Endocrine system Unit 9

Activator: 2.9.2016 What are the 8 glands of the endocrine system? Think back a few chapters, what is translation and transcription? Activator: 2.9.2016

Role of endocrine system Regulates reproduction, growth and development, defenses, balance of nutrients in the blood, metabolism, and energy use 0.5 pounds of endocrine tissue Role of endocrine system

What are hormones? Chemical messengers Hormone means “to arouse” by altering cellular activity What are hormones?

Mechanisms of hormones action Start by circulating in the blood Hormones bind to certain cells or organs Mechanisms of hormones action

Target Cell/Organ- The cell or organ a hormone attaches to In order for the target to respond to the hormone, a protein receptor must be present on the plasma membrane or in the cell Hormone attachment

Activation means the hormone causes a change in the target cell 2 types of hormone activation: Steroids (cholesterol and sex hormones) are lipid soluble Amino-acid based (proteins, peptides, and amines) are non-lipid soluble Hormone activation

1. Steroidal hormone activation Lipid-soluble, so they can move through the plasma membrane 1. Steroidal hormone activation

Hormone diffuses through plasma membrane Step 1

Step 2 Hormone binds to specific receptor protein Becomes a hormone-receptor complex (HRC) HRC enters the nucleus Hormone (H) + Receptor Complex (RC) = HRC Step 2

The HRC binds to DNA Step 3

Step 4 Certain genes in the DNA are altered, new mRNA is transcribed Think back to translation and transcription Step 4

Step 5 mRNA is translated, new protein is created This protein will cause the desired effect to the cell Step 5

Amino-acid hormone activation: Non lipid soluble, so the hormones must attach to the plasma membrane directly Amino-acid hormone activation:

Hormone binds to membrane receptor attached to membrane Step 1

Binding sets off a series of reactions that activates enzymes w/in the cell Step 2

The enzyme then catalyzes (speeds up) a reaction that produces a messenger molecule Step 3

Messenger molecule creates the change desired within the cell Step 4

STEROIDAL Diffuse thru PM H + R = HRC, enters nucleus Bind to DNA Alter genes of DNA & makes new mRNA Make a new protein STEROIDAL

NON- STERIODAL Attach to receptor in PM Enzymes are released Speed up the production of a messenger molecule Messenger molecule creates the desired effect on cell NON- STERIODAL

How do glands know when to release hormones?

How do glands know when to release hormones? Use negative feedback mechanisms to maintain hormone levels in the blood How do glands know when to release hormones?

What are negative feedback mechanisms? Too much of a hormone, the glands stop producing Too little, and the glands produce more What are negative feedback mechanisms?

What kinds of stimuli activate endocrine glands? 3 main categories of stimuli: Hormonal Humoral Neural What kinds of stimuli activate endocrine glands?

Endocrine organs are prodded by other hormones to create their own hormones rhythmic/always working Hormonal stimuli

Example of hormonal stimuli Step 1: Hypothalamus secretes hormones that activate pituitary gland to release hormones. Example of hormonal stimuli

Step 2: Pituitary gland releases hormones that activates adrenal glands AS WELL AS cut off the hormones of the hypothalamus

Step 3: New hormones are released by the adrenal glands into the body AS WELL AS cutting off the hormone production in the pituitary glands This allows the hypothalamus to start producing hormones again

Initiated by low levels of ions or nutrients monitored by endocrine organs Works in short bursts/ Used only when needed Humoral stimuli

Neural stimuli Hormones respond to neural activity Ex) responding to stress Sympathetic nervous system produces norepinephrine which when stressed, which causes increased heart rate, blood pressure, etc. Neural stimuli

Endocrine organs

Pituitary Gland “Master gland” Hangs by a stalk under the hypothalamus 2 parts: Anterior Posterior Very small size of grape Pituitary Gland

Anterior pituitary 6 total hormones produced here. 2 work on non-endocrine targets 4 work on other endocrine glands, these are called trophic hormones Anterior pituitary

