1. Water balance2. Uterine contraction3. Growth, metabolism, and milk secretion4. Ion regulation5. Heart rate and blood pressure regulation6. Blood glucose control7. Immune system regulation8. Reproductive function control
Chemical signals Chemical signalsChemical signals or Ligands - Molecules released from one location that move to another location to produce a response.Intracellular response – produces from one part of a cell and travel to another part of the SAME cell Autocrine Paracrine Neuromodulators Pheromones
Receptors ReceptorsChemical signals bind to proteins and glycoproteins (RECEPTORS)Specificity – Tendency for each receptor site to bind to a specific chemical signal and not the others.
Membrane-bound receptorsExtend across the cell membrane, with their receptor sites outside the surface of the cell membraneResponds to chemical signals that are large, and water-solubleIntracellular receptorsChemical signals DIFFUSES and bind to the intracellular receptor located at the cytoplasm or nucleus
Hormones Hormones Hormones are distributed in the blood to all parts of the body, but only its corresponding target tissue respond to each type of hormone Influences target cells by chemically binding to their receptors. 2,000-100,000 receptors for a particular hormone Hormones that pass in the blood and act on distant cells are called Circulating hormones or ENDOCRINE PARACRINE - Hormones that act on neighboring cells AUTOCRINE – Acts on the same cell Local hormones usually are inactivated quickly
Pituitary and HypothalamusPituitary and HypothalamusPituitary gland / Hypophysis – Small gland about the size of pea Rest in the depression of sphenoid bone inferior to the hypothalamus of the brain. Infundibulum – Stalk connecting the pituitary gland to the hypothalamus Once known as “Master Gland”
Pituitary and HypothalamusPituitary and Hypothalamus
Hormones of the Anterior Pituitary 1. Growth hormone 2. Thyroid-Stimulating Hormone (TSH) 3. Adrenocorticotropic Hormone (ACTH) 4. Gonadotropins a. Leutinizing hormone (LH) b. Interstitial Cell-stimulating hormone (ISCH) 5. Prolactin 6. Melanocyte-Stimulating Hormone
1. Growth Hormone Stimulates the growth of bones, muscles, and other organs by increasing protein synthesis. Resist protein breakdown during periods of food deprivation Secretion of growth hormone is controlled by 2 hormones from the hypothalamus (releasing and inhibitory hormone) Daily peak levels during sleep, also increases during fasting and exercise Dwarfism Gigantism
• In gigantism - ACROMEGALY - facial features and hands become abnormally large• Somatomedins – Protein chemical signal which together with Growth hormone to bind to the receptors of bone and cartilage tissues to stimulate growth
2. Thyroid-Stimulating Hormone (TSH)Binds on Membrane-bound receptors of the thyroid gland, causes to secrete thyroid hormones.↑ TSH- Thyroid gland enlarges
3. Adrenocorticotropic Hormone (ACTH) Binds on Membrane-bound receptors on the cells in cortex of adrenal glands. Increases secretion of Cortisol ( hydrocortisone), which keeps the adrenal cortex from degenerating Binds to melanocytes and increase skin pigmentation. ↑ ACTH - Darkening of the skin
4. GonadotropinsLeutinizing hormone (LH)Interstitial Cell-stimulating hormone (ISCH)Binds on Membrane-bound receptors of the gonads. Regulates growth, development and of functions of gonadsLeutinizing hormone (LH) – Ovulation of oocytes and the secretion of estrogen and progesterone from ovariesInterstitial Cell-stimulating hormone (ISCH) – stimulates interstitial cells of the testes to secrete testosterone.Follicle-Stimulating Hormone – Stimulates the development of follicles in the ovaries and sperm cells in the testes.
5. ProlactinBinds on Membrane-bound receptors in the cells of the Breast, during pregnancy and stimulates the production of milk.6. Melanocyte-Stimulating HormoneBinds on Membrane-bound receptors on melanocytes and causes them to synthesize melanin.↑ ACTH - Darkening of the skin
Hormones of the Posterior Pituitary . A n t i d i u r e t i c2. Oxytoxin h o rBinds on Membrane-bound receptors and m o causes Uterine contraction and milk n e ejection (milk let-down) ( A D H )
Thyroid Gland Thyroid Gland• Made up of 2 lobes connected by the isthmus• Located on either side of trachea, just below the larynx• Largest endocrine gland• Thyroid follicles – small spheres with walls that consist of simple cuboidal epithelium• Each follicle is filled with protein to which thyroid hormones attached.
