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

Hormone Interactions• Permissiveness - When one hormone cannot exert its full

effects without another hormone being present• Reproductive hormones develop the reproductive system (estrogen,

testosterone, LH, FSH), but those do not start working unless the Thyroid hormone is released

• Synergism - More than one hormone produces the same effects at the target cell and their combined effects are amplified

• Glucagon and epinephrine cause the liver to release glucose in the blood – when they act simultaneously, they release about 150% more than what they would by themselves

• Antagonism - When one hormone opposes the action of another hormone

• Ex Insulin lowers blood glucose levels; it is antagonized by glucagon which raises blood glucose levels

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

• Hypothalamus secretes 9 hormones• Pituitary Gland secretes 71q

– 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 Gland• Releases tropic hormones which

influences other endocrine glands

• Regulated by Releasing and Inhibiting Hormones

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

• Adrenocorticotropic Hormone (ACTH)– Influences glucose metabolism

• Prolactin– Hypothalamus secretes Releasing and

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

Posterior Pituitary Gland

• Does not make hormones– Stores and releases them

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