Download Chapter 9 Endocrine System

Chapter 9 Endocrine System
Objectives
 Define hormone and describe the three types
 Explain what makes a target organ
 Describe the role of a receptor
 Describe how hormones work
 Describe three ways hormones are stimulated
 Define negative feedback
 Match the hormones produced with the endocrine glands
 Describe disorders of the endocrine system
Chapter 9 Endocrine System
Endocrine system – maintains homeostasis by directing the
activity of cells by the use of hormones
regulates mood, growth and development, tissue function,
metabolism, reproductive processes
Endocrinology – study of hormones and endocrine organs
Hormones – chemicals that regulate cell activity
 amino acid-based (proteins, peptides, amines)
most hormones
 steroids (made from cholesterol)
sex hormones made from the gonads
adrenal cortex hormones
 prostaglandins (local hormones from cell membranes)
Mechanisms of Hormone Action
hormones increase or decrease the rate of a metabolic
process
target cells (target organs) – must have correct protein
receptor for a specific hormone
Two mechanisms used by hormones…
Direct Gene Activation
Second-Messenger System
Mechanisms cont.
Direct Gene Activation –
by steroidal hormones and thyroid hormone (T3, T4)
lipid soluble
can diffuse through plasma membrane of target cell
enters nucleus
binds to a receptor protein
bind to cell’s DNA
activates genes to transcribe mRNA
mRNA is translated in the cytoplasm for new proteins
Mechanisms cont.
Second-Messenger System –
water soluble, nonsteroidal, amino acid-based
unable to enter the target cell (hydrophobic lipid tails)
hormone binds to receptor on the plasma membrane
receptor activates an enzyme
produces a second messenger molecule (cAMP)
Control of Hormone Release
Negative feedback mechanisms – regulate blood levels of
nearly all hormones
an internal or external stimulus produces enzyme secretion
rising hormone levels inhibit further hormone release
How hormone production is stimulated…
 hormonal stimuli – most common, glands secrete
hormones which stimulate other glands to secrete
hormones
 humoral stimuli – blood levels of ions or nutrients stimulate
the production of hormones (calcium, glucose, etc.)
 neural stimuli – nerve fibers stimulate hormone release
(sympathetic nervous system stimulates release of
norepinephrine and epinephrine during stress)
Hypothalamic/Pituitary System
hypothalamus – located in the brain is the primary link
between the endocrine and nervous systems. Controls the
pituitary gland which controls other glands.
Nerve cells in the hypothalamus receive information sensed
by the brain, such as environmental temperature, light
exposure patterns, and feelings, and relays it to the
pituitary gland which secretes hormones.
Pituitary gland – the “master gland”
makes hormones that control other endocrine glands
Two parts to the pituitary gland…
anterior and posterior lobes
Pituitary Gland
posterior pituitary hormones (not made here)…
(produced in hypothalamus and stored in pituitary)
antidiuretic hormone (ADH) – inhibits diuresis (prevents
excess water excretion by the kidneys) Ethanol inhibits
release of ADH, which leads to urination and dry mouth.
Diuretics interfere with the production of ADH. Prescribed
to lower blood pressure by decreasing blood volume.
oxytocin – contracts uterus during labor
synthetic oxytocic drugs induce labor
Pituitary Gland
anterior lobe hormones (6)…
all are proteins, act through secondary-messenger
systems, and most are regulated by negative feedback
tropic hormones (stimulate other endocrine glands)
thyroid-stimulating hormone (TSH) – thyroid
adrenocorticotropin hormone (ACTH) – stimulates adrenal
cortex
gonadotropic hormones…
leutinizing hormone (LH) – ovaries, causes ovulation
testes, testosterone production
follicle-stimulating hormone (FSH) – stimulates
development of a follicle in the ovaries, sperm in men
Pituitary Gland cont.
nonendocrine targets…
prolactin (PRL) - breasts, stimulates milk production
growth hormone (GH) - growth of muscles and bones
endorphins – produced in response to pain and exercise,
related to morphine
produced by pituitary and hypothalamus
Pituitary Disorders
hyposecretion of GH
pituitary dwarfism
hypersecretion of GH
gigantism – during childhood
acromegaly – during adulthood
hyposecretion of FSH or LH
sterility in males and females
hyposecretion of ADH
diabetes insipidus – excessive urine output
Thyroid Gland
located in the neck
pituitary gland controls the release of thyroid hormones
Thyroid hormones contain iodine, and regulate metabolism
(body temperature and weight), muscle tone, digestion,
heart rate, blood pressure
Without iodine in the diet the thyroid tries to compensate and
enlarges causing goiter.
thyroid hormone – (thyroxine (T4) triiodothyronine (T3))
body’s major metabolic hormone, controls the rate glucose
is burned (body heat and energy)
calcitonin – decreases blood calcium, increases bones
decreases production in adults
Thyroid Disorders
hyperthyroidism (usually results from a tumor)
Graves’ disease – eyes bulge, rapid heartbeat, weight loss,
nervous, and agitated behavior
treated by removing part of thyroid, or drugs
hypothroidism
myxedema – physical and mental sluggishness, puffiness
of the face, fatigue, poor muscle tone, low body
temperature, obesity, dry skin
hyposecretion of thyroxine
cretinism – dwarfism, mentally retarded, dry skin
iodine deficiency
goiter – enlargement of thyroid
Parathyroid Glands
two pairs are embedded in the surface of the thyroid gland
parathyroid hormone (PTH) – stimulates bone destruction to
increase calcium levels in the blood
Parathyroid Disorders
hypoparathyroidism
tetany – blood calcium levels fall too low and muscles
spasm
hyperparathyroidism
massive bone destruction
Pancreas
Both a ducted gland and ductless gland
Ducted…
Secretes digestive enzymes into the small intestine.
