Unit 1 Exam Prep Flashcards
What are the two parts of holoenzymes?
Two parts, protein called apoenzyme and non-protein component called the cofactor (could be loosely bound such as coenzymes or tightly bound such as prosthetic groups)
What is compartmentalization?
Isolate the reaction, substrate or product from other competing reactions
Provide favorable environment for the reaction
Organize enzymes into purposeful pathways
What are Isoenzymes?
Different enzymes that catalyze the same reaction
Usually located in different tissues or organelles
Where is chymotypsin produced? What is it a precursor to? What is the function of its active form?
Produced by pancreas as inactive precursor to chymotrypsinogen
Hydrolyses peptide bond on carbon side of Phe, Tyr, or Trp
What are mechanism-based inhibitors used for? What are some examples?
Mimic or participate in intermediate step of reaction
Penicillin – binds tightly to glycopeptidyl transferases that are required for cell wall synthesis
Allopurinol – “suicide” inhibitor of xanthine oxidase, decrease in urate production, used in the treatment of gout
What are covalent inhibitors?
What are Transition State Analogous?
Form covalent bond with functional groups in catalytic site
Bind more tightly than substrate or product
What are some uses for inhibitors?
Chemotherapy – uses drugs to treat disease
Metabolic control – through allosteric or substrate inhibition and activation
Natural poisons – are secondary metabolites, peptides or proteins
Michaelis-Menten
V(0) = Vmax[S]/(Km+[S])
Km
Affinity of enzyme for a particular substrate
Lineweaver burke plot vs Michaelis Menten
Less points, extrapolation easier,
Reversible inhibitor
Non-covalent bonds, enzyme regains activity through dilution
Irreversible inhibitor
Cannot regain activity through dilution. Covalent interaction between inhibitor and enzyme or very tightly bound EI complex
What are allosteric enzymes? What are the forms that they can take?
Allosteric enzymes are enzymes that change their conformation upon binding an effector. Usually consist of multiple subunits
Subunits can exist in relaxed active (R) or taut inactive (T) conformation
Allosteric effectors promote or inhibit conversion from one conformation to another
Competitive inhibition
Inhibitor binds to the same site as substrate
Inhibition can be reversed by high [S]
Vmax does not change, reachable at high [S]
Km increased, more substrate needed to achieve 1/2Vmax
What is cooperativity binding?
Binding of substrate to one subunit facilitates its binding to the other
First binding is slow – enzyme in T conformation
Triggers the changes in subunits adjacent to high-affinity or relaxed R state
What are some of the advantages of allosteric regulators?
Stronger effect than competitive and noncompetitive inhibitors
May act as activators (don’t occupy active site)
Do not require to resemble S or P
Effect is rapid, as concentration changes in the cell
What are the two most common covalent modifications?
Phosphorylation is the most common modification
AND-ribosylation of Arg or Lys in G-proteins by bacterial toxins
What is protein-protein interaction? Give examples
Can regulate conformation of active sites
PKA – inactive when bound to inhibitory R subunit, activated by cAMP, binding of cAMP to inhibitory subunit changes the conformation of the inhibitor dissociating it from the catalytic site, PKA becomes active
Noncompetitive
Substrate and inhibitor binds at different sites Inhibitor can bind to ES complex Can't be overcome by increased [S] Km does not change Vmax decreased
Regulation by conformational changes
Allosteric activation or inhibition
Phosphorylation or other modifications
Protein-protein interactions
Proteolytic cleavage
What are llosteric activators or inhibitors
Compounds that bind to the allosteric site (not catalytic)
Cause conformational changes that affect affinity for substrate
Allosteric inhibition is the example of noncompetitive inhibition
What are four types of regulation in metabolic pathways?
Rate-limiting step – slowest and irreversible, influences the rest of the pathway
Feedback regulation - product controls its own synthesis
Feed-forward regulation – increase of substrate (disposal of toxic compounds, storage)
Tissue isozymes – same function, different kinetics
What does the lack of chemical signals lead to?
Lack of chemical signals: infertilities (lack of gonadotropin), type I diabetes mellitus (lack of insulin), hypothyroidism (reduced thyroid hormone levels), hormone deficiencies
Calmodulin
Calcium binding proteins, binds to and regulates different protein targets. Has four Ca2+ binding sites. Binding of Ca2+ leads to conformational change.
In the liver, binding of Ca2+ activates GPK, which is an activator of glycogen phosphorylase, a key activator in glycogenolysis
What causes hyperactivity to signals?
Lack of regulation (e.g., hyperthyroidism, cAMP overproduction in cholera or whooping cough)
Proteolytic cleavage
Activates proteozymes and zymogens
Why are some enzymes produced as inactive?
In the example of blood clotting, zymogens are activated in times of damaged blood vessel
What happens in Myasthenia gravis?
Autoimmune neuromuscular disease, (muscle weakness, muscle fatigue)
Autoantibodies against the nicotinic ACh receptors
- inhibit ACh binding to the receptor
- enhance the internalization and destruction of the receptor
Low levels of functional ACh receptors on skeletal muscle, (too little signaling)
Explain impairment of acetylcholine signaling II and treatment (organophosphates)
Organophosphates - irreversibly inhibit ACh esterase - excess ACh not destroyed (too much signaling) - contraction/relaxation cycle in the heart is impaired - death
Treatment: atropine, a muscarinic ACh receptor antagonist
5 Major chemical signals and roles
Neurotransmitters – produced by the nervous system
- AA derivatives, neuropeptides
Hormones – produced by the endocrine system (mostly)
Cytokines – produced by the immune system, regulate
immune function
- interferons, interleukins
Eicosanoids – produced in response to injury or inflammation
- arachidonic acid derivatives
Growth factors – regulate cell differentiation and proliferation
- proteins
Water insoluble chemical signals
Steroid hormones, thyroid hormone, Vitamin D3, require transport proteins (albumin or specific transporters), others are soluble
Insensitivity to signaling molecules
deficient receptors, intracellular signaling pathway, interference from other signaling pathways (e.g., type II diabetes mellitus). Lots of insulin, but cells are not able to react
Explain Intracellular receptors (Type I and III), (steroid hormones)
Type I and III receptors are localized in the cytosol in complex with HSP, when hormone is bound to the receptor, HSP is shed and receptors are dimerized, it translocates to the nucleus and induce gene transcription with the help of co-activators
Explain Type II nuclear receptor signaling (retinoid acid, vitamin D3, thyroid hormone)
Type II receptor localized in the nucleus in a dimer form and is bound to DNA, it is unable to initiate transcription due to corepressor, when hormone is bound, corepressor is replaced by a coactivator, receptor-hormone complex can now induce transcription
Treatment to lack of signals (hormones)
administer the hormone to the patient (insulin injection, gonadotropin hormone treatment)
enhance hormone production (dietary iodine to induce more thyroid hormone production)
Explain G-protein linked receptor
Signal attaches to a receptor, activates G-protein leading to a signal cascade
What are the main second messengers
Cyclic AMP (cAMP) Cyclic GMP (cGMP) Ca2+ Diacylglycerol (DAG) Inositol triphosphate (IP3)
Signaling insensitivity or hyper-reactivity
too much hormone: decrease it, biochemically or surgically (hyperthyroidism)
Signaling at the neuromuscular junction
Chemical signal:
- acetylcholine (ACh)
Signal detection (receptors):
- nicotinic ACh receptor (skeletal muscle) Na+/K+ channel
- muscarinic ACh receptor (heart muscle) G protein-linked receptor
Conversion of signal:
- nicotinic ACh receptor lets Na+ in and K+ out
- muscarinic ACh receptor regulates a K+ channel
Regulation:
- acetylcholine esterase, degrades excess ACh
Which signals can pass freely through the membrane?
