9 - Histology of Endocrine Organs Flashcards
Both of these systems influence the physiologic functions of other organs, but differ by the methods used to communicate and accomplish their influence.
Endocrine System
Nervous System
In the _________ system, it involves membrane depolarization and transmission of a signal from synapses. Communication is rapid but effects on target cells/organs are short-lived.
Nervous
In the _________ system, it involves chemicals called hormones that are distributed throughout the body by the cardiovascular system. Communication is much slower but the effects on target cells/organs are of longer duration.
Endocrine
T/F. Neurons do not secrete hormones.
False. Some neurons do secrete hormones.
This type of hormonal release is controlled by monitoring levels of ions and nutrients in blood and body fluids. An example is the release of parathyroid hormone stimulated by low serum calcium levels.
Humoral Stimuli
This type of hormonal release is stimulated by nerve signals. An example is the release of epinephrine from the adrenal gland in response to a signal from sympathetic nerve fibers.
Neuronal Stimuli
This type of hormonal release is caused by a hormone being secreted into the bloodstream by another endocrine organ or cell. An example is the release of thyroid hormone stimulated by the release of the hormone, TSH, from the pituitary.
Hormonal Stimuli
Endocrine glands are made of _________ cells, which lack a free surface (apical lumen). They are arranged as cords/follicles and some as isolated individual cells. They are derived from epithelia.
Epithelioid
***Only gland that has a lumen is thyroid gland
Endocrine glands are well vascularized, and vessels often have _________ endothelium.
Fenestrated
What are the direct targets of Hypothalamic hormones, and what are the hormones?
Anterior Pituitary – releasing and inhibiting factors that influence its secretion
Kidney and Uterus – releasing ADH and oxytocin (stored in posterior pituitary)
Adrenal Medulla – Hypothalamus oversees ANS, helps via Sympathetic innervation
The hypothalamus releases hormones, collectively referred to as ________ hormones, that stimulate or inhibit release of other hormones from the anterior pituitary.
Tropic
The hypothalamus works indirectly by stimulating secretion of hormones by the anterior pituitary gland. Where do the hormones from the anterior pituitary go to?
Thyroid gland Adrenal cortex Mammary gland Gonads (testes or ovaries) Bone and other organs
These cells from the anterior pituitary secrete TSH, which regulates thyroid gland secretion.
Thyrotropic cells
These cells from the anterior pituitary secrete Prolactin, which stimulates milk production.
Mammotropic cells
These cells from the anterior pituitary secrete ACTH and MSH.
Corticotropic cells
These cells from the anterior pituitary secrete GH.
Somatotropic cells
These cells from the anterior pituitary secrete FSH and LH, which act on the gonads.
Gonadotropic cells
In the origin of the pituitary, ectodermal placode leading to _______ _______ is seen by 3 weeks. This loses it connection with the outside and is near final location by 8 weeks. It joins the diverticulum from the developing _________ of the neural tube.
Rathke’s Pouch
Diencephalon
In the development of the pituitary, the __________ forms the posterior pituitary and the infundibular stalk. _______ _______ forms the rest of the pituitary.
Infundibulum
Rathke’s Pouch
In the development of the pituitary, at what weeks do ACTH, GH, TSH and LH, and FSH start being produced?
ACTH – 7 weeks
GH – 8-9 weeks
TSH and LH – 12 weeks
FSH – 13 weeks
The anterior pituitary constitutes ______ percent of the gland. It is comprised of glandular epithelial cells controlled by _________ released from the hypothalamus.
80
Neurohormones
The posterior pituitary is comprised of axons from the __________ and support cells. The axons carry ______ and _______ for storage and release in the posterior pituitary.
Hypothalamus
ADH
Oxytocin
What are the parts of the anterior pituitary (adenohypophysis)?
Pars tuberalis
Pars intermedia
Pars distalis
What are the parts of the posterior pituitary (neurohypophysis)?
Infundibular stalk
Pars nervosa
This is small and in between the anterior and posterior pituitary. It is a remnant of the lumen of Rathke’s pouch.
Cyst Intermedia
This hormone stimulates the adrenal cortex to secrete stress-related hormones and mediate metabolism.