Thyroid HormonesBinds to intracellular receptors in cells and regulate the rate of metabolism in the body.Participates in normal rate of growth and development.HypothyroidismInfants – Cretinism - Mentally retarded and short in stature, with abnormally formed skeletal structures.Adults – reduced rate of metabolismsluggishness, reduced ability to performroutine task.
HyperthyroidismElevated rate of metabolism, extreme nervousness, and chronic fatigue.Grave’s disease – bulging of the eyes (exopthalmia).Thyroid gland requires iodine to synthesize thyroid hormone.Iodine is taken up by thyroid follicles, hormone synthesisThyroxine / tetraiodothyronine (T4)Triiodothyronine (T3)Lack of iodine results in reduced T3and T4 synthesis
Para-thyroid Gland Para-thyroid Gland• Embedded in posterior wall of the thyroid gland• Secretes parathyroid hormone (PTH) – Regulation of blood calcium – Increases the absorption of Ca+ from the intestine by causing an increase in active vitamin D formation Hyperparathyroidism Elevated Blood Ca+ results in nerve and muscle less excitable, resulting in fatigue and muscle weakness Hypoparathryroidism Reduced Vitamin D formation. Nerves and muscles become more excitable and produce spontaneous action potential. Frequent muscle cramps or tetanus
HyperparathyroidismBones become soft, deformed and easily fractured
Adrenal Glands Adrenal Glands1. Adrenal Medulla – Inner part 1. Epinephrine (adrenaline) 2. Norephinephrine2. Adrenal Cortex – Outer part
Adrenal Medulla – Inner part (narrow or middle) Secretes Epinephrine (adrenaline) and small amounts of Norephinephrine Released in response to stimulation of Sympathetic nervous system Fight or Flight hormones
Pancreas, Insulin, Diabetes Pancreas, Insulin, Diabetes• Endocrine part consist of pancreatic islets a.k.a. “Islets of Langerhans” – has two types of cells.• Alpha cells – secrete glucagon• Beta cells – secrete insulin• A decline in the blood glucose below the normal range causes the nervous system to malfunction (Glucose is the Nervous system’s main source of energy)
Insulin – Released in response the elevated blood glucose levels and increased sympathetic stimulation.• The major target of insulin are the liver, adipose tissue, muscles, and the area of the hypothalamus that controls the appetite, satiety center.Diabetes Mellitus – Result from: (1) secretion of too little insulin from pancreas, (2) Insufficient numbers of insulin receptors on target cells, and (3) defective receptors that do not respond normally to insulin.Triad of Diabetes Mellitus 1. Polyuria - ↑ urination 2. Polyphagia - ↑ food intake 3. Polydypsia - ↑ water intake
(Diabetes Mellitus)Hyperglycemia- Tissues cannot take up glucose effectively, causing blood glucose to become very high.Polyphagia – Glucose cannot enter cells of the satiety center of the brain without insulin, the brain responds as if there were little blood glucose, resulting in exaggerated appetite.Polyuria – Excess of glucose in the blood is excreted in the urine, thus…Polydypsia – Because of polyuria, the person becomes dehydrated and thirsty, thus the need to drink often.
Testes and Ovaries Testes and OvariesTestosterone – Main sex hormone in male Responsible for the growth and development of male reproductive structures, muscle enlargement, growth of body hair, voice changes and male sexual drives.
Estrogen & Progesterone• Development of female reproductive structures and sexual characteristics• Enlarges the breast and distribute fat, which influences the shape of the hips, breast, and thighs.• Maintains menstrual cycle
Thymus Gland Thymus Gland• Lies at the upper part of the thoracic cavity• Plays an important role in immune system• Thymosin – Helps in the development of T-Cells (helps protect the body against infection by foreign organism)• Most important in early life.
Pineal Body Pineal Body• Small pinecone-shaped structure located superior and posterior to the thalamus of the brain.• Melatonin – decrease secretion of LH and FSH by decreasing release of hypothalamic-releasing hormones. Acts to inhibit reproductive system