Hydrophobic, hydrophilic has to go through a receptor to send signal
Ion linked receptor
Chemical signal binds, channel opens or closes. Used in the CNS and the PNS. Example is nicotinic ACh receptor
Adenylyl cyclase
Two receptors, on stimulatory and one inhibitory. Epinephrine/glucagon/ACTH (stimulatory) binds to receptor, it stimulates stimulatory G protein, activates adenylyl cyclase. Prostaglandin E1 and adenosine bind to inhibitory receptors, bind to inhibitory G protein, and deactivates adenylyl cyclase.
What are Enzyme or Enzyme-linked receptors
Either kinases or associated with kinases. Receptor has to dimerize. Signaling requires phosphorylation of receptor. Receptor then binds to signal transducer proteins.
Examples are JAK-STAT, Ser-Thr kinase, and Tyr kinase
What is JAK-STAT used for. What is JAK? What is STAT? Explain the pathway.
Used by most cytokines for signaling.
JAKs are tyrosine kinases associated with the receptor.
STATs are signal transducer proteins.
Receptors bind cytokines, dimerizes, binds JAKs. JAKs phosphorylates each other and the receptor, receptor then binds and phosphorylates STATs. STATs dissociates from receptors, dimerizes, and translocates to nucleus to regulate gene transcription
Explain Ser-Thr kinase receptors
Used by transforming growth factor beta family (TGF-B). R-Smad is the signal transducer that binds to the protein. TGF-B binds to type II receptor, type II phosphorylates type I, which then phosphorylates R-Smad. R-Smad complexes with Co-Smad and translocates to the nucleus to regulate gene transcription
Explain Tyr kinase receptors
Used by many growth factors and insulin. Growth factor binds to the Tyr kinase domain, binds to adaptor proteins, activating ras/raf, which regulates gene transcription
What does MAP-kinase pathway do?
Regulate transcription and translation of genes necessary for glucose metabolism
What does PI3-kinase pathway do?
Glucose transporter (GLUT4) is shuttled to the plasma membrane to enhance glucose uptake by muscle and adipose tissue.
What does PLCy pathway do?
Excess glucose can be stored in glycogen or fatty acids (lipids)
Cholera toxin
Transfers ADP-ribose to stimulatory G-protein complex, adenylyl cyclase remain active. GTP cannot be hydrolyzed to GDP. Causes extreme salt and water efflux from gut epithelial cells to lumen, causing diarrhea.
Explain Thyroid hormone production
Hypothalamus (secretes TSH releasing hormone) —> acts on anterior pituitary —> ant pit releases TSH —> acts on thyroid gland —> releases thyroid hormone —> negative feedback to hypothalamus and anterior pituitary to stop the release of TSH releasing hormone and TSH, respectively
What happens in Grave’s disease (hyperthyroidism)?
Autoantibodies stimulate TSH receptors in the thyroid gland, increasing thyroid hormone production, it down grades TSH production, but has no effect. Negative feedback does not work
Pertussis toxin (whooping cough)
ADP-ribose is bound to inhibitory Gia protein subunit, G protein cannot bind to receptor, adenylyl cyclase cannot be inhibited. Leads to increased mucous in the epithelium
Protein Kinase C G-protein pathway
Signal binds to G-protein linked receptor, activates G subunit, activates phospholipase C, IP3 opens channel in the ER, Ca2+ is released, Ca2+ binds and activates PKC
Ion channel activation
Signal (ACh) binds, activates muscarinic ACh receptor, GDP turns to GTP, opens ion channel
5 mechanisms of signaling regulation
Destruction of signal (ACh esterase destroys ACh)
Decreased synthesis of chemical signal (negative feedback regulation of hormone synthesis in the hypothalamus and the pituitary gland)
Destruction of the functional receptors (desensitization of some receptors to phosphorylation/removal of receptors through endocytosis)
Destructions of second messengers (cAMP/cGMP)
Reversing the effects of kinase (phosphatases)
Trapezius (innervation/artery/action/consequence of damage)
Accessory nerve (CN XI)/superficial transverse cervical artery/elevate shoulders, depress and elevate scapula/shoulder drooping, unable to raise arm overhead
Latissimus dorsi (innervation and artery/action/consequence of damage)
Thoracodorsal nerve (C6-8)/thoracodorsal artery/extend and accuct, rotates humerus (pull up)/unable to pullup
Levator scapulae (innervation and artery/action/consequence of damage)
Dorsal scapular nerve (C5),spinal nerve/C5 artery/elevate scapula/depressed scapula, lateral shift in scapula on injured side)
Rhomboid minor (innervation and artery/action/consequence of damage)
Dorsal scapular nerve (C5)/C5/retract scapula/same nerve injury as levator
Rhomboid major (innervation and artery/action/consequence of damage)
Dorsal scapular nerve (C5)/C5/retract scapula/same as nerve injury as levator
Serratus posterior superior (innervation and artery/action/consequence of damage)
Intercostal nerves 2-5/intercostal arteries 2-5/elevates upper ribs
What is Scapulohumeral rhythm?
Once the humerus passes 30°, scapula must rotate it
Serratus posterior inferior (innervation and artery/action/consequence of damage)
Intercostal nerves T9-T12/arteries/depress lower ribs
What is the composition of cardiolipid? What does it do?
