KSS 310- Endocrine system

Endocrine System

A system made up of glands that release hormones into the bloodstream.

Hormones

Chemical messengers that help maintain homeostasis.

Target Cell

A cell that possesses receptors specific for that hormone.

Steroid Hormones

Hormones derived from cholesterol; lipid-soluble (examples: testosterone, estrogen).

Peptide Hormones

Hormones made of amino acids; water-soluble (examples: insulin, glucagon).

Amine Hormones

Hormones derived from amino acids; may act like either type (examples: epinephrine, thyroxine).

Lipid-Soluble Hormones

Hormones that can diffuse through the cell membrane and bind to receptors inside the cytoplasm or nucleus.

Water-Soluble Hormones

Hormones that cannot cross the membrane and must bind to a receptor on the surface of the cell.

Second Messenger

A molecule activated by a hormone binding to a receptor, often called cyclic AMP (cAMP).

Neural Stimuli

Triggers for hormone release initiated by nerve signals for fast control.

Humoral Stimuli

Triggers for hormone release initiated by changes in blood levels.

Hormonal Stimuli

Triggers for hormone release initiated by other hormones.

Negative Feedback

A feedback loop that stops release when balance is restored (example: high blood glucose → insulin → glucose drops → insulin stops).

Positive Feedback

A feedback loop that amplifies until an event ends (example: oxytocin during childbirth).

Growth Hormone (GH)

A hormone from the anterior pituitary that promotes protein synthesis and fat metabolism.

Thyroid-Stimulating Hormone (TSH)

A hormone from the anterior pituitary that stimulates the thyroid gland.

Antidiuretic Hormone (ADH)

A hormone from the posterior pituitary that promotes water retention.

Oxytocin

A hormone from the posterior pituitary that stimulates contractions during childbirth.

Thyroxine (T4) / Triiodothyronine (T3)

Hormones from the thyroid that increase metabolic rate and accelerate growth.

Calcitonin

A hormone from the thyroid that decreases blood calcium levels.

Parathyroid Hormone (PTH)

A hormone from the parathyroid that increases blood calcium levels.

Epinephrine / Norepinephrine

Hormones from the adrenal medulla that increase heart rate and glycogen breakdown.

Aldosterone

A hormone from the adrenal cortex that increases blood levels of sodium and water, raising blood pressure.

Cortisol

A hormone from the adrenal cortex that promotes glucose production and has anti-inflammatory effects.

Glucagon

A hormone from the pancreas that raises blood glucose levels.

Insulin

A hormone from the pancreas that lowers blood glucose levels.

Estrogen / Progesterone

Hormones from the ovaries that promote the development of female reproductive organs.

Testosterone

A hormone from the testes that promotes the development of male reproductive organs.

Calcitonin feedback loop

increased calcium blood levels -> sensed by thyroid -> calcitonin release by thyroid -> Osteoblasts in bones increase bone deposition -> negative feedback to thyroid

parathyroid feedback loop

Parathyroid detects low Ca level --> releases PTH --> Osteoclasts in bones are stimulated to break down bone --> Ca levels return to normal range

Glucagon Feedback Loop

low blood sugar ->pancreas-> glucagon released -> increase blood glucose-> negative feedback to pancreas

Insulin feedback loop

Rising blood glucose level detected --> pancreas releases insulin --> Liver takes up glucose and stores it as glycogen --> Blood glucose level declines.

Rapid increase during exercise

EPI/NE response to Exercise

increase during prolonged stress

cortisol response to Exercise

Increased with resistance training

GH response to Exercise

Decrease during exercise

Insulin response to Exercise

Increase during exercise

Glucagon response to Exercise

Increases with resistance training

Testosterone response to Exercise

Maintained with exercise

Estrogen response to Exercise

Increased when dehydrated

ADH response to Exercise