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Week 5 Flashcards

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1
Q

Describe the function of oxyphil cells

A
  • larger than principal cells distributed amongst chief cells in the parathyroid
  • has lots of mito
  • appear at puberty/increase with age
  • function unknown
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1
Q

What is dexamethasone suppression test?

A
  • evaluation for cushings disease (excess cortisol)
  • give exogenous steriod (to suppress cortisol production) should reduce ATCH production
  • measure serum cortisol
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2
Q

What is the blood flow to the neurohypophysis?

A
  • superior hypophyseal artery
    • comes in a the infundibulum
    • creates primary capillary plexus in lower hypothalamus
    • secondary capillary plexus in anterior pituitary
  • inferior hypophyseal artery
    • posterior pituitary
  • both capillary plexuses create the hypophyseal portal system
  • hormones leave the neurohypophysis via the hypophsial vein to dural sinuses
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3
Q

What is the embryological origin of andenohypophysis?

A

Oral ectoderm

  • looks very cellular
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3
Q

What are chromopobes?

A
  • Hates color
  • degrandulated acidophils and basophils
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4
Q

What are the properties of the glycoprotein family?

A
  • proteins included
    • thyroid stimulating hormone
    • lutenizing hormone
    • follicle stimulation hormone
  • common alpha subunit and an unique beta subunit
  • differing degrees of glycosylation determines half life
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4
Q

What is panhypopituitarism?

A
  • under secretion of most pituitary hormones
  • Causes
    • pituitary tumors, thrombosis of pituitary blood vessels, trauma
  • Effect
    • lethargy (hypothyroidism)
    • weight gain (decrease fat mobiliztion, lack of adrenocotical and thyroid hormones)
    • loss of sexual function
  • Treatment: thyroxine, cortisol
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5
Q

What is the role of the endrocine system?

A
  • maintains homeostasis be regulating body functions by coordinating the cellular activity
  • regulate
    • Na/H20 balance, blood vol/pressure
    • Ca2+ and phosphate
    • energy balance
    • response to stress
    • reproduction, development, growth
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5
Q

What are the organs of the endocrine system?

A
  • Hypothalamus
  • Pituitary gland
  • Thyroid Gland/parathyroid gland
  • Adrenal glands
  • Pancreas
  • Ovaries/testies
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6
Q

What are the properties osteoclast?

A
  • precursor in bone marrow in a depression called Howships lucanae
  • Responds to calcitonin
    • suppresses boen resorption by osteoclast to decrease Ca2+ levels
  • large, motile, multinucleated
    • contains lysosomal enzymes
    • produces procollagenase
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6
Q

What are the functions of oxytocin?

A
  • Milk ejection
    • contracts myoepithelial cells that surround mammary alveoli
  • Hastens delivery
    • promotes delivery of placenta
    • reduces bleed - contracts uterine SM
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7
Q

Luteinizing hormone (LH)

Target?

Major actions?

A
  • Target
    • ovary
    • Testis
  • Major action
    • Ovary
      • Graafian follicle: increase ovulation, formation of corpus luteum
      • corpus luteum: increase estrogen and progestrone synthesis
    • Testis: increase testosterone synthesis
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7
Q

How is growth hormone secretion regulated?

A
  • Growth hormone and Insulin like growth factors (IGFs)
    • inhibits growth hormone release hormone (GHRH)
    • stimulates growth hormone somatostatin hormone (GHIH)
    • inhibits GH synthesis and release
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8
Q

What does folliculstellate cell do?

A
  • Makes the cellular stroma
    • cell type located andenohypopsis
  • similar to dendritic cells
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8
Q

Describe thyroid Follicular cells

A
  • Origin: endoderm
  • Target for TSH
  • responsible for the prodcution of thyrobulin and release of T3 and T4
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8
Q

What are the symptoms of a pituitary hormone insufficiency?

