Endocrine System

Endocrine System—General Info• Works WITH the Nervous system • Main function is to produce hormones—

chemical messenger influencing other tissues/organs.

• Differs from NS with regard to speed– NS—body will make rapid adjustments to

changes– ES—uses chemical messengers (hormones) to

affect change. Hormones travel via bloodstream. Generally longer lasting.

Endocrine vs Exocrine glands• Endocrine glands—secrete hormones directly into

the blood– anterior pituitary– thyroid– adrenal

• Exocrine glands—deliver hormones into the blood via tubes leading from the gland– sweat glands – salivary glands– mammary glands

Major body processes regulated by ES

• Reproduction• Growth and development• Maintaining homeostasis of electrolytes,

water and nutrients• Regulation of cellular metabolism

Endocrine System—transport Endocrine System—transport hormones…hormones…

• Hormones travel through the blood and bind to receptor proteins– Steroid hormones (cholesterol derived)

• Are lipid soluble and cross the plasma membrane, bind to receptors inside the cell and affect DNA transcription.

– Animation

– Non-steroid hormones (protein based)• Bind to specific membrane receptors and trigger a

signaling cascade inside the target cell which activates necessary enzymes.

– Animation…

Target cells and controlling the ESTarget cells and controlling the ES

• Hormones travels through the entire body via the blood, but only affect specific target tissues.

• The body primarily uses negative feedback loops to determine when to turn on/shut off hormone production.

• Other ways the body controls the ES is through the nervous system and biorhythms.

Negative Feedback loopsNegative Feedback loops

• Works like a thermostat in your house to maintain a constant environment of 68oF.

http://www.endocrinesurgeon.co.uk/endocrine_conditions/What-is-negative-feedback.html

– Turns on the furnace to produce heat if the temperature is too cold and off when the desired temp is reached.

– Turns on AC to cool the house if temp is too high and shuts it off when back to the desired temp..

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HomeostasisHomeostasis

• Negative feedback loops ensure the body returns to “normal” conditions after stimulus.

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Glucose Regulation

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Glucose RegulationGlucose Regulation

Biology, Campbell. 1987. pg 896

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A fuzzy balancing act

Receive, Reaction, Refine

ENDOCRINE REGULATIONENDOCRINE REGULATION

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Stimulation –

regulation of release /triggered release– "sensory" input

• response to substance in the blood (Iodine, glucose)

– hormonal regulation• responds to upstream gland regulation (TSH,

LH...)– neural regulation

• response short term stress 11

Endocrine RegulationEndocrine RegulationRECEIVERECEIVE

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Mechanism of Release– Steroids

• Lipid soluble - readily enter cells– stimulus leads to biosynthesis– transport in blood assisted by carrier proteins

(serum albumin)

Endocrine RegulationEndocrine RegulationREACTREACT

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Mechanism of Release

– Hormones that are NOT steroids or lipids• Water Soluble –

interact with membrane receptors

– synthesized, packaged into vesicles via golgi– vesicles migrate to and collect at release site– activated release, exocytosis to dump contents– typically Ca++ sensitive; regulate Ca++ /

regulate release

Endocrine RegulationEndocrine RegulationREACTREACT

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Endocrine ControlEndocrine Control

• Feedback system for the control of ovulation

16Biology:An Exploration of Life, McFadden&Keeton. 1995. pg 546

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Endocrine System

• Down Regulation-Negative Feedback loop

Endocrine RegulationEndocrine RegulationREFINEREFINE

Blood Ca++ levels Increase

Parathyroids

Bone is degraded

Blood Ca++ levels Decreasestimulates

inhibits

PTH-

+

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Endocrine System

Removal of hormones•The bulk of hormone is cleared by the liver and kidneys •Only a small fraction is removed by target tissue

– protein and amine hormones bind to receptors and are internalized and degraded

• action and elimination is usually quicker (minutes)

– Steroid and thyroid hormones are degraded after hormone-receptor complex binds to nuclear chromatin

• action and elimination are slower (hours-days)

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Endocrine RegulationEndocrine RegulationREFINEREFINE

Endocrine Problems

Dwarfism Characteristics

-Short stature(proportional)

Causeshortage of GH (hypophysial dwarfism)

or defective receptor (Laron Syndrome).

