Foundations Flashcards
How is the cell cycles regulated?
- CDKs
- Cyclins
- Cyclin-CDK complexes
- Tumor suppressors
What is the shortest phase of the cell cycle
mitosis
What are CDKs
they are constitutive and inactive
What are cyclins
regulatory proteins that control cell cycle. They are phase specific and activate CDKs
What is the importance of cyclin-CDK complexes
must be activated and and inactivated for cell cycle to progress. Inactivated by p21, p27, and p57.
What controls p21 activation
p53
What tumor suppressors inhibit G1 to S progression
p53 and hypophosphorylated Rb
What are the different type of cells
- permanent
- stable
- labile
What are examples of permanent cell
Neurons, skeletal/cardiac muscle, RBCs. - remain in Go, regenerate from stem cells
What are examples of stable cells
Hepatocytes, lymphocytes. - enter G1 from Go when stimulated
What are examples of labile cells
bone marrow, gut epithelium, skin, hair follicles, germ cells. - NEVER go to Go, divide rapidly w/ a short G1
What is the role of the Rough ER
- synthesis of secretory proteins and N-linked oligosaccharide addition to proteins
Where in the body are RER found in excess
mucus-secreting goblet cells of small intestine and Ab secreting plasma cells
What are Nissl bodies
RER in neurons. They make enzymes and peptide neurotransmitters
What is the role of free ribosomes
site of synthesis of cytosolic and organellar proteins
What is the role of the SER
steroid synthesis and detoxification of drugs and proteins
What cells are rich in SER
liver hepatocytes and steroid hormone producing cells of the adrenal cortex
How do proteins get into the nucleus
need to have a nuclear localization signal : 4-8 AA sequence rich in L, R, and Proline
What regulates G1 to S phase
- Cyclin D – activated CDK4 –> phosphorylates Rb protein which releases it from the TF E2F which transcribes and synthesizes components needed to progress thru S phase
- Cyclin E - activates CDK2
What regulates G2 to M phase
- Cyclin A - CDK2 complex –> mitotic prophase
2. Cyclin B - CDK1 complex activated by cdc25 = allows breakdown of nuclear envelope and initiation of mitoses
What is the role of the Golgi Appartus
- distribution center for proteins and lipids from the ER to vesicles and plasma membrane
- Modifies N-oliogosaccharides on asparagine
- Adds O-oligosaccharides on serine and threonine
- Adds mannose6-phosphate for trafficking to lyososomes
- glycosylation of proteins
- sulfation of sugars and tyrosines
What are endosomes
sorting centers for material from outside the cell of from the Golgi, sending it to lysosomes for destruction or back to the membrane/Golgi for further use
What is I cell disease
- inherited lysosomal storage disease due to failure of addition of mannose 6-phosphate to lysosome proteins.
What are the clinical manifestations of I cell disease
- coarse facial features
- clouded cornea
- restricted joint movement
- high plasma levels of lysosomal enzymes
often fatal in childhood
What are the vesicular trafficking proteins?
- COP I - retrograde
- COP II - antegrade
- Clathrin : from trans-Golgi to lysosomes or plasma membrane to endosome (receptor mediated endocytosis)
What other proteins are needed for receptor mediated endocytosis
Clathrin, adaptin, and dynamin (plays a role in pinching off the membrane)
What is the role of peroxisome?
membrane enclosed organelle invovled in catabolism of very long fatty acids and amino acids.
What are the 3 ways protein can be degraded?
- proteasome
- lysosomal degradation
- Ca dependent enzymes
What is a proteasome
barrel-shaped protein complex that degrades damaged or unnecessary proteins tagged for destruction w/ ubiqutin
What is are microtubules
cyclindrical structure composed of a helical array of polymerized dimers of alpha and beta subunits. They grow slowly and collapse quickly.
How many GTP are bound to each dimer
2
What uses microtubules
flagella, cilia, mitotic spindles. They also are involved in slow axoplasmic transport in neurons
What helps microtubles w/ transported cellular cargo
Molecular motor proteins.
- Dynenin - retrograde to microtubule
- Kinesin - anterograde to microtubule
What drugs have an effect on microtubules
- mebendazole/thiabendazole
- griseofulvin (antifungal)
- vincristine/blastine
- paclitaxel
- colchicine
What is Chediak-Higashi Syndrome
mutation in lysosomal trafficking regulator gene whose product is required for the microtubule-dependent sorting of endosomal proteins into late multivesicular endosomes.
