Endocrine System Hormones!

The human endocrine system The endocrine system consists of ductless glands that produce hormones. Hormones are chemical messengers that travel through the blood stream and affect activities throughout the body.

Human Endocrine System Diagram Hypothalamus and Pituitary gland Thyroid and Parathyroid glands Thymus Adrenal gland Pancreas Ovary Testes

Main players Hypothalamus-secretes many hormones that regulate the pituitary Pituitary makes hormones that stimulate adrenals, thyroid, growth, and the production of ova and sperm Thyroid-regulates metabolism Parathroid-regulates calcium levels Thymus-T-cell development Adrenals-make adrenalin for flight of fight Pancreas-blood glucose levels

Feedback loops How hormones are controlled!

Negative feedback loops-for homeostasis! Most common way to keep levels steady- homeostasis When gland X releases hormone X, this stimulates target cells to release hormone Y. When there is an excess of hormone Y, gland X "senses" this and inhibits its release of hormone X. Example-glucose homeostasis with insulin

Positive Feedback Loops Less Common When gland X releases hormone X, this stimulates gland X to release more hormone X. This causes a HUGE amount of hormone in a short period of time.

Positive feedback loops One example is the onset of contractions in childbirth. When a contraction occurs, the hormone oxytocin is released into the body, which stimulates further contractions. This results in contractions increasing in amplitude and frequency causing the release of more oxytocin.contractions childbirthoxytocin Lactation also involves positive feedback in that the more the baby suckles, the more milk is produced, via a surge in prolactin secretion. Lactation

Challenge! Which gland produces hormones for fight or flight? Which gland controls and regulates many other glands? Which one makes adrenaline? Which feedback loops contribute to homeostasis?

Excretory System Removes wastes from metabolism Involves lungs (for CO2) Involves kidneys (for urea)-Keep needed water

Human Urinary System Diagram Nephron Kidney Ureter Urinary Bladder Urethra Kidney

How it works The urinary system: the kidneys, ureters, urinary bladder and urethra Eliminate majority of metabolic wastes from the body. nephron is made of a Bowman’s capsule: tubules and capillaries (called the glomerulus) Fluid (filtrate) enters capsule As filtrate passes through the tubule of the nephron, materials needed by the body are reabsorbed and the remainder of the filtrate becomes urine.