Download Anatomy and Functioning of Endocrine System: Hormones, Glands, and Regulation and more Quizzes Animal Anatomy and Physiology in PDF only on Docsity!
Define exocrine glands
Epithelial tissue derivativeDucts transport secretions to body surface or cativtySecretions produced in secretory portion TERM 2
Define endocrine glands
DEFINITION 2 Epithelial derivativeNo ducts, but highly vascularized with leaky vasculature (take up secretions)Hormones released to extraceullular spaceSecretions transported via blood to target tissue to interact with receptorsIncludes endocrine glands, tissues and cells TERM 3
What is the relationship between hormones
and bodily functions?
DEFINITION 3 Hormones are involved in regulation of all majorbody functionsA single hormone usually affects more than one functionOne function is typically regulated by more than one hormoneIe. thyroxin involved in growth/dev, rep, metabolic, contraction of cardiac/smooth muscle, glandular secretion TERM 4
What are the 4 chemical classes of
hormones?
DEFINITION 4 Protein, steroid, amines, eicosanoids TERM 5
Describe protein hormones
DEFINITION 5 ENDOCRINEmost common; can be small or large (3- aas)hydrophilicSynthesized in rough ER (= preprohormones) --> modified and packaged in Golgi (prohormone --> hormone)Storage in cytoplasmic vesicles until stimulus- induced release (usually requires Ca2+ or cAMP)
What are some examples or protein hormone
synthesizing tissues?
hypothalamus, pituitary, endocrine pancreas TERM 7
Describe steroid hormones
DEFINITION 7 Lipid soluble, synthesized from cholesterol (4 aromatic rings)Requires multiple copies of enzymes to produceNot stored --> diffuse freely out of the cell to extracellular fluid/blood TERM 8
What are some examples of steroidogenic
organs?
DEFINITION 8 Testes/ovaries = testosterone/estrogenAdrenal cortex = aldersterone/cortisol TERM 9
Describe amine hormones
DEFINITION 9 Small molecules derived for tyrosine and tryptophanTyrosine = catecholamines (epinephrine/norepinephrine) and thyroid hormones (conjugated tyrosines) -->Tryptophan = serotonin (emotion/appettite/sleep/gut motility/secretion) and melatonin (biological clock) TERM 10
Describe eicosanoids
DEFINITION 10 Small, synthesized form lipids and phospholipids (most from arachidonic acid - component of phospholipids)Serve as local chemical medators with powerful biological effectsie. prostaglandins (inflammation, labor, airway constriction)
Where might a hormone receptor be
localized?
Cell membrane (protein, catecholamines)Cytoplasm (some steroid hormones)In nucleus (some steroid hormones, thyroid hormones) TERM 17
What is the name for the hormone that binds
the receptor?
DEFINITION 17 First messenger TERM 18
What is the second messenger? What are
some examples
DEFINITION 18 The factor released by activation of an effector by the receptor toactivate responsesie. G protein subunits (alpha -- switches GDP for GTP) activates secondary messengerie. cAMP often used as secondary messanger (G protein activates adenylyl cyclase to activate PKA)- catecholamines, LH, glucagon, TSH)ie.phospholipase C - used as secondary messenger (G protein activates serveral cell membrane phospholipids and intracellular Ca ions)- GnRH, TRH TERM 19
How do steroid/thyroid hormones take effect
on intracellular receptors?
DEFINITION 19 Diffuse into cell and associate with receptorComplex will often bind hormone-responsive elements to cause transcription of specific genesAll nuclear/plasma receptors have DNA binding domain near the center of the molecule and hormone-binding domain near C terminusSome steroids also interact with cell surface receptors = faster response TERM 20
Describe the anatomy of the pituitary gland
DEFINITION 20 Enclosed by bone (protection - sella turcica)Just below hypothalamus, connected by stalk (infundibulum)Anterior lobe (adenohypophysis) = glandular tissue; produces 6 major hormonesPosterior lobe (neurohypophysis) = neural tissue; storage and release of 2 neurohormones produced by hypothalamus
What condition is associated with pituitary
adenoma?
