The Endocrine System

Endocrine System
Endocrine vs. Exocrine
Organs are not physically connected
Alters activities of target organs/cells
Purpose: Growth/Development
Reproduction
Regulation
Stress Reactions

Hormones are Activated
By
Hormonal
Humoral
Neural

Gland/Hormone
Functions
Some glands produce >1 hormone
Some hormones produced by >1 gland
Some organs have >1 function
Some hormones have >1 function

Functions of Endocrine
Glands
Endocrine Functions only
Production
Secretion
Contained within other organs which have other functions

Categories of Glands
Central: Pituitary
Hypothalamus
Peripheral: Thyroid
Adrenals
Parathyroids
Thymus
Pineal
Gonads
Pancreas
Others

Hypothalamus
Found on floor of diencephalon
Neural and endocrine functions
Biofeedback mechanism for:
Osmotic pressures
Temperature regulations
Metabolic functions

Pituitary
Extends from Hypothalamus-behind sphenoid bone
“Master Gland” of body
Anterior- Portal network
Posterior- Neural-contains axons of
Hypothalamus neurons

Anterior Pituitary
GH- Growth Hormone
Prolactin
TSH- Thyroid Stimulating Hormone
ACTH- Adrenocorticotropic
FSH- Follicle Stimulating Hormone
LH- Luteinizing Hormone

Posterior Pituitary
ADH- Anti-Diuretic Hormone
Oxytocin

Pituitary Disorders
Acromegaly- Hypersecretion of GH
Dwarfism- Hyposecretion of GH

Thyroid
Inferior to larynx
2 Lobes
T
3
- Triiodothyronine
T
4
- Thyroxine
Calcitonin

Thyroid Disorders
Hypothyroidism- Hyposecretion
Hyperthyroidism- Hypersecretion
 Graves Disease
Goiters- iron deficiencies

Parathyroids
4 small glands posterior surface of thyroid
Parathyroid hormone
Responsible for osteoclast of bone
Decreases blood phosphate levels
(By way of kidneys)
Enhances activation of Vitamin D

Parathyroid Disorders
Hyperparathyroidism
“Moan and groan, stones and bones”

Pineal Gland
Forms part of diencephalon
Melatonin
Inhibits hypothalamus release of gonadotropins
Melatonin-decreases in light/increase in dark ( circadian rhythm)

Thymus Gland
Posterior to sternum, around great vessels
Thymosin
Both lymphatic and endocrine
Lymphatic- produces T-lymphocytes
Endocrine‘programs’ T-cells

The Adrenals
Located on superior end of each kidney
Medulla- inner gland
Cortex- outer gland

Adrenal Medulla
Sympathetic preganglionic fibers synapse on cells in medulla
Release of epinephrine/norepinephrine into general circulation

Adrenal Cortex
Produce over 30 steroid hormones
Three main cortical hormones
Mineralocorticoids
Glucocorticoids
Sex hormones

Mineralocorticoids
Regulate levels of electrolytes and water in extracellular fluid
95% are aldosterone
 Sodium reabsorption
 Potassium excretion

Glucocorticoids
Influence carbohydrate metabolism
Important in body’s response to stress
95% cortisol (hydrocortisone) stimulates gluconeogenesis secretion is regulated by ACTH

Sex Hormones
Androgens (testosterone)
Estrogens
Both are secreted in greater numbers by gonads

Adrenal Disorders
Cushing’s diseasecortisol over-production secondary to increased ACTH
Addison’s Diseasecortisol/aldosterone deficiencies

Gonads
Testes- males
Testosterone
Ovaries- females
Estrogens
Progesterone
Both produce hormones/gametes

Pancreas
Retroperitoneal-posterior to stomach
Exocrine & Endocrine
Endocrineislets of Langerhans
Alpha
Beta
Delta

Alpha cells
20% of islets
Hormone glucagon
Stimulates breakdown of glycogen in liver- raises glucose levels in blood
(glycogenolysis & glyconeogenesis)

