12) Endocrine System Flashcards
What are the major glands of the endocrine system?
- Thyroid gland
- Parathyroid
- Adrenal gland
- Pancreas
- Reproductive glands (Ovaries, Testes)
What is the General Function of Endocrine?
Responsible for synthesis & secretion of hormones that act on specific target organs of tissues
Why is the endocrine system often called a ductless gland?
Because they discharge their
product into interstitial spaces – to be absorbed into the circulatory system
Decribe the gross anatomy of of the thyroid.
- 2 lobes lateral to upper trachea
- Anterior portion of the neck
- Joined in front of the larynx by
the isthmus - Enclosed by fibrous DICT capsule
with septae penetrating the
parenchyma - Function: secretion of T3 & T4
(regulation of the basal metabolic
rate) and calcitonin (calcium
homeostasis) - Stores inactive form of hormone in
follicles
Understanding Thyroid Cells
Follicles are filled with Colloid
Colloid stores the thyroglobulin, which is the inactive form of T3 and T4
cuboidal epithelium surround the colloid and they’re also referred to as follicular cells.
The principal cells produce the glycoprotein component of the thyroidglobulin and convert iodide to iodine
(The principal cells and follicular cells are both in the same area)
Between the principal cells and the follicles, there are cells around it called the parafollicle cells aka C cells. They help with producing calcitonin which which regulates the blood calcium levels
T or F:
The principal cells are the most numerous cell present in
the thyroid.
True
T or F:
The principal cells are NOT responsible for secreting the thyroid hormones as well as thyroglobulin, a glycoprotein.
false
- They are responsible for it
T or F:
In the colloid, the thyroid hormones are stored extracellularly as part of the thyroglobulin which is the main component of the colloid
True
T or F:
The parafollicular cells (C cells) secrete calcitonin, which inhibits osteoclasts from resorbing bone resulting in
decrease in calcium in the blood
* Controlled by the level of calcium in the blood
True
T or F:
The parafollicular cells (C cells) do not have pale / clear cytoplasm, oval nuclei, easy to identify with H&E
F
They are pale and are difficult to identify with H&E
What is the purpose of parafollicular cells decreasing calcium levels?
secrete the hormone calcitonin, which helps reduce blood calcium levels when they are too high
Parafollicular cells and calcitonin reduce blood calcium levels to:
- Prevent the harmful effects of hypercalcemia.
- Maintain a dynamic balance in bone remodeling and calcium homeostasis.
- Complement other regulatory hormones like PTH for smooth physiological functioning.
Where are the parathyroid glands located?
- Parathyroid glands are located attached to the thyroid in the neck to the front of the upper
trachea.
What are the tiny two or three pairs of small pale (coffee-coloured) oval glands embedded in the capsule of the thyroid gland called?
parathyroid glands
- Each gland is about the size of a piece of rice and can be difficult to see macroscopically
The parathyroid hormone (PTH) is very essential to life as the most
important regulator of blood calcium
and phosphorus levels
(regulates serum calcium and
phosphate levels) in partnership with
the thyroid secreting calcitonin)
What do Chief Cells of the Parathyroid Gland do?
Produce and regulate parathyroid hormone (PTH), a hormone crucial for calcium homeostasis.
What does the parathyroid do when the calcium levels are too high or low?
When it’s too high it stop releasing calcium. When it’s too low it starts to release calcium
Adrenal Glands
What is it, where is it, and what are the 2 systems in the organ?
- It produces many important hormones
- Location: upper poles of the kidneys
- ADRENAL CORTEX:
synthesizes & secretes aldosterone, cortisol and androgens - ADRENAL MEDULLA:
secretes catecholamines (epinephrine and norepinephrine)
The adrenal gland layers
- Fibrous capsule: outer layer that encapsulates it
- Zona Glomerulosa
- Zona Fasciculata
- Zona Reticularis
- Medulla
- Central adrenomedullary vein
Cortex layer Zona 1: Glomerulosa
- Secretes mineralocorticoids (aldosterone)
- Function: controls blood pressure
Cortex layer Zona 2: Fasciculata
- Secretes glucocorticoids (cortisol & corticosterone)
- Function: controls immune system, inflammation, stress response
Cortex layer Zona 3: Reticularis
- Presence of lipofuscin is characteristic
- Function: Control reproductive organs and development of male/female characteristics
Adrenal Medulla
Cells are arranged in small cords
- Cells secreting epinephrine - small, spherical neuroendocrine granules
- Cells secreting norepinephrine - larger
neuroendocrine granules
During excitement or stress, large amounts of epinephrine & norepinephrine are released
Pancreas characteristics
The pancreas has both endocrine and exocrine glands
The endocrine is about 10% of the entire organ which is the islet of langerhans. Clump and cord arrangement.
The Exocrine gland is about 90% of the entire organ which is the serous acini.
Acini stains pink because of the enzymes
The Exocrine gland is about ___% of the entire organ which is the _____________.
90%
serous acini
The endocrine is about ___% of the entire organ which is the _______________.
10%
islet of langerhans.
What are the 4 cell types present in the endocrine system in the pancreas?
- Alpha cells produce glucagon in response to low blood sugar
- Beta cells produce insulin
Most abundant cell - Delta cells produce somatostatin, inhibits activity of alpha and beta cells
somatostain: a hormone that regulates a variety of bodily functions by hindering the release of other hormones and the rapid reproduction of cells
- PP (pancreatic polypeptide) cells inhibit enzymatic and alkaline pancreatic secretions
Which gland is known as the “master gland” of the endocrine system?
A) Thyroid
B) Hypothalamus
C) Pituitary
D) Adrenal
C) Pituitary
What hormone is secreted by the pancreas to lower blood glucose levels?
A) Glucagon
B) Insulin
C) Cortisol
D) Thyroxine
B) Insulin
Which hormone is responsible for regulating the body’s sleep-wake cycle?
A) Melatonin
B) Cortisol
C) Growth Hormone
D) Aldosterone
A) Melatonin
The adrenal glands produce which of the following hormones during the “fight or flight” response?
A) Thyroid Hormone
B) Epinephrine
C) Calcitonin
D) Oxytocin
B) Epinephrine
Which gland controls calcium levels in the blood?
A) Parathyroid
B) Adrenal
C) Pancreas
D) Pineal
A) Parathyroid
The hypothalamus is part of the endocrine system and nervous system.
True
The thyroid gland is located in the brain.
False (It is located in the neck.)
Cortisol is a hormone that helps the body respond to long-term stress.
True
The pancreas is only an exocrine gland.
False (It is both endocrine and exocrine.)
The __________ gland regulates metabolism, heart rate, and body temperature by secreting thyroid hormones.
Answer: Thyroid
Hormones travel through the _________ to reach their target organs.
Answer: Bloodstream
The __________ cells in the pancreas produce glucagon, which increases blood sugar levels.
Answer: Alpha
A patient has HIGH T3 and T4 levels and low TSH levels. What condition might this indicate?
Hyperthyroidism (The thyroid is active, leading to excess hormone production, and the pituitary compensates by releasing less TSH.)
A patient has LOW T3 and T4 levels and high TSH levels. What condition might this indicate?
Hypothyroidism (The thyroid is underactive, leading to insufficient hormone production, and the pituitary compensates by releasing more TSH.)
