The cell Flashcards
total body of water
Total body water (TBW) is 60% of body weight [ you are 2/3 water ! ]
increased in new born , decreased in women
intracellular fluid
Is 2/3 of total body water (TBW)
Major cation is ____
Major anion are protein and organic phosphate
Extracellular fluid (ECF)
Is 1/3 of total body water (TBW)
Composed of interstitial fluid and plasma
Major cation is ______
Major anion is Cl- and HCO3-
extra cellular fluid
Plasma is ¼ of ECF
Interstitial fluid is ¾ of ECF
Plasma and interstitial fluids are separated by capillary wall
Homeostatic Mechanisms
Receptors - provide information about stimuli
Control center - tells what a particular value should be (includes a set point)
Effectors - elicit responses that change conditions in the internal environment
Negative Feed back control
Promotes stability, prevents over-excitation
Most common
Positive Feed back control:
Rare , explosive, viscous cycle
LH surge just before ovulation, blood clotting, labor contractions
Proteins:
Provide “specificity” to a membrane
Defined by mode of association with the lipid bilayer
integral protein
peripheral protein
integral: channels, pores, carriers, enzymes, etc.
Span the entire membrane
Are anchored through hydrophobic interactions with the phospholipids bilayer
Include ion channels, pores, carriers, G protein, enzymes etc.
Include hormone receptors
peripheral: enzymes, intracellular signal mediators
Are not embedded in the cell membrane
On both side, are loosely attached to the cell membrane by electrostatic interactions
Control transport of substances across cell membrane
Carbohydrates (3 types)
Glycolipids (approx. 10%)
Glycoproteins (majority of integral proteins)
Proteoglycans
Carbohydrates
Negative charge of the carbo chains repels other
negative charges
Involved in cell-cell attachments/interactions “cell marker”
Play a role in immune reactions
Cholesterol
Present in membranes in varying amounts
Generally decreases membrane FLUIDITY and
PERMEABILITY (except in plasma membrane)
Increases membrane FLEXIBILITY and STABILITY
Cell Membrane“Gate Keeper
Composed primarily of lipid (50%) and protein (50%) Lipids Phospholipid (most abundant) Glycolipid Cholesterol Proteins Channels Receptors Enzymes
cell membrane
50% protein 50% lipid
Lipid bilayer—barrier to water and water-soluble substances
hydrophilic and hydrophobic
Phospholipids have a glycerol backbone, which is hydrophilic (water-soluble) heads, and two fatty acid tails, which is hydrophobic (water insoluble). The hydrophobic tails faces each other and form a bilayer
lipid soluble substances
(e.g. O2,CO2 ,N2, steroid hormones, isoflurane, unionized form of drug, non-polar molecules ) cross cell membrane because they can dissolve in the hydrophobic lipid bilayer
Water-soluble substances
(e.g. ions (Na+ K+, Cl-), glucose, ionized form of drug, polar molecules and water) cannot dissolve in the lipid of the membrane, therefore cannot cross the cell membrane. But they may cross through channels, pores or may be transported by carriers.
peripheral proteins
peripheral: enzymes, intracellular signal mediators
Are not embedded in the cell membrane
On both side, are loosely attached to the cell membrane by electrostatic interactions
Control transport of substances across cell membrane
pinocytosis
– ingestion of smaller particles
phagocytosis
ingestion of larger particles/bacteria
opsonization
binding of IgG antibody on the surface of bacteria enhancing phagocytosis
Mechanism of pinocytosis
a process by which liquid droplets are ingested by living cells. Pinocytosis is one type of endocytosis, the general process by which cells engulf external substances, gathering them into special membrane-bound vesicles contained within the cell.
What is the function of Clathrin?
Clathrin (mechanism of pinocytosis) performs critical roles in shaping rounded vesicles in the cytoplasm for intracellular trafficking. Clathrin-coated vesicles (CCV) selectively sort cargo at the cell membrane, trans-Golgi network, and endosomal compartments for multiple membrane traffic pathways.