A
  • ACTH def - cortisol insufficiency
  • TSH defi. - hypothyroidism
  • Gondatrophin defi. - hypogonadism
  • GH deficiency - failure to thrive and short stature in children
  • ADH deficiency - polyuria and polydipsia
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9
Q

What is hypothalamic disease?

A
  • disfunction of the hypothalamus causing problems with pitiuitary gland hormone secretion and its target organs
  • causes
    • damage from malnutrition
    • genetic disorders
    • radiation
    • surgery, head trauma, lesion, tumor
  • effects - disruptions in
    • body temp regulation
    • growth, weight,
    • Na and water balance
    • milk production
    • emotions, sleep cycles
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11
Q

What are the types of hormones?

A
  • steroid and thyroid hormone
  • Protein/Amino acid hormone
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12
Q

What are the causes of acromegaly?

A
  • GH hypersecretion in adulthood
  • Causes
    • pituitary tumor after adolescence
  • Effect
    • bones grow in thickness: head and spine
    • enlargement of hands and feet
    • elongation of ribs
    • enlarged tongue, liver, kidneys, heart
  • Treatment: somatostatin analongs, surgery
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13
Q

Thyroid stimulating hormone

Target?

Major actions?

A
  • Target
    • Thyroid gland
  • Major actions
    • increase synthesis and secretion of thyroid hormones
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15
Q

What does EC cell do?

A
  • Secretin
    • acts locally to stimulate bicarbonate in pancreas
  • Motilin
    • increases gastric and intestinal motility
  • Substance P
    • NT properties
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15
Q

What do acidophils make?

A
  • GH (somatotroph)
  • Prolactin (mammotroph)
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16
Q

What is blood supply to the andenohypophysis?

A
  • Superior hypophysial artery forms a primary capillary plexus
    • gives of the portal veins
  • hypothalamophypophysial portal system
    • portal veins create secondary capillary plexus in pars distalis
  • blood leaves hypophysial vein to dural sinuses
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16
Q

