FNH 160 FLASHCARDS

Endocrine: communication system in the body that regulates homeostasis through secretion of hormones that act on target cells
Positive feedback: a mechanism that controls secretion of hormones (ex. Oxytocin - childbirth), enhances current effect
Negative feedback: a mechanism that controls secretion of hormones, tries to bring effect back to a homeostatic range
Neuroendocrine reflex: connected to the nervous system, ex. sympathetic nervous system stimulates adrenal medulla to secrete epinephrine
Circadian/diurnal rhythms: has natural pattern of secretion that revolves around a daily cycle (sleep-wake cycle), ex. melatonin increases when you are about to sleep
Hypersecretion: too much hormone secreted into the blood
Hyposecretion: too little hormone secreted into the blood
Hydrophilic (definition and relevance to hormone synthesis and function): Soluble in water - Eg. Epinephrine, insulin, cortisol
Lipophillic (definition and relevance to hormone synthesis and function): Soluble in lipid or fats - Eg: steroids (testosterone, estrogen) and thyroid hormone
cAMP: cycling adenosine monophosphate, small, hydrophilic molecule that is important in intracellular second messenging

Adenohypophysis: anterior pituitary gland, contains glandular epithelial tissue
Neurohypophysis: posterior pituitary gland, contains nervous tissue
Vasopressin: Conserves water during urine formation
Oxytocin: Stimulates uterine contraction during childbirth and milk ejection during breastfeeding
Tropic hormones: regulate hormone secretion by other endocrine glands
Thyroid stimulating hormone: Stimulates thyroid to secrete thyroid hormone
Adrenocorticotropic hormone: Stimulates adrenal cortex to secrete cortisol
Follicle stimulating hormone: In females, stimulates growth & development of ovarian follicles and secretion of estrogen by ovaries. In males, required for sperm production
Luteinizing hormone: In females, responsible for ovulation and luteinization( regulates ovarian secretion of female sex hormones). In males, stimulates testosterone secretion
Growth hormone: Stimulates release of somatomedins from liver, Regulates growth & metabolism
Prolactin: Not a tropic hormone, Enhances breast development and milk production in females
Hypothalamic hypophysiotropic hormones: Releasing and inhibiting hormones released from hypothalamus
Portal system: a vascular arrangement in which blood flows from one capillary bed through a connecting vessel to another capillary bed
Pineal gland: located deep in the middle of the brain, main function is to secrete melatonin
Melatonin: Helps keep body’s circadian rhythms in synchrony with light–dark cycle and promotes sleep, Influences reproductive activity, including onset of puberty, Acts as antioxidant to remove free radicals, Enhances immunity, Slows aging
Clock proteins: concentration in SCN induce cyclic changes in neural discharge from SCN
SCN (Suprachiasmatic nucleus, abbreviation sufficient): contains clock proteins that take a day to synthesize and degrade (in cycles), drives circadian rhythm

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Hyperplasia: increasing cell division and preventing cell death
Hypertrophy: increasing protein synthesis
Somatomedins: peptide hormones secreted primarily from the liver in reponse to GH, act on bone and soft tissues to promote cell division, protein synthesis & growth
Insulin-like growth factor 1 (IGF1): promotes bone growth through promoting growth of cartilage and stimulating activity of osteoblasts, directly promoting growth of chondrocytes
Chondrocytes: cartilage forming cells
Osteoblasts: bone building cells
Osteoclasts: bone breaking cells
Epiphysis: end/knob of long bone
Diaphysis: shaft of long bone
Epiphyseal plate: cartilage between the diaphysis & epiphysis
Acromegaly: large hands and feet, prominent forehead & chin, occurs, GH excess in adulthood
T3 & T4 (full names not required): free form of thyroid hormones that bind to target cells
Thyroid gland colloid: where TG is taken and iodine is secreted to, to create T3 and T4
Thyroglobulin: intermediate form of T3/T4, made from tyrosine in the ER and golgi before being secreted into the colloid
Hyperthyroidism (definition, causes, and symptoms): too much secretion from thyroid gland, Body erroneously produces thyroid-stimulating immunoglobulins (TSI), causes increased BMR
Hypothyroidism (definition, causes, and symptoms): not enough secreted from thyroid gland, Secondary to a deficiency of TRH, TSH, or both, Inadequate dietary supply of iodine, causes decreased BMR
Goitre: an enlarged thyroid gland, occurs when TSH excessively stimulates thyroid gland and it adapts by growing to meet demand, may accompany hypothyroidism or hyperthyroidism but need not be present in either condition