Benign tumor in pituitary = secrete excess growth hormone = gigantism TERM 22
How does the hypothalamus communicate
with the anterior pituitary?
DEFINITION 22 Activity of anterior pituitary is regulated by the hypothalamusVascular:--primary capillary plexus (inferior hypothalamus)--secondary capillary plexus (in adenohypophysis)-- commumicate betwixt eachother via hypothalamic-hypophyseal portal system--stimulation = hormones released from neurosecratory neurons of hypothalamus into portal system = stimulate/inhibit activity TERM 23
What are the hormones of the anterior
pituitary?
DEFINITION 23 Growth hormone/somatotropin (GH/STH)thyroid stimulating hormone/thyrotropin (TSH)adrenocorticotropic hormone/corticotrophin (ACTH)follicle stimulating hormone (FSH)Lutenizing hormone (LH)Prolactin (PRL)All are peptides; most use cAMPGH and prolactin are similarTSH, FSH, LH are similar TERM 24
How does the hypothalamus communicate
with the posterior pituitary?
DEFINITION 24 Via direct neural connection2 neurons: supraoptic and paraventricular that synapse with posterior pituitary capillary networkHormones are stored in vesicles at posterior pituitary until required, then released into capillary bedIncludes ADH (neurosecratory) and oxytocin (paraventricular)ADH = antidiureticoxytocin = birth and lactation TERM 25
Define hypertrophy and hyperplasia
DEFINITION 25 Hypertrophy: increased volumeHyperplasia: increased number of cells
What is the cellular composition of the thyroid
gland?
Follicles (round) formed by follicular cells that produce thyroglobulin (TGB) made of tyrosine residuesLumen of each follicle = colloid (mostly TGB)Parafollicular cells: separate population of endocrine cells that produce calcitonin (involved in calcium homeostasis) TERM 32
How are thyroid hormones produced?
DEFINITION 32 By iodinating the tyrosines on TGBForms thyroxin and triiodothyronine (T4 and T3)REQUIRES presence of TSHFollicular cells accumulate iodide from blood by Na/I cotransporter in basal membrane and convert it to iodine (I2) with thyroid perxoidase (TPO) which then binds TGB = mono and di -iodotyrosine (MIT and DIT); T4 = 2 DITs (more common); T3 = MIT + DITTransport TGB with MIT/DIT into cell (endocytosis) and proteolysis to release T and T3/MIT and DIT from TGB TERM 33
What happens after thyroid hormones are
produced?
DEFINITION 33 Free T3/T4 diffuse though basal membrane into capillariesMITs and DITs hydrolyzed by cytoplasmic diodinase enzyme = tyrosine and iodine which are recycled within follicular cellDeiodinase in the cytoplasm of target tissues will convert T4 to T3 (T3 has all of the biological activity) - TH receptors in nucleus (also cell membrane/cytosol) TERM 34
What is the function of of thyroid-binding
globulin?
DEFINITION 34 TBG (not to be confused with TGB)Thyroid hormones bind this protein and others produced by the liver (incl ablumin and TTR)Bound = not available for biological activity; also protected from immediate degradationMeans 99.5% of thyroid hormones are bound and 0.5% is for biological activity TERM 35
What is the function of thyroid hormones?