Endocrine DisordersEndocrine Disorders

Short stature, can be caused by any one of more than 200 conditions, most of which are genetic and result in disproportionate body structure.

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Gigantism

Characteristics- Extreme height (8-9 ft, proportional structures)

Cause- Excessive GH during

development

Endocrine DisordersEndocrine Disorders

www.endotext.org

Gigantism is extremely rare (only a few hundred known cases total). Cause of excess of GH excess varies but often is linked to Acromegaly

Endocrine Problems

Acromegaly-Characteristics

abnormal bone growth joint aches

thick coarse oily skin impaired vision

excessive sweating sleep apnea

abnormal menstruation skin odor

erectile dysfunction headaches

fatigue and weakness decreased libido

enlarged lips nose and tongue skin tags

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Endocrine DisordersEndocrine Disorders

Acromegaly-

Cause-excess GH in adulthood.

Usually benign adenoma

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HypothyroidisimCharacteristics-

Fatigue, weakness, weight gain or resistance to weight loss, course dry hair, dry rough pale skin, hair loss, cold intolerance, muscle cramps and aches, constipation, depression, irritability, memory loss, abnormal menstruation, decreased libido.

High TSH with low T3/T4.

Endocrine DisordersEndocrine Disorders

thyroid.about.com

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Cause- Not enough thyroid hormone.

Hasimoto’s disease- autoimmune disease

Medical treatments- removal, damage or pituitary deficiency.

subclinical hypothyroidism

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– HyperthyroidismCharacteristics- palpitations, heat

intolerance, nervousness, insomnia, breathlessness, increased BM, decreased menstruation, fatigue, fast heart rate, trembling, weight loss, muscle weakness, warm moist skin, hair loss, staring gaze.

Low TSH

high T3/T4 levels

Endocrine DisordersEndocrine Disorders

pro.corbis.com

www.avondalevet.com

Causes- Graves’ Disease, autoimmune disease

(antibodies attach to thyroid and over stimulate T3 production)

Benign tumor- nodule (few cells)out of regulation

Thyroiditis- temporary swelling – of gland (postpartum)

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Cushing’s DiseaseCharacteristics-

central body obesity Osteoporosisglucose intolerance kidney stonesHypertension excess hair growthmenstrual irregularity emotional liability“Buffalo hump” “moon” face

Cause- Excess Cortisol

tumor of the lungs, pituitary or adrenal glands

Endocrine DisordersEndocrine Disorders

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Endocrine DisordersEndocrine Disorders

Diabetes-Most common Endocrine disorderConsistent elevated blood sugar

Characteristics- frequent hunger, thirst, urination, blurred vision, fatigue, weight loss, poor wound healing, dry mouth, dry itchy skin, impotence, recurrent infections. Erratic blood sugar.

– normal blood glucose: 80-120mg/100 ml, – diabetes: as much as 600mg/100ml of blood

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DiabetesCauses-

Type 1 -insulin deficiency Type 2 -insulin resistance

hormone disturbance AgromegalyCushing’s

Gestational diabetes- temporary condition caused by pregnancy

placenta metabolizes insulin quickly.

Endocrine DisordersEndocrine Disorders

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ENDOCRINE DISORDERS

Adrenal disorders: Adrenal insufficiency Addison's disease Congenital adrenal hyperplasia Mineralocorticoid deficiency Conn's syndrome Cushing's syndrome adrenogenital syndrome Pheochromocytoma Adrenocortical carcinoma GRA/Glucocorticoid remediable aldosteronism Glucose homeostasis disorders: Diabetes mellitus Hypoglycemia Idiopathic hypoglycemia Insulinoma Metabolic bone disease: Osteoporosis Osteitis deformans (Paget's disease of bone) Rickets and osteomalacia