ACTH
This hormone stimulates melanocytes to produce melanin.
MSH
What are the cells of the Pars Distalis (in anterior pituitary)?
Acidphils
Basophils
Chromophobes
Sinusoidal (fenestra) capillaries
What are the types of acidphil cells in the anterior pituitary?
Somatotrophs – secrete GH
Mammotrophs – secrete Prolactin
What are the types of basophil cells in the anterior pituitary?
Corticotrophs – secrete ACTH
Thyrotrophs – secrete TSH
Gonadotrophs – secrete FSH/LH
This portion of the pituitary lies between Pars Distalis and Pars Nervosa. It is rudimentary in adults, and its function is unknown.
Pars Intermedia
Pars Intermedia contains small basophils and colloid-filled follicles lined by _________ epithelium. It frequently contains the _______ ______, which is remnant of lumen of Rathke’s pouch.
Cuboidal
Cyst Intermedia
This portion of the pituitary is continuous with the median eminence of the hypothalamus via the infundibular stalk. It does NOT manufacture hormones, rather it stores and releases them from axon terminals.
Pars Nervosa
The Pars Nervosa consists of hypothalamic unmyelinated axons called _______ _______, which are expanded axonal nerve terminals storing ADH and Oxytocin.
Herring bodies
The Pars Nervosa contain _________, which are glia-like and support the nerve fibers. It also has fenestrated capillaries.
Pituicytes
Hypothalamic hormones are released into special blood vessels, called the _________ ________ _________, controls the release of anterior pituitary hormones.
Hypophyseal Portal System
What does a portal system consist of?
A portal system is two capillary plexuses (beds) connected by veins.
In the Hypophyseal Portal System, the ______ ______ artery is connected to the Primary Capillary Plexus. This plexus is connected to the Secondary Capillary Plexus via the _______ ______ veins.
Superior Hypophyseal A.
Hypophyseal Portal Vs.
Explain the steps of hormone release from the anterior pituitary involving the Hypophyseal Portal System.
1) When appropriately stimulated, hypothalamic neurons secrete releasing or inhibiting hormones into the Primary Capillary Plexus.
2) Hypothalamic hormones travels through the Hypophyseal Portal Vs. to the anterior pituitary where they stimulate or inhibit release of hormones made in the anterior pituitary.
3) In response to releasing hormones, the anterior pituitary secretes hormones into the Secondary Capillary Plexus. This in turn empties into the general circulation.
The posterior pituitary gland releases hormones via the ________ ________ tract.
Hypothalamo-Hypophyseal
This hormone from the posterior pituitary targets the kidney. It regulates sodium and water retention.
Antidiuretic Hormone (ADH)
This hormone from the posterior pituitary targets uterine smooth muscle and stimulates lactation, as well as induces birth. It may be involved in sexual arousal and pair and social bonding.
Oxytocin
Explain the pathway for hormones to the posterior pituitary in the Hypothalamo-Hypophyseal tract.
1) Hypothalamic neurons synthesize Oxytocin or ADH.
2) Oxytocin and ADH are transported down the axons of the Hypothalamo-Hypophyseal tract to the posterior pituitary.
3) Oxytocin and ADH are stored in neurosecretory bodies in the posterior pituitary.
4) When associated hypothalamic neurons fire, nerve impulses arriving at the neurosecretory bodies cause Oxytocin or ADH to be released into the blood.
This is an out-pocketing of the diencephalon’s roof of the 3rd ventricle. It has a flattened cone-shape and is 3-mm in diameter. It is covered with Pia Mater.
Pineal Gland
The Pineal Gland has a role in growth, development, and circadian rhythms. It synthesizes ________ and _______.
Melatonin
Serotonin
What does the Pineal Gland consist of?
Pinealocytes
Neuroglia
Calcified granular material (brain sand)
The calcified granular material (brain sand) in the Pineal Gland is composed of ________ ________ crystals located in intercellular spaces that show up at the beginning of early childhood. It is an important radiogenic marker (for midline brain). It is secreted by _________.
