Hormones and Signaling Pathways

• Lipid-derived substances are not chemical structures of hormones
• Hormones can be produced and act locally
• Gastrin is not an example of a hormone produced by classical endocrine glands
• Clathrin is essential coat protein for receptor-mediated endocytosis
• Neurotransmitters have signals limited in distance traveled and area of cell influenced
• T3 is not an example of protein and peptide hormones
• False: protein and peptide hormones cannot circulate unbound in the blood
• Signal transduction of integration relates to the ability of a system to receive multiple signals and produce a unified and appropriate response
• Ligands can originate from nucleotides, amino acids, retinoids, and fatty acid derivatives.
• True: antagonists are shaped differently than the original agonist of the receptor so they block the effect
• Steroid hormones are derived from cholesterol
• Collagen is rich in proline, and Glycine is rich in peptides
• False: the adrenal cortex normally produces smaller amounts of sex hormones and larger amounts of adrenocortical hormones
• Steroid hormones cross the cell membrane via simple diffusion or passive transport
• Termination of hormone action occurs through:
• Dissociation of hormone from receptor
• Sequestration of hormone
• Internalization of the receptor-hormone complex through endocytosis
• Spontaneous closure of a phospholipid bilayer to form a sealed compartment is energetically favorable because it avoids the exposure of hydrophobic hydrocarbon tails to water and is more stable
• False: The Hypothalamic-Pituitary-Adrenal axis is regulated via negative feedback loop
• The hypothalamus is a place of neurological and endocrine connection
• The hypothalamus and pituitary gland can regulate the function of:
• Thyroid glands
• Adrenal glands
• Osmoregulation
• Metabotropic receptors:
• Are membrane receptors of eukaryotic cells
• Act through intracellular second messengers
• Initiate metabolic steps to modulate cell activity
• GPCRs
• GnRH is not an example of posterior pituitary secretion
• False: the capillaries in the hypothalamic-hypophyseal portal system are continuous, allowing for a rapid exchange between the hypothalamus and pituitary
• Prolactin promotes mammary gland development and milk production
• Ligands are not a role of membrane proteins
• True: hormones produced and secreted in the neurohypophysis are vasopressin (ADH) and oxytocin
• The correct order of hormone release is: hypothalamus (releasing hormone) → hypophysis (tropic hormone) → target gland (target hormone) → increase in hormone
• Oxytocin is not produced by the adrenal gland, whereas cortisol, aldosterone, and epinephrine are produced by the adrenal gland
• Cytosolic ribosomes synthesize proteins for use in the nucleus and mitochondria
• The layers of the adrenal cortex, from superficial to deep, are glomerulosa, fasciculata, and reticularis
• Cholesterol conversion to pregnenolone in steroidogenesis is not exclusive to ACTH action, it occurs in the mitochondria and is regulated by ACTH
• Steroid hormones are stored in the cells where they are made
• A receptor in the nucleus is not a component of the GPCR mechanism, whereas a plasma membrane receptor, G-protein, and a guanosine nucleotide binding protein (GDP/GTP) are components
• Zona glomerulosa produces mineralocorticoids and aldosterone
• An increase in potassium stimulates aldosterone secretion, independently of RAAS
• Hypoglycemia, inflammation, pathogens, and physical trauma cause the release of glucocorticoids
• Type I collagen is found in bone, skin, and ligaments, but not in the basal lamina
• Cortisol affects protein, lipid, and carbohydrate metabolism, as well as the immune system
• The effect of cortisol on lipid metabolism does not result in emaciated patients
• More epinephrine is produced from chromaffin cells than norepinephrine
• Catecholamines cause an increase in heart rate and force of contraction, vasoconstriction of skeletal muscle and liver arterioles, and lipolysis in adipose tissues
• The thyroid produces T3, T4, and calcitonin
• Thyroid hormones T3 and T4 cannot circulate unbound in the blood
• Follicular cells synthesize thyroid hormones, and the colloid stores them
• Tyrosine is one of the main amino acids responsible for making the chain of thyroglobulin
• Iodide comes from the diet
• The Na+/I- cotransporter is a secondary active transporter
• Organification describes the oxidation of iodide to iodine and tyrosine iodination, as well as the coupling of iodinated tyrosines
• Deiodinases are responsible for turning T4 into T3 in target tissues
• T3 and T4 are released and freely pass through the thyroid follicle cell membrane into the bloodstream
• An increase in the rate of metabolism and stimulation of hormone production through release of TSH stimulates a rapid adjustment to maintain a normal amount of free hormone
• T4 and T3 hormones are cleared from the plasma through conjugation, excretion by the liver into the bile, and excretion by the kidney into the urine
• Thyroid hormones control cellular metabolism, increase the basal metabolic rate of cells, and increase lipolysis, but not decreasing the numbers and activity of mitochondria
• Hyperthyroidism can cause diarrhea
• Hyperplasia or tumors of the thyroid gland is not the main cause of hypothyroidism
• The parathyroid has two cell types: chief cells and oxyphil cells
• C-cells do not produce parathyroid hormone (PTH)
• Decreased levels of ionized calcium stimulates the release of PTH
• Interstitial fluid and blood have the smallest calcium pool, but the largest concentration of ionized calcium
• Somatotropes are the most abundant cells in the adenohypophysis tissue
• Regulation of calcium involves control of calcium movement between ECF and bones and kidneys
• Osteoblasts are responsible for the formation of new bone tissue
• Osteoclasts receptors stimulate the production of osteoclast-activating factor
• Ligase is not a catabolic enzyme
• Increasing the reabsorption of phosphate does not result in an increase in ionized calcium in the blood
• The gastrointestinal tract (GIT) utilizes calcitriol to promote ionized calcium absorption
• Calcitonin does not increase the movement of calcium from bone
• Ruminants use interferon tau for maternal recognition of pregnancy
• Increased gastrointestinal smooth muscle excitability is not a symptom of hyperparathyroidism
• Hyperphosphatemia is not a common diagnostic factor indicating hypoparathyroidism

