Endocrine System Lecture Notes

This set of flashcards covers key concepts from the lecture notes on the endocrine system, focusing on hormone functions, signaling pathways, and physiological roles.

What is the function of tanycytes in the 3rd ventricle?

They are cuboidal epithelial cells that interact with cerebrospinal fluid.

What different neuron inputs regulate the anterior pituitary?

The anterior pituitary receives inputs from parvicellular neurons, and has extrinsic triggers like cold and diet, and intrinsic triggers like blood pressure.

What is the neurosecretory cell's role?

They receive sensory stimuli from the CNS, conduct action potentials, and synthesize and release hormones.

What stimulates anterior pituitary hormone secretion?

Factors in portal blood from the hypothalamus, parvicellular neurons, and hormones.

What inhibits TSH secretion?

Thyroid hormones act through negative feedback.

How does GHRH influence growth hormone secretion?

GHRH stimulates growth hormone (GH) secretion and is negatively regulated by GH, IGF-1, and somatostatin (SST).

What is the effect of somatostatin on the pituitary?

Somatostatin inhibits the release of growth hormone and prolactin.

What is the primary action of AVP (arginine vasopressin)?

AVP promotes water reabsorption in the kidneys and constricts blood vessels to increase blood pressure.

Describe the mechanism of action of calcitonin in the body.

Calcitonin lowers blood calcium levels by inhibiting osteoclast activity and increasing calcium excretion in kidneys.

What triggers the release of gastric acid in the stomach?

Gastrin stimulates parietal cells, which secrete hydrochloric acid.

How is blood calcium level maintained by parathyroid hormone (PTH)?

PTH increases blood calcium levels by promoting osteoclastic activity, enhancing renal reabsorption, and stimulating vitamin D activation.

What is Kallmann syndrome?

A condition where GnRH secreting neurons fail to migrate, leading to delayed puberty and lack of secondary sex characteristics.

What role does glucagon play in metabolism?

Glucagon increases blood glucose levels by promoting glycogenolysis and gluconeogenesis in the liver.

What are the effects of short-term versus long-term fasting on hormone levels?

Short-term fasting can increase levels of glucagon, while long-term fasting will elevate cortisol and decrease insulin sensitivity.

How does estrogen affect calcium regulation in bones?

Estrogen inhibits osteoclast activity and promotes bone formation, thus reducing calcium resorption.

What is the relation between PTH and vitamin D?

PTH stimulates the activation of vitamin D, which enhances intestinal absorption of calcium.

What physiological changes occur during dehydration?

During dehydration, osmolality increases, stimulating AVP release to conserve water in kidneys and raise blood pressure.