Histology #8 (Endocrine) Flashcards
Hypothlumus
Location - In the brain between the thalumus and the pituitary halnd
Function -
1. Connects the nervous and endocrine systems
2. Receives signals input from many brain regions
3. Endocrine control center for maintaining homoestasis (monitors body for homoestasis)
- Releases hromones for antrior pititary regulation (releases hormones that act on the pituitary–> pituitary then releases hormones to effect organ)
- Produces ADH and oxytocin (released in the posterior pittutary)
Hypothelumus feedback + function
Overall - signals the pitutary gland to then release or inhibit its own hormones
Modultes a broad range of boldily functions to mainatin homeostasis:
1. Body tempertre
2. Blod pressure
3. Hunger and thirst
4. Sense of fullness when eating
5. MOod
6. Sex drive
7. Sleep
Hypotheliumus histology
Hypothelumus is connected directly to the posterior pituitray and the highly ceullarluzed antiorir pitutary
Image – see hypothelumus at the top ; bottom is the pituitray - connected by the pituitary stalk
Pituitary gland
Secretes hormones that have a direct/indirect effect on many other endocrine glands
Made up of two lobes:
1. Antior lobe (adenophypophis) –> Hypothelimis Hypohysea portal system
2. Posterior love (neurophypophis) –> Hypothalamic-Hypophyseal tract
Image - axons and tracts of nerves come into the posterior lobe ; antrior lobe is only a network of blood vessels
Pituitary gland Antioior lobe
Composed of:
1. Par Tuberalis
- Cuboidal epithelial
- hypophyseal portal vessles
2. Pars intermedia
- Cuboidal epithelium
- Layer of tissue filled with Coilloid-filled cysts
3. Pars distalis
- Cells arraged in thcik cords bordering on sinusiidal capilaries (allows cells to secrete hormones to capialries)
- Secretes the majority of hormones
- Largest region
Pituitary gland Antioior lobe staining
Chrompahil = cell that stains easily with dyes (in antrior lobe)
Types of cells in Antrior lobe:
1. Acidophiles (stains PINK) - growth hormone + prolactin
2. Basophils (stains PRUPLE) - Corticotrophin + Thryroid stimulating hormone + Follicle stimulating hromone + Letinizing hromeon
Have Fenetrated capilaries (in antior lobe)
Pituitary gland Antioior lobe staining - IMAGE 2
Pink arroes = Acidophils
Purple Arrows = Basophils
Pituitray galnd - Anteiror Lobe Secretions
Secretes:
1. Growth hormone - promotes body growth + targets growth plate in bone
2. Prolactine = Development of mmamry galnd during pregancey + stimulates milk production
3. Corticotrophin (ACTH) - stimulates adrenal cortext to produce glucocoticoids
4. Thyrodi stimulate homrone - Stimulates synethsis + secretion of thryoid hormones
5. Follicle stimulating Hormone - Promotes ovarian grwth/secretion of estrogen + promotes spermogensis/secretion of androgen binding protein
6. Liteinzing hromone - induce ovulation + stimultes testes (leydig cells) to synthesize and release testrone
Pituitray galnd - Posterior Lobe
Made up of 2 sections:
1. Infundibulum (pititray stalk)
- Contains non-mylinated axons
2. Pars Nervosa
- Conatins non-mylinated axons + has fenestrated capilaries + secretes hormones
Secrets:
1. Oxytosin - Contraction in birth + breast feeding
2. ADH - arterial constriction + water balance
Cells pituitray gland - posterior lobe
- Contains non-mylinated axons (nuerosecretry cells)
- Cell bodies are located in the hypothlumus ; only axons in posterior lobe - Contains supports glial cells (Pituicytes)
- Fenestrated capilaries
IMAGE - See non-mylinated axons + see the supporting glial cells
Hemeostatsis regulation by the hypothlumys
Overall - Hypotheumus = a control center that uses isgnlas form the body to monitor and mianatin homeostasis
Uses Negative feedback
Negative Feedback
Regulatory mechanism whose output decreases the processes that led to that output
- Helps maintain stabilized sytsem and steady state
- Autoregulation
Image - have detection by the hypothelumus –> respond to released hromone –> go to pituary –> pituitray releases hromone –> hormone goes to effect –> hypothlymus sees wehn we are in homoestsis –> stop secreting hormones
Hypothalamic-Pituitray-Adrenal Axis (Feedback)
- Detect stress
- Respond - Hypothelimic sees tress and releases CRH –> casues Pititratu release of ACTH
- Hormones effect organ - ACTH causes the adrenal gland releases cortisol (increases BP + increase glucose)
- Feedback - Negative feedback to the hypothelumus and pititary gland to slow the release of CRH and ACTH
- Hypothlumus see sincrease in cortisol in blood –> slows down and stops cyle