DEFINITION 35 Stimulate metabolic rate by increasing size/number of mitochondria, increasing synth of enzymes in resp chain, increasing membrane Na/K ATPase concentration and activity = increase resting metabolic rateAlso important for normal growth/development of skeletal/nervous system/maturation of reproductive systemCan also have an effect on glucose transport and ATPase activity in muscle
Describe the hyopthalamus-pituitary-thyroid
axis
Anterior pituitary releasees TSH on thyroid = stimulation of thyroid hormone productionTIH is inhibitory signal from hypothalamusTRH is stimulatory signal from hypothalamusT and T4 and inhibitory for hypothalamus and pituitary TERM 37
Describe hypothyroidism
DEFINITION 37 Too little iodineHashimoto's thyroiditis = antibodies against thyroid gland = goiter (increase size of thyroid to compensate for low production), low metabolic rate/poor resistance to cold and high TSH b/c no negative feedbackCan cause cretinism = physical and mental retardation in babies when mother doesn't get enough iodine TERM 38
Describe hyperthyroidism
DEFINITION 38 Too much iodineGraves disease = autoimmune = production of thyroid stimulating immunoglobins (TSI) which bind and permanently switch on TSH receptors = continuous release of thyroid hormones = very low production of TSH, goiter (trying to meet demands of constant release), increased metabolic rate/weight loss/muscle wasteing, exophthalmos (patches of fat behind eyes grow = push eyes out of sockets) and rapid/irregular heart beat TERM 39
Describe the structure of adrenal glands
DEFINITION 39 Inner adrenal medulla = catecholamine-secreting nervous tissue (part of SNS)Outer adrenal cortex = 80% of the gland and is steroid-secreting tissue TERM 40
Describe the adrenal medulla and its function
DEFINITION 40 Highly modified post-ganglionic neuronsProduce catecholamines (epinephrine and norepinephrine) that are stored in vesicles similar to neurotransmitterReleased in response to stress/exercise/fight or flight
Describe the effects of
PTH
Released during hypocalcemiaSkeleton: fast movement of small amount of available Ca in fluid of bone ("labile pool") to plasma or activate bone resorption of Ca into bloodKidney: stimulate active transport in kidney distal tubules to reabsorb calcium + promotes elimination of PO4 (which helps Ca deposition in bones) + activate vitamin D by kidneysAlso indirect effect on small intestine TERM 47
What does vitamin D do to help
hypocalcemia?
DEFINITION 47 Increases absorption of Ca released form ingested foods (otherwise only 15% absorbed of 1000mg) TERM 48
What is the function of calcitonin?
DEFINITION 48 Is a calcium lowering (hypocalcemic) factor synthesized by C cells of thyroidHigher blood levels calcium = higher calcitoninMay have role in maintaining bone integrity during high calcium demands TERM 49
What are the two major metabolic pathways?
DEFINITION 49 Anabolic -- synthesis of compounds that use energe (ie. insulin and growth hormone)Catabolic -- oxidative processes that release energy (ie. glucagon, epinephrine, cortisol)Metabolism of carbs, fats and proteins makes up metabolic pool of body TERM 50
How are carbohydrates metabolized?
DEFINITION 50 Glucose -- pyruvate -- acetyl CoA -- citric acid cycle -- CO2excess glucose stored as glycogen in liver/skeletal muscle or as triglycerides in adiposeGlucose blood levels kept in tight physiological range (is the only E molecule for the brain, and ketones)
How are fats metabolized?
Fatty acids -- acetyl CoA -- ketones or enter cytric acid cycleExcess fatty acids stored as triglycerides in adiposeProlonged fasting uses fat storage mainly TERM 52
How are proteins metabolized?
DEFINITION 52 Not a large source of E (mostly for protein synth)Prolonged fasting = proteins break down to amino acids and converted to glucose = E for brainExcess taken up in liver and transformed into glucose and fatty acids for storageAutophagy: breakdown and storage of aas TERM 53
What is metabolism like in absorptive state?
DEFINITION 53 Absorptive = fed (period after meal ingested)Dietary glucose is major source of E TERM 54
What is metabolism like in postabsorptive
state?
DEFINITION 54 Post-absorptive = fasting (begins after 4 hours of having eaten)Liver produces glucose for metabolismAdipose tissue releases fatty acids TERM 55
What organ mainly controls blood sugar
levels?
DEFINITION 55 The liver (increases glycogen storage in event of high blood sugar, starts gluconeogenesis in event of low blood sugar)
How is glucagon sythesized? How does it
have an effect?
