Transcript ENDOCRINE GLANDS

ENDOCRINE GLANDS
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Endocrine glands secrete hormones into the bloodstream.
Hormones are chemical messengers traveling through the bloodstream
Target cells:
Bodies response to hormones are slower and longer lasting
Glands: (fig. 42-3)
organ that produces a secretion and released from that cell
Endocrine glands: Produce secretions and release directly
Exocrine glands: Release secretions through ducts: sweat glands
THYROID GLAND (see fig. 42-5)
Wraps around the upper part of the trachea just below the larynx
Produces the hormone, thyroxine; need iodine in your diets
affects most cells of the body by regulating metabolic rates
Hyperthyroidism: too much thyroxine is produced
Hypothyroidism: too little thyroxine is produced
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Hypothyroidism is associated with goiter and cretinism
The thyroid gland also secretes calcitonin
Parathyroid Gland
Attached or embedded to the back of the thyroid gland
Secretes parathyroid hormone (PTH) (reabsorption of Ca in kidneys)
Regulates the calcium levels (removal results in muscle spasms)
Works with calcitonin and vitamin D for muscle and nerve function
When removed injections of PTH are necessary or tetany sets in
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Adrenal Glands
Sits on top of each kidney
Adrenal Cortex: 80% mass of the gland
corticosteroids: essential for normal body functions
aldosterone- regulates reabsorption of Na and excretion of K
cortisol- controls the rate of metabolism of carbos, lipids,
and proteins, & helps us cope with stress.
Decreased activity results in Addison Disease
weight loss, low blood pressure and possible death
treatment: doses of adrenal cortical hormone
Increased activity results in Cushing syndrome
obesity, increase blood sugar, weakening bones
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Adrenal Medulla
Produces neurohormones
adrenaline- Increases heart rate, blood pressure, and blood to
skeletal muscles. Increases conversion of glycogen to glucose and
stimulates the rate of metabolism during stressful situations
noradrenaline- stimulates the heart muscle
These actions get us ready for fight or flight
Reproductive Glands
gonads- body’s reproductive glands
ovaries- produces eggs
estrogen- development of ova and physical characteristics such
as reproductive system, widening hips, and breast development.
progesterone- Prepares the uterus for the arriving embryo
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Testes- produce sperm
androgens- Normal sperm development and production, growth of
facial hair, increase body size, and deepening voice.
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Pancreas
Both an exocrine and endocrine gland
islets of Langerhans
Each islet is composed of beta cells that secrete insulin and alpha
cells that secrete glucagon which regulate glucose level in the body
Insulin: Results from glucose levels rising.Beta cells release insulin
and target cells of the liver, muscles, & fat tissue.
Glucagon: 1-2 hrs. after eating, blood glucose drops, alpha cells
release glucagon. This stimulates cells to break down glycogen and
increase glucose levels.
Fat cells break down fats to be used to make carbohydrates
Diabetes Mellitus: undersecretion of insulin (Fig. 42-9)
Glucose in the blood is so high the kidneys can’t absorb all the
glucose, so it is excreted it the urine.
Two Types: Juvenile-onset (Type-I) & Adult-onset (Type-II)
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Pituitary Gland & Hypothalamus
Why known as the Master Gland?
Place where nervous system and endocrine interact
Secretes 9 hormones that directly regulate body functions
Controls the release of hormones by several other glands
Divided into two parts: anterior and posterior pituitary
Posterior: secretes antidiuretic hormone (ADH) and oxytocin
ADH-reabsorb water from kidneys
Oxytocin- contraction of uterus, release of breast milk
In males ?????????????????
Anterior: follicle stimulating and luteinizing hormones control the
growth, development and functioning of ovaries and testes
thyroid stimulating, adrenocorticotropic, growth (somatatropin,)
melancocyte-stimulating prolactin, & (SEE FIG. 42-11)
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Pituitary Gland Disorders;
giantism, & dwarfism
acromegaly: no height increase due to bones ossifying; but
diameter of toes and fingers increases, enlarged jaw
treatment: surgery, radiation, &/or hormone therapy
treatment: surgery, radiation, or hormone therapy
Hypothalamus: Attached to the posterior pituitary
controls secretions of the pituitary, influenced by levels of
hormones in the blood.
Neurosecretory cells extend axons into posterior pituitary
vesicles release contents (ADH & oxytocin)
so it controls the posterior pituitary & the activity of the body
Produces releasing hormones which are secreted directly into
capillaries and then into veins, and more capillaries. It enters the
anterior pituitary, affecting the production of pituitary hormones.
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