Calcium Phosphate
Pinealocytes
This gland is characterized by structures called follicles, consisting of a layer of follicular cells (simple cuboidal to columnar epithelium) surrounding a fluid called colloid.
Thyroid
In the Thyroid, colloid contains _________, a storage form of the thyroid hormones T3 and T4 (iodine-containing hormones).
Thyroglobulin
This gland is the only one to store hormones outside of its cells.
Thyroid
***Inside the follicular lumen as colloid!
________ hormones control basal metabolism, oxygen usage, body temperature, etc.
Thyroid
Thyroglobulin is synthesized in the rER, glycosylated in the Golgi, and secreted by exocytosis into the lumen of the follicle, called ________.
Colloid
Thyroid hormone is iodinated at the apical surface, forming ______ and ______ that is bound to Thyroglobulin.
T3
T4
______ stimulates internalization of Thyroglobulin via endocytosis where it is degraded, freeing T3 and T4.
TSH
T3 and T4 is released from the (APICAL/BASAL) surface of the follicle cells into the circulation.
Basal
These cells lie just outside the follicles in the Thyroid, and they secrete calcitonin when blood levels of calcium are HIGH.
Parafollicular C cells
How does calcitonin (from Parafollicular C cells) work to lower circulating calcium levels?
– Stimulate secretion of calcium by kidneys (pee it out)
– Decreasing the calcium-releasing activity of osteoclasts
– Increasing osteogenesis by osteoblasts (use calcium to make bone)
This thyroid pathology is due to abnormal antibodies stimulating TSH receptors, causing over-secretion of T3 and T4. Symptoms include elevated metabolism, sweating, rapid heart rate, weight loss, and eyeballs may protrude. Can be treated with a thyroidectomy or anti-thyroid drugs.
Grave’s disease
This thyroid pathology is due to insufficient T3 and T4 production. It is often an autoimmune disease-causing follicle cell death. Symptoms include low metabolic rate, weight gain, lethargy, chillness, edema, and being mentally sluggish. Can be treated with synthetic T3/T4.
Hypothyroidism
This is a thyroid enlargement most commonly due to iodine deficiency. Follicle cells keep producing Thyroglobulin but cannot iodinate it to make TH (T3 and T4).
Goiters
***More prevalent in areas of iodine deficiency, like 3rd world countries.
These are small ovoid glands lying on the posterior surface of the thyroid gland that release PTH. There are usually two pairs but can be more.
Parathyroid Glands
Parathyroid glands have a major importance in regulating serum ________ and ________ levels.
Calcium
Phosphate
These cells in the Parathyroid gland release PTH. The secretion of PTH occurs when the blood concentration of calcium falls below the normal range (9.5-10.5 mg/dL). Secretion stops when levels return to normal.
Chief (Principle) cells
These cells are also in the Parathyroid gland, but their function is unknown.
Oxyphil cells
When blood calcium levels drop below 9.5 mg/dL, then the parathyroid releases PTH into the bloodstream. What does the release of PTH cause to happen?
– Stimulates osteoclasts to resorb bone and release its calcium stores
– Increase calcium retention by kidneys
– Stimulates kidney to convert an inactive form of Vitamin D to calcitriol (active Vitamin D), because calcitriol increases calcium absorption by the intestines
***Basically the exact opposite of Calcitonin (from Parafollicular C cells in Thyroid)
How is the adrenal gland divided?
Adrenal Cortex – Outside
Adrenal Medulla – Inside
***Capsule lies outside the cortex, but it has no functions
What are the subdivisions of the Adrenal Cortex?
Zona Glomerulosa
Zona Fasciculata
Zona Reticularis
What is secreted from the Zona Glomerulosa?
Aldosterone
What is secreted from the Zona Fasciculata?
Cortisol (main hormone)
Androgens (a little bit)
What is secreted from the Zona Reticularis?
Androgens (main hormone)
Cortisol (a little bit)
This portion of the Adrenal Gland has a distinctive yellow color due to stored lips in its cells. It also has more than 25 different steroid hormones (corticosteroids) that it secretes, which are vital for survival.
Adrenal Cortex
The Zona Glomerulosa contains mineralocorticoids, specifically _________, which influences sodium and potassium levels.
