Cell Bio Flashcards
K+
Intracellular: 139, Extracellular: 4
Na+
Intracellular: 5-15, Extracellular
Ca2+
Intracellular: <0.0002, Extracellular: 1.8
Cl-
Intracellular: 4-15, Extracellular: 116
HCO3-
Intracellular: 12, Extracellular:
Proteins (-)
Intracellular: 138, Extracellular
Osmolarity
Intracellular: 287 mOsm, Extracellular: 287 mOsm
pH
Intracellular: 7.06-7.13, Extracellular: 7.4
Fick’s Law of Simple Diffusion
F = (KA/x)*C
Simple Diffusion
Rapid over short distances Requires no energy, no proteins Permeability constant is directly proportional to lipid solubility, inversely proportional to size
Ion channels
Gated (ligand, voltage, mechanical) Selective based on size, chemical nature Fastest
Facilitated Diffusion
Molecule binds to protein, causing conformational change, binding affinity decreases, cargo is released on other side of membrane Saturatable Slower than channels Bi-directional Dependent on concentration
Primary Active Transport
Uses ATP hydrolysis as energy source Works against concentration gradient Ex. Na-K- ATPase pump (3 Na+ out, 2 K+ in) Saturatable
Secondary Active Transport
Uses Na+ gradient as energy source Saturatable
Symport
Secondary active transport, Na+ in, glucose/AAs in (against concentration gradients)
Antiport
Secondary active transport, Na+ in, Ca2+/H+ out (against concentration gradients)
Hydrostatic Pressure
Water flows from high to low pressure (generally out of blood vessels and into cells)
Osmotic Pressure
Water flows from low to high solute concentration (generally out of cells and into blood vessels b/c of higher protein concentration in plasma)
Isotonic solutions
Same concentration as extracellular fluid (no volume change)
Hypertonic solutions
Cell is in higher concentration than normal extracellular fluid (movement of water out of cell, cells shrivel)
Hypotonic solutions
Cell is in lower concentration than normal extracellular fluid (movement of water out of cell, cells swell)
Tissue Edema
High BP in capillaries, low plasma protein concentration –> lower osmotic pressure, lymphatic obstruction
Nernst Equation
60 log (Co/Ci) Exactly equal and opposite to concentration gradient for a given ion
Resting Membrane Potential
-70 to -90 mV
Pinocytosis
Non-specific Cell membrane invaginates to form vesicle that encloses a bit of ECF and whatever is dissolved in it (ions, small molecules)
Phagocytosis
Non-specific Specialized cells extend pseudopodia to engulf large particles or cells, vesicles form phagosomes, which merge w/ lysosomes
Receptor-mediated endocytosis
Highly specific Molecules (ligands) bind to specific protein receptors in cell membranes, areas invaginate, Adaptin acts as a linker between membrane protein and clathrin Dynamin and other proteins wrap around neck of forming vesicle and aid in its pinching off from source membrane Clathrin is released from vesicle
v-SNARE
Found on vesicle membranes
t-SNARE
Found on target membranes
Rabs
GTPases that facilitate and regulate vesicle docking and association of t- and v-SNAREs
Endosomes
Membrane-bound compartments in which endocytosed material is sorted, then sent to different regions of the cell pH of 5 (late endosomes) to 6 (early endosomes)
Lysosomes
Primary site of intracellular digestion Contain degradative enzymes including proteases, nucleases, lipases, phosphatases, glycosidases (all acid hydrolases)
Autophagy
Damaged or senescent organelles are surrounded by membrane and delivered to lysosomes for degradation
Constitutive secretion
Unregulated vesicle fusion and exocytosis
Regulated secretion
Regulated membrane fusion and exocytosis via response to stimulus/signal (like hormone or NT)
Lipid rafts
Cholesterol, sphingolipids, proteins
Composition of lipid membrane
Phosphatidylcholine (outside) Sphingomyelin (outside) Phosphatidylethanolamine (inside) Phosphatidylserine (inside) Phosphatidylinositol (inside) Glycolipids (outside)- minor Cholesterol restricts movement, increase rigidity
alpha-helices
Transmembrane proteins Most common form of proteins Amphiphatic Single pass or multipass
beta-barrels
Transmembrane proteins Multipass Rigid Usually restricted to mitochondrial membranes Pore-forming
Band 3
Anion membrane transport protein in RBCs
Aquaporin
Water membrane transport protein in RBCs
GLUT 1
Glucose membrane transport protein in RBCs
Kidd antigen protein
Urea membrane transport protein in RBCs
RhAG
Gas membrane transport protein in RBCs
Spectrin
Most abundant protein in RBC skeleton Forms long, flexible heterodimers (association of alpha and beta chains)