Describe negative feedback

A
  • product of the stimulus will reduce the initial stimulus
  • most common control of hormone release
  • protects against excess hormone production
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16
What is long loop negative feedback?
* systemic hormone produced feeds back all the way to the hypothalamic-pituitary axis * tertiary endocrinopathy
17
What are the 3 zones of the of the adrenal cortex?
* Zona glomerulosa * Zona fasciculate * Zona reticularis
18
What are the types of endocrine disorders?
* hormone deficiency * autoimmune destruction * deficiency of precursor * hormone resistance * receptor mutations * functional * hormone excess * tumors/mutations * autoimmune activation
19
How do somatomedins (IFGs) work?
* made in liver and site of action (bone and tissues) * stimulates chondrocytes and osteoclasts * increase bone elongation
20
What does PP cell do?
* secretes pancreatic polypeptide * Stimulates * gastric chief cells * Inhibits * bile secretion * intestinal motility * pancreatic enzymes * bicarbonate secretion
21
Growth Hormone (GH) Target? Major Actions?
* Target * most tissues * Major actions - increases * growth in stature and mass - organized addition of new tissue * IGF-I production * protein synthesis * fat utilization * decrease glucose utilization
22
What is the function of chromaffin cells?
* release epinephrine (80%) and norepinephrine (20%) * store opioid peptides
24
Properties of protein/amino acid hormones
* mostly water soluble * bind to hormone in cell membrane * MOA: act via 2nd messengers like cAMP, cGMP, Ca2+, Na+ * Majority of hormones * synthesized as 'preprohormonnes" * require post-translational processing * Short half life
25
What inhibits growth hormone secretion?
* Somatostatin * obesity * increase in blood glucose and FA * aging * IGFs * GH
25
What are the results of a pituitary gland tumor?
* increased secretion of * prolactin (prolactinomas) * GH (somatrotrophic adenomas) * ACTH (corticotrophic adenomas) * Decreased secretion of * LH/FSH (gondadotrophic adenomas) * Thyrotrophic adenomas * rare usually large when diagnosed * visual impairment if tumor is compressing optic nerve
26
What causes syndrome of inappropriate ADH secretion (SIADH)?
* Problem * inappropriate ADH secretion * increases water retention causes atria of heart to be stretched * increased ANF and decreased plasma renin activity * hyponatremia and decreased plasma osmolality * Causes * Ectopic: ADH secreted from lung cancer * Eutopic: stroke, infection
27
What are the hormones that produced by the anterior pituitary gland and what are there targets?
* Thyrotropin - thyroid gland * Growth hormone * Corticotropin * with ACH - increases blood glucose level * Follicle stimulating and luteinizing - testes/ovaries * Prolactin - mammary gland
28
What is short loop feedback?
* anterior piuitary hormone feeds back on the hypothalamus to inhibit secretion of hypothalamic releasing hormone * secondary endocrinopathy
29
What is diurnal hormone variation?
* hormone secretion determined by circadian rhythm * set by pacemaker in hypothalamus * 24 hour pattern * low hormone levels at night * Levels peak in waking hours then decline as day progresses
31
What is the structural features of the thyroid?
* Encapsulated * CT extends down from the surface and forms lobules * Structural unit: follicles * lined by epithelium surrounding a lumen fille dwith collodial material enclosed by basal lamina
32
What is the dawn phenomenon?
* wake up because the surge of hormones * hormones result in increase in blood glucose * body will respond by releasing insulin
33
What is ultrashort loop feedback?
* hypothalamic hormone inhibits its own secretion * tertiary endocrinopathy
34
What are the two cell types in the thyroid?
* Follicular cell * parafollicular (C cell)
34
What is positive feedback?
* original stimulus results in an increased stimulation for hormone release * important during childbirth and lactation * regulated by the presence or absence of stimulation
35
What are the two cell types of the parathyroid gland?
* Principal (chief) cells * Oxyphil cells
37
What are the four types of cells in the adenohypophysis?
* Acidophils * Basophils * Chromophobes * Folliculostellate
37
What do basophils make?
* FSH and LH (gonadotrophs) * TSH (thyrotroph) * ACTH (corticotroph)
37
How is T3 and T4 made?
* Iodine pump, pumps iodide above serum levels in the thyroid follicular cell and it diffuses into the lumen of the follicular cell * Thyroid peroidase and thyroglulin are exocytosized into lumen * Thyroid peroxidase activates iodide into iodine * 2 iodine link to each thyroglobulin * Thyroglobulin yields 4 molecules of T3 and T4 * Idothyroglobulin reenters the cell to fuse with lysosome and proteolysis of the idothyroglobulin to form the final forms of T3 and T4