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Adrenal cortex: secretes steroid hormones
Adrenal medulla: secretes catecholines (norepinephrine and epinephrine)
Mineralocorticoids: regulate blood pressure, Influence mineral balance (Na+ and K+)
Aldosterone: helps maintain Na+ balance in blood, Activated by renin–angiotensin–aldosterone system by factors related to a reduction in Na+ and a fall in blood pressure,
Glucocorticoids: Major role in glucose metabolism and stress response
Cortisol: Stimulates hepatic gluconeogenesis (synthesis of glucose), Inhibits glucose uptake and use by tissues (not brain), Stimulates protein degradation, especially in muscle, Facilitates lipolysis (breakdown of fat), Plays key role in adaptation to stress: Increases blood glucose to prepare body for flight/fight or fasting
Androgens: sex hormones, mainly DHEA, that affect females where it governs Growth of pubic and axillary hair, Enhancement of pubertal growth spurt, and Development and maintenance of female sex drive
Cushing syndrome: hypersecretion of cortisol, increased lipolysis and protein breakdown, bruises easily, fat deposits around abdomen, impairs ability to repair tissue
Catecholamines: epinephrine and norepinephrine
Epinephrine: secreted during a stress response by the sympathetic nervous system
Adrenergic receptors (alpha1 &2, beta 1 &2): alpha-1: excitatory, Constriction of blood vessels (norepinephrine), alpha-2: inhibitory, ↓sympathetic nerve activity (& digestive function) (epinephrine, beta-1: inhibitory (heart), Heart rate and force of contraction (norepinephrine), beta-2: relaxation, Dilate bronchioles, bladder, smooth muscle on digestive organs, metabolic effects (increase blood glucose) (epinephrine)
Stress: Generalized nonspecific response of body to any factor that overwhelms or threatens to overwhelm the body’s ability to maintain homeostasis
Stressor: can be physical, chemical, physiological, infectious, or psychological/emotional, social

Metabolism: Includes reactions involving the catabolism (breakdown), anabolism (synthesis), and transformation of proteins (into amino acids), carbohydrates (into glucose), and fats (into fatty acids) for energy
Catabolism: the breakdown or degradation of large, organic molecules within cells, includes Hydrolysis of large cellular molecules occurs during digestion, converting these into smaller subunits that can be absorbed (ex. digesting carbohydrates into glucose to be absorbed) and Oxidation of smaller subunits to yield energy for ATP production (ex. amino acids being apart of urea to be excreted or used as metabolic fuel in cells)
Anabolism:the buildup or synthesis of larger organic macromolecules from small organic subunits, usually requires ATP energy, results in Manufacture of materials needed by the cell and Storage of excess ingested nutrients not immediately needed for energy production or use as cellular building blocks, ex. amino acids being used to synthesize body proteins (structural and secretory) or transformed into fatty acids if in excess)
Glucose: the subunit of carbohydrates
Fatty acid: the subunit of fats
Amino acid: the subunit of proteins
Glycogen: long term stores of glucose
Triglyceride: the form of fat used by most target cells, long term store of fat
Absorptive state: the fed state, fuel consumed must be stored for later use, secretes insulin, Absorption of glucose, fat and amino acids from the diet → increased levels of these nutrients in the blood
Postabsorptive state: the fasted phase, fuel stores must be broken down to provide energy sources for the body, secretes glucagon, Lack of nutrient ingestion and absorption means blood levels of glucose, amino acids, and fats decrease
Insulin: Hormone of the absorptive (fed) state, Decreases blood glucose and promotes anabolism and storage of fuel nutrients
Glucagon: Hormone of the post-absorptive (fasted) state, Increases blood glucose and promotes release of stores and catabolism of fuel nutrients
Diabetes Mellitus: a condition when glucose cannot be taken up by the target cell receptors or cannot be secreted, causes high blood glucose in the blood and has many health implications