Cellular Organelles

• Lysosomes are membranous cellular organelles responsible for digesting macromolecules

Carbohydrates

• Sucrose is made up of glucose and fructose

Intercellular Communication

• Gap junctions and chemical signaling are types of intercellular communication

Electron Transport Chain (ETC)

• The ETC can be uncoupled from ATP synthesis, mostly generating heat instead of ATP

Fatty Acid Release

• During a satiated period, fatty acids are released from adipose tissue (TAG), freely in the blood

Lipid Emulsification

• TAGs are hydrolyzed by pancreatic lipase and co-lipase

Fatty Acid Synthesis

• De novo fatty acid synthesis happens mainly in the cytosol of mammary glands, liver cells and adipose tissue cells.

Peptide Bonding

• The condensation reaction required for peptide bonding is ATP dependent and non-spontaneous

DNA Template Strand

• The template strand of DNA does not contain codons

Protein Structure

• Folding of domains, final arrangement of domains, and 3-D arrangement of polypeptide chain in space is the tertiary protein structure

Binding Sites

• Binding sites are usually very specific for a particular ligand/substrate and the binding is not irreversible

Michaelis Constant (Km)

• Km varies with enzyme concentration and does not reflect the affinity of an enzyme for its substrate

Enzyme Regulation

• Effectors bind noncovalently to a site other than the active site

Passive Diffusion

• Molecules dissolve in the phospholipid bilayer in passive -simple diffusion and passive- facilitated diffusion

Growth Phases

• Nucleation, elongation, and steady state describe the growth of microtubules

Structural Proteins

• The "coiled-coil" dimer describes intermediate filaments

Cell Membrane Lipids

• All of phospholipids, sterols, cholesterol, and glycolipids are main cell membrane lipids

Fatty Acids

• Saturated fatty acids tend to form paracrystalline structures, which are seen at low temperatures

Connective Tissue

• In connective tissues, the extracellular matrix is what bears most of the mechanical stress to which the tissue is subjected, not the cells.

Catecholamines

• Acetylcholine is not a catecholamine

GPCR Pathway

• The GPCR cAMP pathway is not activated by the Gq protein complex

Second Messengers

• CREB is not a second messenger

Hormones

• Protein and peptide hormones comprise the majority of hormones

Neurohypophysis

• The neurohypophysis does not produce ADH and oxytocin