Result - Autoregulated temperary response to a stessful event
Thyroid gland
Singe bilobed endocrine gland
Location - Antior to the tachea ; inferior to the larynx
Covering:
1. True capsule - fibroelastic connective tissue
2. False capsue - Pre-tracheal layer of cervical fascia
Structural and functional units = Thryoid follciles –> made up of Follcicular cels + Parafolicular cells + basemment memebrane
Thyroid gland Folicular cells
Overal - follicular cells line the thyroid follicle
- Rest of the basement membrane
Vary in size
Simple squmous = metabolically inactive
Simple cuboidal = metabolicaly active
Lumen formed by cell is filled with geltnous coloid
- Colloid is made by glycoprotein thyroglobulin
- Colloid is Acidophilic (stains PAS positive)
Image - shows PAS ; arrow shows colloid
Thyroid gland Folicular cells histology #2
See Folicular cells + coiloid
Thyroid Gland Parafoliclar cells
Parafoliclar cells = Distrubuted between follcicular cells and the basement membrane
Large + polyhedral + pale staining cells
- Oval + Eccentric nuceli
Function - Secretes calcitonin –> maintains calcium homeostasis
Can stain with IHC - stain for cacitonins = can see parafoliclaular cells
Image - see colloid + folicul;ar + parafolcilar cells
Thryoid function
Overall - Increases cellular metabolsim
- Increases respiration + thermogensis –> increases oxygen consumption + heat + basal metabolic rate
Acts on neary all systems (cardio + pulinary + nervous)
Thryoid function on cardiovascular
Icreases mycoadial intracceular calcium –> increases muclar contraction force and speed –> increases stoke volume + CO +HR
Thryoid function on Pulimary
Increases respiration rate + increases erthropoeitin/hemoglobulin –> increases oxygen delivery
Thryoid function on nervous
Increases wakefulness + alternternns in CNS
Thyroid Hormone from folicular cells
Folluclular Cells secerte:
T3 (triiodothryionine)- Active hormone
T4 (thryxine) - Less active form
- converted to T3 by type I (periphery) or type II (CNS) deionidases)
Thyroid Hormone from parafolliclar cells
Parafolliclar cells secrete:
Calcitonin - Oposses aarthryoid parathyroid hromone –> decreases blood calcium level
Synthesis fo Thryoid Hormones
DON’T memorize
Regulation of Thyroid Hormones
T3 and T4 = uses a nagetive feedback loop
- Thryoid releasing hromone producded in the hypothelymus
- TRH stimulates the release of thyroid of TSH
- TSH triggers secretion of T3 and T4
- T3 and T4 inhibit section of TSH by acting on hypothelumys and pitutitary
Calcitonin regulated by level of blood calcium
- Higher blood caclium = greater secretion
Parathyroid
LOOK AT OWN SLDIES
Adrenal Glands
Location - On top of each kidney
Two regions - Corext + Medula
Functions:
1. Maintains water and Na homeostasysis
2. Control Blood presure
3. Regulate body’s adative stress resonse
Adrenal Coretxt
Overall - produces steroid hrpmones
Cells = aranged in a cord-like manner within a widespread capilary network
Corext = devided into three zones
1. Zona Glamerulosa
2. Zona Fasciculata
3. Zona reticularis
Adrenal Coretxt Zona glomerulso
Outter zone
Composed of closley packed rounded/arched cords of columnary or pyridmidal cells with many capilaries
15% of total glandular volume
Main secretory product - Aldostrone
Aldostrone
Mineralcorticoid
Regulates electroplye and water balance and blood pressure
Adrenal Coretxt Zona Fasciulata
Middle zone
Long straight cords of large cuboidal cells seperated by capialries
Cells have lipid droplets - appear vacuolated in image
75-80% of total glandular volume
Main secretroy product - cortisol + small amounts of weak andorgens
Cortisol
Gluccocotrid - increases blood glucose levels + modulates cytokine products + anti-inflmaatory effect
Adrenal Coretxt Zona Reticularis
Inner zone
Narrow dense layer of smaller cells arranged in a netwokr on irregular cords
Cells more heavily stains than in other zones (because have fewer lipid dorplets and more lipfusin pigement)
7% of glandular volume
Main secretory producy DHEA + Small amounts of gluccoticoids
DHEA
Weak androgen
Converted to testrone in males and females
Three zones in adrenal Corext
Three zones in adrenal Corext Image #2
Adrenal medulla
Function - Produces stress hormones to inituate fight/flught response
Inner part of adrenal gland
Adrenal medulla histology
Adrenal medulla hormones sectresion
Secretes catacholmines –> sceretes Epinephrine + norepinephrine
Catcholamine secretion
Catcholamine secretion is upregulated during fear + stress + trauma
Example Fight or flight
