The Endocrine System

Chapter 11

Gland types Endocrine glands

Send secretion DIRECTLY into blood stream

Ex: pituitary, thyroid, pancreas

Exocrine glands Send secretion into a

DUCT that carries secretion to its destination

Ex: salivary, lacrimal, pancreas

Terminology Endocrinology: the study of the structure, function, and

disorders of the endocrine system Hormone: chemicals secreted by endocrine glands Hypersecretion: over secretion (too much) of a hormone Hyposecretion: under secretion (not enough) of a hormone Target cells: specific body areas that are affected by

circulating hormones (traveling in blood stream) Local hormones: act on local or nearby cells without

traveling through blood; example: prostaglandins (PGs) Distress: bad stress that is negative and harmful Eustress: good stress that is positive and productive

Hormone function Control growth & development Govern reproductive system operation Regulate body function

Secretion, metabolism, internal clock

Remember feedback loops? Endocrine glands & hormones work by way

of feedback loops Negative Feedback Loops: will reverse action

Hormone levels are too high so secretion DECREASES/STOPS

Most are this type Positive Feedback Loops: will enhance action

Hormone levels are too low so secretion INCREASES/BEGINS

10 Endocrine glands (see p. 291, fig. 11-2) Hypothalamus (1) Pituitary (1) Pineal (1) Thymus (1) Thyroid (1) Parathyroids (4) Adrenals (2) Pancreas (1) Ovaries (2) Testes (2)

Hypothalamus Major link with nervous system Location/Cavity

Cranial cavity; below thalamus Hormones (2) & function

Releasing Factors (RF’s): stimulate production of hormones

Inhibiting Factors (IF’s): ceases production of hormones

These RF’s and IF’s stimulate the pituitary gland

Pituitary Gland = Hypophysis Location/Cavity

Cranial cavity; posterior to optic chiasm 2 lobes:

Anterior lobe (larger) Secretes 7 hormones

Posterior lobe (smaller) Secretes 2 hormones

Anterior Pituitary Hormones (7) & function

Prolactin (PRL) milk production Melanocyte Stimulating Hormone (MSH) melanin

production *Luteinizing hormone (LH)* sex hormone production

from gonads *Follicle stimulating hormone (FSH)* gamete

production from gonads *Adrenocorticotropic hormone (ACTH)* adrenal cortex Human growth hormone (hGH) mitotic rates *Thyroid Stimulating hormone (TSH)* thyroid

hormones

* Denotes tropic hormones; they control other endocrine glands.

Posterior Pituitary Hormones (2) & function

Oxytocin (OT) Promotes uterine contractions Synthetic OT = pitocin

Anti-diuretic hormone (ADH) Regulates water levels in blood Often called “water retaining” hormone Alcohol consumption interrupts its secretion

Pituitary Disorders Hypersecretion

hGH gigantism (adolescence) hGH acromegaly (adulthood)

Hyposecretion hGH dwarfism ADH diabetes insipidus

Pineal Gland Small, pine-cone shaped Location/Cavity

Cranial cavity; inferior to corpus callosum Hormone (1) & function

Melatonin sleep/wake cycles; menopause (females)

Thymus Gland Location/Cavity

Mediastinum; posterior

to sternum, between lungs Hormone (1) & function

Thymosin immunity Adversely affected by stress, so immunity is

often lowered as a result

Thyroid Gland Location/Cavity

Neck; inferior to larynx Hormones (3) & function

Triiodothyronine (T3) energy & metabolism Thyroxine (T4) energy & metabolism Calcitonin decreases blood calcium levels

Iodine is needed in the diet in proper amounts to maintain proper T3 & T4 levels. If iodine is inadequate, a goiter can develop.

Thyroid Disorders Hypersecretion

T3 & T4 = Grave’s disease Incredibly thin; bulging eyes

Hyposecretion T3 & T4 = cretinism (infancy) T3 & T4 = myxedema (adulthood)

Overweight; fluid retention

Parathyroid Glands Smallest of all endocrine glands Location/Cavity

In neck; one on each lobe of thyroid gland Hormone (1) & function

Parathyroid hormone (PTH) increases blood calcium levels Antagonist to calcitonin from thyroid

Pancreas Islets of Langerhans are the endocrine portion Also serves in digestion (exocrine) Location/Cavity

Abdominal; connected by mesentery to stomach & duodenum

Hormones (2) & function Glucagon increases blood sugar Insulin decreases blood sugar

Glucagon & insulin are antagonists to each other.

Pancreas Disorders Hypersecretion

Glucagon hyperglycemia (high blood sugar) = diabetes mellitus

Insulin hypoglycemia (low blood sugar) Hyposecretion

Glucagon hypoglycemia (low blood sugar) Insulin hyperglycemia (high blood sugar)

Adrenal Glands Location/Cavity

Abdominal; one sits on top of each kidney Divided into 2 regions

Outer region = adrenal cortex Subdivided into outer, middle, & inner zones

Inner region = adrenal medulla

Adrenal Gland (continued)• Hormone groups (5) & function

• Adrenal medulla• Epinephrine (adrenalin) & norepinephrine

(noradrenalin) Fight-or-flight• Adrenal cortex

• Outer (zona glomerulosa)• Mineralocorticoids such as aldosterone

• Middle (zona fasciculata)• Glucocorticoids such as cortisol

• Inner (zona reticularis)• Sex hormones such as androgens

Adrenal Disorders Hypersecretion

Cortisol Cushing’s disease Fat displacement = buffalo hump; moon-shaped face

Hyposecretion Cortisol Addison’s disease

frail

Ovaries Female gonad Location/Cavity

Pelvic; held in place by ligaments Hormones (2) & function

Estrogen female secondary sex characteristics Progesterone pregnancy

Testes Male gonad Location/Cavity

Not in a cavity for temperature regulation Hormone (1) & function

Testosterone male secondary sex characteristics; libido

Hormone classes Lipid soluble

Dissolve in lipids 3 examples:

Steroid hormones Cortisol, estrogen,

progesterone Thyroid hormones

T3 & T4 Nitric oxide

Gaseous neurotransmitter

Water soluble Dissolve in water 4 examples:

Amine hormones Epinephrine,

norepinephrine, melatonin

Peptide hormones ADH & OT

Protein hormones hGH, insulin

Eicosanoid hormones PGs & Leukotrienes

You MUST know…1. Location of the glands

2. Hormone names

3. Hormone abbreviations (if applicable)

4. Hormone function

5. Disorders

*You will need to spend some time with this information. Make flash cards, flow charts, graphic organizers, etc. to help organize the information.