Transcript 8.2 Hormones that Affect Blood Sugar

Hormones that Affect
Blood Sugar
Pancreatic Hormones
• Produced in the islets of Langerhans.
– Beta (β) cells produce insulin.
– Alpha (α) cells produce glucagon.
Hormonal Response to High
Blood Sugar
• ↑ blood sugar = release of insulin.
• Causes muscle, liver and other body cells
to become permeable to glucose.
• Glucose stored as glycogen.
• Result = ↓ blood sugar.
Hormonal Response to Low
Blood Sugar
• ↓ blood sugar = release of glucagon.
• Promotes breakdown of glycogen into
glucose, which is released into the blood.
• Result = ↑ blood sugar.
QUESTION 1
What happens when the body does not
produce insulin or the receptors no
longer responds to insulin?
Diabetes
• Type I Diabetes (Insulin Dependent):
– Early degradation of beta cells.
– Unable to produce insulin.
• Type II Diabetes (Non-Insulin Dependent):
– Decreased insulin production or ineffective use
of insulin.
– Controlled with diet, exercise and oral drugs.
Suffer from hyperglycemia (high blood sugar).
QUESTION 2
If glucose is not taken into body cells,
how does the body produce energy?
Diabetes
•
Absence of insulin means little or no
glucose in body cells.
– Cells metabolize fats and proteins for
energy.
QUESTION 3
If a person has very high blood sugar,
how does this impact filtration?
QUESTION 4
With respect to kidney function and
water balance, what happens when
glucose reabsorption does not occur?
Diabetes
•
Kidneys are unable to reabsorb all of
the blood glucose, so excess glucose
appears in urine.
•
People with untreated diabetes are
thirsty. Why?
Try This!
Describe why a person with untreated
diabetes would urinate frequently. Refer to
the two osmotic gradients in urine formation
in your answer.
Adrenal Glands
• Each composed of two glands.
1. Adrenal medulla  short-term stress.
2. Adrenal cortex  long-term stress.
Adrenal Medulla
• Produces epinephrine (adrenaline) and
norepinephrine (noradrenaline).
• “Fight-or Flight Response”.
– ↑ blood sugar (glycogen  glucose).
– ↑ HR, breathing rate & cell metabolism.
– Dilation of blood vessels.
– Pupil dilation.
Adrenal Cortex
• Produces 3 types of hormones:
– Glucocorticoids.
– Mineralcorticoids.
– Sex hormones.
Adrenal Cortex
• Glucocorticoids (e.g., cortisol):
– ↑ blood amino acids.
• Converted to glucose.
• Repairs damaged tissues.
– Fats broken down into fatty acids to ↑
available energy.
– ↓ insulin to ↓ blood glucose uptake (except
brain).
Fight or Flight and Blood Sugar
Why block insulin during fight-or-flight
response?
Hormones that Affect
Metabolism
Two Major Glands
• Thyroid Gland
• Parathyroid Gland
Thyroid Gland
• Thyroxine (T4)
• Triiodothyronine (T3)
– Both need iodine to be made.
– Used to oxidize sugar and other nutrients.
– More T4 in the blood will “boost metabolism”
Hypothyroid or Hyperthyroid
If the thyroid gland produces T4 and T3,
hormones that regulate metabolism, what
would happen if:
a) The thyroid stopped producing T4 and
T3? (hypothyroidism)
b) The thyroid could not stop producing T4
and T3? (hyperthyroidism)
Calcitonin
Calcitonin is also released by the thyroid,
and it counter-acts parathyroid hormone
(PTH) by:
• Inhibiting Ca2+ absorption by the intestines
• Increases Ca2+ reabsorption in the
nephrons of the kidney
Thyroid Negative Feedback
Loop
Acronyms:
• TRH – Thyroid Releasing Hormone
• TSH – Thyroid Stimulating Hormone
What happens if the body lacks
iodine?
Goiter
Parathyroid Glands
• Four groups of cells on the thyroid gland.
• Release a hormone called parathyroid
hormone, or “PTH”.
– PTH raises the calcium levels in the blood.
Negative Feedback
Human Growth Hormone
(HGH)
• Too much? - Giantism
• Too little? - Dwarfism
• Produced in and released
from the anterior
pituitary gland.
Famous Example:
How did Andre the Giant
die?
Human Growth Hormone
• Cause cells to grow in size and in number.
• Promotes protein synthesis.
• Promotes the breakdown of fats.
– ↑ GH, muscles use fatty acids as energy
– Loss of fat during growth spurts
Growth Hormone Doping?
• Some athletes believe that taking human
growth hormone supplements will increase
their athletic performance.
– In small groups, look up the practice of
“doping” with human growth hormone. Come
to a consensus about whether or not this
practice is safe. Be prepared to back up your
stance with evidence.