Phospholipid with 4 FA tails - Decrease permeability into mitochondria
Supraspinatus muscle (innervation and artery/action/consequence of damage)
Suprascapular artery
What does Clathrin do?
Helps transport particles from the Golgi by creating vessels. Also used in pinocytosis, the typically nonselective process of ingestion of fluid and small particles. Clathrin comes off after vesicle formation
What are the three types of cytoskeleton?
Microtubules: hollow and polar, used for movement in cell
Intermediate filaments: like a rope, gives integrity
Actin filaments: cell migration, integrity, muscle
What is the function of cytoskeleton?
Structural support (cell shape and protection), intracellular organization (transport of organelles to specific sites), Cell motility (contraction, changes in shape, cell migration, actions of cilia and flagella)
Hematoxylin and eosin (H&E)
Hematoxylin: basic violet dye → binds to ACIDIC structures (DNA)
Eosin: acidic pink dye → binds BASIC structures
Infraspinatus muscle (innervation and artery/action/consequence of damage)
Suprascapular artery/circumflex scapular artery
Serratus anterior (innervation and artery/action/consequence of damage)
Long thoracic nerve (C5-C7)/protraction and rotation of scapula
Ribonucleoprotein particles
Condensation of new RNA (heterogenous or hnRNPS), RNA splicing (remove introns)
What is the function of Microvilli?
Increase surface area for absoption/secretion, and thus are found on cells such as those lining the intestines
What is the function of Cilia?
Transport matter along the cell surface. They are found on columnar cells liking the uterus and oviduct, bronchi, and spinal cord central canal
SER Function
Lipid and cholesterol synthesis
How would you mount a sample with active enzymes and preserved cell components?
Rapidly freezing tissues
Simple cuboidal epithelium location and function
ducts of many glands as well as most kidney tubules. protective barrier and has a secretory and absorptive functions
Simple columnar epithelium location and function
They line the stomach, intestine, uterus, oviducts, small bronchi of the lung, paranasal sinus, ependymal cells of spinal cord, the wall of some large kidney ducts
The major function of simple columnar epithelium is protection, secretion, absorption, and transport
What happens when cells are keratinized?
Cytoplasm and nucleus are replaced with keratin
Basal lamina composition
Collagen type IV, the glycoprotein lamin, the glycoprotein fibronectin, as well as a proteoglycan (heparin sulfate)
Laminin
Means of attaching the basal lamina to the epithelium. It has binding sites for integrins. It is a cross-shaped trimer and it is important for cell recognition and adhesion
Integrins
A class of epithelial cell integral membrane proteins, and collagen type IV and other components of the basal lamina
Basement membrane
Thicker than basal lamina, two basal laminas together. Prominent in tissues such as kidney glomerulus and lung alveoli
What are stereocilia, what are its functions?
Elongated, branched microvilli found only in the epididymis where they increase surface area and the cochlea of the inner ear where they are involved in sensory signal generation
Glycocalyx
Filamentous fuzzy coating overlying the microvilli surface. It helps protect the cell from chemical and physical injuries
Ciliary Dynein
Motor protein attached to a microtubule. It is used for moving cargo along microtubule within a cell. It is necessary for flagellar motion. A mutation in ciliary dynein would most likely result in infertility
Lateral and basal cell specializations
Specializations that are typically involved with either increasing surface area or attachment to adjacent cells or tissue
Zonula occludens or tight junctions
Nearest the apical surface, runs completely around the cell perimeter. Two primary functions, first being the prevention of water-soluble molecules from passing between cells but fusing to the plasma membrane of adjacent cells. The next is to maintain the plasma membrane protein polarity
Zonula adherens or belt desmosomes
Basal to the tight junction in many epithelial cells. They are not meant to prevent leakage, they just connect the cells together. It also provides some rigidity to the apical portion of the cell
Macula adherens or desmosomes
Located below belt desmosomes in epithelia. Makes firm cell-cell attachments and help distribute shear forces
Hemidesmosomes
Attaches basal cell membrane to the underlying basal lamina
Gap junctions
Involves many connexons in adjacent cell membranes forming channels across membranes. Permits movement up to 1.5kD
Hyperplasia
Increase in the number of cells in a tissue. Often arises as inflammation or irritation
Metaplasia
Epithelial tissue transforms to a different type of tissue. This can be triggered by cigarette smoking
Dysplasia
Changes in the normal morphology and organization of cells making up a tissue. Early stage of cancer
What is Glycoprotein and give examples
At least one sugar bound to AA side chains. An example would be fibronectin and laminin
What is Fibronectin? Where is it found?
A type of glycoprotein made up of fibroblasts found in the basal lamina. It is important for cell to cell or cell to substrate recognition and adhesion
Ground substance
Noncellular CT component, GAGs and glycoproteins
GAGs
Linear, unbranched polysaccharide of repeating disaccharide units, hydrophilic, allows for rapid diffusion of water soluble particles
Proteoglycans
Core protein with bound GAGs
Hyaluronic acid
Unique GAGs of many thousand disaccharides, many proteoglycans attached, forming large aggregates. Highly viscous and found in synovial fluid, cartilage, and vitreous humor of the eye. It is highly porous but serves as a barrier to protect from bacteria (can be broken by hyaluronidase)
Collagen
3 alpha chains that are formed in the RER. It is rich in Gly, Lys, and Pro that are hydroxylated. It is first synthesized as a procollagen with propetides at both ends to keep it from prematurely coiling completely. Procollagen is transported out of the cell from the Golgi. N and C procollagen peptidases then cleave procollagen. Collagen monomers can come together to form fibrils
Collagen Type I, how is it stained?
Fibril forming. Found in skin, bones, tendons, blood vessels, and cornea. It is the most abundant and stains red (acidophilic)
Collagen Type II
Fibril forming. Found in hyaline and elastic cartilage, invertebral disk, vitreous body
Collagen Type III
Fibril forming. Found in the blood vessels, fetal skin. Part of reticular CT
Collagen Type IV
Network forming. Found in the basal membrane. It does not form fibers
Adipose function and two types
A type of loose CT. Fat cells (adipocytes), they store and make triglycerides, they are fully differentiated and do not divide.
