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84 Cards in this Set

  • Front
  • Back
Functions of thyroid gland
Regulate tissue metabolism
Regulate tissue growth
2nd regulation of plasma Ca++
Location of thyroid gland
2nd and 3rd tracheal rings
Origin of thyroid gland
Downgrowth of the base of the tongue (thyroglossal duct)
Cell type enclosing follicle of thyroid gland
Simple cuboidal epithelial cells
Main cell type of thyroid
Follicular epithelial or principal cells
Secondary cell type of thyroid
Parafollicular or "C" cells
Product of Parafollicular cells
Calcitonin (regulate Ca 2+)
Changes in thyroid epithelium due to activity
Hyperactive = Columnar shape, colloid is reduced

Hypoactive = Squamous shape, colloid is increased
Product of follicular cells
What is thyroglobulin?
Storage form of thyroid hormone
Iodinated thyroglobulin
Enzyme of follicular cells
Thyroperoxidase, iodinates thyroglobulin close to microvilli of follicular cells
Functional changes to make thyroid hormone
Tyrosine residues added in golgi
Iodinated in lumen
Products in cytoplasm of follicular cells of thyroid gland
Thyroglobulin= monoidotyrosine
Location of iodide pump?
Basement membrane of follicular cells
How iodine is produced?
From oxidation of iodide
Fate of T1, T2, T3, T4
T3, T4 = active thyroid hormone and exocytosed out of basal surface into basket of fenestrated capillaries
T1, T2 = Deiodinated and recycled
How is thyroid activated?
TSH from Basophilic thyrotrophs from anterior pituitary
Location of TSH receptors
Basal surface
Responses to TSH
Hypertrophy and hyperplasia of follicular cells
Increased production and iodination of thyroglobulin
Increased re-uptake and lysosomal digestion of iodinated thyroglobulin
Increased secretion of T3 and T4
Monitors Plasma levels of T3/T4
Neurosecretory neurons in the hypothalamus
Functions of thyroid hormone
Calorigenisis- increase energy production and oxygen consumption (basal metabolic rate)
Regulation of water and ion transport
Regulation of protein, fat, and carbohydrate metabolism

Growth promoting effects
Acts with Growth hormone to promote skeletal development
Symptoms of hypothyroid
Mentally and physically sluggish
Low basal metabolism
Mental retardation
Decreased glucose absorption
Weak heart beat
Symptoms of hyperthyroid
Restless, irritable, anxious
Elevated basal metabolism
Mentally alert
Increased glucose absorbtion in GI tract
Stunting of physical and mental development
Mental deficiency
Hashimoto's disease
Hypothyroidism like,
Auto-immune response to thyroglobulin (destruction of follicular cells)
Enlargement of thyroid gland from hypertrophy and hyperplasia of follicular cells

Caused by
Iodine deficiency
Graves disease
Iodine deficiency
Decreased T3/T4 output
Increased TSH release by pituitary, follicular cell hyertrophy (parenchymatous goiter)
Graves disease
Direct stimulation of follicular cells by plasma IgG (thyroid stimulating immunoglobulin)
Protrusion of the eyebolls (exopthalamos) due to build up of water in retroorbital tissues
Origin of parafollicular cells
Neural crest
Amine precursor uptake and decarboxylation cell line
Structures shared/not shared between para/follicular cells
Share basement membrane
Para do not touch lumen
Actions of calcitonin
Decrease Ca++ through
Inhibit osteoclast activity
Promoting Ca++ excretion from kidneys
Response of calcitonin
Released in response to elevated plasma levels of Ca++
Actions of Ca++
Membrane permeability and excitability in muscles/nerves
Enzyme activity
Blood clotting
Receptor binding
Maintenance of acid/base balance
Ca++ absorption
From small intestine through vitamine D derivative 1,25 dihyroxycholecalciferol
Hypercalcemia symptoms
Ectopic calcification of soft tissues
Kidney stones
Hypocalcemia symptoms
<9mg/100mL plasma

Hyperexcitablity of neurons
Prolonged skeletal muscle contractions (tetany)
Aberrant (abnormal)cardiac muscle contraction and rhytmicity
Origin of inferior parathyroids
3rd pharyngeal arch descend with thymus
Origin of superior parathyroids
4th pharyngeal pouch descend with thyroid
Chief cell product
Parathyroid hormone from pro-parathyroid hormone
Half life of parathyroid hormone
18 min
types of chief cells
light = inative
dark = active PTH secreting
PTH effects
Increase plasma calcium

