The Endocrine System (Chemical Control System) Hormones – Steroid Hormones – Protein Hormones Negative feedback The Pituitary Gland Posterior and Anterior Lobe of the Pituitary Metabolism and Thyroid T 4 Parathyroid Hormone and Calcium Blood Sugar and the Pancreas Stress and adrenaline Cortisol

Chemical Signals The endocrine system is the system of glands which secretes a type of hormone directly into the bloodstream to control/regulate the body. – Hormones: chemicals released by cells that affect cells in other parts of the body – Endocrine Hormones: chemicals secreted by endocrine glands directly into the blood

Endocrine System Works in conjunction with the Nervous System to control organs and tissues. Nervous System – responds quickly to environmental changes Endocrine System – takes longer but maintains control over a longer duration of time

Types of Hormones There are two types of hormones 1)Steroid Hormones 2) Protein Hormones

Steroid Hormones Made from cholesterol (lipid) Not Soluble in water (but are in fat) Diffuse into target cells where they combine with receptor molecules in the cytoplasm. Hormone-Receptor complex moves into nucleus and activates a gene to produce a specific protein. Examples: Male and Female Sex Hormones

Protein Hormones Contain chains of amino acids of varying length Soluble in water Combine with receptors on the cell membrane It’s combination with hormone receptors on the membrane cause a sequence of events which brings about changes inside the cell – Ex/ increase protein production Examples: Insulin, Growth Hormone

Differences Between Steroid & Nonsteroid Hormones The hormone and receptor enter the nucleus and bind to DNA Steroid hormone receptor nucleus DNA proteins Non-steroid hormone receptor second messenger Chemical reactions activated enzymes Steroid hormones enter into the cell. Steroid hormone diffuses through the cell membrane Steroid hormone binds to a receptor within the cell. Steroid hormone causes DNA to make proteins. Nonsteroid hormone binds to receptor on the cell membrane. Receptor stimulates a 2 nd messenger with in the cell. 2 nd messenger starts a series of chemical reactions in cytoplasm. 2 nd messenger reactions activate enzymes. Non-steroid hormones do not enter the cell.

Two types of Glands based on how they release or produce a substance. Exocrine Glands – Release their secretions thru tubes called “ducts”. !. Out of the body 2. Directly into digestive system Endocrine Glands – Usually release their hormones directly into the blood.

It was once thought that only glands produced hormones Nearly all cells have been shown to produce small amounts of a hormonelike substance called prostaglandins

Endocrine system video

Major Glands Glands create hormones (C) Hypothalamus –S–Stimulates the pituitary gland to release hormones –H–Helps control growth, reproduction, body temp (B) Pituitary gland –C–Controls cell growth –S–Stimulates other glands (A) Thyroid gland –R–Regulates metabolism, growth, development (D) Thymus –A–Allows WBCs to mature to fight infection

(E) Adrenal Glands –Controls “fight or flight” response –Increases breathing, alertness, blood pressure (F) Pancreas –Controls glucose level in blood Gonads: influence sexual development (H) Testes (XY): produces testosterone (G) Ovaries (XX): produces estrogen, progesterone

The Pituitary Gland Has control over all other endocrine glands Interacts with the nervous system (hypothalamus-pituitary complex)

Posterior Lobe of Pituitary Stores hormones produced by the hypothalamus ADH – acts on kidneys to restore water balance Oxytocin – uterus contractions in labour – milk production in Mammary glands

Anterior Lobe of Pituitary Produces its own hormones Release of these hormones is still regulated by the hypothalamus Thyroid Stimulating Hormone Reproductive Stimulating Hormones Growth Hormones Prolactin Adrenocorticotropic Hormone (ACTH)

Growth and Anterior Pituitary Growth Hormone (GH) promotes protein synthesis by increasing the uptake of amino acids by cells Too little GH – dwarfism Too much GH - gigantism

Metabolism and Thyroid Thyroid Gland Mainly Produces Thyroxine (T 4 ) and Calcitonin

T4T4 The 4 stands for 4 iodine atoms, therefore, you need iodine in your diet to produce these hormones If you lack iodine, thyroxin is not produced so your anterior pituitary continually sends signals (thyroid stimulating hormones) to your thyroid to produce it. This over stimulation causes the thyroid to enlarge creating a swelling in the neck called a goiter

Parathyroid Hormone and Calcium

Blood Sugar and the Pancreas alpha and beta cells are found in the Islets of Langerhans in the pancreas. Produce glucagon or insulin depending on blood sugar level of the body

Insulin allows cells to take up glucose from the blood after you have eaten  decrease blood glucose Glucagon converts glycogen  glucose in the liver when your blood glucose is to low

Diabetes is characterized by a persons inability to use insulin effectively

Endocrine system and diabetes

Stress Stress hormones provide more blood glucose to cope with the elevated energy requirements brought on by stress

Epinephrine (Epi) - Adrenaline Response to stress Produced in the adrenal gland Mobilizes (breaks down) stored energy  increase blood glucose  increase energy quickly! Increases alertness/awareness Accelerates heart rate Increases the activity of the respiratory system Prepares your body to do something fast like run from a bear, lift a car off your child, etc.

Adrenaline

Cortisol Produced in the adrenal gland It is released in response to stress and a low level of blood glucose. Its primary functions are to: 1.increase blood glucose through gluconeogenesis 2.suppress the immune system 3.aid in fat, protein and carbohydrate metabolism