Two types are white (unilocular), which are most abundant, energy storage and brown (multilocular), which aids in the production of heat. This is mostly found in embryos
Reticular fibers
Very thin, found in hematopoietic organs such as the spleen, lymph nodes, and the red bone marrow. Also found in the liver, endocrine glands, endometrium and smooth muscles. It is made up of loosely packed collagen type III held together by proteoglycans and glycoproteins. It does not stain with H&E, it is argyrophilic, it binds silver salts and it shows up black
Elastic fibers (composition and staining)
Can stretch 150% in length, it is found in expanding tissues such as the lungs, aorta, and the skin. It is poorly stained with H&E, orcein stains it purple-black. It is made up of elastic core and fibrillin (glycoprotein)
Marfan’s syndrome
Mutation of fibrillin, wide range of symptoms such as the weakening of the vascular walls and causing aortic rupture
Fibroblasts
Most common in cells in the CT proper, it makes CT fibers and ground substance. It has a pale nucleus and lots of RER and GA. Fibrocytes are the inactive form, it is smaller, darker nucleus. Myofibroblasts are fibroblasts with actin filament bundles, they are prevalent in wound healing
What are Mesenchymal cells?
Part of embryonic CT. Multi-potential cells from embryonic mesoderm, found only in embryo. They are replaced by pluripotential cells in adults
Mast cells
Inflammatory response cells
Types of mast cells
Secretory granules – fill cytoplasm, contains chemicals for inflammatory response. They are basophilic, therefore they are died blue
Primary mediators – pharmacological agents in granules like heparin (anticoagulant), histamine (vasodilation)
Secondary mediators – not stored in granules, made for immediate release like leukotrienes (cause vasodilation, bronchial contraction, and vascular permeability)
Immediate hypersensitivity reaction – allergic reaction from granule release after antigen introduction
Macrophages (resident/elicited)
Digestion of debris, dead cells, and invaders
Resident – not activated, reside in CT along collagen
Elicited – Mobilized to a site in response to stimulus
What is Reticular tissue? Where is it found?
A type of loose CT. Mostly type III collagen, developing blood cells found in between reticular network, framework for marrow, smooth muscle, lymphoid and liver
Plasma cells
Found throughout CT, they produce antibodies
Mucous
Part of embryonic CT. Rich in hyaluronic acid. Type I and III, mostly in umbilical cord
CT Proper components
Loose CT
Dense CT
Loose Areolar
A type of loose CT, most abundant, found in the dermis, below body cavity lining, between muscle fibers
Skin functions
Thermoregulation (blood supply, sweat glands), protection, sensory perception, excretion, metabolism and UV absorption
Keratinocytes
Stack of cells in the stratum spinosum. It makes keratin and forms a water barrier
Stratum basale
Cuboidal or columnar cells attached to the basal lamina by way of hemidesmosomes. K5 and K14 isoforms are formed here.
Stratum basale + deepest layer of stratum spinosum
Stratum germinativum
Stratum spinosum
Thickest layer of the epidermis. Bottom layer is mitotically active. Cytokeratins are located here. Tonofilaments attached by desmosomes give them a spiny appearance. Produces lamellar bodies (membrane coating granules), which are secretory vesicles containing phospholipids. Has K1 and K10
Stratum granulosum
1-5 rows of flattened keratinocytes. Last layer with nuclei. Keratohyalin granules are stained basophilic. Apoptosis is initiated in this layer, the last layer of living keratinocytes. Has K2 and K11, but also some K1 and K10
Flaggrin precursors
Break up to become multiple flaggrins. Flaggrins cement keratin filaments together
Stratum lucidum
Only found on thick skin, which is one continuous row of dead cells. It is packed with keratin instead of organelles
Stratum corneum
Very flat, fully keratinized cells. The keratin is coated with involucrin to protect underlying soft tissue from abrasion and drying out. Squames are found here, which re dead cells. Desquamation is the process of scaling off skin. Turnover takes around 20-30 days
Keratinization
Process of cells from going from granulosum to fully keratinized cells
Icthyosis
Thickening of the stratum corneum. Increased mitotic activity in the basal layer
Psoriasis
Increase in cell proliferation, decrease in mitotic cycle in the stratum basale and spinosum, increased thickness
What is defective in Epidermolysis bullosa simplex (EBS), what happens and what are some of the symptoms?
Defect in K5 and K14, basale keratin becomes much weaker and lyse under pressure, blisters form on the skin areas of repeated trauma
Epidermolytic hyperkeratosis
K10 defect, stratum spinosum and granulosum cells lyse under pressure
Melanocytes
Found in the stratum basale, must less than keratin. They are octopus shaped. Melanin migrates over nucleus to shield DNA from UV ray, only found in basal cells
Langerhans cells
Stellate-shaped cells found in stratum spinosum. They stimulate T-lymphocytes and serve as antigen-presenting cells for allergic response
Melanosomes
Specialized organelles with tyrosinase, they convert tyrosine into DOPA, which is converted into melanin
Merkel Cells
Scattered in basal keratinocyte in the stratum basale. Prominent in the fingertips. They are associated with afferent nerve endings and they form mechanoreceptors
Papillary layer
Layer right below the stratum basale. Includes papillary dermal ridges and dermal papillae
Papillary dermal ridges
Reflected on the skin surface (dermatoglyphs – fingerprints)
Dermal papillae
Finger-like projections on the skin. They increase surface area and strengthen interface
Reticular layer
Dense, irregular collagenous CT deep to papillary, thicker collagen bundles
Blood supply
Thermoregulation
Cutaneous plexus – at dermis-hypodermis border
Subpapillary plexus – papillary layer, capillary loops and extends into dermal papilla for convective heat loss and nutrient delivery to epidermis (by diffusion)
AV shunts – anastomoses, extends between plexuses for thermoregulation
Meissner’s corpuscles
A sensory innervation. Light touch mechanoreceptors
Pacinian corpuscles
A sensory innvervation. Deep pressure receptors in reticular layer, central nerve ending surrounded by many rings of fibroblasts and collagen. It can be either reticular or dermis
Sebaceous glands
Outgrowth of external root sheath. Basal cells fill with lipid, gland lumen and die
Eccrine sweat glands
Over most of the body. Ducts are lined with cuboidal epithelium. It is used for thermoregulation by evaporative heat loss
Apocrine sweat glands
Found in axillary, areolar, and anal regions. It secretes viscous sweat with proteins, lipids, and ammonia
Why are the elderly at a higher risk for trauma-induced layer separation?
Reduced epidermal blood supply. They have a smoothing of epidermis-dermis junction
What are the 3 types of cartilage?
Hyaline, Elastic, and Fibrocartilage
Which one is the most common cartilage, what is it used for, and where is it commonly found?
Hyaline cartilage, it is used for long bone formation and it forms the epiphyseal plate. It is found in the nose, the larynx, the ventral ribs, tracheal rings, bronchi, and synovial joints
Where do chondroblasts arise?
