Transcript Endocrine System - Salisbury Composite High School

Endocrine System
Types of hormones and homeostasis
Negative feedback
Endocrine glands overview
The pituitary
Posterior pituitary
Anterior pituitary
Thyroxin - metabolism
PTH and Calcitonin - blood calcium
Insulin / glucagon – blood sugar
Adrenal Glands
Other glands
Recap: Homeostasis
• Homeostasis – is a state of equilibrium where
an organism’s internal environment remains
relatively constant, despite ongoing
environmental changes.
Recap: Negative Feedback
• prevents chemical
imbalances in the body.
• Once the body has
responded to a change in
the environment, the
effect is detected,
receptors are activated,
and further response is
inhibited.
Examples of Negative Feedback
Two Categories of Glands
1. Exocrine Glands –products do not enter the
bloodstream, but are released by ducts or tubes
into a body cavity, or out of the body.
Ex) sweat glands, and salivary glands.
2. Endocrine Glands –release hormones into
the blood stream
Hormones in the Body
Hypothalamus
• Produces Anti-Diuretic Hormone and
Oxytocin
-stored in the posterior pituitary gland
• Produces releasing and inhibiting factors to
control the pituitary gland
Pituitary Hormones
• Pituitary Gland
– the master gland
Posterior Pituitary –stores and releases
ADH and oxytocin
Anti-Diuretic Hormone (ADH) – increases
water re-absorption by the kidneys when the
blood becomes too concentrated with solutes
– Diabetes insipidus – excessive urination,
dehydration and thirst resulting from a lack of
ADH, usually caused by a tumor
Ex) Oxytocin –
stimulates uterine
contractions during
childbirth, and
triggers initial milk
production
– Pitocin – is a
synthetic form of
oxytocin that is
often given to
induce labour.
Anterior Pituitary – produces hormones
which are controlled by releasing factor
secreted by the hypothalamus.
Ex) Thyroid Stimulating Hormone
(TSH) – stimulates the thyroid gland to
release thyroxin (controls metabolism) and
calcitonin (controls blood calcium)
Ex) Adrenocorticotropic Hormone
(ACTH) – stimulates the adrenal cortex to
release aldosterone and cortisol which
regulate the release of fatty acids in the
blood and regulate fat metabolism
Ex) Prolactin Hormone (PRL) –
stimulates milk production in the
mammary glands after birth, suckling or
other stimulation may result in the “let
down” reflex
Ex) Follicle Stimulating Hormone (FSH) –
stimulates the production of gametes (sperm
and egg) in the male and female reproductive
systems
Ex) Luteinizing Hormone (LH) – stimulates
the production of hormones (estrogen,
progesterone and testosterone) in the male and
female reproductive systems
Ex) human Growth Hormone (hGH) –
regulates the growth of bones and tissues
during childhood by assisting amino acids
across cell membranes for protein
synthesis.
• Gigantism –
overproduction of
growth hormone
during the growth
years, results in very
large individuals (79 ft)
• often have diabetes
and other medical
issues.
• Acromegaly – overproduction of growth
hormone during the adult years, results in
excessive growth of the cartilage of the nose,
hands, feet, jaw, tongue and internal organs.
The World’s tallest woman.
Defen is 34 years old and 7ft 8" tall.
• Dwarfism –
underproduction of
growth hormone
during the growth
years and
adolescence, results in
individuals of short
stature with
proportionate or
disproportionate size.
• Extra: Melanocyte Stimulating
Hormone (MSH) – affects skin
pigmentation
Thyroid Gland
The thyroid gland is responsible for
the secretion of two hormones:
1. Thyroxin – increases the rate of
cellular respiration by increasing
oxygen uptake in cells
-Regulates metabolism
2. Calcitonin – decreases the concentration
of blood calcium
-Decreases the rate that calcium leaves the
bones, reduces intestinal uptake of
calcium, and reduces reabsoprtion of
calcium by the kidneys. (Works in
opposition to parathyroid hormone)
Thyroid Disorders
• Hyperthyroidism – excessive production of
thyroxin results in nervousness, weight loss,
sweating, tachycardia, hyperactivity
• Hypothyroidism – underproduction of
thyroxin results in sluggishness, depression,
weight gain, tiredness, goiter
– Goiter may also be caused by a lack of
iodine in the diet.