Single chain polypeptideProglucagon (longer) is processed to mature glucagon by prohormone convertase 2 (PC2) in alpha cells (PC1/3 in intestine)Glucagon acts through G-prot coupled receptor that acts on cAMP/PKA to increase glygogen breakdown TERM 62
How is glucagon regulated?
DEFINITION 62 Low glucose/amino acids stimulate secretionHigh glucose inhibits; fatty acids inhibitHormonal: GIP, cholecystokinin = stimulatory; GLP-1, somatostatin = inhibitory; insulin = inhibitoryNeural: SNS and PSNS stimulate TERM 63
Define diabetes
mellitus
DEFINITION 63 Chronic metabolic disorder characterized by increased blood glucose levels (hyperglycemia) due to impaired insulin secretion/actionRequires symptoms of diabetes + >200mg/dl glucose plasma level and fasting glucose plasma level of
126mg/dl TERM 64
Describe Type 1 diabetes and where it comes
from
DEFINITION 64 Insulin dependent/juvenile onset; correlation with HLAStarvation due to no/low insulin b/c no/low Beta cells (autoimmune - genetic and environmental) ie. Ab against exogenous insulinCan also get through viruses (if epitope is similar to B cells)Not likely to get without precipitating eventNot treated = ketoacidosis, decrease blood to extremities and deathTreat by adminstration of insulin and watching blood glucose levels TERM 65
Describe type 2 diabetes and whiere it comes
from
DEFINITION 65 Not insulin dependentUsually associated with obesity (involves insulin resistance - decreased response to insulin in target tissues/defects in glucose-stim insulin secrMay have increased basal insulin to compensate for lack of sensitivitySlow onset, less severe than Type 1Genetic and aquired factorsHyperglycemia due to less glucose uptake and more gluconeogenesis
Describe gestational diabetes
Diabetes only during pregnancy, similar to type 2Several hormones block actions of insulin = less sensitive to insulin (manage with special diet and supplemental injections of insulin) TERM 67
What are some acute symptoms of
diabetes
DEFINITION 67 Glucosuria - high blood glucose (too high for renal excretion)Polyuria - frequent urination due to glucose osmolarityPolyphagia - excessive food intake due to lack of glucose uptakeKetoacidosis - lack of insulin causes high amount of liolysis which forms ketones (acids) in the blood TERM 68
What are some chronic symptoms of
diabetes
DEFINITION 68 Neuropathy - loss of sensation in peripheryCardiovascular disease - artherosclerosis, high BPMicrovasculature (lack of feeling in extremities due to low blood flow)Nephropathy - slow; kidney failureRetinopathy - blindness TERM 69
What is an alternative treatment for Type 1
diabetes?
DEFINITION 69 Pancreatic islet transplantation = endogenous source of insulinWould need life-long immunosuppression, often have insufficient donor islets TERM 70
What is the treatment for type 2 diabetes?
DEFINITION 70 Exercise, diet, weight lossOral hypoglycemic drugs (increase insulin sensitivity, stimulate insulin secretion, suppress liver gluconeogenesis, slow down glucose asbsorption for GI tract)
Where do testes develop? When do the drop?
testes, ducts and blood vessels develop in body cavity near the kidneys and are connected to floor of scrotum via gubernaculum (strong fibrous cord)By the 3rd month, the testes descend to the pelvisDrop into scrotum one or 2 days after birth TERM 77
What cells constitute the seminiferous
tubules?
DEFINITION 77 Sertoli cells (proper sperm cell development)Leydig cells (between seminiferous tubules; secrete testosterone) TERM 78
What are the stages of spermatogenesis?
DEFINITION 78 Spermatogonium -- divide -- primary spermatocyte -- divide -- 2 secondary spermatocyte -- divide -- 4 spermatids -- development to form spermatozoonDevelops from outside of Sertoli cells to inside (happens at the tight junction between cells) TERM 79
What is the function of Sertoli cell in
spermatogenesis?