Arises from rounded, congregated mesenchyme cells
Origin of fibroblasts
From mesenchyme at the peripheral edge of developing cartilage
Perichondrium
It envelops cartilage for growth and maintenance. It envelops cartilage where it is not a joint
Chondronergic cells
Inner cell layer of the perichondrium. They differentiate in to chondroblasts
Chondrocytes
Former chondroblasts, completely surrounded in matrix. Cell body fills lacuna, but shrinks in tissue preps, so lacuna appears as cavity
Isogenic groups
Small chondrocyte clusters in central mature cartilage region from mitosis. They are recently divided cells
Major matrix components of cartilage
Collagen Type II, GAGs (stains basophilic), and Chondronectin
Chondronectin
Glycoprotein binding matrix component(collagen/chondroitin) and integrins
Explain the growth of cartilage
Chondroblasts begin secreting and surround themselves with matrix (lacuna), they then get pushed away from each other in a process known as interstitial growth. Perichondrium envelops cartilage for growth and maintenance, appositional growth takes place when the cartilage grows in width
Cartilage aging
Cartilage is unable to regenerate in adults. Chondroblats migrate to small, damaged parts but larger damage results in dense collagenous CT scar. Chondrocytes die and matrix calcification occurs. This leads to reduced mobility and joint pain
pH pKa, pH = pKa
pH pKa – deprotonated
pH = pKa – half is protonated, half is deprotonated
What is Rhizomelic chondrodysplasia punctata? What are some of its symptoms?
Mutations in peroxisomes, preventing them from making plasmalogens. It is characterized by skeletal abnormalities, distinctive facial features, intellectual disability, and respiratory problems
Plasma membrane composition and concentration
Proteins: 50%
Lipids: 40%
Carbohydrates: 10%
Lipid to protein ratio on plasma membrane examples (mitochondria and brain)
Inner membrane mitochondria has more proteins because of ATPase. Myelin has more lipids for insulation. High fatty acid diet can be used as treatment for someone with intractable epilepsy
Eicosanoids
Signaling molecules made by oxidation of 20 carbon fatty acid (leukotrienes, prostaglandin, prostacycline, thromboxanes)
Lecithins
Composed of phosphatidyl choline, it is used to test fetal amniotic fluid for lung maturity. It keeps the lungs from collapsing. Compared to sphingomyelin, ratio has to be 2 or higher to denote maturity
Paroxysmal Nocturnal Hemoglobinuria
Hematopoietic stem cells, cannot link GPI anchors (PI glycans) to proteins, RBCs lose protection from cascade and lysed. Look for anemia, hemoglobin in urine, and thrombosis. Dark urine
What are two ways to assess for fetal lung development?
Lecithins and glycerol
Trans fats and it increases the risk of what?
Phospholipids with trans double bonds, which further decreases membrane fluidity. They increase the risk of cardiovascular disease
Which phospholipid has a role in apoptosis?
Phosphatidyl serine, it’s supposed to be on the cytosolic side, but when flipped, it signals that the cell is about to undergo cell death
Sphingolipids
They serve in intercellular communication, they are the antigenic determinants of ABO blood groups, they can be receptors for viruses and bacterial toxins
Sphingolipidoses cause
Caused by the deficiency of lysosomal enzymes that degrades sphingolipids
Cystic fibrosis cause
CFTR gene, which leads to a defective chloride channel. A point mutation (Phe 508) leads to cystic fibrosis
Deficiency in GLUT-1 leads to a decrease in what?
Cerebrospinal fluid.
What are peripheral proteins bound to? What are lipid-anchored proteins bound to?
Peripheral proteins are bound to either lipids or integral proteins. Lipid anchored proteins may be bound to the inner or outer surface of the membrane
Electrolytes and specific electrolytes in ECF? In ICF?
ECF: bicarbonate and inorganic ion. Specific is Na+ and Cl-
ICF: bicarbonate and inorganic ion. Specific is K+ and phosphates
Osmolarity
Osmolality
Which was does water go?
Osmolarity – osmoles of solute per liter solution
Osmolality – osmoles of solute per kg solvent
Water goes from low osmolarity to high osmolarity
What happens during low plasma osmolarity?
Water is retained in the tissue
Hyponatremia cause
Quick consumption of large amounts of water
What is cystine?
Two cysteine linked by a disulfide bond formed under oxidative conditions
What is Cystinuria?
Amino acid absoroption disease. Intestine cannot absorb the cysteine, and the kidney cannot reabsorb it. Patients develop kidney stones in the bladder, kidney, and ureter
Isoelectric point
The pH where the overall charge is 0
What happens in sickle cell anemia?
Deoxy HbS polymerizes in RBCs and deforms them. Inflexible RBCs block capillaries leading to insufficient delivery of oxygen to issues (anoxia) and severe pain (crises). Abnormally shaped RBCs are then destroyed by macrophages, leading to hemeolytic anemia
What is the function of glycosylation?
It increases the solubility of the protein. This determines the ABO blood type
What is glycation?
Covalent bonding a sugar or a lipid with a sugar molecule such as fructose or glucose without the controlling action of an enzyme. HbA1c is a glycated version of HbA
What is lipid addition?
It enables protein to be inserted in the plasma membrane without having a transmembrane region
What is GPI anchoring and what happens to hematopoietic stem cells if it becomes defective?
It can cause RBC, WBC, and platelets to lack GPI anchored proteins on their surfaces. This leads to their lysis by its own immune system, leading to hemolytic anemia, hemoglobin in urine, or thrombosis
What is edema and what causes it? What can it lead to?
It is an accumulation of fluid in the interstitial space. It is caused by an increased flow of fluids in the bloodstream and the decrease of their return. It can lead to CHF, increased blood pressure, severely impaired circulation, and decrease in plasma protein concentration (hypoproteinemia)
Hypoproteinemia can result from what?
Liver disease – failure to synthesize plasma proteins
Kidney disease – damage to glomerular capillaries, resulting in protein loss in urine
Starvation – intake of AA is insufficient to support plasma protein synthesis
What happens when fatty acids is metabolized to ketone bodies?
It causes ketoacidosis as blood and cellular pH drops
What are the three main regulators of pH and which is the fastest?
Buffer is the fastest, respiration comes second, renal is the slowest
What happens to respiration with the change of pH?
If pH falls, you breathe rapidly to expire CO2, if pH rises, you breathe shallowly to conserve CO2
What happens during metabolic acidosis?
Increased production of H+ by tissues. H+ is buffered by HCO3-, making it H2CO3, which is converted to CO2. Hyperventilates.
What happens when the anion gap is low? high?
