Chapter 12: The Endocrine System- Glands and Hormones

Hormones

Chemicals that have specific regulatory effects

• Released into surrounding fluid
• Regulate growth, metabolism, reproduction, and behavior
• Controlled by negative feedback

Target tissues

specific tissue for specific hormone; through receptors in the plasma membrane

Amino acid compounds

proteins and amino acids; all but adrenaline and gonadotropins

Steroids

derived from steroid cholesterol (lipid); produced by adrenal cortex and sex glands –sterone (steroid hormone)

Hormone Regulation

• Negative Feedback
• Positive feedback in case of oxytocin
• Rhythmic patterns

• Chemical messengers that have specific regulatory effects on target tissues
• Regulate growth, metabolism, reproduction and behavior

What are hormones and what are some effects of hormones?

Target tissue

What name is given to the specific tissue that responds to a hormone?

Amino acid compounds and steroids

Hormones belong to what two chemical categories?

Negative feedback

What is the most common mechanism used to regulate hormone secretion?

Pituitary Gland

• AKA Hypophysis
• Resides in the Sella Turcica
• Stimulates other glands to secrete
• Controlled by the hypothalamus
• Connects to the hypothalamus by the infundibulum

Anterior Lobe

• “Master Gland”
• Releases hormones that affect the working of other glands
• -tropin: hormones that stimulate other glands trop/o (acting on, influencing)

Releasing hormones

chemical messengers that come from the hypothalamus to release hormones from the anterior lobe

Portal system

pathway that releasing hormones travel from hypothalamus to the anterior lobe, circulatory pathway

Anterior Lobe Hormones

– Growth Hormone (GH) somatotropin
– Thyroid-stimulating Hormone (TSH) thyrotropin
– Adrenocorticotropic Hormone (ACTH) cortic/o (cortex)

– Prolactin (PRL) lact/o (milk)
– Follicle-stimulating Hormone (FSH)- gonadotropins

– Luteinizing Hormone (LH)- gonadotropins

Posterior Lobe Hormones- Antidiuretic Hormone(ADH)

decreases water excretion, Too much ADH raises BP, constricts arterioles

Diabetes Insipidus

too little ADH, too much output of fluids

Oxytocin

labor and lactation oxy (sharp, acute) toc/o (labor)

Pituitary Tumors

• Depends on the cells that involved
• Under activity develops obesity, sluggishness, ovary and testes problems

Gigantism

excess growth hormone in children

Acromegaly

excess growth hormone in adults acr/o (end, extremity) - megaly (enlargement)

Hypothalamus

What part of the brain controls the pituitary?

GH, TSH, ACTH, PRL, FSH, LH

What are the hormones from the anterior pituitary?

ADH, Oxytocin

What hormones are released from the posterior pituitary?

Thyroid Gland

• Located in the neck between the larynx and trachea
• Largest endocrine gland
• 2 lobes connected by the isthmus
• Hormone: thyroxin (T4) and triiodothyronine (T3)
• Metabolic rate, energy, protein metabolism
• Calcitonin – released when blood calcium is high

Goiter

enlargement of the thyroid gland

Simple goiter

uniform overgrowth

Adenomatous (nodular) goiter –

irregular appearing, tumor formation

Endemic goiter

lack of iodine

Hypothyroidism

thyroid underactivity

Infantile hypothyroidism (Cretinism)

lack of physical growth and mental development

Thyroiditis

inflammation of the thyroid due to autoimmunity

Hashimoto thyroiditis

destruction of thyroid by surgery, radiation, certain drugs, failure to produce TSH

Myxedema

hypothyroidism, fatigue, dry skin and hair, edema, slow heart beat, sensitive to cold

Graves disease

hyperthyroidism

Exophthalmos

bulging of eyes due to swelling behind the eyes
• Intense nervousness, weight loss, rapid pulse, sweating, tremors

Thyroid storm

sudden onset hyperthyroidism, can be fatal

Parathyroid Glands

• 4 glands embedded in the posterior of the thyroid gland
• Parathyroid Hormone(PTH)
• Promotes calcium release from bone into the bloodstream
• Negative feedback

Calcium Metabolism

Bones, teeth, nerves and muscles

Calcitonin

hormones released by the thyroid that lowers the amount of calcium in the blood

PTH

promotes release of calcium into the blood when levels are low

Calcitriol (Vit D)

increases intestinal absorption of calcium

Disorders of the Parathyroid Glands

• Low concentration of serum calcium
• Series of muscle contractions in the hands and face called tetany
• Excess production of PTH draws calcium from bones causing fragile bone

Increases metabolic rate

What is the effect of thyroid hormones on cells?

Iodine

What mineral is needed to produce thyroid hormones?

Goiter

What is the term for an enlarged thyroid gland?

Calcium

What mineral do PTH and calcitriol regulate?