Endoplasmic Reticulum
Network of microtubules where proteins are “processed”
Site of intracellular calcium storage
Smooth ER has no ribosomes [ form lipids/steroids]
Rough ER has ribosomes
Ribosomes (80S)
are factories for protein synthesis
60S and 40S subunits
golgi apparatus
Secretory functions
Final packing
Lysosomes
Digestive system of cell– contain hydrolases
Allow phagocytosis of bacteria
Remove damage tissues “ recycling centers”
Peroxisomes
Similar to lysosomes
Help in detoxification (e.g. alcohol )
Secretory vesicles
from the golgi Exocytosis stimulated by Ca++
Mitochondria
POWERHOUSE” of cell
More active cells have more mitochondria; like _____HEART
Have electron transport chain
Convert food stuff into energy in the form of ATP
via the process of oxidative phosphorylation
CN-, CO inhibit ATP synthesis
Contains their own DNA
Maternal inheritance of mitochondrial diseases. Why?
Microtubules
Provide skeleton and rigid support to cell Drugs that act on microtubules Griseofulvin (Anti-fungal) Mebendazole (Antihelminthic) hook warm Vincristine ( Anti-cancer) Paclitaxel ( anti-breast cancer) Colchicine ( Anti-gout)
Nucleus
Command and control Center” of cell
Contain DNA – Gene
Chromosomes are condensed genetic material
Nuclear Membrane
have thousands of pores
Chromatin
(condensed DNA) is found in nucleoplasm
Nucleoli
Accumulation of RNA
Forms ribosomes
Lysosomal Storage diseases
tay sachs
intracellular connections
tight junctions
Attachment between cells, often epithelial cells
May be ‘tight’ (impermeable), as DCT or ‘leaky’ (permeable) as in PCT
Gap junctions “communicating junctions”
Are the attachments between cells that permit intercellular communication
Permits current flow and electrical coupling between myocardial cells
Offers least resistance to flow of ions
In MI these gap junctions close leading to ____________
b-oxidation of fatty acids explain-
Degradation and oxidation of fatty acids is called -oxidation occurs only in the mitochondria.
First ,Fatty acids are transported into the mitochondria. This is a carrier mediated transport by carnitine shuttle. Once inside the mitochondria, the fatty acids splits away from the carnitine .
The fatty acid molecule is degraded in the mitochondria and results 2 molecules of Acetyl-CoA.
The Acetyl-CoA molecules formed by -oxidation in mitochondria enter the Citric Acid cycle
Tremendous amount of ATP (146 molecules) are formed by -oxidation from one molecule of fatty acids (Guyton page 823)
atp is used for
Transportation of substances across membrane
Synthesis of compounds
Muscle contraction
The end product of carbohydrate, protein and fat metabolism is
Acetyl-CoA
Kartagener’s syndrome
(Immotile cilia syndrome) is due to a dynein arm defect, resulting in immotile cilia
Sinus inversus- heart on the right and liver on the left.
Sterility in male and female; Why? Sperm is unable to swim women can’t move eggs down
Recurrent sinusitis; Why?
Brochiectasis
dna
Deoxyribo nucleic acid
Double stranded
Located mainly in nucleus
Contains nitrogenous base, sugar and phosphate
NB are Adenine, guanine, cytosine and thymine
Deoxyribose sugar
rna
Ribo nucleic acid
Single stranded
Located in nucleus and cytoplasm
Contains nitrogenous base, sugar and phosphate
NB are adenine, guanine, cytosine and uracil
Ribose sugar
Pyrimidines
(Cytosine,Uracil, Thymine) have one ring (CUT the Py[pie] Pyramidines)
Uracil found in RNA, thymine in DNA
Purines
(Adenine,Guanine) have two rings. PURe As Gold
osmolarity formula
2(Na)+0.055(GLUCOSE)+0.36(BUN)
DNA ligase
by which repairs are made
DNA polymerase
new” DNA is proofread by
Transcription– Formation of mRNA
Step1. RNA polymerase binds to the promoter sequence
Step2. The RNA polymerase temporarily “unwinds” the DNA double helix
Step3. The polymerase “reads” the DNA strand and adds complementary RNA molecules to the DNA template
Step4. “Activated” RNA molecules react with the growing end of the RNA strand and added (3’ end)
Step5. Transcription ends when the RNA polymerase reaches a terminating codon, releasing both the polymerase and RNA strand
local anesthetics can be ionized form or unionized form
(lah+)-ionized
la-unionized
Chediak-Higashi syndrome
Chediak-Higashi syndrome- defective microtubules; decrease phagocytosis; increase infections (bubble babies)
dna strand
Helical double-stranded structure (twisted ladder) of the gene. The outside strands are composed of phosphoric acid and the sugar deoxyribose. The internal molecules connecting the two strands of the helix are purine and pyrimidine bases; these determine the “code” of the gene
what end do nucleotides get added to
Nucleotides are always added to the 3’ end
amino acid production
A messenger RNA strand is moving through two ribosomes. As each “codon” passes through, an amino acid is added to the growing protein chain, which is shown in the right-hand ribosome. The transfer RNA molecule transports each specific amino acid to the newly forming protein.