2 Non-endocrine targets Growth hormone (GH)- division of cells, growth of bones and muscle Prolactin (PRL) - Milk production of the breasts 2 Non-endocrine targets

4 endocrine gland targets The 4 tropic hormones stimulate: Follicle-stimulating (FSH)- Helps regulates menstrual cycle and egg production in women, sperm production in men Luteinizing (LH)- Thyroid-stimulating (TSH)- stimulates the thyroid to release its hormones Adrenocorticotrophic (ACTH)- stimulates the adrenal glands to release their hormones 4 endocrine gland targets

Works directly with the hypothalamus to secrete the hormones produced by the hypothalamus Posterior pituitary

2 hormones from posterior pituitary 1. Oxytocin (OT) :common in women, stimulates contractions during labor, sex, and also causes milk ejection 2. Antidiuretic hormone (ADH) Kidneys reduce water excretion (inhibits urine production) 2 hormones from posterior pituitary

Large gland made up of two bulbs on each side of the trachea Thyroid hormone Calcitonin Thyroid gland

Major metabolic hormone- Controls the rate at which glucose is converted into energy and heat Also controls normal tissue growth and development Thyroid Hormone

Decreases calcium levels in the blood by depositing calcium in the bones Only secreted when calcium levels are high Calcitonin

Tiny masses of tissue found on the posterior surface of the thyroid gland Parathyroid glands (4)

Releases osteoclasts Opposite role of calcitonin Effect of PTH

Adrenal glands Curve over the top of the kidneys Adrenal cortex Adrenal medulla Adrenal glands

Hormones of the adrenal cortex 3 types: Mineralocorticoids Glucocorticoids Sex hormones Hormones of the adrenal cortex

Regulate mineral (or salt) & water balance in the blood Mineralocorticoids

Glucocorticoids Increase blood glucose levels Inhibit some pain-causing molecules (anti-inflammatory) Glucocorticoids

Both produced in small amounts throughout life regardless of gender Androgens (male sex hormone) Estrogens (female sex hormone) Testosterone is an androgen Sex hormones

Hormones of the adrenal medulla Epinephrine Norepinephrine Produced by stimulating SNS Hormones of the adrenal medulla

Epinephrine and norepinephrine AKA adrenaline and noradrenaline Increase blood glucose and rate of metabolism Spark the “fight or flight” response Epinephrine and norepinephrine

The pancreas houses tiny little endocrine glands called the pancreatic islets Insulin Glucagon Pancreas

Roles of insulin and glucagon Both regulate the amount of sugar in the blood, but in opposite ways Roles of insulin and glucagon

Small gland located in the brain Pineal gland

Melatonin Effects how tired we are Levels rise and fall throughout the day: High levels = drowsy Levels are lowest around noon Melatonin

Thymus gland Located in the upper thorax, posterior to the sternum Produces thymosin Thymus gland

Thymosin Highly useful in immunity and defenses of the body Stimulates the production of disease fighting T-cells Only active until you hit puberty – slowly shrinks and is replaced by fat Thymosin

Gonads Grouped by male and female organs Female gland: ovaries Male gland: testes Gonads

Ovaries Produce sex cells (ova, or eggs) Also produce 2 hormones: Estrogen Progesterone Ovaries

Hormones of the ovaries Estrogen stimulates development of the female reproductive organs Progesterone acts with estrogen to bring about and regulate the menstrual cycle Hormones of the ovaries

Testes Produce sex cells (sperm) Also produce androgens (testosterone is the most common) Testes

Hormones of the testes Androgens stimulate: Development of the male reproductive organs Secondary sex characteristics Increases sex drive Hormones of the testes

developmental gland: the placenta The placenta is a temporary organ formed during pregnancy, found in the uterus developmental gland: the placenta

What does the placenta do? Helps to increase levels of estrogen and progesterone in the mother This improves the lining of the uterus, further development of breasts, and lactation What does the placenta do?