37
What is the embryological origin of the parathyroid?
mesoderm
37
Follicle Stimulating Hormone (FSH) Target? Major actions?
* Target * Ovary * Testis * Major actions * Ovary - increase folliculogenesis and estrogen synthesis * Testis - sperm maturation
38
What is the ACTH stimulation test?
* useed to evaluate adrenal insufficiency * give exogenous ACTH (stimulates cortisol production) * measure serum cortisol
39
What is the structure of the adrenal gland?
* Encapsulated * Cortex * 3 zones * Medulla * Chromaffin cells
40
What are the causes of Dwarfism?
* Causes * congenital defect * pituitary tumor or trauma causing panhypopituitarism (decreased in all anterior pituitary hormones secretion) * Effect * slow and reduced growth * juvenile appearance * if panhypopituitarism will also have hypothyroidism, hypogonadism, and low glucocorticoids * treatment: human GH _+_ thyroxine, cortisol
42
What are the parts of the andenohypopysis?
* Para tuberalis - connecting stalk to hypothalamus * Para distalis - anterior lobe * Para intermedia - part that touches neurohypophysis
43
What stimulates growth hormone secretion?
* Secretion stimulation * GHRH * Ghrelin * starvation, protein deficiency (chronic) * decrease in blood glucose and FA * exercise, excitement, trauma, estrogen and androgens, sleep
45
What are Herring Bodies?
* Swellings at the distal of hypothalmohypophysical axons * Storage for oxytocin and vasopressin
47
Describe the neural innervation of the neurohypophysis
* Two hormones and neurophysis (protein carrier) are synthesized in hypthalamus and sent down unmyelinated axons to neurohypophysis via **hypothalamoneurohypophysial tract** * Supraoptic nuclei * Antidiuretic hormone (vasopressin) * paraventricular nucleus * oxytocin
48
Beta-lipotropin (Beta-LPH) Target? Major actions?
* Target * fat * major actions * possibly increase fat mobilization * little activity in humans
50
What occurs with enzyme 21 hydroxylase (CYP21A2) gene deficiency?
* required for cortisol and aldosterone synthesis * results in adrenal insufficiency
51
Prolactin (PRL) Target? Major actions?
* Target * mammary glands * hyopthalamus * Major actions * mammary glands: increases milk secretion and growth of mammary glands * hypothalamus: decreases GnRH
51
What is the function of Antidiuretic hormone (ADH)/vasopressin (AVP)?
* secretion is in response to a decrease in plasma volume and increase in plasma osmolality * Function * reabsorption of water - targets collecting tubules * binding causes increase in cAMP and causes the insertion of aquaporin-2 into the luminal membrane * vascular SM contraction * binding causes IP3, DAG to increase intracellular Ca2+
52
What are the properties of the growth/prolactin hormone family?
* belong to same gene family * both are polypeptide hormones
54
What are the cell types of the pineal gland?
* pinalocytes * produces melatonin at night * serotonin during day * Neuroglial cells * brain sand
56
Properties of cell surface receptors
* ligand recognition domain * intregral protein with cyoplasmic effector domain * hormone initiates intracellular signaling cascade
58
What are the hormone binding proteins?
* Corticosteroid binding globulin (CBG) * Sex hormone binding glogulin (SHBG) * Thyrotropin binding globulin (TBG) * Albumin (non specific)
59
How does growth hormon affect body organ growth?
* increases the size and number of cells * causes specific differentiation of certian cell types
61
What is the function of the principal (chief) cells?
* release parathyroid hormone (PTH) * increases Ca2+ indirectly * binds to receptors on osteoblasts to release osteoclast stimulating factor * made in rER * Paler, smaller cell * slow longer term homeostatic action
61
What is a pulsatile pattern of secretion?
* hormone released in regular pulse * varies in amplitude and frequency * continuous release can limit hormone action through desensitization
63
What are the parts of the neurohypophysis?
* Infundibulum - connecting stalk * median eminence - superior port that is on either side of the hypothalamus * infundibular process - the actual stalk * Para nervosa - neural lobe
64
Function of zona glomerulosa
* secretes mineralcorticoids - mainly aldosterone * regulated by renin (angiotensin system and ACTH) * regenertative zone of adrenal cortex
66
What does D-1 cell?
* secretes VIP (vasoactive intestinal peptide) * makes sure that blood glucose doesnt go too low. * its releases glycogen * stimulates pancreatic exocrine secretion and gut motility
68
What is open loop?
* No feedback * refers to control of hormone secretion by CNS stimulation * regulated by depletion of hormone in absence of further CNS stimulation * Epi
70
What is the embryological origin of the pineal gland?
neuroectoderm
71
How is the adenohypophysis formed?