Junctional complex
Complex of f-actin, protein 4.1, and actin-binding proteins dematin, adductin, tropomyocin, and tropomodulin in RBC Bound to spectrin
Ankyrin
Couples spectrin to Band 3 in RBC skeleton
Protein 4.1
Couples junctional complex to Glycophorin C in RBC skeleton
Regulate RBC deformability
Geometry (SA:V) Cytoplasm viscosity (hemoglobin) Deformabliity of membrane
Mitochondria (function)
Generate ATP Regulate concentration of certain ions in cytoplasmic matrix
Cytochrome c
Protein in intermembrane space Associated w/ cell death
Products of soluble enzymes in mitochondrial matrix
CO2 and NADH
Electron Transport Chain
Maintains proton gradient Consists of: - NADH dehydrogenase complex - Ubiquinone - Cytochrome b-c1 complex - Cytochrome c - Cytochrome oxidase complex
Chemiosmotic coupling
Movement of H+ back into matrix causes generation of ATP within ATP synthase enzyme
Mitochondria DNA (structure)
Closed circular molecule Encodes 13 enzymes, 2 rRNAs, 22 tRNAs used in translation Possess complete system for protein synthesis
White adipose tissue (function)
Metabolic energy storage, insulation, cushioning, hormone production, source of metabolic water
Brown adipose tissue (function)
Thermogenesis (heat production)
Insulin
2 chain polypeptide, A and B chains held together by disulfide bonds
Produced in B-cells (central) in islets of Langerhans in endocrine pancreas
Long term weight regulation
Acts on liver, skeletal muscle, adipose tissue
Stimulates uptake of glucose from circulation
Stimulates glycogen synthesis
Stimulates glycolysis
Stimulates glycerol synthesis
Inhibits lipase activity
Stimulates uptake of AAs into cells
Inhibits protein catabolism
Stimulated by: blood glucose levels above 70 mg/dL, certain AAs, increased FA levels, circulating gastrin, CCK, secretin, parasympathetic stimulation, incretins (GIP, GLP-1)
Inhibited by: decreased in blood glucose level, sympathetic stimulation, epinephrine
Angiotensin
Synthesized in lver Contributes to hypertension
Adiponectin
Hormone derived from white adipose tissue Stimulates FA oxidation Decreases plasma triglycerides and glucose concentration Increases insulin sensitivity
Resistin
Hormone derived from white adipose tissue Increases insulin resistance
Steroid hormones
Converted from inactive form by enzymes in adipocytes
Growth factors
Linked to metabolic abnormalities and diabetes Includes: TNF-alpha Transforming Growth Factor b Insulin-like growth factor I Cytokines
Ghrelin
Short term weight regulation Produced by gastic epithelial cells Acts on anterior pituitary to release GH Appetite stimulant
Peptide YY
Short term weight regulation Produced by small intestine Acts on hypothalamus Appetite suppressant
Leptin
Long term weight regulation Derived from white adipose tissue Inhibits food intake and loss of body weight Stimulates metabolic rate Acts as circulating satiety factor (controls food intake when body’s energy store is sufficient) Communicates fuel state of adipocytes
Neural mobilization
Important during exposure to severe cold and during periods of fasting Norepinephrine initiates metabolic steps that lead to activation of lipase (Triglycerides are broken down into glycerol and FA, enter capillary, bind to albumin, carried to other cells that use fatty acid as fuel)
Hormonal mobilization
Insulin promotes lipid synthesis, suppresses lipid degradation Thyroid hormone increase Adrenal steroids increase Glucagon increase GH increase TNF-alpha involved in development of insulin resistance (Triglycerides are broken down into glycerol and FA, enter capillary, bind to albumin, carried to other cells that use fatty acid as fuel)
White adipose tissue:
unilocular
large, spherical, flattened nucleus, rim of cytoplasm
Brown adipose tissue
Multilocular
Smaller, spherical, round eccentric nucleus
Cellular atrophy
Reduction in cell size
Caused by:
- decreased functional demand
- ischemia (also causes atrophy in corresponding organ and reduction in cellular and organ function)
- starvation or malnutrition
- decreased trophic stimulation (hormones in uterus, denervation due to cut nerve)
- chronic inflammation (gastic mucosa)
- increased pressure (hydrocephalus, bed sores)
- chronic disease (cachexia)
- aging
Cellular hypertrophy
Increase in cell size and functionality (also increase in organ size and functionality, sometimes hyperplasia)
Caused by:
- increased functional demand (hypertension)
- increased growth factor stimulation (gravid uterus)
