Endocrine and Lymphatic/ Immune Systems

Endocrine System – works with the Nervous System to coordinate and integrate

the activity of body cells

Endocrinology• Endo = inside or within

• Crine = Secrete

• Ology = study of

• Hormon – to excite

• Definition = Study of hormones and how they work in the body

• Hormone – a mediator molecule that gets released in one part of the body but regulates the activity of cells in other parts of the body

Functions

• Work with Nervous System to coordinate body functions

• Maintain homeostasis within the body

Hormone Facts

• Two types of glands in the body– Exocrine

• Secretes products to outside of body

– Endocrine• Ductless glands and make hormones• Secrete products inside the body

• Organs– Hypothalamus, thymus, pancreas, ovaries,

testes, kidneys, stomach, liver, small intestine, skin, heart, adipose tissue, placenta

Hormone Travels• Circulating Hormones – True Hormones

– Affect specific target cells– Stay in the blood stream

• Local Hormones - Pseudohormones– Act on neighboring cells– Do not enter the blood stream

• Paracrine – act locally, but affect cell types other than those releasing them

– Somatostatin – secreted by the pancreas – stops the release of insulin

• Autocrine – chemicals that exert their effects on the same cells that secrete them

– Prostaglandins - released by smooth muscle cells to make the smooth muscles contract

Chemical Classes of Hormones

• Lipid-soluble hormones– Dissolve in fats

• Water-soluble hormones– Dissolve in water

Lipid-Soluble Hormones

• Steroids– Derived from cholesterol– Cortisol, Estrogen, Testosterone, Aldosterone,

Androgens, Calcitriol, Progesterone

• Thyroid Hormones– T3 and T4

• Nitric Oxide– Hormone and neurotransmitter

Water-Soluble Hormones• Amines – made by modifying amino acids

– Epinephrine and norepinephrine, melatonin, histamine, serotonin

• Peptide Hormones – chains of amino acids– Antidiuretic hormone, oxytocin, HGH, Thyroid-stimulating

hormone, adrenocorticotropic hormone, FSH, LH, Prolactin, melanocyte-stimulating hormone, insulin, glucagon, somatostatin, parathyroid hormone, calcitonin, gastrin, secretin, cholecystokinin, erythropoietin, leptin

• Protein Hormones – more complex chains of amino acids – subtype of peptide hormones

• Eicosanoid – derived from a 20-carbon fatty acid– Prostaglandins– Leukotriens

How Hormones work

• Lipid-Soluble – diffuse through the lipid bilayer of the plasma membrane and bind to receptors within target cells

• Water-Soluble – cannot diffuse through the membrane– Bind to Integral Proteins on the membrane

surface

Control of Hormone Secretion

• Hormones are secreted in short bursts

• Regulated by– Signals from NS

• Hypothalamus signals the Pituitary Gland to make and realease hormones

– Chemical changes in the blood– Other hormones

Hypothalamus and Pituitary Gland

• Hypothalamus is the “Master” of the Pituitary Gland– Major link between the NS and ES– Secretes 9 hormones

• Pituitary Gland– Secretes 7 hormones– Two Lobes: Anterior and Posterior– Rests in the Sella Turcica

• Hypothalamus and Pituitary Gland are connected by the INFUNDIBULUM

Anterior Pituitary Hormones• Human Growth Hormone (HGH)

– Most plentiful Ant. Pituitary Hormone• Gigantism – too much HGH – typically reach 8ft• Pituitary Dwarfism – too little HGH – 4ft. or under, body is

properly proportioned

• Thyroid-Stimulating Hormone– Stimulates Thyroid gland to make and secrete

Thyroid Hormone which has 2 forms: T3 and T4 m• Invtrsdrd nsdsl mrysnoliv tsyr snf nofy hrsy ptofuvyion

– Released in response from TRH hormone of the Hypothalamus

Thyroid Problems• Hypothyroidism

– Underactive thyroid gland• Adults - Myxedema – low metabolism, cold, constipation,

thick/ dry skin, puffy eyes, edema, lethargy and mental sluggishness

– If myxedema is from a lack of Iodine, the thyroid gland can enlarge and protrude and become an endemic goiter

– Why salt is now IODIZED; Goiter Belt

• Infants – Cretinism – mental retardation, disproportionate body size, thick tongue and neck – might be a genetic defect of fetal thyroid or a lack of iodine in mother’s diet

– Can be prevented by hormone replacement therapy if diagnosed early enough

» Most states test newborns to check for hypothyroidism at birth

Thyroid Problems

• Hyperthyroidism – overactive thyroid– Grave’s Disease – believed to be autoimmune

because people who have this disease have abnormal antibodies that mimic TSH and will stimulate the release of TH

• Increased metabolism, sweating, irregular/ rapid heart beat, nervousness, weight loss

• Signs – enlarged thyroid (goiter), exophthalmos

• Treatment – Thyroidectomy or treatment with Radioactive Iodine which will destroy most of the active thyroid cells