Beta Cells
75% of islets
Hormone- insulin
Decreases glucose levels

Glucose Metabolism
Organic components of food:
Carbohydrates (instant-energy)
Glucose
Fats
Fatty acids/glycerols
Proteins
Amino acids

Carbohydrate
Metabolism
Insulin is released by humoral, hormonal, neural means
Increased glucose
Parasympathetic stimulation
Gastrointestinal hormones

Carbohydrate
Metabolism
60% of carbohydrates are stored as glycogen in liver
If muscles are not exercised after eating-stored as muscle glycogen

Glycolysis
Glucose is broken down into pyruvate and lactate- releasing 2ATPs
(Anaerobic metabolism)
Krebs Cycle

Fat Metabolism
A third of any glucose passing through liver is converted to fatty acids
Fatty acids are converted to triglycerides and stored in adipose tissue

Fat Metabolism
Without insulin, fat is broken back down into triglycerides/cholesterol  CAD
Fatty acids are also broken down into ketone bodies

Protein Metabolism
In absence of insulin- protein storage stops and breakdown begins (muscle)
Amino acid breakdown for energy leads to increased urea in urine  organ dysfunction

Pancreas Disorders
Diabetes-
 Type 1- Juvenile onset
 Type 2- Mature onset
 Gestational diabetes

Type 1 Diabetes
Insulin dependant
S/S: polyuria polydipsia polyphagia blurred vision weight loss

Type 2 Diabetes
Generally non-insulin dependant
Has ability to make small amounts of insulin
Can develop into insulin dependant

Gestational Diabetes
Develops during pregnancy
Deficiencies in insulin leads to inability to metabolize carbohydrates
Generally disappears after delivery

Insulin Agents
Early- porcine, bovine
Recent- genetic engineered human insulin
Protein
Rapid, intermediate and long-term
Combination of long-term, rapid each day

Insulin Types
Regular- Fast acting
0.5-1 hour onset
6-8 hour duration
NPH- Intermediate
1-1.5 hour onset
24 hour duration

Insulin Types
Ultralente- Long acting
4-6 hour onset
36 hour duration
Oral agents:
 Diabinese (chlorpropamide)
 Orinase (tolbutamide)
 Micronase (glyburide)
 Glucotrol

Diabetic Emergencies
Hypoglycemia
Hyperglycemia
Diabetic Ketoacidosis (DKA)
Hyperosmolar Hyperglycemic
Nonketotic Coma (HHNK)

Hypoglycemia
Rapid on-set
< 60 mg/dl
Causes: too much insulin decreased intake salicylates excessive activity emotional stress chronic alcoholism beta blockers hypothermia sepsis

S/S of Hypoglycemia
Altered LOCs- irritability, nervousness, confusion, combative
Cool, clammy
Weak, rapid pulse
Snoring,  salivation
Normal BP

Diabetic Ketoacidosis
Fat metabolism leads to ketoacids
Acidosis leads to  K + in circulation & hyperkaluria  K + deficiency
Osmotic diuresis  dehydration, electrolyte imbalances

S/S of DKA
Warm, dry skin
Dry mucous membranes
Tachycardia, thready pulse
Postural hypotension
Weight loss
‘Polys’

S/S of DKA
Abdominal pain
Anorexia, nausea/vomiting
Acetone breath
Kussmauls
Decreased LOC

Hyperosmolar
Hyperglycemic
Nonketotic Coma
Generally Type II diabetic
Osmotic diuresis secondary to  sugars
Not acidotic as in DKA
Factors: Geriatric
Preexisting diseases
Increased insulin requirements
Medication use- thiazide, diuretics
Parenteral/enteral feedings

S/S of HHNK
Weakness
Thirst
Polyuria
Weight Loss
Extreme dehydration

Treatment of Diabetic
Emergencies
Hypoglycemia- ABCs
IV- NS
Monitor ECG
Oral, IV Dextrose
Poss. Glucagon IM
Poss. Thiamine
Monitor glucose!

Treatment of Diabetic
Emergencies
Hyperglycemia (DKA, HHNK)-
ABCs
O
2
IV- NS
Monitor ECG for abnormalities