Pituitary gland disorders: Diabetes insipidus Hypopituitarism Pituitary tumors Pituitary adenomas Prolactinoma Acromegaly, gigantism Cushing's disease Parathyroid gland disorders: Primary hyperparathyroidism Secondary hyperparathyroidism Tertiary hyperparathyroidism Hypoparathyroidism Pseudohypoparathyroidism Sex hormone disorders: Disorders of sex development or intersex disorders Hermaphroditism Gonadal dysgenesis Androgen insensitivity syndromes Hypogonadism Gonadotropin deficiency Kallmann syndrome Klinefelter syndrome

Ovarian failure Testicular failure Turner syndrome Disorders of Gender Gender identity disorder Disorders of Puberty Delayed puberty recocious puberty Menstrual function or fertility disorders Amenorrhea Polycystic ovary syndrome Thyroid disorders: Goiter Hyperthyroidism and Graves-Basedow disease Hypothyroidism Thyroiditis Thyroid cancer Tumours of the endocrine glands not mentioned elsewhere Multiple endocrine neoplasia MEN type 1 MEN type 2a and 2b

Endocrine DisordersEndocrine Disorders

Review of Endocrine System

•Quick review of info…

Endocrine System

• Glands and the hormones they produce…you will need to know these for the test.

• Study earlier rather than later!

Pituitary

• Known as the master gland as it is not only responsible for many hormones, it also acts as a regulator for other glands in the endocrine system.

Pituitary Gland Hormones

• ADH (Antidiuretic Hormone)–Responsible for

maintaining water balance in your body.

Pituitary Gland Hormones

• Oxytocin–Responsible

for causing uterine contractions during and after birth.

Pituitary Gland Hormones

• GH (Growth Hormone)–Causes growth in humans…big

surprise huh?

Pituitary Gland Hormones

• TSH (Thyroid Stimulating Hormone)–Influences

your thyroid gland

Pituitary Gland Hormones

• ACTH (Adrenocorticotropic Hormone)–Regulates the

adrenal glands

Pineal Gland

Pineal Gland Hormone

• Melatonin–Helps your

body adjust to various amounts of daylight

Thyroid Gland

• Location: Surrounds windpipe

Thyroid Hormones

• Thyroxine–If iodine is

present, it will control the metabolism of glucose in the body.

Thyroid Hormones

• Calcitonin–Responsible

for depositing blood calcium into bones

Parathyroid Glands• Location—

attached behind the thyroid– Years ago, they used to

remove the parathyroids with the thyroid if the thyroid was damaged. This lead to death in patients…OOPS!

Parathyroid Hormone

• PTH (Parathyroid hormone)– Responsible for

pulling calcium from bones and depositing it into the bloodstream.

Thymus Gland• Location:

Longish gland in the middle of your chest.

Thymus Hormone

• Thymosin–Assists the immune

system

Adrenal Glands

• Location: Located right on top of kidneys

Adrenal hormones

• Aldosterone–Maintain

blood salts (primarily Na+, K+)

Adrenal hormones

• Cortisone: – Kicks in to help

body with long term stress.

Adrenal hormones

• Epinephrine– Kicks in when

body undergoes short term stress

– Test-taking, car accident, caught in a lie…etc.

Pancreas

• Location: Found right behind the stomach

Pancreas hormones

• Insulin–Decreases

blood sugar

Pancreas hormones

• Glucagon–Increases blood sugar

Ovaries

• Small, almond shaped organs on the ends of the fallopian tubes.

Ovary hormones

• Estrogen and Progesterone– Responsible for

sex characteristics and controlling the menstrual cycle

Testes

• Testosterone– Responsible for male secondary sex

characteristics

Other structures and the ES

• Heart– ANP will increase the

Na+ excretion and inhibit smooth muscle contraction

Other structures and the ES

• Kidney– Renin will cause

vasoconstriction of the blood vessels (increases blood pressure)

Other structures and the ES• G.I. Tract

– There are many polypeptide hormones that act on the GI tract.

– Most hormones will increase intestine motion and enzyme production

Other structures and the ES• Placenta

–HCG: maintains embryo growth in first 90 days gestation

Other structures and the ES

• Placenta–Estrogen and Progesterone help

maintain uterus health–Lactogenic Growth hormone

help with milk production after birth of baby

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www.abbottdiagnostics.com.