High anion gap —> metabolic acidosis, Low anion gap —> respiratory acidosis
What happens during respiratory acidosis?
Insufficient expiration of CO2 from lungs, CO2 in the blood increases, puts carbon anhydrase in favor of proton production, blood H+ is increased
What happens during respiratory alkalosis?
Excessive expiration of CO2 by hyperventilation, blood CO2 is decreased, H+ is decreased, pH increases, HCO3- goes down
What happens during metabolic alkalosis?
Prolonged vomiting causes excessive loss of H+, pH is increased, HCO3 is increased, breathe less to increase blood CO2
What happens to pH levels if a child were to consume large amounts of aspirin?
They become acidotic
What happens to hemoglobin when it binds a proton?
Affinity for oxygen decreases
What is the major contributor to buffering urinary pH and why must it be kept at a low concentration?
Ammonium (NH4+) and because of its toxic properties
What secretes HCl and what is it used for?
HCl is secreted by parietal stomach cells, strong acidity denatures ingested proteins
What neutralizes stomach content when it is released to the lumen of the small intestine? What secretes it?
Bicarbonate, it is secreted by pancreatic cells and intestinal lining
Name a tertiary structure that has a pocket on the protein that is essential to its function
Myoglobin has a heme group that binds to the pocket, thus, oxygen
What amino acid is most likely to be found spanning the domain of a transmembrane protein and why?
Leucine, because it is hydrophobic
What are chaperonins used for?
They help in protein folding
What determines the folding of a protein?
It’s primary structure, the amino acid sequence
What causes acute hemolytic anemia?
G-6-P dehydrogenase deficiency, proteins are denatured and precipitate in the cells
What causes a1-antitrypsin deficiency? What are its effects?
Excessive degradation of elastin. Lungs will have a lower elastin content, leading to the collapse of small airways when the patient exhales, leading to emphysema. The liver is also affected
What happens in amyloidosis?
Misfolded proteins are precipitated in different tissues/organs. Their precipitation can cause organ failure. They are beta sheet rich structures
What causes Prion disease (Mad-Cow Disease)? How is it contracted? What is its genetic form?
The denaturation of the prion protein in the brain. It causes an excess in beta sheets. The genetic form is known as Creutzfeldt-Jacob disease
What happens in AL amyloidosis?
Antibody lightchain fragments are precipitated in the kidney. This is frequent in multiple myeloma
What happens in Alzheimer’s disease? What does it cause?
Beta-amyloid protein is precipitated. It causes brain degeneration
Why does capillaries have a lower pH?
Because it has more protons. Protons bind better and stabilize deoxygenated (T) form of Hb. This will allow the unloading of oxygen to the tissues
What happens in methemoglobinemia? What are some of its symptoms?
Fe2+ is oxidized to Fe3+ via nitrates or oxidation drugs. This leads to a higher level of methemoglobin, which cannot bind oxygen. Causes chocolate colored blood, bluish skin, SOB, headaches, and seizures
Where does the synthesis of procollagen chains occur? Which AA residues are hydroxylated? Which are glycosylated?
RER, Lys and Pro are hydroxylated. Some hydroxylysine are glycosylated
Where does the triple helix form? What stabilizes the triple helix? Where are propeptides cleaved?
The triple helix is formed in the RER. Hydrogen bonds and hydroxyproline stabilizes them. Propeptides are cleaved in the ECM
Which enzymes need Fe2+ and vitamin C as cofactors?
Prolyl and lysyl hydroxylase
How are covalent crosslinks between collagen fiber created? What enzyme cofactor is involved? Where does it take place?
The covalent crosslinks are created through oxidized lysine and hydroxylysine, oxidation is canalized by lysyl oxidase. It needs Cu2+ as a cofactor. It takes place in the ECM
What happens in Scurvy? What are some of the symptoms?
Prolyl and lysyl hydroxylase do not function due to the lack of vitamin C. Collagen triple helix is less stable and cross linking is reduced. Symptoms would be bleeding gums, loose teeth, spots and bruises on the skin, as well as delayed wound healing
What happens in the classic type of Ehlers-Danlos syndrome? Vascular type? Kyphoscoliotic type? Symptoms?
Classic type: type V collagen, hyperextensive skin, delayed wound healing, atrophic scars, joint hypermoblity
Vascular type: type III collagen, arterial, intestinal, and uterine ruptures
Kyphoscoliotic type: mutation in lysyl hydroxylase, hyperextensive skin, delayed wound healing, joint hypermobility, progressive scoliosis
What happens in osteogenesis imperfecta? Symptoms?
Type I collagen mutations. Increased incidence of fractures, short stature, grey or brown teeth, blue sclera (eye)
What causes Alport syndrome? What does it affect? What are some of its symptoms?
It is caused by mutations in type IV collagen genes. It affects the glomerular basement membrane and it can lead to renal failure. Some of its symptoms include hematuria, proteinuria, renal insufficiency and hearing loss
What does elastin do? Where are they found? Where are they synthesized? What two molecules are necessary for their assembly?
It allows tissue to stretch and contract. They can be found in the blood vessels and lungs. They are synthesized in the ER. Microfibrils and fibrillins are required for their assembly
What causes Marfan syndrome? What are its symptoms?
It is caused by mutations in fibrillin-1, incorrect formation of elastic fibers. Microfibrils are deficient, which means that elastic fibers will also be deficient. It leads to a very tall structure, long limbs, hyper flexible joints, discoloration of the lens of the eye, dilation of the aorta, heart problems
What happens in junctional epidermolysis bullosa?
Mutations in laminin and integrins, causing a deficiency. They mainly affect the basement membrane below the epidermis and mucosal membranes. Main symptom is fragile skin
Where does fertilization usually occur? Where does it implant?
In the ampulla of the uterine tube. It eventually implants into the endometrium of the uterus
What are blastomeres?
It is the dividing cells during cleavage
In a morula, what is the inner cell mast and what is the outer?
ICM = embryoblast OCM = trophoblast
Give some examples of anomalies during the first week of gestation
Dizygotic/monozygotic twins. Conjoined twins. Ectopic pregnancy
After two weeks, what happens to the embryoblast? Trophoblast?
It forms the bilaminar germ disc, forming the epiblast and the hypoblast. The trophoblast forms the syncitiotrophoblast and the cytotrophoblast
What does the ectodermal layer give rise to?
CNS, PNS, sensory epithelium, eyes, nose, ear, and subcutaneous glands (sweat glands), pituitary gland, and the tooth enamel
What happens during the third week of development? How do you know that it started?
