Endocrine System (Pt. 3) Flashcards
(215 cards)
What are the main functions of parathyroid hormone (PTH)?
- Regulates calcium, magnesium, and phosphate
- Increases osteoclast activity (releases calcium from bones)
- Reduces calcium/magnesium loss in urine
- Increases phosphate excretion
- Promotes active vitamin D (calcitriol) formation
How does PTH affect bones?
PTH increases osteoclast activity, which breaks down bone and releases calcium and phosphate into the blood.
How does PTH affect the kidneys?
PTH reduces calcium and magnesium loss in urine, increases phosphate excretion, and stimulates the production of calcitriol (active vitamin D).
How does PTH promote vitamin D activation?
PTH stimulates the kidneys to produce calcitriol, the active form of vitamin D, which enhances calcium, phosphate, and magnesium absorption from the digestive system.
What triggers the release of parathyroid hormone (PTH)?
Low blood calcium (Ca²⁺) levels trigger the release of PTH to restore calcium balance.
How does PTH increase blood calcium levels?
PTH increases osteoclast activity, which breaks down bone and releases calcium into the bloodstream.
How does PTH help increase calcium absorption?
PTH stimulates the kidneys to produce calcitriol, which enhances calcium absorption from the digestive system into the blood.
How does PTH affect urinary calcium excretion?
PTH reduces calcium and magnesium loss in urine, conserving these minerals in the bloodstream.
explain the negative feedback system of PTH:
Stimulus: Decreased blood calcium levels.
Control Center: The parathyroid glands detect low calcium levels.
Response:
- PTH Release: The parathyroid glands release PTH.
- Effectors: PTH stimulates osteoclasts to break down bone, releasing calcium into the blood, and affects kidneys to reabsorb more calcium.
Result: Increased calcium levels in the blood.
Return to homeostasis
Does the posterior pituitary gland produce hormones?
No, it stores and releases hormones made by the hypothalamus.
What two hormones are stored and released by the posterior pituitary?
Oxytocin (OT) and Antidiuretic hormone (ADH).
How is oxytocin (OT) released into the bloodstream?
It is stored in the posterior pituitary and released via a capillary network.
How is ADH released into the bloodstream?
It is stored in the posterior pituitary and released through the same capillary network as oxytocin.
How do oxytocin and ADH reach the bloodstream from the posterior pituitary?
They pass through the hypophyseal veins to reach their target tissues.
What triggers the variation in ADH secretion?
Blood osmolarity and osmotic pressure.
How does ADH affect urine and sweat output?
ADH decreases urine and sweat output by absorbing water when the blood is thick (dehydrated) or when blood pressure is low.
How does ADH affect urine and sweat output when blood is thick (dehydrated) or blood pressure is low?
ADH decreases urine and sweat output by absorbing water.
What happens to ADH secretion when blood volume increases?
ADH secretion decreases.
What happens to ADH secretion when blood volume decreases?
ADH secretion increases.
What is the function of ADH in high blood osmolarity or low blood pressure?
It helps the kidneys retain water, reducing urine and sweat output.
How does increased blood volume affect ADH secretion?
It decreases ADH secretion, allowing more water to be excreted.
What happens to ADH secretion when blood volume is low?
ADH secretion increases to conserve water and maintain blood pressure.
Q: What role does ADH play in regulating hydration and blood pressure?
A: It balances the body’s water retention and blood pressure levels.
Q: How does sweating affect blood plasma?
A: Sweating causes a loss of blood plasma, increasing blood osmolality.