Human Endocrine System Endocrine System groups of endocrine

Human Endocrine System

Endocrine System groups of endocrine glands that produce hormones are chemical messengers ◦ substances that are made by one organ that have an effect on another organ

. When the body needs to bring about a long-term change, those messages are sent through the endocrine system.

Types of Glands Endocrine glands - Ductless chemicals are hormones travel through the blood vessels until they reach the target organ

Hormones work by binding to specific chemical receptors on target cells Receptor: protein whose shape fits that of a specific messenger molecule such as a hormone Target cells: cells that have receptors for a particular hormone

Hormone Action

Endocrine Functions Regulates metabolism Maintains salt, water, and nutrient balance in the blood Controls the body’s response to stress Regulates growth, development, and reproduction

HYPOTHALAMUS Location: Lower brain –links nervous and endocrine system. Function: controls pituitary gland

The Hypothalamus produces a set of chemicals called releasing factors that stimulate the pituitary to release Hormones

PITUITARY Location: Base of brain Function: “Master gland”– releases hormones that control many other glands. Pea-sized

PITUITARY

PITUITARY Hormones Secreted: Thyroid Stimulating Hormone (TSH): stimulates thyroid to produce thyroxine Growth Hormone (GH): Stimulates the growth of bones

PITUITARY Hormones Secreted: Lutenizing Hormone (LH): Stimulates development of ovaries and testes Follicle Stimulating Hormone (FSH): Stimulates gonads to produce sperm and eggs

PITUITARY Hormones Secreted: Oxytocin: Stimulates Uterine contractions during childbirth and milk production in female breast after childbirth

How Do Hormones Know Which Part of Your Body to Affect? Hormones travel toward target cells – designed to receive the chemical message they carry. Target cells have specific receptors molecules on them that lock into the hormone like a lock-n-key.

THYROID Location: Front part of neck “Bow-tie” or “Butterfly” that hugs the trachea

Thyroid Gland produces a hormone called thyroxin is the only molecule in our body that utilizes iodine

Thyroxin regulates the rate of metabolism by stimulating cell respiration

PARATHYROID Location: Hormone 4 tiny glands embedded in thyroid gland Produced: Parathyroid Hormone (Parathormone, PTH): regulates Calcium levels in blood.

Parathyroid Glands PTH causes bone cells (osteocytes) to take Ca 2+ out of bone and put it into the blood calcium blood level INCREASE ◦ Ca 2+ effects the release of neurotransmitters of the neurons

PANCREAS

PANCREAS: “ISLETS OF LANGERHANS” Location: glands found within the pancreas Function: regulates blood sugar levels

The Pancreas pancreas is the ONLY gland that is BOTH exocrine and endocrine! cell clusters called the Islets of Langerhans produce hormones there are 2 cell types on the pancreas

The Pancreas (beta) cells make a hormone called insulin stimulates the cells to absorb glucose by making the plasma membranes more permeable blood glucose levels DECREASE

The Pancreas (alpha) cells make a hormone called glucagon causes the liver to hydrolyze glycogen into glucose blood glucose levels INCREASE

Homeostasis Insulin and glucagon are ANTAGONISTIC PAIRS They work against each other to control glucose levels in the blood

Adrenal Glands Location: Triangular glands that sit on top of kidneys Hormones Produced: ◦ Cortisol: Stimulates conversion of fat and protein into glucose. ◦ Adrenaline/Epinephrine: In times of stress it increases blood sugar, heart, & breathing rates

ADRENAL Other Hormones Produced: Aldosterone – stimulates the reabsorption of Na+ in the nephron tubule Cortisone – reduces swelling in tissues Androgen – steroids similar to the male sex hormone

GONADS: OVARIES & TESTES

GONADS: OVARIES & TESTES OVARIES Location: in the pelvis of female Hormones Produced: ◦ Estrogen- development of female secondary sex characteristics ◦ breast development ◦ changes in fat distribution which bring about changes in body shape ◦ menstrual cycle

GONADS: OVARIES & TESTES OVARIES Hormones Produced: ◦ Progesterone- increase uterine lining for fetus development during pregnancy.

GONADS: OVARIES & TESTES Location: in the scrotum of male Hormones Produced: ◦ Testosterone- development of male secondary sex characteristics ◦ thicker, darker body hair ◦ increased muscle development ◦ thickening of vocal chords

Feedback Mechanisms Self-regulated way to maintain proper levels of hormones in body. Two Types: ◦ Negative feedback: A change in the opposite direction from the current condition to bring your body back to homeostasis Positive feedback: An increase in an already existing condition that moves your body further away from homeostasis.

Examples of Positive Feedback Blood Clotting - increase enzymes released by platelets causes an increase fibrin production which aids in clotting of damaged area Childbirth- contractions cause babies head to press on cervix, which causes release of Oxytocin causing more contractions until baby is delivered…

Examples of Negative Feedback Maintaining thyroid hormone levels in your body Recognizing when levels are high or low and making appropriate adjustments)

Maintaining Thyroid Hormone Levels in Your Body Hypothalamus detects level of thyroxine in blood… If LOW – tells pituitary to secrete TSH, which tells thyroid to secrete thyroxine. If HIGH – tells pituitary to stop secreting TSH, so that thyroid will STOP secreting thyroxine. HOMEOSTASIS is restored!!