Gastrulation occurs, in which the trilaminar germ layer forms by the invagination of the epiblast cells. Gastrulation begins with the appearance of the primitive streak and node on the surface of the epiblast. The epiblast migrate into the primitive streak and pit, they detach from epiblast (invagination) and begin to migrate
Describe the formation of CNS. What does the neural tube become?
Ectoderm thickens (neural plate) because of the inductio of the notochord and prechordal mesoderm, neural folds approach each other in the midline region, begins to fuse to form the neural tube, it then proceed to both ends. Before the ends close, they are called the neuropores. The neural tube becomes the brain and and the narrow spinal cord
What abnormalities can occur during gastrulation? How do they form?
Holoprosencephaly – deficiency of craniofacial midline structures, may be caused by high doses of alcohol
Sirenomelia – with insufficient mesoderm in the caudal part of the embryo
Sacrococcygeal teratoma – tumors form from remnants of primitive streak
Situs invertus – transposition of organs occur in the thorax and abdomen
What happens to the neural crest and name some structures that are derivatives of the neural crest
They migrate to the underlying mesoderm. They eventually form the posterior root spinal ganglia, adrenal medulla, Schwann cells, anterior part of the skull, and others
How does head development occur during gastrulation?
Signals are received from the anterior visceral endoderm, establishing the cranial end. Primitive streak forms caudally under control of genes in the primitive node
What are the derivatives of the paraxial mesoderm? What are the derivatives of those?
Paraxial mesoderm turn into somites.
Ventromedial sclerotome – cartilage and bone of the axial skeleton, including the vertebral column
Dorsomedial (epimeric) – forms the intrinsic muscles of the back
Dorsolateral (hymoperic) – muscles of the limbs and body wall
Dorsal dermatome – dermis of the skin
What are some of the derivatives of the intermediate mesoderm?
Differentiates into urogenital structures such as the kidneys and gonads
What does the lateral plate mesoderm divide into? What are the some of the derivatives of those?
Somatic or parietal layer, joins overlying ectoderm to form ventural lateral body walls
Splanchnic or visceral layer, joins underlying endoderm, forms the wall of the gut
The is the role of the intraembryonic cavity?
It secretes serous fluid, it later forms the peritoneal, pericardial, and pleural cavities of the adult
Where are blood vessels derived from?
First they are derived from extra embryonic mesoderm surrounding the yolk sac. Later on, they become derived from lateral plate mesoderm
What is the role of the liver in early development? What takes over?
It is the major hematopoietic organ by week 6. It sends stem cells to colonize the bone marrow, which becomes the definitve hematopoietic organ by the seventh month
What is the main organ derivative of the endoderm? How does it form?
It forms the gastrointestinal tract by the lateral and cephalocaudal folding of the fetal trilaminar germ disc. It also contributes to the urinary bladder, urethra, thyroid and parathyroid glands, liver and the pancreas
Where does the chorion come from? Where is the yolk sac during this time? What does that attachment later form?
The chorion is formed by the extraembryonic mesoderm and the two layers of trophoblast, the yolk sac remains attached to the chorion by way of the connecting stalk, which later forms the umbilical cord with the vitelline duct
What separates the maternal and fetal circulation?
The fetal capillary endothelium and the syncitiotrophoblast. Together they form the “placental barrier”
What are the two parts of the placenta? Which belongs to the fetal and which belongs to the maternal?
The fetal portion is the chorion frondosum, the maternal is the decidua basalis
What is the function of the corpus luteum? What maintains it during the first two months of pregnancy? How? What happens after the end of the fourth month?
The corpus luteum produces progesterone and estrogen. It is maintained by the secretion of syncitiotrophoblast during the first two months of pregnancy through the secretion hCG. By the end of the fourth month, the placenta then produces enough progesterone to maintain the pregnancy if the corpus luteum were removed
What happens when the amniotic fluid, which provides shock absorption, fetal movement, is overproduced? Underproduced?
Polyhydraminos occurs with its overproduction. It prevents swallowing and absorption because it affects anencephaly or the interstitial atresia
Oligohydramnios occurs with its overproduction, which causes renal agenesis (kidneys fail to develop), amnion rupture, resulting in clubfoot or lung hypoplasia
What are the two types of bone formation? Describe them
Intramembranous ossification, in which embryonic tissue or mesenchyme directly develops into bone. This is seen mainly in the skull
Endochondral ossification, in which mesenchyme must first differentiate into hyaline cartilage, which is later replaced to bone
What is spina bifida? What are the three types? What are their differences?
Spina bifida is the arches of different vertebrae, often with protrusion
Spina bifida cystica is the defect of spinal cord
Spina bifida occulta is when the defect is not apparent due to the growth of hair or pigmented skin
What is amelia? What is meromelia? What causes them?
Amelia is the total absence of a limb, meromelia is the partial absence of one or more limb
The skull is divided into two parts. What are they? What do they form?
Viscerocranium forms the skeleton of the face. Neurocranium encloses the brain
The skull is a derivative of what two parts?
Partly from paraxial mesoderm and partly from neural crest cells
What is the cranial vault? Why is the cranial base called the chondrocranium?
Cranial vault are the flat bones that form the neurocranium. The cranial base is called the chondrocranium because it was formed mainly by endochondral ossification
Why are sutures important in bone development? What are fontanelles?
Sutures are important because these are the sites where the bone can grow on surfaces. Fontanelles are areas where more than two bones meet. The anterior fontanelle is where an infant’s soft spot is located
What causes craniosynostosis? What is the most common type? Describe it.
It is caused by the premature fusion of sutures. It can be caused by mechanical factors. Compensatory growth occurs at the unaffected sutures. Scaphocephaly is the most common form, which is due to the premature fusion of the sagittal suture
What does the anterior divisions of the anterior rami innervate? What about the posterior divisions of the anterior rami?
The anterior innervates the flexor muscles of the extremities. Posterior innervate the extensor compartments of the extemities
What explains the striations of skeletal muscle fibers?
The arrangements of their myofibrils
What muscles are missing in Poland sequence? What are its manifestations?
The pectoralis minor and part of pectoralis major are missing. The nipple and areola may be displaced or absent
What is arthrogryposis? What causes it?
It is multiple joint contractures due to muscular, neurogenic, or connective tissue anomalies. It can be cause by uterine crowding, limiting fetal movement, causing abnormal joint development.
The two basic types of neurons are motor and sensory. Which one is multipolar with multiple dendrites? Which one is pseudounipolar?
Motor is multipolar with multiple dendrites. Sensory is pseudounipolar
Where is the cell body of a lower motor located? Where is its axon located? What is the collection of nerve cell bodies inside the CNS called?
