Endocrine_system

Endocrine System

system comprising glands that secrete hormones directly into the bloodstream to regulate bodily functions. HOMEOSTASIS

Hormones

Chemical messengers produced by endocrine glands that coordinate various body functions.

Negative Feedback

reduces the output or activity of an organ or system to maintain normal functioning. HOMESTASIS

Positive Feedback

A feedback mechanism that enhances the output created by a stimulus, pushing levels out of normal ranges.

Thyroid Gland

An endocrine gland that produces hormones like thyroxine (T4) and calcitonin, regulating metabolism and calcium levels.

Oxytocin

A hormone that stimulates uterine contractions during childbirth and milk ejection during breastfeeding.

Feedback Control Mechanisms

Regulatory processes that govern hormone secretion and maintain homeostasis in the body.

Pituitary Gland

'master gland', it secretes various hormones that regulate other glands in the endocrine system.

Adrenal Glands

Glands located above each kidney that secrete hormones such as adrenaline, cortisol, and aldosterone.

Pancreas

An organ with both endocrine and exocrine functions, responsible for producing insulin and glucagon to manage blood glucose levels.

Thymosin

A hormone produced by the thymus gland that is involved in the development of T-lymphocytes.

Gonads

Reproductive organs that produce sex hormones, responsible for the development of secondary sex characteristics.

Glucagon

A hormone produced by alpha cells in the pancreas that raises blood glucose levels by breaking down glycogen.

Insulin

A hormone produced by beta cells in the pancreas that lowers blood glucose levels by facilitating cellular glucose uptake.

Hypothalamus

A brain region that controls the pituitary gland and regulates many homeostatic functions.

Steroid Hormones

Lipid-soluble hormones derived from cholesterol, such as cortisol and testosterone.

Peptide Hormones

Water-soluble hormones consisting of chains of amino acids, such as insulin and growth hormone.

Amino Acid Derivative Hormones

Hormones derived from amino acids, primarily water-soluble EXCEPT thyroid, cant diffuse across plasma membranes, examples include adrenaline and thyroid hormones.

Homeostasis

The maintenance of stable internal conditions within the body, regulated by feedback mechanisms.

Epinephrine

A hormone released by the adrenal medulla that increases heart rate and energy availability, also known as adrenaline.

Calcitonin

A hormone produced by the thyroid gland that helps reduce blood calcium levels.

explain the mechanism of lipid soluble hormones

Steroid hormones diffuse through cell membranes and bind to intracellular receptors, forming a hormone-receptor complex that regulates gene expression and protein synthesis. This complex then translocates to the nucleus, influencing the transcription of specific genes.

explain the mechanism of water soluble hormones

Water soluble hormone cannot diffuse across the plasma membrane of target cells.

The hormone binds to a receptor molecule located on the surface of the cells of the

target tissue. This forms hormone - receptor complex

• The binding of hormone activates G protein which in turn triggers enzyme

adenylate cyclase inside the cell.

It catalyses conversion of ATP to cAMP (secondary messenger)

• The secondary messenger molecule activates protein kinases that cause change in cell metabolism by activating enzymes or opening ion channel

what are Parathyroid Glands?

They secrete parathyroid hormone which increases

plasma calcium concentrations (opposite effect to

calcitonin).

• Stimulates the breakdown of calcium in the bones and

causes it to be released into the blood