Aldosterone
Aldosterone targets kidney function and is mostly secreted in response to low ________ _______ or ________ _______. It is controlled by the renin-angiotensin system.
Blood pressure
Blood volume
The Zona Fasciculata contains glucocorticoids, specifically ________, which influences glucose metabolism and the immune system.
Cortisol
Cortisol is released under the control of ________ from the anterior pituitary.
ACTH
Cortisol deals with stress and mediates glucose metabolism and serves as negative feedback mechanism for the immune system giving an __________ action.
Anti-inflammatory
These hormones influence secondary sex characteristics, and are primarily secreted by the Zona Reticularis.
Androgens
The Adrenal Medulla forms the inner core of each Adrenal gland. It primarily consists of clusters of large, spherical cells called _________ cells which are the target of sympathetic neurons.
Chromaffin
In the Adrenal Medulla, when stimulated by the sympathetic division of the ANS, one population of cells secretes the hormone _________ and a second population secretes the hormone _________.
Epinephrine (Adrenaline)
Norepinephrine (Noradrenaline)
This type of Chromaffin cell is smaller with granules, and less electron dense (appears lighter).
Epinephrine cells
This type of Chromaffin cell is larger with granules, and more electron dense (appears darker).
Norepinephrine
This type of adrenal gland syndrome is a hyposecretory disorder usually in both glucocorticoids (cortisol) and mineralocorticoids (aldosterone). Blood glucose and sodium levels drop, there is severe dehydration and low BP along with fatigue and loss of appetite. It is usually caused by an autoimmune disease or due to inherited metabolic disease leading to deficiencies in hormone-producing enzymes.
Addison’s Disease
This type of adrenal gland syndrome is due to hypersecretion of glucocorticoids (cortisol) because of either an ACTH-secreting pituitary tumor or a tumor in the adrenal cortex. It is characterized by high serum glucose levels, protein loss in muscles, muscle weakness, and lethargy. Rare in humans.
Cushing’s Syndrome
The following symptoms describe what disease?
- Swollen face (Moon face)
- Buffalo hump
- High glucose levels
- Weight gain
- Sweating
- Thinning skin
- Muscle weakness
- Lethargy
- Depression of immune and inflammatory responses
Cushing’s Syndrome
For the Pancreas, it has an endocrine and exocrine portion. The exocrine portions makes up most of the gland and it aids in _________.
Digestion
Exocrine cells of the Pancreas are organized in structures called ________ ________. Endocrine cells are organized into clusters called ________ ________ or ________ _______ ________, which are scattered among the exocrine cells.
Pancreatic Acini
Pancreatic Islets
Islets of Langerhans
In the endocrine portion of the Pancreas (Islets of Langerhans), what cells are present and what hormones do they secrete?
Alpha cells – Glucagon
Beta cells – Insulin
Delta cells – Somatostatin
F cells – Pancreatic Polypeptide
When blood glucose levels drop, ________ is released from Alpha cells in the Pancreas to stimulate the release of glucose from liver glycogen stores.
Glucagon
When blood glucose levels are elevated, ________ is released from Beta cells in the Pancreas to promote glycogen storage in the liver and entry into cells.
Insulin
In the Pancreas, Delta cells release __________ to slow the release of insulin and glucagon, thereby controlling the rate of nutrient entry into the bloodstream and cells. These cells are stimulated by high levels of nutrients in the bloodstream.
Somatostatin
In the Pancreas, F-cells release ________ ________ which inhibit the release of somatostatin.
Pancreatic Polypeptide
Each Islet of Langerhans is supplied by afferent arterioles, forming a network of capillaries lined by fenestrated endothelial cells. This network is called the ________ _______ _______.
Insuloacinar Portal System
Capillaries leaving the Islet of Langerhans supply blood to the _______ ______ surrounding the islet. This vascular system enables a local action on the exocrine pancreas of hormones produced in the islet.
Pancreatic Acini
***Remember, Pancreatic Acini are the exocrine part of the Pancreas
Pancreatic Acini can also receive blood via an independent arterial system called the _______ _______ _______.
Acinar Vascular System