What are clinical presentations of Chediak-Higashi Syndrome
recurrent pyogenic infections, partial albinism, and peripheral neuropathy
Describe the structure of cilia
- 9+2 arrangement of microtubules.
- Axonemal dynenin - ATPase that links peripheral 9 doublets and causes bending of cilium by differential sliding of doublets
- gap junctions allows cilia to communicated w/ each other
What is Kartagener’s syndrome
aka Primary Ciliary dyskinesia
- immotile cilia due to a dynenin arm defect
- male infertility, decreased female fertility, bronchiectasis, recurrent sinusitis, associated w/ situ inversus
What are other components of the cytoskeleon
- actin and mysoin - microvilli, muscle contraction, cytokinesis, adherens junctions
- intermediate filaments -
What is the composition of the plasma membrane
asymmetric lipid bilary. Contains cholesterol and phospholipids As well as sphingolipids, glycolipids, and proteins.
What does a high cholesterol content due to the plamsa membrane
decreased fludity, and increases melting temperature
What are the various immunohistochemical stains for?
- Vimentin
- Desmin
- Cytokeratin
- GFAP
- Neurofilaments
- Peripherin
- Nuclear lamins
- connective tissue - found in sarcomas
- muscle - rhadomyosarcoma
- epithelial cells (desmosomes and hemidesmosomes) - carcinomas
- neuroglia (astrocytes, Schwann cells)
- axons
- neurons
- nuclear envelope and DNA
Tell me about the Na-K ATPase pump
3 Na out and 2 K in. During cycle, pump is phosphorylated.
What drug can inhibit the NaKATPase
cardiac glycosides (digoxin and digitoxin) - inhibition of the pump leads to an indirect inhibition of Na/Ca exchange so Ca increases inside the cell --> increasing cardiac contractility
What is the most abundant protein in the human body
Collagen
Where is type 1 collagen found
BONE, skin, tendon, dentin, fascia, cornea, late wound repair
Where is type 2 collagen found
Cartilage (including hyaline), vitreous body, nucleus pulposus
Where is type 3 collagen found
Reticulin - skin, blood vessels, uterus, fetal tissue, granulation tissue
What is the type 4 collagen found
basement membrane
What cells do collagen synthesis take place in?
fibroblasts
What are the steps of collagen synthesis?
- RER - translation of collagen alpha chains (preprocollagen) – usually Gly-X-Y (prolin and lysines)
- Hydroxylation in ER - requires Vit C
- Glycosylation in ER of hydroxylysine and formation of procollagen via hydrogen and disulfide bonds (triple helix of 3 collagen alpha chain)
- exocytosis into extracellular space
- Cleavage of disulfide rich terminal regions = insoluble tropocollagen
- Covalent lysine-hydroxylysine cross linkage making collagen fibrils via Cu containing lysyl oxidase
What is osteogenesis imperfecta
genetic bone disorder. Most common form is AD w/ abnormal type I collagen. Type II OI - fatal in utero
What are the features of the common OI form
- multiple fractures w/ minimal trauma; may occur during the birth process
- blue sclerae due to translucency of connective tissue over the choroidal veins
- hearing loss
- dental imperfections due to lack of dentin
What is Ehlers-Danlos
faulty collagen synthesis during the cross-linking process
What are features of Ehlers-Danlos
hyperextensible skin, tendency to bleed, hypermobile joints, berry anuerysms, organ rupture.
What are the collagen types affects
- Type III
2. Type 1 and 5 most frequently in sever classic syndrome
What is Alport syndrome
due to a variety of gene defects resulting in abnormal type 4 collagen.
- x-Linked recessive
What are the features of Alport syndrome
progressive hereditary nephritis and deafness. may be associated w/ ocular disturbances
What is elastin
a stretchy protein w/in skins, lungs, large arteries, elastic ligaments, vocal cords, ligamenta glava.
What is the component of elastin
- rich in proline and glycine - the nonhydroxylated forms
2. topoelastine w/ Fibrillin scaffolding
How is elastin degraded
elastase which is normally inhibited by alpha1-antitrypsin. A defect in antitrypsin will lead to excess elastase and panacinar emphysema or liver problems
What is Marfan’s syndrome
-defect in Fibrillin. Heart problems, tall, long fingers
What is apoptosis
programmed cell death, requires ATP. there are two pathways but both ends up activated cytosolic caspases that mediate cellular breakdown. No inflammation is involved with this.
what are the histology features of apoptosis
- cell shrinkage
- nuclear shrinkage
- basophilia
- membrane blebbing
- nuclear fragmentation (karyorrhexis)
- formation of apoptotic bodies which are then phagocytosed
What can trigger apoptosis
p53, cytokines, cytotoxic T cells, cell stress, absence of GFs
What is the intrisinc pathway for apoptosis involved in?
involved in tissue remodeling in embryogenesis, occurs when a GF is withdrawn from a proliferating cell population, also occurs after exposure to injurious stimuli
What are the steps for the intrinsic pathway for apoptosis?
