Chapter 18- Endocrine System

glands release

hormones

hormones…

regulate the many and varied functions of an organism

hormones bind to..

receptors

receptors are…

recognition sites in the various target tissues on which hormones acts

Endocrine glands

secrete hormones directly into bloodstream

Exocrine glands

send chemical substances (milk, saliva, tears, sweat) via ducts to the outside of the body

Anatomical structures of the thyroid gland

1. Thyroid

2. Trachea

3. Thyroid membrane 

   1. Isthmus 

Thyroid function:

2 Hormones:

1. Thyroxine or Tetraiodothyronine (T4) (increase metabolism)

2. Triiodothyroine (T3) (increase metabolism)

• these hormones aid cells in their uptake of O2 and regulate metabolic rate

Calcitonin: stimulates calcium to leave the blood and enter the bone

Parathyroid Glands

4 small oval bodies located on the dorsal aspect of the thyroid gland

• Parathyroid hormone (PTH): causes calcium to mobilize from bones into the bloodstream (increases blood calcium)

Adrenal Glands

• located on top of each kidney

• each consists of 2 parts

1. Adrenal cortex (outer)

2. Adrenal Medulla (inner)

Adrenal cortex

OUTER

• secretes corticosteroid or steroids, chemical derived from cholesterol

Adrenal Medulla

INNER

• secretes catecholamines, chemical derived from A.A’s 

Adrenal cortex also secretes

1. Glucocortoids: influence metabolism of sugars, fats and proteins (cortisol) and are anti-inflammatory (cortisone) influences - SUGAR

2. Mineralocrticoids: regulate electrolytes.

• Aldosterone: reabsorption of Sodium/ excretion of potassium- influences SALT

3. Sex hormones: androgens (testosterone) and estrogens influence secondary sex characteristics

Adrenal medulla secretes…

2 types of catecholamine hormones

1. Epinephrine (adrenaline): increases HR and BP, dilates bronchial tubes, releases glucose from storage 

2. Norepinephrine (noradrenaline): constricts vessels to raise BP

• both are sympathomimetic agents 

Pancreas is located…

near and partially behind the stomach

Pancreas endocrine function

• Islet of Langerhans produce:

  • Insulin: promotes movement of glucose into cells and promotes storage as glycogen (lowers blood sugar, glucose —> glycogen)

  • Glucagon: promotes movement of glucose into the blood by breaking down glycogen stored in liver cells (raises blood sugar. Glycogen —> glucose)

Pituitary gland

• pea sized gland in depression of skull (sella turicia), = hypophysis 

  • Anterior Lobe (adenohypophysis)

    • secretes releasing and inhibiting factors = secretes horomones

  • Posterior lobe (neurohypophysis)

    • secretes hormones directly to= stores and releases hormones

Hypothalamus controls…

secretions of the pituitary via releasing factors (hormones)

Anterior pituitary

• Growth hormone (GH) or somatotropin (STH): stimulates growth of bones and soft tissues

• Thyroid- stimulating hormone (TSH; throtropin)

• Adrenocorticotropic hormone (ACTH): stimulates adrenal cortex

• Gonadotropic hormones (FSH, LH)

• Prolactin (PRL)

posterior pituitary

stores and releases hormones synthesized by the hypothalamus

• Antidiuretic hormone (ADH, vasopressin): increases reabsorption of water by kidneys

• Oxytocin (OT)

Male hormone

Testosterone

• maintains germ cell formation and secondary sex characteristics 

Female hormones

Estrogen and progesterone

• maintains menstrual cycle, release of ovum, secondary sex characteristics, preparation of uterus for pregnancy

ovaries

located in lower abdomen of female

• responsible for egg production and estrogen and progesterone secretion

cortisol

secreted by adrenal cortex

• increases blood sugar

estradiol

estrogen secreted by the ovaries

Follicle- stimulating hormone (FSH)

• stimulates hormone secretion and egg production by ovaries and sperm production by testes

glucagons

secreted by alpha islet cells of pancreas

• increases blood sugar

Luteinizing hormone (LH)

