Human AnaPhy C8 - The Endocrine System PDF

Chapter 8 The Endocrine System Fundamentals of Anatomy and Physiology  The Endocrine System Maintains internal environment (homeostasis) Hypothalamus: sends chemical signals to pituitary Endocrine glands ▪ Ductless ▪ Secrete hormones directly into bloodstream ...

Chapter 8 The Endocrine System Fundamentals of Anatomy and Physiology  The Endocrine System Maintains internal environment (homeostasis) Hypothalamus: sends chemical signals to pituitary Endocrine glands ▪ Ductless ▪ Secrete hormones directly into bloodstream  The Endocrine System Second messenger system of the body Uses chemical messages (hormones) that are released into the blood Hormones control several major processes: ▪ Reproduction ▪ Growth and development ▪ Mobilization of body defenses ▪ Maintenance of much of homeostasis ▪ Regulation of metabolism.  Hormone Overview Hormones are produced by specialized cells Cells secrete hormones into extracellular fluids Blood transfers hormones to target sites These hormones regulate the activity of other cells  Mechanisms of Hormone Action Hormones affect only certain tissues or organs (target cells or organs) Target cells must have specific protein receptors Hormone binding influences the working of the cells  The Functions of Hormones 1. Control cellular respiration, growth, and reproduction 2. Control body fluids and electrolyte balance 3. Control secretion of other hormones 4. Control behavior patterns 5. Regulate reproductive cycles, growth, and development 6. Chemical control functions as negative feedback loop 7. Negative feedback involves a response that is the reverse of the change detected  Control of Hormone Release Hormone levels in the blood are maintained by negative feedback A stimulus or low hormone levels in the blood triggers the release of more hormone Hormone release stops once an appropriate level in the blood is reached  Negative Feedback Thermoregulation (if body temperature changes, mechanisms are induced to restore normal levels) Blood sugar regulation (insulin lowers blood glucose when levels are high ; glucagon raises blood glucose when levels are low) Osmoregulation (ADH is secreted to retain water when dehydrated and its release is inhibited when the body is hydrated)  The Classification of Hormones Modified amino acids (Simplest) ▪ Epinephrine, Norepinephrine, Oxytocin, and Vasopressin Proteins ▪ Insulin and Growth hormones Steroid (Lipids) ▪ Cortisol, Estrogen, and Testosterone  The Hypothalamus of the Brain Controls secretions of the pituitary gland Nerve cells produce chemical signals ▪ Releasing hormones ▪ Releasing inhibitory hormones Controlled by negative feedback from endocrine system The Major Endocrine Glands and Their Hormones  Pituitary Gland Also called the hypophysis ▪ Size of a pea/grape ▪ Hangs by a stalk from the hypothalamus ▪ Protected by the sphenoid bone Has two functional lobes ▪ Anterior pituitary (adenohypophysis) – glandular tissue ▪ Posterior pituitary (neurohypophysis) – nervous tissue.  The Anterior Pituitary Gland Growth Hormone (GH): cell metabolism and growth Causes amino acids to be built into proteins Causes fats to be broken down for a source of energy Decreased production ▪ Dwarfism: childhood Increased production ▪ Gigantism: childhood ▪ Acromegaly: post puberty Controlled by two releasing hormones from hypothalamus. Dwarfism Gigantism Acromegaly  The Anterior Pituitary Gland Thyroid-stimulating hormone (TSH) ▪ stimulates thyroid Adrenocorticotropic hormone (ACTH) ▪ stimulates adrenal cortex Melanocyte-stimulating hormone (MSH) ▪ stimulates melanocytes  The Anterior Pituitary Gland Gonadotropic hormones ▪ Regulate hormonal activity of the gonads Follicle-stimulating hormone (FSH) ▪ Females - stimulates ovarian follicle development ▪ Males - stimulates sperm cell production  The Anterior Pituitary Gland Luteinizing hormone (LH) ▪ Females - stimulates ovulation and progesterone production ▪ Males - stimulates testosterone production Lactogenic hormone (LTH) / Prolactin ▪ stimulates milk production in females ▪ function in males is unknown  The Posterior Pituitary Gland Antidiuretic Hormone (ADH) / Vasopressin ▪ Increased water reabsorption in kidney tubules ▪ Deficiency results in diabetes insipidus ▪ Regulated through osmoreceptors ▪ Dehydration causes water conservation  The Posterior Pituitary Gland Oxytocin ▪ Contraction of uterine smooth muscles ▪ Constriction of mammary gland cells (lactation) ▪ Given after childbirth to constrict blood vessels to minimize risk of hemorrhage. The Posterior Pituitary Gland and Its Hormones  The Thyroid Gland Located below larynx on either side of trachea Requires iodine  The Thyroid Gland Hormones Thyroxine / Tetraiodothyronine (T4): metabolism Triiodothyronine (T3): metabolism Calcitonin: regulation of calcium and phosphate concentration  The Thyroid Gland Goiter ▪ Abnormal enlargement of your thyroid gland. Hypothyroidism ▪ Lowered metabolic rate ▪ Cretinism (child) ▪ Myxedema (adult) Hyperthyroidism ▪ Elevated metabolism ▪ Graves’ disease o Exophthalmia  Goiter Myxedema. Cretinism Graves’ disease  The Parathyroid Glands Located within the posterior thyroid gland Chief cells secrete parathormone (PTH) PTH: ▪ stimulates bone cell release of calcium and phosphate ▪ stimulate osteoclasts to remove calcium from bone ▪ stimulate the kidneys and intestine to absorb more calcium ▪ raise calcium levels in the blood  The Parathyroid Glands Hyperparathyroidism o Breakdown of bone matrix Hypoparathyroidism o Low calcium level in blood. Position of the parathyroid glands  The Adrenal Glands. Located on top of each kidney  The Adrenal Glands Adrenal medulla: ▪ Epinephrine and Norepinephrine (fight-or-flight) o These hormones prepare the body to deal with short-term stress. Adrenal cortex: ▪ Aldosterone – regulates sodium reabsorption and potassium excretion by the kidneys ▪ Cortisol – stimulates the liver to synthesize glucose ▪ Androgens – male sexual characteristics; female sex drives  The Adrenal Glands Disorders Addison’s disease ▪ lack of adrenal cortex hormones Cushing’s syndrome: ▪ too much adrenal cortex hormones  The Pancreas Islets of Langerhans ▪ Beta cells: insulin production ▪ Alpha cells: glucagon production o Blood glucose levels regulated by negative feedback  The Pancreas Disorders Low blood glucose: acidosis High blood glucose: excess kidney production with high amounts of glucose, dehydration Diabetes mellitus: insufficient insulin production  The Testes and the Ovaries Testes: testosterone ▪ Development of male reproduction structures ▪ Development of male sex characteristics Ovaries: estrogen and progesterone ▪ Development of female reproductive organs ▪ Development of female sex characteristics ▪ Control menstrual cycle  The Thymus Gland Located posterior the sternum Secretes thymosin ▪ Important for T cell production ▪ Important in developing the immune system Thymus shrinks as we age  The Pineal Gland Located in the brain near the thalamus between the two cerebral hemispheres Melatonin ▪ Inhibits reproductive functions ▪ Regulates body rhythms ▪ Sleep-Wake patterns Serotonin: neurotransmitter and vasoconstrictor ▪ Stimulates smooth muscle contractions ▪ Inhibits gastric secretions  The Pineal Gland.  Thank You! Do you have any questions for me before we go?