Download Endocrine System

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
Thymus
Adrenal gland
Thyroid and
Parathyroid glands
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 steadyhomeostasis
• 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.
• Lactation also involves positive feedback in that
the more the baby suckles, the more milk is
produced, via a surge in prolactin secretion.
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
Kidney
Ureter
Urinary
Bladder
Urethra
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.