Examples of Negative Feedback Maintaining proper sugar levels in your body by releasing insulin and glucagon when necessary)

Examples of Negative Feedback Maintaining proper body temperature at 98. 6 F By your body by shivering and sweating)

Fig. 45 -11 Pathway Negative feedback – Stimulus Endocrine cell Blood vessel Target cells Response

Maintaining Proper Sugar Levels in Your Body

What is happening here? Graph of secretion of hormones

Malfunctions of the Human Endocrine System Too MUCH or too little of any hormone disrupts homeostasis in your body. The levels need to be just right!

Diabetes Mellitus Diabetes mellitus is perhaps the best-known endocrine disorder It is caused by a deficiency of insulin or a decreased response to insulin in target tissues It is marked by elevated blood glucose levels

Diabetes Must take insulin injections or Diet Control Causes many problems including Vascular disease and Blindness Very taxing on kidney, could lead to kidney failure

Mechanism of Diabetes

Type I diabetes mellitus is an autoimmune disorder in which the immune system destroys pancreatic beta cells Type II diabetes mellitus involves insulin deficiency or reduced response of target cells due to change in insulin receptors

Growth Hormone Malfunction Too MUCH human Growth Hormone (h. GH) Results in Giantism or Acromegaly Too LITTLE Growth Hormone (h. GH) Results in Dwarfism

Growth Hormone Malfunction The world's tallest man, Sultan Kosen Measured at 8 feet 1 in. was in NYC last year as part of his Guinness Book of World Records’ Tour

Thyroid Malfuctions Too MUCH Thyroxine Hyperthyroidism: includes weight loss, increased heart rate and blood pressure ◦ thin body ◦ nervousness ◦ Excitability

Thyroid Malfuctions Too LITTLE Thyroxine Hypothyroidism: Slows body processes, fatigue, slow heart rate, weight gain

Thyroid Malfunctions Goiter: Thyroid gland becomes severely enlarged

Thyroid Malfunctions Goiter: Caused By: Low level of Thyroxin in the body Thyroid enlarges to compensate for low level A diet deficient in Iodine ◦ Not common in America because we have Iodized Salt

Goiter

Goiters

Thyroid Malfunctions Graves’ disease is a form of hyperthyroidis in humans It is an autoimmune disease that affects the thyroid. It can also affect the eyes causing them to bulge

Review Questions…

Review Questions… How do hormones know which cells in the body to affect? What is the difference between positive and negative feedback? Provide an example of negative feedback. Provide an example of positive feedback. What symptoms would a person with a hyper secretion of growth hormone exhibit?

Review Questions… What symptoms would a person with a hypo secretion of thyroxin exhibit? What is the one gland in the body that is both an endocrine and an exocrine gland? How do glucagon and insulin regulate the blood sugar level of a person? What might be lacking in the diet of a person who develops goiter?

Question #1 The two systems that work together to maintain homeostasis in most animals are the ◦ Nervous and endocrine ◦ Nervous and locomotive ◦ Endocrine and excretory ◦ Excretory and locomotive

Question #2 Structures that are adapted to convert a stimulus into a nerve impulse in the body is known as ◦ Receptors ◦ Effectors ◦ Muscles ◦ Glands

Question # 3 In a reflex arc, the pathway for an imupulse is along a sensory neuron directly to a motor neuron through ◦ A receptor ◦ The brain ◦ An effector ◦ An interneuron

Question # 4 Which two terms are most closely associated with the endocrine system? ◦ Digestive glands and enzymes ◦ Neurons and neurotransmitters ◦ Receptors and effectors ◦ Ductless glands and hormones

Question # 5 Many animals have complex reproductive cycles and growth patterns that are regulated by chemical secretions known as ◦ Hormones ◦ Intercellular fluids ◦ Antibodies ◦ Neurotransmitters

Homeostasis A state of balance in the body

Homeostasis A condition in which the internal environment of the body remains relatively constant despite changes in the internal and external environment.

Feedback Mechanisms Maintain or restore homeostasis

Negative Feedback Loops Consist of Three Parts:

1. Receptor monitors conditions and detects changes

2. Control center determines next action and sends a message

3. Effector receives directions from the control center; produces a response that restores the homeostasis

Temperature Regulation in Homes thermostat detects house getting cooler furnace turns off furnace turns on to release heat thermostat detects room temperature has increased

Regulation of Blood Sugar through Negative Feedback Hyperglycemia Stress Pancreas-beta cells Sensor and Control center Negative Feedback: Insulin release inhibited Blood glucose is reduced Liver and Muscle cells take up glucose from the blood Effectors Insulin is released into blood

Regulation of Thyroxin through Negative Feedback Low conc. of thyroxin in blood Pituitary gland Sensor and Control center Stress Negative Feedback: TSH secretion inhibited Thyroxin levels in the blood increase Thyroid gland secretes thyroxin Effectors Thyroid stimulating hormone (TSH) released

Guard Cells in Leaf

Guard Cells in Leaf plant detects water shortage water levels return change to normal; stomata guard cells change shape to open stomata transpiration is reduced guard cells shape to close