Endocrinology

Nervous System

Transmits high-speed chemical signals that are short term and very specific, using specialized nerve cells.

Endocrine System

Sends slower, longer-term chemical signals that can affect multiple cells, using hormones secreted by endocrine glands.

Neurotransmitters

Chemicals that send signals in the nervous system.

Hormones

Chemical signals secreted by endocrine glands that affect target cells with appropriate receptors.

Target Cells

Cells that have specific receptors for binding neurotransmitters or hormones.

Signal Transduction Pathway

Process activated by chemical (ligand) binding to a receptor, causing a conformational change leading to cellular activity.

Tropic Hormones

Hormones that affect other endocrine glands, such as those released by the pituitary gland.

Hydrophilic Hormones

Water-soluble hormones that are typically unable to pass through cell membranes and instead bind to cell surface receptors.

Hydrophobic Hormones

Lipid-soluble hormones that can pass through cell membranes and often bind to intracellular nuclear receptors.

Anterior Pituitary Gland

Part of the pituitary gland that contains endocrine cells controlling hormones via releasing or inhibiting signals from the hypothalamus, signals pass through portal veins.

Posterior Pituitary Gland

Extension of the brain that releases hormones made by the hypothalamus into the bloodstream.

Secretin

A hormone by endocrine cells, released in response to low pH in the duodenum, signaling the pancreas to raise pH levels.

Adrenal Glands

Glands that found on top of the kidneys, deal with stress responses, consists of medulla and cortex.

Diabetes Mellitus

Condition characterized by deficiency of insulin or lack of responsiveness to insulin, leading to elevated blood glucose levels.

Catecholamines

Hormones released from the adrenal medulla in response to stress, includes adrenaline and nor-adrenaline.

Sex Hormones

Steroid hormones produced by testes and ovaries that drive biological sex characteristic formations.

Insulin

Hormone that lowers blood glucose level by stimulating glucose uptake into cells.

Glucagon

Hormone that raises blood glucose level by stimulating the breakdown of glycogen in the liver.

Feedback Regulation

Process by which hormone levels are regulated, often through negative feedback loops.

Hypothalamus

Brain region that coordinates the endocrine system and initiates appropriate endocrine responses based on internal and external information.

Thyroid Hormones

Key hormones (T3 and T4) involved in regulating metabolic processes and development.

Faults with thyroid hormones

May result in hyperthyroidism or hypothyroidism, leading to various metabolic disorders and symptoms.

Growth hormone

Tropic and non-tropic hormone, regulates growth via production of insulin like growth factor produced by the liver.

Parathyroid glands

Found on surface of thyroid glands, secretes PTH which stimulates calcium uptake and vitamin D activation in kidneys.

PTH and Calcitonin

Antagonistic hormones, calcitonin reduces blood calcium PTH vice versa.

Blood glucose rising

Insulin secreted by beta cells of the pancreas, stimulates conversion of glucose to glycogen and triglycerides.

Blood glucose decreasing

Glucagon secreted by alpha cells of the pancreas, stimulates breakdown of glycogen to glucose.

Adrenal gland medulla

Produces catecholamines to intiate fight or flight response

Corticosteroids

Produced in adrenal cortex in stress response, controlled by endocrine signalling from anterior pituitary, causing ACTH from hypothalamus to signal adrenal gland.

Adrenal Cortex

Secretes corticosteroids that primarly regulate metabolism

Thyroid hormone decrease

Hypothalamus secretes TRH, stimulates anterior pituitary to release TSH, which in turn stimulates endocrine cells in thyroid gland to secrete T3 and T4.

Thyroid hormone feedback control

TSH release by anterior pituitary inhibits release of TRH by hypothalamus, furthermore, thyroid hormones inhibit TSH and TRH release.

Anterior pituitary tropic hormones

FSH and LH, TSH and ASTH

Anterior pituitary non-tropic hormones

Prolactin and MSH

Anterior pituitary hormones tropic/non-tropic

Growth hormone, endorphins

Posterior pituitary hormones

Anti-diuretic hormone, oxytocin