Flat bone: sternum, mostly spongy bone
Long bone: femur, mostly compact bone
Irregular bone: vertebra
Short bone: uniform (toe bones)
Spongy bone: not as dense or strong as compact bone, but can withstand strain and is light, makes up epiphysis of long bones
Medullary cavity: inside of the diaphysis, contains bone marrow, and nerve and blood supply
Compact bone: very dense and strong, make up diaphysis of long bones
Osteon: structure of bone, central canal surrounding nerve or blood vessel for bone marrow
Bone remodelling: process of constantly rebuilding and maintaining bone, Releases Ca2+ , P, and other minerals from bone
Osteoclasts: bone breaking cells
Hypercalcemia: too much secretion of calcium, weakens bones and reduces excitability
Hypocalcemia: not enough secretion of calcium, causes overexcitability of nerves, muscle spasms
Parathyroid hormone: primary regulator of Ca2+, pulls Ca2+ from bone when plasma calcium levels decrease
Vitamin D: helps increase absorption of dietary calciumin small intestine, activated in liver and kidneys
Calcitonin: inhibits osteoclast activity when plasma calcium levels are high
Fast exchange (of calcium): PTH promote membrane channels that pull calcium from the bone fluid pool within bones into the plasma
Slow exchange (of calcium); dissolution of mineral calcium to increase plasma Ca2+

Skeletal muscle: found mostly around bone to generate movement
Cardiac muscle: found only around heart
Smooth muscle: lines organs or internally in tubes
Striated/unstriated: striation occurs when there is a pattern of light and dark bands of contracting proteins
Muscle fibres: multinucleated, elongated, and cylindrically shaped and usually extend entire length of muscle
Myofibril: contractile component of muscle fibre, made of repeating units
A band: dark bands made of myosin, also includes any overlap of actin filaments
I band light bands made of actin
Sarcomere: contractile units within the myofibril
Sarcolemma: plasma membrane of muscle fibre
Sarcoplasmic reticulum: specialized endoplasmic reticulum in muscle fibre
Thick filaments (myosin): make up A (dark) bands
Thin filaments (actin): made up I (light bands)
Tropomyosin: band that covers the myosin binding site on actin filament
Troponin: holds the actin filament and tropomyosin together
Sliding filament theory: during muscle contraction, thin filaments from opposite sides of each sarcomere sliding closer together between thick filaments
Cross-bridge cycle: when Ca2+ is present, troponin and tropomyosin is released to uncover the myosin binding site on actin, causes a power stroke, and returns to original position when new ATP added to myosin cross bridge and Ca2+ is not present
Power stroke: occurs when myosin head cross bridge with actin filament to pull filament inwards
T-tubules: tubes that run through the sarcoplasmic reticulum to send action potential through it, causing Ca2+ release towards thin filaments in myofibril
Motor neuron: is stimulated by afferent neurons, and sends action potential towards sarcolemma to stimulate muscle fibre

Tendon: where muscle attaches to bone to contract muscle
Muscle origin: point where muscle is attached to bone and can be stimulated
Muscle insertion: where muscle is moved
Isotonic contraction: due to angle of muscle causing contraction
Concentric contraction: muscle shortening
Eccentric contraction: muscle lengthening
Isometric contraction: muscle being held in specific position, does not move bone and produces tension
Muscle fatigue: when ATP stores are running low, an exercising muscle can no longer respond to stimulation with same degree of contractile activity
Central fatigue: Occurs when motor neurons no longer adequately stimulated
Slow-oxidative fibres (Type 1): fibers that undergo aerobic metabolism, are less strong but have longer duration
Fast oxidative fibres (Type 2a): fibers intermediate from slow oxidative and fast glycolytic, can use but aerobic and anaerobic metabolism
Fast-glycolytic fibres (Type 2x): fibers that undergo anaerobic metabolism, strong burst of energy but very short duration
Aerobic metabolism: Requires oxygen & mitochondria, Efficiently generates large amounts of ATP from glucose or fat, Functions for longer durations
Anaerobic metabolism: Does not require oxygen or mitochondria, Generates less ATP and only uses glucose (glycolysis), Only functions as long as glucose or glycogen supply is present (short lasting)
Myoglobin: required during aerobic metabolism, found in striated muscle
Atrophy: loss of muscle mass, when muscle mass is not used regularly and have regressed
Sarcopenia: reduced regeneration of muscle. Occurs with aging