The cell body is located within the gray matter of the CNS. Its axons are located within peripheral nerves. A collection of nerve cell bodies is called a nucleus
Where is the cell body of a psudounipolar neuron located?
Their cell body is in the peripheral nerve, located within a sensory ganglion
What are motor end plates? It is also known as what?
They are specialized synapses found between motor neurons and skeletal muscles. They are also called neuromuscular junctions
Between the ventral and dorsal roots, which one is motor and which one is sensory?
Ventral root is motor and dorsal is sensory
What does the posterior (dorsal) primary ramus supply? The anterior (ventral) primary ramus? Are primary rami motor or sensory?
Dorsal supplies structures of the back. Ventral supplies the structures of the anterolateral body wall and the extremities. Primary rami are mixed, both sensory and motor
What information does GSA carry? GSE?
GSA carries pain, temperature, touch, and position sense from muscles and joints
GSE carries the contraction of skeletal muscle fibers
What information does GVA carry? GVE? Which one makes up the autonomic nervous system?
GVA carries information from glands, blood vessels, and internal organs
GVE fibers innervate smooth muscle, cardiac muscle, or gland. It makes up the autonomic nervous system
Explain the reflex arc. Are reflexes autonomic or somatic?
The tapping of a reflex in the tendon sends a signal through the afferent limb, instead of sending the signal back to the brain, it goes through interneurons to send the signal to the efferent limb directly. Reflexes are both autonomic and somatic
Either the somatic efferent fibers or autonomic efferent fibers have two-neuron linkage. Which one is it? What is that linkage called?
Autonomic fibers have two linkages, it is called the autonomic ganglion
What is the thoracolumbar division? The craniosacral division?
Thoracolumbar is the sympathetic division. Craniosacral is the parasympathetic division.
Explain referred pain and how it occurs
They are visceral pain that may be referred to in the body wall or extremities. It is probably a result of the convergence of visceral afferent and somatic afferent nerve fibers on sensory neurons within the same segment of the spinal cord
What is the difference between compact bond and Cancellous bone? What can be found between the gaps?
Compact bone has no gaps, it is found on the bone exterior. Cancellous bone on the other hand, is know as spongy bone. Hematopoietic material can be found between the gaps
What is the difference between diaphysis and epiphysis? The middle of the bone has a hollow space, what is it filled with?
Diaphysis is the main shaft of the cortical bone. The middle is hollow space filled with yellow marrow Epiphysis is the enlarged ends of the bone, it is mostly cancellous bone, the insides are filled with red marrow
What is the periosteum? What are its main functions?
It is a tough membrane of dense, irregular fibrous CT. It covers the entire bone except at the joint regions. It anchors ligaments and tendons to the bone. It is also involved in formation and repair
What is the endosteum? What are its functions?
It is a thin CT membrane that lines the medullary cavity and functions in bone growth and remodeling
What are the differences between fibrous, cartilaginous, and synovial joints?
Fibrous joints are held together by tightly dense fibrous CT. Cartilaginous are held together by hyaline or fibrocartilage. Synovial joints are complex, fluid filled joints
What is the difference between synarthrosis, ampiarthrosis, and diarthrosis?
Synarthrosis is immovable joint (or one with a very limited ROM). Ampiarthrosis has little movement, diarthrosis is freely moveable joints
What is the composition of synovial joints?
2 or more articular surfaces that are covered with hyaline, a joint capsule, and synovial fluid
Each muscle fiber is surrounded by a thin sheet of CT called a what? The muscles bundle into groups called? That is surrounded by another membrane called what?
Endomysium, they bundle together to form a fasciculi, which is surrounded by permysium. Fasciculi bundled together forms the epimysium
What are synovial sheaths? Bursae?
They wrap around tendons as they traverse confined spaces. Bursae separates tendons from bony prominences or skin areas subject to friction
Aspirin (molecular mechanism, effects, treatments)
Covalent acetylation of cyclooxygenase (COX), which is a key enzyme in prostaglandin synthesis. It inhibits COX
Alcohol poisoning
Drink alcohol —> ethanol in body.
Alcohol dehydrogenase breaks down ethanol, which requires NAD+.
NAD+ is exhausted, NADH builds up.
NADH competes with NAD+ in binding with alcohol dehydrogenase receptors.
NADH also blocks fatty acid oxidizers, you end up with buildup of fat in the liver (fatty liver)
Acetaldehyde (molecular mechanism, effects, treatments)
It is highly reactive and toxic. It is a product of ethanol oxidation. It is responsible for liver diseases associated with chronic alcoholism
What is the catalytic triad?
Composed of Serine-Aspartate-Histidine (SDH). These AAs cooperatively interact with each other and substrates. They cut off the aromatic rings
Penicillin (molecular mechanism, effects, treatments)
Binds very tightly to glycopeptdyl transferase, which is required for cell wall synthesis. It is a transition state analogue (resembles transition state)
Allopurinol (molecular mechanism, effects, treatments)
It is a “suicide” inhibitor for xanthine oxidase, it decreases rate production, which is used in the treatment of gout
Heavy metal toxicity (molecular mechanism, effects, treatments)
It caused by tight binding of metals to a functional group.
Mercury binds to SH groups of many enzymes, it reacts with selenium, which is required for such selenoenzymes as thioredoxin reductase, which can greatly increase cellular oxidative damage
Lead replaces the functional metals in enzymes (Ca2+ in calmodulin)
Aluminum interferes with ion transport by binding to transferrin and albumin that can cause anemia
Iron can cause iron overload, leading to iron toxicity, leading to anemia and it can cause liver failure
Physostigmine (molecular mechanism, effects, treatments)
ACh esterase inhibitors (reversible), it elevates ACh levels. It is used for myasthenia gravis, more efficient signaling for few receptors
Dexamethasone (molecular mechanism, effects, treatments)
Anti-inflammatory steroid drug, 30x more efficient in signaling pathway than natural cortisone
B1 blockers
Targets andrenergic receptor, which is a G-protein linked receptor. It is used for cardiac arrythmias
a1-andrenergic agonists
a1-andrenergic receptors on smooth muscle cells mediate vasoconstriction through G-protein linked receptors, which is PKC. They are used in decongestants and eye drops
Serenomelia
Lack of mesoderm, caudal part doesn’t form
The isozymes that catalyze the first step in glucose metabolism varies by the tissue. What are these isozymes and where are they found?
Hexokinase is found in RBCs. Glucokinase is found in the liver and pancreatic beta cells.
