The Endocrine System (Hormones)By:William Collins,Hannah Legaspi, Alex

Nguyen, and Carrie Suen

Basic Definitions● The Endocrine System- a collection of glands and the

hormones that they create that are in charge of regulating and creating long term changes within your body.

● Glands-are groups of cells that produce and transmit chemicals (hormones) to the body through the bloodstream (endocrine) or into cavities inside the body or its surface (exocrine). Made from epithelial cells.

● Epithelium- aka epithelial cells are cells that line the organs of your body and help produce secretions that those organs use.

● Hormones- are the chemical messengers of your body that are created by glands.Unlike neurotransmitters they work very slow and provide a long term effect on your body.

Endocrine System ● Coordinates activities of organ systems

○ metabolism○ growth and development○ tissue function○ sexual function ○ reproduction ○ sleep

● Helps maintain homeostasis● Use of negative feedback mechanism

○ e.g. rise in blood glucose level causes pancreas to release insulin, promoting glucose uptake by the liver, muscles, and other cells

Exocrine Glands● Is the most common type of gland in the body.● In comparison to Endocrine Glands, Exocrine

glands have ducts. These ducts primary function are to collect the secretions by the exocrine glands until they fill the duct causing them to rise towards the surface they are in contact with.○ Skin (Sweat glands), Tongue (Salivary

Glands),

Types of Exocrine Ducts

Exocrine Secretion● In the exocrine glands there are three methods of exocrine

secretion:○ The Merocrine method involves vesicle transportation

within the gland. The product is produced within the glandular epithelial cell and then the vesicle is used to collect and transport the product to the surface of the cell. Most exocrine glands work in this way

○ The Apocrine method involves pinching a portion of the glandular epithelial cell that contains the product off from the cell. This results not only in the release of the product but also the other molecules that made up the epithelial cell. The mammary glands work in this way

○ The last method of secretion, Holocrine involves the death of the epithelial cell where typically the product is made. In this scenario, the secretory cell breaks off from the gland and its contents become the secretion. Present in some sweat glands located in the pubic regions.

Diagrams of Exocrine Secretion

Endocrine Glands• Secrete products into bloodstream,

which delivers them throughout the bodyo Only target cells can respond to certain

hormoneso Cell response to hormone

Hormone and receptor proteins (key fits a lock)

• Examples:o Adrenal, Hypothalamus, Ovaries,

Parathyroid, Pineal, Pituitary, Testes, Thyroid

Hormones• Communication• Act at a distance between body parts and travel in the

bloodstream from the gland to target cells• Secretions produced by neurosecretory cells

(hypothalamus)o Through capillary network between hypothalamus and

pituitary glando Some secretions stimulate or prevent pituitary

secretion of hormones• Not all hormones act between body parts

o e.g. prostaglandins and growth factors (local hormones)

• Pheromones - affect chemical signals that influence the behavior of other individuals

Peptide Hormones• Peptide hormones - type of hormone

that is a protein, peptide, or derived from an amino acido e.g. growth hormone affect cell metabolism

leading to changes in the structure of bone

• Most hormonal glands secrete peptide hormones

• Actions of peptide hormones can vary

Protein Hormones These are protein hormones you need to know:

● ADH- signals to the kidney that it needs to reabsorb more water.Made by the hypothalamus

● Angiotensin-makes the kidney reabsorb more NaCl (salt) and water which helps it to lower your blood pressure.

● Aldosterone-absorbs the Na+ (sodium ion) and water. Its produced by the adrenal glands and it helps to increase your blood pressure.

● Glucagon-it increases the glucose levels in the blood by hydrolyzing glycogen in the liver. Its produced in the pancreas.

● Insulin-decreases glucose levels in the blood, by storing glucose as glycogen in the liver. It is also produced by the pancreas

Protein Hormones● Calcitonin- produced by the thyroid,it decreases the Ca+ levels

in the blood by storing Ca+ in bone and allowing the kidney to urinate more Ca+ out.

● PTH-parathyroid hormone, produced by the parathyroid. This increases blood Ca+ levels by accessing stored Ca+ in bone and telling the kidney to reabsorb (keep) more Ca+ ions.

● Adrenaline-produced by adrenal glands. Acts as the “fight or flight” hormone.(epinephrine)

● Oxytocin-produced by the hypothalamus, released by the posterior pituitary. It causes uterine contractions during labor.