Tiger chasing you –> actuvates the stress sytem (sympathetic nervous system activation) –> Adrenal gland secretes catecholimines –> Body reacts to hormone signaling
Epinephrine vs. Norepinephrine
Epineprhin - ONLy made by teh adrenal medulla (hormone)
Norepinephrine - Made by the sympathtic nervous system and the adrenal medulla (neurotranmitter + hormone)
Goiter
Overall - Irregular growth of the thryoid
- Non-cancerous enlargment of the thyroid
Symptoms - Swelling nech + nodules in thryoid + diffculties swallowing + horse voice
Goiter causes
Goiter causes:
1. Iodine deficney - iodine is needs to make thyroid hromones –> no iodine.= thyroid is bigger because make more cells to try and make more thryoid hormone
2. Graves (Hyperthyroidsm) –> Thryoid follicles make more TSH = more thryoid hromone
3. Hashimotos (Hypothyrodism)
- Autoimmune attack of thyroid gland –> no thryoid hromone production
4. Thyroditus
5. Thyroid cancer
6. Pregnacey - hCG made in preganncey mimic TSH = causes thyroid to make more thyroid hromone
Graves vs. hashimotos
Graves - AB targets TSH = make more hromone
Hashimotos = AB targets thyroid gland cells = get cell death = make less hormone
Goiter Histology
Left - normal
Right - englargment of follicle
Types of goiter
- Colloid Goiter (endemic) - only in several areas
- Happens with iodine defincey
- Non-txic goiter
- Toxic - caused by hypo/hyperthryodism
- Nodular goiter
- Multinodular goiter
Risk factors for goiter
Living in area where iodine containing foods are in short supply
Obesity
Insulin resistence
Metabolic syndorme
Exposed to radiation on neck
Family history of thyroid disease
Being female and pregenant
Age
Goiter diagnosis and treatment
Ultra sound + blood tests (anti-TPO and anti-TG) + biodpsy (tests for cancer) + thryoid scan + CT scan or MRI
Treatment - medication + surgery + radioactive iodine
- Medication for hypothyrodism (give thyroid hormone)
- If beccomes too large = can be painful –> could become cancerous –> have surgery to remove thryoid gland
- Can give radioactive iodine to kill thryoid gland
Addison’s disease
Adrenal cortext doesn’t produce enough glucocorticois and minocortocids (adrenal insufficney)
- Zona fosiolata = secretes glucoocortocoids
- Glucocorticois + Minocortocids Hormones = regulate BP + eletolights + stress
- Have low Cortocoids
Causes - autoimmune attcj on adrenal cortext
- Can also stem from hemerapge + tumor + infection
Addison’s disease histology
Left - nromal
right - Disease – layer is thin + plasma infiltration + lymphocytes infiltration
Addison’s disease symptoms
Hyperpigmentaion of skin and mucocous membranes (Ex. JFK)
Poor apetite and wight loss
Low BP
GI upset
High cravings for salty foods
Addison’s disease treatment
Treatment - pateints receive lifelong sterioid hormone replacment therapies + must take more cortisol if pateint has perioidic episodes of illness
Pititary Ademona Classification
- Based on size
- Based on function
Pititary Ademona Classification (size)
Smallest - microadenoma –> macroadenima –> giant tumors
MRI - see a ginat tumor (goes to optic chiasm)
Pititary Ademona Classification (function)
- Non-functioning - effects non-sectroy cells –> No increase in hormone BUT still has secondary effects
- Can cause blindness (optic interferance) + hypopituitrims (compression on nearby secretory cells) + headches/naseua (because increase intercranial pressure) - Functioning/secrting - neoplasm of cells that can scerete hormones in pituitray
- Causes hyerpitutarism (high hormone level)
Pituitray adenomas stats
10% of people develope pituitary adenomas
- Micro = most common –> very minmal role in health = negligible effects on pateints
40% of pituitary adenimasl are non-functional
40% of pitutitary adenomas are prolactinomas –> tumors that secrete prolactin hormone
Prolactinoma
Cancer of lctatrophes (lactatrphes make prolactin)
Most common form of pituitray adenocracinma
- Type of secreting adenoma
Effects nearly all organss
Prolactin signlaing is espcially prominent during pregnacey and lactation
Hyperprolactinemia = assocuated with obseity + insulin resistnce + non-alchol fatty liver disease
Prolactinoma Diagnosis
Left - giant tumor –> right is removal of tumor after surgery
Most common treatment = surgery
Prolactinoma Histology
NOT in image BUT can use IHC on functional tumors (Ex. stain for prolactin)
- Use IHC for the hormone being secreted to see caner invasion
Bottom of image = high cell count
Right = Somatatroph adenima –> see more cells in the bottom section compared to normal pituitary
