter of water, varies with temp

T or F: These two solution would have the same osmolarity: 1 mole of glucose in 1 L or water, 1 mole of NaCl in 1 L of water

False. Glucose will not dissociate, NaCl will dissociate to Na and Cl. (Osmolarity = concentration x number of dissociable particles; mOsm/L = mmol/L x number of particles/mol)

Formula for plasma osmolarity

2 x plasma Na (meq/L) + Glucose (mg/dL) /18 + BUN (mg/dL) /2.8

Movement of water from area of low concentration to high concentration across a semi-permeable membrane

Osmosis

Osmosis: example of impermeant solute

Glucose (effective osmole)

Osmosis: example of permeant solute

Urea (ineffective osmole)

Osmosis: effective osmole use in the treatment of brain edema

Mannitol

Osmosis: osmotic pressure from large molecules (proteins)

Oncotic pressure

Osmosis: weight of the volume of a solution divided by weight of equal volume of distilled (pure) water

Specific gravity

Number between 0 and 1 that describes the ease with which a solute permeates a membrane

Reflection coefficient One: No solute penetration (Albumin),(+) water flow Between 0 and 1: some solute penetration (most substances) Zero: complete solute penetration (urea), (-) water flow

Why is secondary active transport called as such?

It indirectly relies on the Na-K-ATPase pump

What are the characteristics of active transport?

Saturation: Tm occurs once all transporters are used Stereospecificity: recognizes D or L forms Competition: chemically-related solutes may compete

Which is faster? simple or facilitated diffusion?

At low solute concentration: facilitated \> simple At high solute concentration: simple \> facilitated

Examples of primary active transport and secondary active transport

Primary: Na-K-ATPase pump Secondary: SGLT-1 in the SI, SGLT-2 in the PCT

Transport mechanisms: Ca-ATPase pump in the cell membrane

PMCA (Plasma membrane Ca2+ ATPase)

Transport mechanisms: Ca-ATPase pump in the SR and ER

SERCA

Transport mechanisms: functions of the Na-K-ATPase pump

prevents cellular swelling, contributes to the resting membrane potential

Transport mechanisms: functional subunit by the Na-K-ATPase pump inhibited by cardiac glycosides

alpha subunit

Transport mechanisms: in all epithelial cells, Na-K-ATPase pump is found in the basolateral side EXCEPT:

choroid plexus

Why do RBCs swell when chillled?

Decrease ATP synthesis --\> Decrease activity of Na-K-ATPase pump