mrna
which carries genetic code from nucleus to cytoplasm. They are long single stranded molecules containing codons —code triplets for amino acids
trna
acts as carrier to transport amino acids to ribosomes
rrna
which are present in ribosomes and synthesize proteins translation
transcription
The formation of mRNA is called transcription and is controlled by RNA polymerase
translation
mRNA moves to the cytoplasm and dictates the formation of proteins (translation)
clavulanic acid+ beta-lactamase
augmenting
simple diffusion
Lipid-soluble molecules move readily across the membrane
(rate depends on lipid solubility)
Water-soluble molecules cross via channels or pores
Primary Active Transport
Na+/K+ ATPase (Sodium pump)
Keeps intracellular K+ high and intracellular Na+ low by moving 3Na+out and 2K+ in, using ATP
Maintains normal cell volume. How?
Insulin stimulates Na+/K+ pump , corrects hyperkalemia by moving K+ into the cells.
Beta agonist e.g. ritodrine (Yutopar), terbutaline and epinephrine stimulate Na+/K+ pump Hypokalemia
Beta blockers Hyperkalemia
Ouabain and digitalis inhibit the Na+-K+ pump. na/k pump atp. ca/atpase pump ca in sarcomplasmic reticulum. H/K/ATPase - proton pump.
Secondary Active Transport co porters
Postulated mechanism for sodium co-transport of glucose,
amino acids, hc03
dna replication
nucleotides are added to the 3’ end dna is proof read by dan polymerase
repairs are made by dan ligase
bind to 30s subunit of bacterial ribosome inhibiting protein synthesis
aminoglycosides. tetracycline
chloramphenicol, erythromycin, lincomycin. clindamycin
bind to 50s bacterial ribsomsome
sulfonamide
inhibit bacterial synthesis of folic acid
rifampin
blocks bacterial mRNA synthesis
quinolone- cipro, norfloxacin, nalidixic acid
inhibit bacterial dna gyrase topoisomerase II
penicillin cephalosporin vancomycin
interfere with bacterial call wall synthesis
polymyxin
disrupt permeability of bacterial cell membrane- leakage of cell contents
metronidazole
disrupts microsomal dna snythesis
clavulanic acid plus beta lactamase
augumentin
secondary active transport counter transport (antiport) exchange
examples- sodium goes in, calcium went outside. sodium goes in, hydrogen goes out. na/hco3 inside and cl/hydrogen go out.
GLUT4
In diabetes mellitus, glucose uptake by muscle and adipose cells is impaired because the carriers for facilitated diffusion of glucose (GLUT4) require insulinIn diabetes mellitus, glucose uptake by muscle and adipose cells is impaired because the carriers for facilitated diffusion of glucose (GLUT4) require insulin
Cardiac glycosides (digitalis)
Cardiac glycosides (digitalis) increase the force of contraction by inhibiting Na/K ATPase in the myocardial cell membrane. As a result of this inhibition, the intracellular [Na] increases, diminishing the Na gradient across the cell membrane Na/Ca exchange (a mechanism that extrudes Ca from the cell) depends on the size of the Na gradient and thus is diminished, producing an increase in intracellular Ca. Higher the Ca, more forceful will be the contraction of myocardial cell.
excotyosis
Release of neurotransmitters from the nerve terminals
extrusion of cellular contents