• Cretinism – hypothyroidism in a developing
infant results in permanent and severe
retardation and stunted growth
Thyroid Surgery
Parathyroid Gland
• a set of four pea-sized glands embedded in the
posterior portion of the thyroid.
• Parathyroid Hormone (PTH) – increases
blood calcium
– increases removal of calcium ions from bones
and increases re-absorption of calcium ions
from the kidneys.
• Tetany – underproduction of the parathyroid
(low blood calcium) resulting in muscle
spasms, convulsions and nervous twitches
• Osteoporosis – demineralization of the
bones due to overproduction of the
parathyroid, or lack of calcium
– very common after menopause due to lowered
estrogen levels (estrogen counters the effect of
PTH)
The Pancreas
• Islets of Langerhans – are glandular clusters of
cells in the pancreas that produce insulin and
glucagon
Alpha cells – produce glucagon, which
stimulates the conversion of glycogen to
glucose by the liver raising blood glucose
Beta cells – produce insulin, which stimulates
the uptake of glucose by the body’s cells,
lowering blood glucose
Regulation of Blood Sugar
Blood Sugar Disorders
• Diabetes Mellitis –sugar diabetes or
hyperglycemia
– blood sugar is very high (while cellular
glucose is too low)
– increased urination, fruity odour on the
breath, weight loss, fatigue, blindness
– Type I /Juvenile Onset – the inability
to produce insulin, degeneration of beta
cells
– Type II / Adult Onset – decreased
insulin production or ineffective use of
insulin (may be related to insulinase)
• Diabetic Coma – slow onset, lack of insulin
that result in the brain being deprived of
glucose, and eventually shutting down (insulin is
required)
• Insulin Shock – sudden excess amount of
insulin causing dizziness, sweating, hunger,
confusion, normal urine output (sugar is
required)
• main
Adrenal Glands
• located just above the kidneys
• composed of outer cortex and an inner
medulla which produce different
hormones.
Adrenal Medulla
Adrenaline/Epinephrine – released to elicit the fight
or flight response during short term stress, causes:
• increased blood glucose
• increased heart rate
• increased metabolism
• increased blood flow to the skeletal muscles
• decreased rate of digestion
• relaxes smooth muscles in the walls of the
bronchioles
Adrenal Cortex
-stimulated
by Adrenocorticotropic Hormone
Produces three classes of hormones:
1. Sex hormones – small amounts of both male
and female sex hormones are released by the
adrenal cortex. Over-activity causes
masculinization of females and feminization
of males.
2. Cortisol – is a glucocorticoid( steroid that
binds with glucocorticoid receptors)
-long term stress
-breaks down muscle proteins to produce amino
acids which are converted into glucose in
response to stress
- stimulates the metabolism of fatty acids raising
the blood glucose.
- counter the inflammatory response.
• Aldosterone – is a mineralocorticoid (steroid
that binds to mineralocorticoid receptor).
– regulates Na+/K+ levels and maintains blood
pressure.
– promotes absorption of Na+ ions by the
kidney, drawing in water and thus increasing
blood pressure.
Adrenal Disorders
• Cushing’s
Syndrome – over
activity of the adrenal
cortex resulting in
edema, moonlike face,
masculinization of
females, and high
blood sugar.
• Addison’s Disease – under-activity of the
adrenal cortex resulting in low blood
pressure, acidosis, fainting, increased risk
of infection and bronzing of the skin.
Extra: Other Hormones
• Thymus – secrete thymosin that stimulates
maturation and differentiation of the T-cells in the
immune system (most active in children with
developing immune systems)
• Melatonin – secreted by the pineal gland,
regulates circadian rhythms such as sleep/wake
cycles, migration, mating and sexual
development.
• Prostaglandins
– made by tissue not glands
– Not delivered in blood
– Act on the cells that make them or nearby
tissue
• Link
• Pheromones – are messengers that act between
individuals of a species, secreted to attract a
mate, mark territory, provide warning of danger.