Ductless...
secretes insulin and glucagon by the islets of Langerhans
glucagon – raises blood sugar levels
insulin – lowers blood sugar levels
diabetes mellitus – body does not make enough insulin
Adrenal Glands
located on top of the kidneys and composed of two parts
 outer adrenal cortex – secretes corticosteroids such as
cortisone which are anti-inflammatory.
sex hormones
androgens (male sex hormones)
estrogens (female sex hormones)
 inner adrenal medulla – secretes catecholamines
epinephrine (adrenaline) and norepinephrine in response
to stressors such as fright, anger, caffeine
increases heart rate, blood pressure, and blood glucose
Adrenal Gland Disorders
hyposecretion of adrenal cortex hormones
Addison’s disease – bronze tone of the skin, weak muscles,
hypoglycemia, burnout, suppression of immune system
hypersecretion
Cushing’s syndrome – swollen “moon face”, “buffalo hump”
of fat on upper back, high blood pressure, hyperglycemia,
weak bones, severe depression of immune system
hypersecretion of sex hormones
masculinization – beard in females
Gonads – secrete sex hormones
controlled by pituitary gland hormones (FSH, LH)
responsible for secondary sex characteristics
 ovaries – secrete estrogen and progesterone
 testes – secrete androgens such as testosterone.
Pineal Gland
located near the center of the brain and is stimulated by
nerves from the eyes
secretes melatonin at night – promotes sleep
hypersecretion -seasonal affective disorder (SAD) causes depression,
oversleeping, weight gain, tiredness, sadness
Thymus Gland
located in the upper thorax
decreases in size in adulthood
thymosin – development of white blood cells, T cells
Hormone – Gland – Function - Disorder
FSH
Follicle Stimulating Hormone
Anterior Lobe of Pituitary
stimulates production of ova and sperm
Hormone – Gland – Function - Disorder
Insulin
Pancreas
reduces blood glucose
Hypoglycemia
Diabetes Mellitus
Hormone – Gland – Function - Disorder
Calcitonin
Thyroid
reduces blood calcium levels
muscle spasms
osteoporosis
Hormone – Gland – Function - Disorder
Oxytocin
Posterior Lobe of Pituitary Gland
contraction of uterus
during childbirth &
milk production
Hormone – Gland – Function - Disorder
Thymosin
Thymus Gland
T Lymphocytes
Hormone – Gland – Function - Disorder
PTH
Parathyroid hormone
Parathyroid
raises blood calcium level
increase blood Ca, weak bones
Tetany, muscle spasms
Hormone – Gland – Function - Disorder
ADH
Antidiuretic hormone
Posterior lobe of Pituitary Gland
retention of water by kidneys
reduces urine output
Diabetes insipidus
Hormone – Gland – Function - Disorder
Melatonin
Pineal Gland
daily and seasonal rhythms
SADS, depressed mood
insomnia
Hormone – Gland – Function - Disorder
TH
Thyroid Hormone
Thyroid Gland
stimulates metabolism
Goiter, Graves Disease, exophthalmy
Cretinism, Myxedema
Hormone – Gland – Function - Disorder
Estrogens
Ovaries
female secondary sex
characteristics, uterine lining
growth
Hormone – Gland – Function - Disorder
LH
Luteinizing hormone
Anterior lobe of Pituitary Gland
stimulates ovaries & testes
Hormone – Gland – Function - Disorder
Epinephrine
Adrenal medulla
raises blood glucose,
fight / flight response
alarm state
Hormone – Gland – Function - Disorder
Androgens
Testes
male secondary sex
characteristics, sperm formation
Hormone – Gland – Function - Disorder
Gonadocorticoids
Adrenal cortex
androgens & estrogens
Hormone – Gland – Function - Disorder
GH
Growth Hormone
Anterior lobe of Pituitary Gland
growth of bones and muscles
gigantism, acromegaly
pituitary dwarfism
Review of glands and their hormones
Glucagon
Pancreas
raises blood glucose
Review of glands and their hormones
PRL
Prolactin
Anterior lobe of Pituitary Gland
milk production
Review of glands and their hormones
Glucocorticoids (cortisol)
Adrenal Cortex
increases blood glucose
Cushing’s syndrome
Addison’s Disease
Review of glands and their hormones
Progesterone
Ovaries
growth of uterine lining
Review of glands and their hormones
TSH
Thyroid-stimulating hormone
Anterior lobe of Pituitary Gland
stimulates thyroid gland
Review of glands and their hormones
Mineralocorticoids
Adrenal Cortex
regulate mineral content in blood
Review of glands and their hormones
MSH
Melanocyte Stimulating Hormone
Pituitary (intermediate lobe)
darker skin