Increase release of osteoclast stimulating factor
Promote Kidney Ca++ resorption inf distal convoluted tubules
Promote synthesis of 1,25 dihyroxycholecalciferol (Ca++ absorptive aid)
Oxyphil cells
Don't appera untill age 7
Unknown function
Full of mitochondria
Location of most of islets
Tail of pancreas
cell types of pancratic islets
Alpha, Beta, Delta, F cells, G cells?
Alpha cells
Located a periphery of islet
Nucleus indented
Eccentrically placed electron dense core
Secrete glucagon
Raises blood glucose levels by promoting the ormation of glucose from glycogen stored in liver (glycogenolysis)
Beta cells
Small, most numerous cell
Center of islets
Electron dense core
Secrete insulin
Regulate blood glucose levels:
Promote glucose transfer from plasma to target tissues
Stimulate conversion of glucose to glycogen in liver hepatocytes
Loss or hypo secretion of Beta cells
Diabetes Mellitus
1) Hyperglycemia due to decrease uptake of glucose
2) Increase glucose in the urine (Glucosuria)
3) Increase water excretion (poly uria)
Type 1 vs. Type 2 diabetes
Type 1 = reduced beta secretion
Type 2= Adult, defect in insulin receptors
Delta cells
Larger than alpha/beta cells
Lightly electron dense secretory vesicles
Secrete somatostatin
Neurotransmitter and a neurohormone in different tissues
1) in hypothalamus, somatostatin= inhibits growth hormone release
2) In the pancreas hromone acts in paracrine to inhibit glucagon and insulin release (secondary regulator)
F cells
Pancreatic polypeptide secretors
Pancreatic polypeptide
Stimulate release of gastric secretion in gut
Inhibit bile secretion in the gall bladder
G cells
Secret Gastrin
Increases HCL secretion in stomach
Increases gastric motility
A, B and D cells
Connected by gap junctions and thus can effect each other through paracrine effects
Regulation of glucagon and insulin
Plasma glucose
branches of inferior, middle, superior adrenal arteries
Capsular arteries
Branching of adrenal arteries
Inferior, superior, middle adrenal arteries to
Capsular arteries to
Cortical arterioles and medularry arterioles
Three major categories of steroid hormones of adrenal cortex and effects
Glucocorticoids- effect carbohydrate metabolism

Mineralocorticoids- effect fluid and electrolyte balance

Gonadal Steroids- similar to hormones secreted by testis
What controls adrenocortical hromone release?
ACTH release from basophils in the anterior pituitary and Renin/angiotensin system
3 layers of adrenal cortex
Zona Glomerulosa
Zona Fasciculata
Zona Reticularis
Cell type in zona glomerulosa
Small pyramidal or columnar cells arranged in spherical aggregates
Secretion of zona glomerulosa
Action of Zona glomerulosa hormones?
Promote resorption of Na+ from distal convoluted tubules of the kidney, sweatglands, and salivary glands
Control of zona glomerulsosa
Mainly renin/angiotensis system but also ACTH
Zona fasciculata cells type
Long radially oriented cords of secretory epithelial cells separated by capillaries

Apical cytoplasm has short microvilli that extend into the capillary sinusoids and numerous mitochondria
Zona fasciculata secretions
Glucocorticoids (cortison, cortisone, corticosterone)
Action of zone fasciculata secretions
Down regulate immune response by inhibition of lymphocyte production and turnover

Modulation of carbohydrate metabolism by promoting the formation of glucose from protein

Suppression of inflammatory response by decreasing production of T-cells and Plasma cells
Control of cortisol
Negative feedback from:

Corticotrophs in the anterior pituitary (via ACTH release)

Hypothalamic neurosecretory cells which release CRH
Zona reticularis cells
Numerous secondary lysosomes, deeply staining nuclei, few lipid droplets evident
Secretion of zona reticularis

Steroidal androgens (continuously released)
Cinical siginificance of zona reticularis
Andrenogenital syndrome
-male secondary sexual characteristics

Precocious development in prepubertal males
Addison's Disease
Hypo adrenalism- atrophy of adrenal cortex

Weakness and drowsiness due to low blood glucose (glucocorticoids)

Increase ACTH secretion

decreased blood pressure due to decreased extracellular fluid volume (minarlocorticoids)

Decreased absorption of Na+ and Cl- ions in kidneys

Darkening of exposed skin

Low BP
Cushings disease

-Can result from excessive synthetic glucocorticoid use
-Redistribution of fat around the neck, face (moon face) and abdomen
-Wasting of limb musculature and thinning of bones due to antianabolic effects of glucocorticoids on protein synthesis
-Thining of skin and loss of fat causes redskin due to blood vessels shwoing through
Origin of chromaffin cells
From sympathetic ganglion cells of the celiac plexus that migrate into the adrenal cortex

(neurons that have lost axonal and dendritic processes and function as secretory cells)
2 types of catecholamine secreting cells and location
Round, moderately electron dense granules that fill vesicles, they tend to cluster around the adrenal sinusoids (distant from BV)

Norepinephrine secreting cells- Flattened or ovoid granules with eccentrically located high electron dense core surrounded by a less electron dense ring, tend to cluster around the adrenal arteriols and away from sinusoids
Chemical difference between norepinephrine and epinephrine
1 methyl group
epinephrine to norepinephrine transformation
Glucocorticoid induced
Cells closest to sinusoids are bathed in glucocorticoids from adrenal cortex.
Catecholamine function
Respond to environmental and emotional stresses

Elevate plasma glucose levels (stimulate glycogenolysis)

Increase BP and cardiac output

Dilation of coronary and skeletal muscle blood vessels

Cutaneous vasoconstriction