*Muscle cells after the hormone epinephrine binds to a receptor in the plasma membrane● Breakdown of glycogen to glucose,

provides energy for ATP production● Binding results in formation of cyclic

adenosine monophosphate (cAMP)● cAMP activates a protein kinase

enzyme, and this enzyme in turn activates another enzyme, and so on○ i.e. enzyme cascade

● Many molecules of glycogen are broken down to glucose, which enters the bloodstream

*Epinephrine never enters the cell

Steroid Hormones• Steroid hormones - type of hormone

that has the same complex of four carbon rings, but each one has different side chains; derived from cholesterol

• Only the adrenal cortex, the ovaries, and the testes produce steroid hormones

• Thyroid hormones act similarly to steroid hormones, despite different structures

Steroid HormonesImportant hormones you need to know:

● GnRH-Produced by the hypothalamus. “Tells” the pituitary to make FSH and LH

● FSH-Follicle stimulation hormone; aids in egg and sperm development. Made by the pituitary and under the control of GnRH levels

● LH-luteinizing hormone. Tells the gonads to either release estrogen or testosterone.

● Progesterone-It is secreted by the corpus luteum and by the placenta and is responsible for preparing the body for pregnancy and, if pregnancy occurs, maintaining it until birth (thickens the uterine lining)

● Estrogen-secreted by ovaries, develops eggs and is responsible for the secondary sexual characteristics in females.

● Testosterone-helps sperm develop; responsible for the secondary sexual characteristics in males

● Steroid hormones are able to enter the cell because they are lipids

● Once they have entered, the hormone binds to a receptors

● In the nucleus, the hormone-receptor complex binds with DNA and activates certain genes.

● mRNA moves to the ribosomes in the cytoplasm and protein synthesis follows

*Steroids act more slowly than peptides because it takes more time to synthesize new proteins than to activate enzymes already present in cells. However, their actions are longer lasting.

Break TimeFun Video: https://www.youtube.com/watch?v=uUr3j82qLQc

Helpful Video: https://www.youtube.com/watch?v=UqEgTUlG8FU

Hypothalamus● Hypothalamus - regulates the

internal environment through the autonomic system (e.g. heartbeat, body temperature, and water balance)○ It controls the glandular secretion

of the pituitary gland (connected)

Pituitary Gland• Posterior Pituitary

*Hormones ADH and oxytocin are produced by neurosecretory cells in hypothalamus

o Antidiuretic hormones (ADH) released when blood is too concentrated in kidneys, it causes water to be reabsorbed no longer released when blood is too dilute

• negative feedbacko maintaining stable conditions and

homeostasis inability to produce ADH causes diabetes insipidus

(watery urine) release of ADH is inhibited by the consumption of

alcoholo Oxytocin

causes uterine contractions (childbirth) and milk decrease (nursing)• more oxytocin released• positive feedback (not to maintain homeostasis

and stable conditions)

Pituitary Gland cont. • Anterior Pituitary

o controlled by hypothalamus by producing hypothalamic-releasing and -inhibiting hormones

o hormones produced affect other glands Gonadotropic hormones Adrenocorticotropic hormone

(ACTH) Thyroid-stimulating hormone

(TSH) o hormones under hypothalamic control

and do not affect other glands Prolactin (PRL) Growth Hormone (GH) Melanocyte-stimulating hormone

(MSH)

Thyroid Gland• Triiodothyronine (T3) and thyroxine (T4)

o gland actively acquires iodine• Thyroid Hormones increase metabolic rate

o stimulate all body cellso more glucose broken down, more used energy

• Thyroid Problemso simple goitero congenital hypothyroidism (cretinism),

myxedemao exophthalmic goiter

• Calcitonin (antagonistic)o regulates blood calcium levelo calcium into bones

Parathyroid Gland• Parathyroid Hormones (PTH, antagonistic)

o blood phosphate (HPO42-) level decrease

o blood calcium level to promote osteoclasts’ activity and release of calcium

bones in bones promotes reabsorption of calcium by the kidneys so it is

not excreted In kidneys, brings activation of vitamin D, which

stimulates the absorption of calcium from the intestine o insufficient PTH production (hypoparathyroidism) results in

tetany

Adrenal Glands• Hypothalamus exerts control

over the activity of the adrenal glandso initiates nerve impulses

● Stress prompts hypothalamus to stimulate the adrenal glandso short-term stress: epinephrine

(adrenaline), norepinephrine (noradrenaline)

o long-term stress: mineralocorticoids, glucocorticoids

Adrenal Glands cont.• Glucocorticoids

o cortisol (produced by adrenal cortex) raises blood glucose counteracts the inflammatory response

• Mineralocorticoidso aldosterone

primarily targets the kidney, where it promotes renal absorption of sodium and renal excretion of potassium

renin-angiotensin-aldosterone system atrial natriuretic hormone (ANH) is the antagonistic

hormone• Addison disease

o low level of adrenal cortex hormones

Testes• Produce androgens (e.g. testosterone)

o stimulates male characteristics such as large vocal cords, pubic hair, etc.

o responsible for sex driveo anabolic steroids (supplemental) - similar

chemicals with serious side effectso affect sweat glands, expression of baldness in

genes, and etc.