- agonists/drugs
Simple squamous epithelium
Locations/Function
- vascular endothelium/exchange, barrier in CNS
- body cavities, mesothelium/exchange and lubrication
- Bowman’s capsule/barrier
- respiratory spaces in lung/exchange
Stratified squamous epithelium
Locations:
- epidermis
- oral cavity and esophagus
- vagina
Function: barrier, protection
Pseudostratified epithelium
Locations/Function:
- trachea and bronchial tree/secretion, conduit
- ductus deferens/secretion, conduit
- efferent ductules of epididymis/absorption, conduit
Simple cuboidal epithelium
Locations/Function:
- small ducts of exocrine glands/absorption, conduit
- surface of ovary/barrier
- kidney tubules/absorption and secretion
- thyroid follicles/absorption and secretion
Simple columnar epithelium
Locations/Function:
- small intestine and colon/absorption and secretion
- stomach lining and gastric glands/secretion
- gallbladder/absorption
Stratified cuboidal epithelium
Locations:
- sweat gland ducts
- large ducts of exocrine glands
- anorectal junction
Function: barrier, conduit
Stratified columnar epithelium
Locations:
- largest ducts of exocrine glands
- anorectal junction
Function: barrier, conduit
Transitional epithelium
Location
- renal calyces
- ureters
- bladder
- urethra
“urothelium”
Function: barrier, distensible property
Merocrine secretions
Product is delivered in membrane-bound vesicles to apical surface of cell and released via exocytosis
Ex. pancreatic acinar cells
Apocrine secretions
Product is released in apical portion of cell surrounded by thin layer of cytoplasm in envelope of plasma membrane
Ex. lactating mammary gland, apocrine glands of skin, ciliary glands of eyelid, ceruminous glands of external meatus
Holocrine secretions
Product accumulates in cells, released through apoptosis
Ex. sebaceous glands of skin, tarsal glands of eyelid
Simple tubular gland
Location: intestinal glands of colon
Features: straight tube formed by secretory goblet cells
Simple coiled tubular gland
Location: eccrine sweat gland in skin
Features: secretory coiled portion deep in dermis
Simple branched tubular gland
Location: mucus-secreting glands of pylorus in stomach
Features: branched tubular glands w/ wide secretory portion that produce viscous mucous secretion
Simple acinar gland
Location: paraurethral and periurethral glands in urethra
Features: outpuching of transitional epithelium
Branched acinar gland
Location: mucus-secreting glands of cardia in stomach
Featuers: secretory portions formed by mucus-secreting cells, short single duct opens into lumen
Compound tubular gland
Location: submucosal glands of Brunner in duodenum
Features: coiled secretory portions deep in submucosa
Compound acinar gland
Location: excretory portion of pancreas
Features: alveolar-shaped secretory units formed by pyramid-shaped serious secreting cells
Compound tubuloacinar gland
Location: submandibular salivary gland, mammary gland, lacrimal gland
Features: both mucous branched tubular and seirous branced acinar secretory units
Mucous secretion
Viscous, slimy secretions
Extensive glycosylation of mucus proteins with anionic oligosaccharides, PAS positive
Flattened nucleus
Ex. goblet cells, secretory cells of sublingual salivary glands, surface cells of stomach
Serous secretions
Watery secretions
Proteins are poorly or not glycosylated
Round/oval nucleus
Ex. parotid gland, pancreas (submandibular gland has both!)
Processing of insulin
- Transcription into mRNA/translation of mRNA on ribosome
- Initial translation of signal sequence and binding to rER
- Synthesis of preproinsulin in lumen of ER
- Processing to proinsulin in lumen of ER (by cleavage of signal sequence)
- Processing to insulin in Golgi (by cleavage of C-peptide by carboxypeptidase E)
- Packaging and storage in secretory vesicle
- Signal-dependent deliver to PM/ exocytosis
Glucagon
Secreted by a-cells (peripheral) in islets of Langerhans in endocrine pancreas
Acts on liver, adipose tissue
Stimulates release of glucose in blood
Stimulates gluconeogenesis
Stimulates proteolysis
Mobilizes fats from adipose cells
Stimulates hepatic lipase
Stimulated by: blood glucose levels below 70 mg/dL, low levels of FA, high protein meals, parasympathetic stimulation, sympathetic stimulation
Inhibited by: increase in blood glucose levels, insulin
Somatostatin
Produced in D cells (peripheral) in islets of Langerhans in endocrine pancreas
Inhibits insulin AND glucagon
Regulates GH
GLP-1
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