- increase in pro-apoptotic signals : Bax, bak, bcl-x
- decrease in anti-apptotic signals: Bcl2
- they increase mitochondrial permeability and cytochrome C is released
- binds to cytosolic Apaf-1 which activates caspase 9
What are the steps for the extrinsic pathway for apoptosis?
- Ligand receptor interactions: Fas ligands binds to CD95 –> FADD activates caspase 8
- Immune cells such as killer T cells release perforn and granzyme B
What is necrosis?
enzymatic degradation and protein denaturation of a cell resulting from exogenous injury. Intracellular components extravasate and there is an inflammatory process.
What are the various types of necrosis?
- coagulative - heart, liver, kidney
- liquefactive - brain, bacterial abscess, pleural effusions
- caseous - TB, systemic fungi
- Fatty - peripancreatic fat
- Fibrinoid - blood vessels
- Gangrenous - dry or wet; common in limbs and in the GIT
What type of cell injury is reversible w/ O2?
- decreased ATP synthesis
- cellular swelling
- nuclear chromatin clumping
- decreased glycogen
- fatty change
- ribosomal detachment
What type of cell injury is irreversible?
- nuclear pyknosis, karyolysis, and karyorrhexis
- Ca influx –> caspase activation
- plasma membrane damage
- lysosomal rupture
- mitochondrial permeability
What areas of the following organs are susceptible to ischemia/infarction?
- heart
- brain
- kidney
- liver
- colon
- subendocardium (LV)
- ACA/MCA/PCA boundary areas
- straight segment of the PT (medulla), thick ascending limb (medulla)
- areas around the central vein (zone 3)
- splenic flexture, rectum
Where do red infarcts occur?
loose tissue w/ collaterals such as liver, lungs, or intestines or following reperfusion
where do white infarcts occur
solid tissues w/ single blood supply such as heart, kidney, and spleen
What are the cell injury byproducts of the following organs?
- heart
- skeletal muscle
- hepatocyte
- salivary glands
- pancreas
- RBCs
- CK, LDH, troponin
- CK, aldolase, LDK
- AST, ALT, alk phos, GGT
- amylase
- amylase and lipase
- LDH, haptoglobin, bilirubin
What are the various types of shock?
- hypovolemic/cardiogenic
2. septic
What happens w/ hypovolemic/cardiogenic shock?1
- low output failure
- increased TPR
- low cardiac output
- cold, clammy patient due to vasoconstriction
What happens w/ septic shock?
- high output failure
- decreased TPR
- dilated arterioles and high venous return
- hot patient due to vasodilation
What is atrophy?
reduction in size or number of cells. Decreased metabolic activity b/c of decrease proteins, autophagy, increased protein degradation.
What are causes of atrophy?
- decreased hormones - menopause
- decreased innervation - motor neuron damage
- decreased blood flow
- decreased nutrients
- increased pressure (nephrolithiasis)
- occlusion of secretory ducts (CF)
What are charactersitics of inflammation?
- redness
- pain
- heat
- swelling
- loss of function
What happens to the vasculature during inflammation?
increased vascular permeability, vasodilation, and endothelial injury
What happens to the cellular component during inflammation?
PMNs extravasate from circulation to injured tissue to participate in inflammation through phagocytosis, degranulation, and inflammatory mediator release
What are components of acute inflammation?
- PMNs, eosinophils, Ab mediated
- Rapid onset, lasts minutes to days
- outcome = complete resolution, abscess formation, and progression to chronic inflammation
- IL 1/6/TNFalpha
what are components of chronic inflammation?
- mononuclear cell mediated
- persistent destruction and repair
- blood vessel proliferation, fibrosis
- Granulomas
- outcomes = scarring and amyloidosis
what are granulomas?
nodular collections of epithelioid macrophages and giants cells. Mediated by TNFalpha
What are patterns of inflammations?
- serous - transudate
- fibrinous - exudate
- pus
What causes cell aging?
- there is a fixed number of times a cell can divide
- telomeres - shortened by each round of division
- telomerases elongate the telomeres. germs cells have a lot of this E. Cancer cells figured out how to activate telomerase
- restricting caloric intake increases lifespan
What is leukocyte extravasation?
neutrophils exit from blood vessels at sites of tissue injury and inflammations
What are the steps of leukocyte extravasation?