• stimulates ovulation in females and testosterone secretion in males

parathrome (PTH)

secreted by parathyroid glands

• increases blood calcium

Vasopressin

• raises water reabsorption and raises BP

Catecholamines

hormone derived from an AA and secreted by the adrenal medulla 

Corticosteroid

hormone produced by adrenal cortex

glucocorticoid

steroid hormone secreted by the adrenal cortex; regulates glucose, fat and protein metabolism

mineralocorticoid

steroid hormone secreted by the adrenal cortex to regulate mineral salts and water balance in body

sympathomimetic

pertaining to mimicking or copying the effect of the sympathetic nervous system

Aden/o

gland

adrenal/o

adrenal glands

gonad/o

sex glands (ovaries and testes)

pancreat/o

pancreas

parathyroid/o

parathyroid gland

pituitar/o

pituitary gland; hypophysis

thyr/o

thyroid gland

thryoid/o

thyroid gland

andr/o

male

calc/o

calcium

calici/o

calcium

cortic/o

cortex

outer region

crin/o

secrete

dips/o

thirst

estr/o

female

gluc/o or glyc/o

sugar

home/o

sameness

hormon/o

hormone

kal/i

potassium

lact/o

milk

myx/o

muscus

natr/o

sodium

phys/o

growing

somat/o

body

ster/o

solid structure

toc/o

childbirth

toxic/o

position

ur/o

urine

-agon

assemble 

gather together 

-in

a substance

-ine

a substance

-tropin

stimulating the function of

-uria 

urine conditon

eu-

normal

good

oxy-

rapid

sharp

acid

pan-

all

goiter

enlargement of thyroid 

hyper secretion of thyroid

• Hyperthyroidism

• Graves disease (too much thyroid hormone)

  • Exophthalmos and proptosis (when eyes protrude)

hypo secretions of thyroid 

• hypothyroidism

  • Myxoedema (not enough hormones)

  • Cretinism (mental retardation caused by severe iodine deficiency)

Neoplasms Thyroid

Thyroid carcinoma

Hyper-secretions parathyroid

• hyperparathyroidism

  • loss of bone density

  • kidney stones

  • hypercalcemia

Hypo-secretion parathyroid

hypoparathyroidism

• muscle and nerve weakness

• tetany

• hypocalcemia

Hyper-secretion adrenal cortex

• Adrenal virilism

  • Amenorrhea (no menstruation)

  • hirsutism (growth of male like hair after puberty)

  • acne

  • voice deepening

• Cushing syndrome

  • Obesity

  • moonface

  • thoracic fat deposition

Hypo-secretion adrenal cortex

Addison disease

• Deficient mineralcorticoids and glucocortcoids

• hyponatremia

• fatigue

• weakness

• weight loss

• low BP

Hyper-secretion Adrenal medulla

Pheochromocytoma

• benign tumor of adrenal medulla

• excess epinephrine and norepinephrine

• hypertension

• tachycardia

• palpitations

• severe headaches

• sweating

• flushing of face

  • muscle spasms

Hyper- secretion Pancreas

Hyperinsulinism

• hypoglycemias

• convulsions

• fainting

hypo-secretions pancreas

Diabetes mellitus

• lack of insulin secretions or restistance of insulin to promoting sugar, starch anf at metabolism in cells

Type 1: childhood onset,

Type 2: adult onset

Hyper-secretion Pituitary gland ANTERIOR

• acromegaly

• gigantism

Hypo-secretion pituitary ANTERIOR

• dwarfism

• panhypopituitarism 

Hyper-secretion Pituitary gland POSTERIOR

Syndrome of inappropriate ADH (SIADH)

• excess ADH

• excess water retention

Hypo-secretion Pituitary gland POSTERIOR

Diabetes insipidus

• deficient ADH

• Polyuria and polydipsia

fasting plasma glucose

measures circulating glucose in a pt who has fasted at least 8 hours

serum and urine tests

measures hormones, electrolytes, gluciose etc in blood and urine as indicator of endocrine function

thyroid function tests

measures T3 and T4 and TSH in bloodstream 

Expophthalmometry

a clinical technique for measuring the forward displacement of an eye using an instrument called an exophthalmometer