DEFINITION 79 Form blood-testes barrier via tight junctionsProvide nourishment to developing sperm cellsSecrete fluid into lumen to force spermatozoa into epididymisSecrete androgen-binding protein (ABP) which binds testosterone = maintain high concentration required for proper spermatogenesisSecrete inhibin (released into interstitium to get to blood; regulation of FSH secretion) TERM 80
What is the function of the epididymis? Vas
deferens?
DEFINITION 80 Epididymis: maturation (14-20 days)Vas deferens: storage; connects with duct of seminal vesicle = ejaculatory duct within prostate gland then to uretra
Where does the vas deferens cross the
abdominal wall?
At the inguinal canal (identical on either side)Inguinal hernia = intestines enter scrotum via inguinal canal TERM 82
What do the seminal vesicles
produce?
DEFINITION 82 Secretes alkaline solution (60% semen volume) that includes fructose (used to produce ATP), vesiculase (coagulating enzyme) and prostaglandins (induce contractions of vagina/uterus to facilitate fertilization) TERM 83
What does the prostate produce?
DEFINITION 83 30% of seminal volume; milky, slightly acidicContains citrate, enzymes, seminalplasmin (antibiotic) and PSA TERM 84
Describe prostatitis; prostatic cancer
DEFINITION 84 Prostatitis: benign enlargement of prostate; leads to difficulties in urinationProstatic cancer: very prevalent form of cancer; screening involves looking for elevated PSA in blood TERM 85
What is the function of Cowper's gland?
DEFINITION 85 Produces thick alkaline mucus to neutralize traces of acidic urine
What happens when a primordial follicle is
selected for ovulation?
Primordial follicle becomes primary follicle (follicular cells grow and become cuboidal = granulosa cells)This happens during monthly cycle (to many primordial follicles) TERM 92
How do primary follicles becomes secondary
follicles?
DEFINITION 92 Accumulate multiple layers of granulosa cells and acquire additional external layer of theca cells TERM 93
When does a secondary follicle become a
tertiary (Graafian) follicle?
DEFINITION 93 With the development of a fluid-filled antrum (next to oocyte) and rapid growth TERM 94
What happens between the formation of the
tertiary follicle and ovulation?
DEFINITION 94 One follicle becomes dominant (much larger antrum) and ovulates (releases what is now a secondary oocyte - primary oocyte undergoes first meiotic division just prior to ovulation = large secondary oocyte + first polar body)Ovulation = release secondary oocyte + granulosa cells TERM 95
When does the primary oocyte become the
secondary oocyte?
DEFINITION 95 Just prior to ovulation (produces large secondary oocyte and small polar body)
What is the time frame for follicular growth?
What are the phases of this folliculogenesis?
It takes many months to grow to the dominant phasePreantral (gonadotropin-independent): controlled by locally produced growth factors (autocrine/paracrine) = growth/differentiationAntral (gonadotropin-dependent) = tertiary to release: controlled by FSH, LH, estrogen and growth factors (ie. GnTP) = additional growth and selection of dominant follicle TERM 97
What happens to the follicle after ovulation?
DEFINITION 97 It becomes the corpus luteum which has endocrine functions TERM 98
What are the two phases of the ovarian cycle?
DEFINITION 98 Follicular phase (days 1-14) = maturing follicles (selection and development of dominant follicle; start at tertiary)and culminates in ovulationLuteal phase (15-28) = presence of CL and culminates in menstruation unless egg is fertilized TERM 99
What effect does estrogen have on GnRH?
What does this do to FSH and LH secretion?
DEFINITION 99 Changes hypothalamic GnRH pulse frequency/amplitude = control release of FSH and LH from anterior pituitaryMore estrogen = more LH/FSH TERM 100
Where does estrogen come from at the
beginning of the follicular phase? What does
this cause?
DEFINITION 100 Relatively low amounts of estrogen from 3 or 4 tertiary follicles = negative feedback on hypothalamus = lower GnRH = favors FSH release over LH