Ovaries• Produce estrogen and progesterone

o estrogen at puberty stimulate the maturation of

ovaries and other sexual organs necessary for oocyte development responsible for the development of female

secondary characteristics (e.g. layer of fat beneath the skin, larger pelvic girdle, etc.)

o both are required for breast development and the regulation of the uterine cycle

Pineal Gland

• Produces melatonino circadian rhythms - 24-hour physiological

cycle

• Human sexual development• Young children who have a brain

tumor that has destroyed their pineal gland experience puberty at an early age.

Thymus Gland• Reaches its maximum size and is

most active during childhoodo as age increases, it shrinks

and becomes fatty• Some lymphocytes that originate

in the bone marrow pass through the thymus and change into T lymphocytes

• Produces thymosinso aid in differentiation of T

cells o may stimulate immune cells

Pancreas

Blood Glucose Concentration Regulation• Blood glucose concentration refers to the

amount of glucose/sugar (primarily glucose) in the blood. o The optimal level is around 4 to 8 millimoles

per dm3 of blood.• Glucose concentration is maintained through a

positive/negative feedback system.Overabundance causes a halt in production, and a lack causes a jumpstart. The pancreas is connected to the bloodstream through chemical signals.

Regulation

Cont.

Pancreas: Regulation Summary *IB

Glucagon (alpha cells)- secreted while the body is passive (not eating) with low levels of glucose. Targets liver and adipose tissue. 1. Stimulates the liver to break down glycogen into glucose/use fat and protein instead of glucose for energy. Glucose conservation. 2. Adipose tissue cells form glycerol and fatty acids from the breakdown of fat. Liver uses this to form more glucose. Glucose production.

Insulin (beta cells)- After eating. Stimulates the uptake of glucose by cells- liver, muscle, and adipose tissue cells. Formed into glycogen in liver and muscle cells- fat in adipose tissue. Muscles Cells build protein, while adipose tissue keeps fat (glucose reserve)

DiabetesMedical condition where your blood glucose levels are too high.

Results when a hormone produced by the pancreas, called insulin, is not being produced enough or is not functioning as intended.

Insulin is responsible for carrying glucose to the cells in your body. Glycogen, protein, and fat are the end products.

Type 1 Diabetes (Juvenile onset) *IB

Occurs when the body fails to produce insulin. Typically thought to be caused by an outside agent.

The body’s immune system attacks the pancreatic cells that produce insulin.

Once the body turns to the metabolism of fat, ketones start to build up, leading to acid blood and serious harm.

A lack of insulin prevents cells from absorbing glucose which hinders them from producing energy.

Possible results: hypoglycemia- symptoms. Solutions: Pancreas transplant or insulin capsules.

Type 2 Diabetes (Adult-onset) *IBOccurs when the body develops insulin resistance through receptor impairment.

This is when the body is unable to use insulin the right way.

Insulin deficiency occurs as Type 2 Diabetes gets worse. This is when the pancreas produces less and less insulin and a lack of glucose transporters.

Solutions: Healthy Diet/Exercise and drugs to 1. stimulate increase in insulin 2. enhance glucose metabolism.

Summarizing Chart

Type 1 Diabetes Type 2 Diabetes

The onset is usually early, sometime during childhood.

The onset is usually late, sometime after childhood.

Beta cells do not produce enough insulin. Target cells become insensitive to insulin.

Diet by itself cannot be used to control the condition. Insulin injections are needed to control glucose levels.

Insulin injections are not usually needed. Low carbohydrate diet can control the condition.

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"Biology (Mader), 10th Edition." Image PowerPoints. McGraw Hill, n.d. Web. 19 Mar. 2014.

"Endocrine System." KidsHealth - the Web's Most Visited Site about Children's Health. Ed. Steven Dowshen. The Nemours Foundation, 01 Mar. 2012. Web. 19 Mar. 2014.

"Glands." Glands. McGraw Hill, 1999. Web. 19 Mar. 2014.

"Hormones: MedlinePlus." U.S National Library of Medicine. U.S. National Library of Medicine, n.d. Web. 18 Mar. 2014.