Parathyroid Hormone

• Controls calcium balance within the blood

• Hyperparathyroidism – rare, usually happens because of a tumor –

Ca gets leached from the bones – bones will soften and deform as their mineral salts are replaced by fibrous CT – high blood Ca can suppress the nervous system and cause kidney stoes

Parathyroid Hormone

• Hypoparathyroidism– Usually after some type of parathyroid trauma

or removal during thyroid surgery, extended lack of dietary Mg

• Hypocalcemia – tetany (loss of sensation, muscle twitches, convulsions)

• Untreated – symptoms progress to respiratory paralysis and death

• Was how the Parathyroid gland was discovered

Anterior Pituitary Hormones• Follicle-Stimulating Hormone

– Hypothalamus – Anterior Pituitary – Testes, Ovaries

– Stimulates production of sperm and maturing of follicles (eggs)

• Luteinizing Hormone – Controlled by the hypothalamus– Stimulates secretion of estrogen and

progesterone and ovulation in females; in males it stimulates the release of testosterone

Anterior Pituitary Hormones

• Prolactin– Hypothalamus secretes Releasing and

Inhibiting Hormones to control Prolactin– Makes the body recognize a pregnancy– Stimulate milk production in women

Posterior Pituitary Hormones

• Oxytocin– Enhances muscle contraction during childbirth– After childbirth – stimulates milk production

and delivery of the placenta– Pitocin to induce labor – synthetic verson

• Antidiuretic Hormone or Vasopressin– Diabetes Insipidus – excessive urine and

intense thirst – results in fluid retention, headache, disorientation

Cushing’s Syndrome

• Excessive Cortisol in the blood stream

• Persistent hyperglycemia

• Loss in muscle and bone protein

• Water and salt retention

• Swollen “moon” face

• Redistribution of fat – buffalo hump

• Ease in bruising

Hypoglycemia – low blood glucose

• Stimulates the hypothalamus to release GHRH (growth-hormone-relasing-hormone) and GHRH goes to the Anterior Pituitary

• Anterior Pituitary is then stimulated to release HGH into the blood stream

• HGH – stimulates the release of insulin-like growth factors that speed up the breakdown of liver glycogen into glucose

• As a result, blood glucose rises to the normal level (90mg/100mL of blood plasma)

• An increase in blood glucose above the normal level inhibits (stops) the release of GHRH

NEGATIVE FEEDBACK

Hyperglycemia – abnormally high blood glucose

• Stimulates the hypothalamus to secrete GHIH (Growth-hormone-inhibiting-hormone) while inhibiting the release of GHRH

• GHIH travels to the Anterior Pituitary and prevents it from releasing Growth Hormone

• Low levels of GH in the blood stream and IGFs slows down the breakdown of glycogen in the liver and glucose is released into the bloodstream more SLOWLY

• Blood glucose falls to its normal level• A decrease in the blood glucose below the normal level

inhibits the release of GHIH

NEGATIVE FEEDBACK

Congenital Adrenal Hyperplasia• Genetic disorder in which a person lacks the

enzymes needed to make Cortisol

• If there is low or no cortisol, another hormone (ACTH) stimulates enlargement of the adrenal glands

• Causes Virilism– Females – masculinization – growth of a beard,

deep voice, body hair similar to male, growth of clitoris to resemble a penis, loss of breasts

– Males – same as females – over-masculinization

Addison’s Disease• Cause – ACTH is blocked from it’s receptors

• Symptoms – lethargy, anorexia, nausea, vomiting, weight loss, hypoglycemia, weakness, bronzed appearance to skin

• Treatment – hormone replacement and increasing sodium in diet

• JFK had this

Diabetes• Diabetes Mellitus (mell = honey sweetened)

– Inability to produce insulin– 4th leading cause of death in the US– Causes glucosuria (excessive glucose in the urine)– Key defining symptoms

• Polyuria – excessive urine production due to an inability of the kidneys to resabsorb water

• Polydipsia – excessive thirst• Polyphagia – excessive eating

– Genetic and Environmental components– 2 types – Type I and Type II

Type I Diabetes – Insulin-dependent Diabetes Mellitus

• Insulin level is low because the person’s immune system destroys the pancreatic beta cells that make the insulin

• People with this must have daily doses of insulin to prevent death

• Develops in people younger than age 20

• If not treated properly can lead to blindness and kidney disease

Type II Diabetes – Non-insulin-dependent Diabetes Mellitus

• Most common, 90% of all cases of diabetes

• Typically found in obese people over age 35

• Can be controlled through diet, exercise and weight loss– Can be temporary

• No shortage of insulin, rather the target cells become less sensitive to it

Gestational Diabetes• Occurs in pregnant women who may or may

not have had diabetes before the pregnancy

• Pregnancy hormones block mom’s insulin receptors from being able to absorb insulin

• Glucose can’t get absorbed properly so it is transferred to the baby– Baby grows more than it should – can lead to

marcosomia (fat baby)– Concerns for during and after birth

• Goes away immediately after giving birth