* Floor of diencephalon and the roof of the mouth fuse together * Roof of mouth makes the Rathke's Pouch then attaches the diencephalon
72
How does GnRH regulate the release of LH?
* GnRH is released in a pulsatile fashion which is critical for gonadatropin secretion * spike in GnRH release which causes a very fast releease of LH into the peripheral blood
74
Function of zona fasciculate
* Thick middle zone * form parallel cords seperated by sinusoids * cells contain lipid droplets so larger * secrete glucocorticoids (coricosterone and cortisol) * Controlled by ACTH
75
What are the types of secretion?
* Autocrine * Paracine * Endocrine * Synaptic secretion
76
What is the blood supply of the adrenal gland?
* superior and middle adrenal arteries create capsular plexus * supplies three zones with fenestrated cortical capillaries (sinusoids) * to medulla - duel blood supply * medullary artery from the inferior adrenal artery and bypasses the cortex and joins with branches from cortical capillaries to form medullary venous sinuses * duel blood supply required for synthesis of epinephrine and to inhibit axonal growth * PNMT that activates epi activated by cortisol
77
Properties of steroid and thyroid horomones?
* lipid soluble * Derived from enzymatic modication of cholesterol * Bound to a plasma transport protein (globulins) but not active till free * Diffuse through cell branes to intracellular receptors * some can bind to surface * MOA: Alther rate of gene transcription
79
How are protein hormones synthesized?
* ribosomes create a peptide chain called a preprohormone * after this point everything is post-translational modification * enzymes in the ER chop off the signal sequence to create an inactive prohormone * prohormone goes through Golgi * enzymes and the prohormone bud off in a vesicle * enzymes chop the prohormone into one or more active peptides * vesicle is exocytosized * hormone goes to it target
80
How does growth hormone affect skeletal growth?
* increases proliferation of epiphyseal cartilage * increase conversion of cartilage to new bone * increase length of long bones and skeleton - until epiphyses of long bones fuse with shafts * increase bone thickening (proliferation of periosteal osteoblasts) * increase bone remodeling
81
What are the causes of gigantism?
* GH hypersecretion during childhood * cause * hyperactivity of otherwise normal cells * pituitary tumor * effect * rapid growth of all tissues * hyperglycemia * treatment: somatostatin analogs, sugery
82
Function of zona reticularis
* Inner most layer * graveyard of cortex * secrete mainly weak androgenic steroids * controlled by ACTH
83
What are the properties of Pro-opiomelanocortin (POMC) family?
* polypeptide hormone products of POMC gene * cleavage of POMC by endopeptidases (prohormone convertases)
84
Adrenocorticotripic Hormone (ACTH) Target? Major actions?
* target * adrenal cortex (Zona fasciculata) * Major actions * increases synthesis and secretion of adrenal cortical steriods
85
What is the embryological origin of neurohypophysis?
Neural ectoderm
86
What is episodic hormone release?
* response-stimulus coupling enables endocrine system to remain responsive to physiological demands * secretory episodes occur with different periodicity
87
What is the cause of diabetes insipidus?
* Problem * unable to conserve water due to decrease ADH synthesis or insensitibity to ADH at collecting ducts * Causes * trauma, tumors, infection * Principle symptoms * increases water loss from kidneys and triggers increase in thrist (polydipsia)
88
How does a radioimmunoassay (RIA) work?
* Mix a known amount of radio labeled hormone with antibody * add parients serum containing hromone to compete with the bound radio labeled hormone * percipitate antigen/antibody complex * measure radioactivity * Calculate patient hormone level based on radiation detected
89
Types of regulation of hormone release
* Hormonal * Tropic hormones * Feedback loops * neutrient/ion regulation * glucose * Ca2+ * Neural * adrenal medulla releasing epi
90
Properties of an intracellular (nuclear) receptor
* Respond to steroid hormones, Vit D, and thyroid hormones * Can be intermediate with surface receptors * receptor can be unbound in the cytosol * Results in changes in transcription and gene expression
91
How do you interpretate hormone levels?
* normal levels vary according to age and gender * pattern of hormone release can be affected by * illness * nutrition * look for regulatory factors
92
Describe the properties of parafollicular (C cell)
* Origin: neural crest * located in clusters and doesnt extend to lumen * APUD cell, EC, part of DNES * produces calcitonin * Decreases Ca2+ * targets osteoclasts by reducing ruffling, # * promotes Ca2+ excretion into the urine in the kidneys

Block 3 (8 decks)

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