- Rolling - mediated by selectins which are increased due to inflammatory cytokines. Sialyl-Lewis on leukocytes bind to selectine
- Tight Binding - LFA-1 (integrin) on leukocytes bind to ICAM1
- Diapedesis: leukocytes travel b/w endothelial cells and exits blood vessels. PECAM-1
- MIgration - cells travel through interstitium to site of injury guided by chemotactic signals.
What are some chemotactic signals?
C5a, IL8, LTB4, and Kallikrein
What are the various ways that free radicals can damage cells?
- membrane lipid peroxidation
- protein modification
- DNA breakage
How is free radical injury initiated?
radiation exposure, metabolism of drugs, redox reaction, NO, transition metals, leukocyte oxidative burst
How can free radicals be eliminated?
- by enzymes - catalase, superoxide dismutase, GSH peroxidase
- spontaneous decay
- antioxidants - vitamins A, C, E
What pathologies are included w/ free radical injury?
- retinopathy of prematurity
- bronchopulmonary dysplasia
- CCl4, leading to liver necrosis ( fatty change)
- Acetaminophen overdose (fulminant hepatitis)
- Fe overload (hemochromatosis)
- Reperfusion after anoxia especially after thromblytic therapy
During wound healing, angiogenesis takes places. What are the 2 ways that angiogenesis can take place?
- growth of new vessel from preexisting vessel. VEGF, endothelium grows, MMPs modify and create new endothelium and basement membrane
- VEGF can recruit endothelial progenitor cells to connect up to existing vessel
What are the various steps of wound healing?
- Immediate (0-3 hrs) : clot formation and increased vessel permeability
- w/in 2 days - neutrophil migration
- 2-3 days after wound : deposition of granulation tissue and collagen; angiogenesis; epithelial cell proliferation; dissolution of clot; wound contraction mediated by fibroblasts
- 3-5 days : granulation tissue w/ Type 3 collagen
- Remodeling: 1 week after wound. Type 3 collagen is replaced by type 1 collagen. Increased tensile strength of tissue. Vit C and Zinc needed for new collagen.
What are common granulomatous disease?
- TB - caseating
- fungal infxns
- syphilis - T. pallidum
- Leprosy - M. Leprae
- Cat scratch disease - Bartonella Henselae
- Sarcoidosis
- Crohn’s Disease
- Wegners
- Churg- Strauss
- Berylliosis, silicosis
- foreign bodies
What can happen w/ anti TNF drugs in an granulomatous diease?
TNF-alpha from macrophages induce and maintain granuloma formation. W/ this drugs a side effect can cause sequestering granulomas to breakdown leading to disseminated disease
What are the characteristics of a transduate?
- hypocellular, protein poor
- low specific gravity < 1.012
- due to increased hydrostatic pressure, decreased oncotic pressure, and Na retention
What are the characteristics of an exudate?
- cellular, protein rich
- specific gravity > 1.020
- Due to lymphatic obstruction and inflammation
Where is CRP made?
it’s an acute phase reactant made in the liver
What is the role of CRP
part of the innate immune system - opsonizes bacteria and activates complement
- can be secreted from atherosclerotic plaques to activate local endothelial cells to induce prothrombotic state to increase adhesions of endothelium leukocytes
When is CRP elevated and what can decrease it?
- elevations are strong indicators for MI, stroke, PAD
- lowered by smoking cessation, wt loss, statins, and exercise
What is ESR?`
product of inflammation that coats RBCs and causes aggregation. When aggregated the RBCs call at a faster rate within the test tube
When do you see increased ESR
- infections - osteomyelitis
- inflammation (temporal arteritis)
- cancer
- pregnancy
- SLE
When do you see decreased ESR
- sickle cell
- polycythemia vera
- CHF
What are some important genes of embryogenesis?
- Sonic hedgehog gene
- Wnt7 gene
- FGF gene
- Homeobox Gene (hox)
Tell me about sonic hedgehog gene
- produced at base of limbs in zone of polarizing activity
- anterior to posterior axis
- CNS development
- mutation can cause holoprosencephaly
Tell me about Wnt-7 gene
- produced at apical ectodermal ridge
2. necessary for proper organziation along dorsal ventral axis
Tell me about FGF gene
- produced at apical ectodermal ridge
- stimulates mitosis of underlying mesoderm, providing for lengthening of limbs
- mutation = short limbs