Lecture 4: Endocrine Flashcards
What is the endocrine system?
A system of hormone-secreting glands that regulate and coordinate many body functions
List the endocrine organs (7)
- Hypothalamus (brain)
- Pituitary gland (brain)
- Pineal gland (brain)
- Thymus → Thyroid + Parathyroid glands (larynx)
- Adrenal gland (kidneys)
- Pancreas (abdomen)
- Gonads (ovaries + testes)
Where is the binding site for steroid hormones?
Nucleus
Alters mRNA after binding
Where is the binding site for peptide hormones?
cell surface
GPCR → activates 2nd messengers
What are the functions of the hypothalamus (3)?
- Regulation of the pituitary gland:
- Axons travel down the pituitary stalk and synapse in the posterior pituitary
- Connections to the portal system (network of capillaries) allow the hypothalamus to stimulate the anterior pituitary to release hormones
Does the posterior pituitary gland produce its own hormones?
No
Pars Nervosa is the same as the ______ pituitary
posterior
What is the function of Herring bodies? Where are they located?
- store hormones from the hypothalamus
- located in the posterior pituitary
Does the anterior pituitary gland produce its own hormones?
Yes
What two hormones does the posterior pituitary secrete?
- Vassopressin (ADH)
- Oxytocin
Hypothalamus makes vassopressin + oxytocin → secreted by posterior pituitary
Pars Anterior is the same as the ______ pituitary
anterior
What two cells secrete hormones in the anterior pituitary?
- Acidophils
- Basophils
Only have acidophils in anterior pituitary
What two hormones do acidophils secrete?
- Growth Hormone (GH)
- Prolactin (PRL)
What hormones do basophils secrete (4)?
- Thyrotropin (TSH)
- Follitropin (FSH) or Leuteotropin (LH)
- Corticotropin (ACTH)
- Melanocyte stimulating hormone (MSH)
What are 1, 2, 3, and 4?
The cells circled in red secrete GH + PRL. What are these cells called?
Acidophils (pink stain)
The cells circled in dark blue secrete TSH, FSH, LH, ACTH, and MSH. What are these cells called?
Basophils (dark stain)
What type of cells are A, B, and C?
What two cells are shown in this image?
Axons and pituicytes
Identify C (red) and D (dark blue)
Identify A and B
What is the function of the pineal gland (pineal body)?
secretes melatonin = role in sleep
released by pinealocytes
How does daytime affect the pineal gland?
Daytime inhibits the pineal gland → no melatonin
How does nighttime affect the pineal gland?
Nighttime activates the pineal gland → secretes melatonin
Where is brain sand located?
Pineal gland
Identify the structures circled in red
What type of cells (2) do the follicles in the thyroid contain?
- Follicular cells
- Parafollicular cells
What do the follicular cells secrete?
Follicular cells = principal cells → secrete thyroid hormones (T3 + T4)
What do the parafollicular cells secrete?
Parafollicular cells = C cells → secrete calcitonin
- Anatagonist towards parathyroid (PTH)
- Role in regulating Ca2+ secretion
Where are thyroid hormones precursors made?
Colloid = inner lumen
Only makes precursors
How is hormone secretion regulated by iodide in the thyroid (4)?
- Iodide gets transported into the colloid (inner lumen) of the follicle
- In the colloid, iodide generates thyroid hormone precursors
- Precursors get transported out of the colloid and into the follicular cells
- In the follicular cells, thyroid hormone (T3/T4) is produced and secreted
What causes a goiter? What is the result?
- Lack of iodide → decreased thyroid hormone (T3/T4)
- Result = enlarged thyroid gland
Identify A, B, C and D
What zone is A? What zone is the black arrow pointing to?
Identify A and B
What structures are the yellow arrows pointing to? What structures are the black arrows pointing to?
Identify A, B, and C
Identify A, B, C, D, and E
Identify A, B, and C
Identify C, D, and E
Identify A, B, C, D
Identify C and D
Identify A, B, and C
Identify A and B
What does calcitonin stimulate in the bone?
calcium salt deposit
Calcitonin = ↑ bone Ca2+ ↓blood Ca2+
Osteoclasts degrade _____ matrix and release _____ into the blood
- bone
- Ca2+
What does the parathyroid gland release?
parathyroid hormone (PTH)
- Takes Ca2+ out of the bone to release into the blood
- PTH = ↑ blood Ca2+ ↓ bone Ca2+
Where is the parathyroid gland located?
Behind the thyroid gland
The thyroid acts as an antagonist by secreting calcitonin from C cells to work against PTH
What are the two types of parathyroid cells?
- Chief cells
- Oxyphil cells
What is the function of chief cells?
secrete parathyroid hormone (PTH)
Not the same as chief cells in the stomach
What are oxyphil cells?
inactive chief cells
What is the function of the parathyroid gland? How does it do this (2)?
-
Regulates blood Ca2+ levels:
1. A decrease in blood Ca2+ stimulates the release of PTH from chief cells
2. PTH causes an increase in blood Ca2+ by breaking down bone
What are the 3 zones of the adrenal gland from outermost to innermost? What does each zone secrete?
- Zona Glomerulosa = secretes aldosterone (salt)
- Zona Fasciculata = secretes cortisol (sugar = sweet)
- Zona Reticularis = secretes androgens (sex)
What does the medulla secrete?
secretes epinephrine + noepinephrine
“MEN”
The adrenal gland divides into the _____ and _____.
- cortex
- medulla
Identify the cell type:
a. Acidophils
b. Chief cells
c. Oxyphil cells
d. Parafollicular cells
c. Oxyphil cells
Which region of the adrenal gland is responsible for producing norepinephrine?
a. Zona reticularis
b. Zona glomerulus
c. Zona fasciculata
d. Medulla
d. Medulla
Identify this region:
a. Reticularis
b. Fasciculata
c. Glomerulosa
d. Medulla
b. Fasciculata
Calcitonin is important in the regulation of blood calcium levels. Which endocrine organ and cell type are responsible for the secretion of calcitonin?
a. Parathyroid gland; oxyphil cells
b. Thyroid gland; parafollicular cells
c. Pancreas; islet of Langerhans
d. Posterior pituitary gland; herring bodies
b. Thyroid gland; parafollicular cells
- Vasopressin (ADH) and oxytocin are hormones produced by which organ?
a. Hypothalamus
b. Pineal gland
c. Anterior pituitary gland
d. Adrenal gland
a. Hypothalamus
