Download The Endocrine System

The Endocrine System
Comparing Nervous & Chemical
Regulation
• Nervous system:
– Sends electrochemical impulses through neurons
– Sends message quickly and directly to specific body part
– Rapid response
• Endocrine system:
– Releases chemicals called hormones from ductless glands
– Hormones travel through blood stream to target organ
– Slower in producing an effect but effect lasts longer
http://www.youtube.com/watch?v=R218fFZhq4c&safe=active
• Both systems:
• Help to maintain balance or homeostasis
Types of Glands
• Exocrine glands: (glands with ducts)
• Ex: bile, saliva
• Endocrine glands: (“ductless glands”)
– Secretions transported by bloodstream
• Ex: hormones like adrenaline
• Hormones:
– “Chemical messengers”
– Released into bloodstream at one part of body and
cause effect elsewhere at a particular target tissue
• Target Tissue:
– recognizes and responds to a specific hormone by
means of receptor proteins
– Effect may be to stimulate or inhibit
http://www.youtube.com/watch?v=HrMi4GikWwQ&safe=active
Regulation of Hormone Secretion
• Rate of secretion varies with
needs of body
• Negative Feedback Loop
– Change occurs that triggers
series of events that
eventually reverses the
change
• Helps keep constant levels
– Ex: blood glucose levels
• Ex: Thermostat in house
Feedback Loops Maintain Balance
• Temperature Control in Body
– Hypothalamus (region in brain)
• Maintains body temp. at set point
.
– Temp drops
• stimulates muscles to shiver
generating heat
• Once temp restored, stops shivering
– Temp. rises
http://www.youtube.com/watch?v=_Qb
D92p_EVs&safe=active
• stimulates body to sweat
• Once temp. restored stops sweating
Glands of the Human
Endocrine System
Pineal Gland
• Pea sized gland attached to base of brain
– Secretes melatonin
– Regulation of sleep cycle
Pituitary Gland
• Small gland attached
to base of brain at
hypothalamus
• “Master gland”
controls activity of
many other glands
Hypothalamus
Controls the Pituitary
• Hypothalamus
– Controls release of
hormones by pituitary
http://www.youtube.com/watch?v=qJj
_-3dZ4ZQ&safe=active
– Receives information
from nervous system to
help control gland
– Link between nervous
and endocrine systems
Hormones of the Pituitary Gland
• TSH
– thyroid stimulating hormone
– Stimulates production and release of
thyroxine by thyroid gland
http://www.youtube.com/watch?v=Vae5CcaPN_8&safe=active
Hormones of the Pituitary Gland
• ACTH
– adrenocorticotropic
hormone
– Stimulates release of
hormones from cortex
of adrenal glands
• Ex: cortisol
Hormones of the Pituitary Gland
• Human Growth Hormone:
– Controls growth of body,
muscles, long bones and
cartilage
– Too much: gigantism and acromegaly
– Too little: dwarfism
http://www.youtube.com/watch?v=AX48MPIDyYw&safe=active
Hormones of the Pituitary Gland
• FSH:
– follicle stimulating
hormone
– Stimulates
development of egg
cells in ovaries and
sperm in testes
• LH:
– luteinizing hormone
– Causes egg release
in ovary
Hormones of the Pituitary Gland
• ADH:
– antidiuretic hormone
– Controls water
reabsorbtion by kidney
– When released, more
water is absorbed in
nephron, making urine
more concentrated
Thyroid Gland
• Secretes thyroxine
– Contains iodine
– Need iodine in diet for it to
function properly
• Secretions controlled by
pituitary
• Regulates metabolism
– how we release energy
from food
• Too much thyroxine
– Hyperthyroidism
• Eyes protrude, goiter
• Too little thyroxine
– Cretinism
• Short stature, mental
retardation
Parathyroid Glands
• 4 tiny oval glands
embedded in back of
thyroid
• Secretes parathyroid
hormone
• Regulates calcium
metabolism
• Needed for proper
nerve and muscle
function
http://www.youtube.com/watch?v=g1U_HNi7sDU&safe=active
– Low blood calcium – increases hormone
• stored calcium released from bones into blood
– High blood calcium– decreases hormone
• excess calcium stored in bones
• Too much parathyroid hormone
– Too much calcium taken from bones (brittle)
• Too little parathyroid hormone
– Low blood calcium causes skeletal muscles to
contract violently (tetany)
Thymus Gland
• Located in upper chest near the heart
– Helps in development of T-lymphocytes to
defend against infection
Adrenal Glands
• On top of kidneys
• Has two layers
– inner medulla
– outer cortex
• Hormones help
body deal with
stress and “fight or
flight response”
• Adrenal Medulla:
– Secretes Adrenalin
– In response to sudden stress (fear, anger, pain)
– Increases heartbeat, blood pressure, breathing
Fight of Flight Response:
http://www.youtube.com/watch?v=4g25d7_Afmc&safe=
• Adrenal Cortex:
– Secretes
• Cortisol
– Regulates sugar metabolism
Pancreas
• Islets of Langerhans
– small clusters of hormone
secreting cells
– One type secretes insulin
– One type secretes glucagon
• Work together to control
glucose levels in blood
• After digestion, glucose levels in blood increase
• Insulin Secreted: lowers blood glucose
– increases rate glucose moves into cells from
bloodstream
– promotes excess glucose to change into glycogen
in liver
• In between meals, when blood glucose low
• Glucagon Secreted: Raises blood glucose
– Promotes change of glycogen stored in liver to
become glucose in blood stream
• Diabetes
– Failure to produce enough
insulin
•
•
•
•
Glucose not absorbed by cells
Blood glucose levels high
Excess sugar in urine
Can go into diabetic shock,
cause blindness, heart
disease and even death
– Test blood sugar levels
regularly, get insulin shots
http://www.youtube.com/watch?v=qzjjW--I-2Q&safe=active
The Gonads
• Secrete sex
hormones
• Related to
development of
secondary sexual
characteristics
• Production of egg
and sperm cells
• Ovaries:
– Secrete estrogen and progesterone
– Stimulates development of female reproductive
system and secondary sexual characteristics
– Controls menstrual cycle
• Testes:
– Secrete male sex hormone testosterone
– Stimulates development of male reproductive
system and secondary sexual characteristics
• Anabolic Steroids:
– chemicals derived from testosterone
– Help build body mass and muscle strength
– Can cause liver and kidney disorders, high blood
pressure, aggressive behavior and low sperm count,
impotence, acne, stunted growth, heart problems
– In women can cause masculinization, stop menstruation
Major Focus Questions
• What are hormones and how do they control the
activity of specific target tissues in the body?
• What are the functions of the human endocrine
glands and their hormones?
• How is hormone secretion regulated through
negative feedback?
• Compare and contrast the nervous and
endocrine systems
• Crash Course: Endocrine System
• http://www.youtube.com/watch?v=WVrlHH
14q3o&safe=active
• http://www.youtube.com/watch?v=YI2qYR
WzSZ4&safe=active