Adrenal Glands

• AKA Suprarenal glands
• Located on top of kidneys
• Medulla – inner portion
• Cortex – outer portion
• Ren/o (kidneys)

Adrenal Medulla

Released due to Sympathetic Nervous System stimulus

Hormones: epinephrine (adrenaline) and norepinephrine (noradrenaline)

Fight –or-Flight hormones

Nephr/o (kidney)

Glucocorticoids

• Maintain body’s reserve of carbs
• Increases in times of stress, raises amino acids and fatty acids, stores in adipose tissue
• Suppresses inflammatory response, promotes healing
• Cortisol
• Cortic/o (cortex)

Mineralocorticoids

• Regulation of electrolyte balance
• Control sodium reabsorption and potassium secretion

Aldosterone

acts on kidneys to increase reabsorption of Na+, preventing depletion of Na+ in the blood.

Sex Hormones

• Small amounts
• Little effect on body

Disorders of the Adrenal Cortex- Addisons Disease

low levels of hormones, muscle atrophy, weakness, skin pigmentation, disturbances in salt and water balance
Autoimmune

Disorders of the Adrenal Cortex- Cushing Syndrome

hypersecretion of cortisol

obesity with round face,
thin skin, bruises easily,
muscle weakness, bone
loss elevated blood sugar

Epinephrine

What is the main hormone produced by the adrenal medulla?

Glucocorticoids, mineralocorticoids, and sex hormones

What three categories of hormones are released by the adrenal cortex?

Maintains glucose levels in times of stress

What effect does cortisol have on blood glucose levels?

Islets of Langerhans

• Endocrine portion of pancreas
• Islets are scattered throughout pancreas
• Hormone – Insulin (Beta-cells) insul/o (pancreatic islets)
• Assists in the uptake of glucose in the cells for energy
• Increases the rate of metabolism of glucose into glucogen by the liver and skeletal muscles
• Then the liver changes glucogen into fatty acids, then fats, then adipose tissue

Alpha Cells

Hormone – Glucagon
Works with insulin to regulate blood sugar

Cause liver to release stored glucose into the
blood stream raising blood sugar levels

Diabetes Mellitus

• Not enough insulin production, or
• Body does not respond adequately to insulin
• Liver increases production of glucose

Hyperglycemia

high blood glucose
hyper- (above, excessive) glyc/o (sugar, glucose)

polyuria

Kidneys excrete excess glucose, increasing urine output

polyphagia

Body feels it is starving , so more food is ingested

polydipsia

More excretion of water triggers thirst mechanism

Type I

autoimmune destruction of beta cells, no insulin production

Type II

adult onset, preventable; obesity, insulin is not being used adequately

Metabolic Syndrome – (Insulin Resistance Syndrome)

associated with high lipids and obesity

Gestational Diabetes

during pregnancy

Sex Glands

• Female ovaries, male testes
• Development of sexual characteristics (secondary sex characteristics)

(Sex) Hormones

– Testosteone (all male sex hormones are called androgens) andr/o (male)
– Estrogen
– Progesterone

Pineal Gland

• Hormone: melatonin
• Produced only during “dark periods” meaning sleep
• Sleep-wake cycles

Insulin and glucagon

What two hormones produced by the islets of the pancreas regulate blood glucose levels?

Insulin

What hormone is low or ineffective in cases of diabetes mellitus?

Secondary sex characteristics

Sex hormones confer certain features associated with male and female gender. What are these features called as a group?

Melatonin

What hormone does the pineal gland secrete?

Hormone-Producing Organs

Stomach and small intestines

Erythropoietin

from kidneys, stimulates RBC production in red bone marrow -poiesis ( making, forming)

Atrial Natriuretic Peptide

produced in the atria of the heart to increase sodium secretion by the kidneys and lower BP

natr/i (sodium)

Thymus

immunity development in early life, atrophies as an adult

Placenta hormones

changes in uterine walls and prepare breasts for lactation

Prostaglandins

• Local hormones that stay close to the site of the origin in minute quantities

• Broad range of activities when stimulated: constriction of blood vessels, intestines, and bronchioles by altering smooth muscle contractions; platelet function, nerve impulse transmission, fat metabolism, immune response (promotes fever and intensifies pain).

Hormones and Treatment

• Animal, synthetic, genetic engineering from recombinant DNA
• Growth hormone for children that have a deficiency
• Insulin for diabetics
• Adrenal steroids (corticosteroids) for inflammatory processes
• Epinephrine for allergic reactions

Hormones and Stress

• Fight or flight response
• Release of epinephrine, ACTH (raises glucose levels), growth hormone, thyroid hormones
• Must return to normal levels after stress is gone
• If cortisones remain high, immune response is compromised
• Other: heart disease, HTN, ulcers, insomnia, back pain, headaches

Kidneys

What organ produces erythropoietin?

Bones

What organ produces osteocalcin?

Heart

What organ produces ANP?

Epinephrine, cortisol, ADH, growth hormone

What are four hormones released in times of stress?

Aging and the Endocrine System

• Pancreas – Type II diabetes
• Thyroid – decrease in hormones; medication given after blood screening
• Gonadotropic hormones decrease in both sexes