Dense bodies: anchors actin filaments
Intermediate filaments: to hold dense bodies in place and support cell shape
Calmodulin: binds to Ca2+ to activate protein kinase that leads to phosphorylation of myosin head
Latch state: myosin can stay bound to actin to maintain tension without using additional ATP
Multi-unit smooth muscle: Consists of discrete units (cells) that function independently of one another. Function similar to skeletal muscle fibres
Single-unit smooth muscle (visceral smooth muscle): Muscles contract as a group (as a “single unit”), also called visceral smooth muscle
Pacemaker potential: Membrane potential gradually depolarizes on its own due to shifts in ions across the membrane (opening of ion channels), When membrane depolarizes to threshold, action potential is generated, Repolarizes only to depolarize again; self-generating action potentials
Slow wave potentials: These are gradually alternating hyperpolarizing and depolarizing swings in potential, These changing potentials do not induce action potentials or muscle contraction on their own, but alter the likelihood that an action potential can be fired

Hard and soft palate: Forms roof of oral cavity (separates mouth from nasal passages)
Uvula: seals off nasal passages during swallowing
Bolus: food after chewing and mixing with saliva
Xerostomia: lack of saliva, Caused by medications or problems with salivary glands, Symptoms: difficulty chewing and swallowing, difficulty with speech. increased dental caries
Swallowing: Moves food from mouth to stomach (main motility in pharynx * Oropharyngeal phase: Involves movement of the bolus from the mouth to pharynx and then esophagus. This stage begins with voluntary actions of the tongue, and requires coordinated movements to ensure food does not enter the airways. * Esophageal phase: Movement of the bolus down the esophagus. This involves involuntary contractions of the esophagus (peristalsis) to move the bolus to the stomach.
Stomach: divided into 3 sections based on structural and functional distinctions: the fundus, body, and antrum * Fundus: above the esophagus opening * Body: middle portion * Antrum: lower portion, has heavy musculature
Enterogastric reflex: Intrinsic and extrinsic nerves of the duodenum send signals to inhibit stomach muscle contraction
Mucous cells: line gastric pits and secrete a thin watery mucus
Chief cells: secrete pepsinogen, an inactive form of the main protein digesting enzyme in the stomach
Parietal cells: Secrete HCl and intrinsic factor, intrinsic factor needed for absorption of vitamin B12
Pepsinogen & pepsin: HCl activates pepsinogen to become its active form, pepsin, by cleaving off a small fragment
Gastrin: secreted by G cells, Stimulate motility & release of HCl and pepsinogen
Histamine: secreted by ECL cells, stimulates release of HCl
Somatostatin: secreted by D cells, negative feedback to parietal, G & ECL cells, turns of HCl secretion
Chyme: chyme product of churning and digestion in stomach

Trypsinogen and trypsin: trypsinogen is the inactivated form of trypsin, which is the enzyme that digests proteins in small intestine
Pancreatic amylase: enzyme that digests carbohydrates in small intestine
Pancreatic lipase: enzyme that digests fats in small intestine
Hepatocytes: liver cells that surround central vein in liver
Bile salts: secreted from the gall bladder to the small intestine, emulysifyies fats, neutralizes chyme, and digests nutrients
Enterohepatic circulation: bile salts are synthesized in the liver and stored in the gall bladder to be secreted, can then be reabsorbed into the gall bladder
Villi (villus – singular): lines the mucous layer in the small intestine
Microvilli (brush border): lines the villi in the small intestine for optimal absorption
Migrating motility complex: When most of meal has been absorbed, segmentation contractions cease, replaced by migrating motility complex. These are slow peristaltic waves that sweep the intestines clean between meals
Ileocecal sphincter: The junction between the small and large intestine is the ileocecal valve (ileum to cecum), prevents chyme from re-rentering small intestine and colonic bacteria from entering small intestine
Brush border enzymes: peptidases further digest smaller peptides into peptides and amino acids, and disaccharidases further digests disaccharides into monosaccharides
Large intestine: Contents received from small intestine consist of indigestible food residues, unabsorbed bile, and remaining fluid * Cecum: connected to the ileocecal sphincter * Ascending colon: first part of large intestine * Transverse colon: middle part of large intestine * Descending colon: third part of large intestine * Sigmoid colon: part of large intestine before the rectum * Rectum: where feces is stored before defacation * Haustra: a single unit of the contraction
Haustral contractions: Similar to segmentation of small intestine but occur due to contraction of circular muscles of the haustra
Mass movements: Triggered by the gastrocolic (gastro = stomach, colic = colon) reflex, move colonic contents into distal part of large intestine
Defecation reflex: stretch receptors in rectum causes relaxation of anal sphincter, voluntary movement allows for defecation