The Endocrine Reproductive Systems The Endocrine System The

The Endocrine & Reproductive Systems

The Endocrine System �The endocrine system is made up of glands that release hormones into the blood.

Hormones & Glands �Hormones deliver messages throughout the body. Hormones - chemical messengers that are released in one part of the body and affect cells in other parts of the body. �Hormones act by binding to specific chemical receptors on cell membranes or within cells. �Cells that have receptors for a particular hormone are called target cells. If a cell does not have receptors for a particular hormone, the hormone has no effect on it.

Hormones & Glands �A gland is an organ that produces and releases a substance or secretion. Exocrine glands – release secretions from ducts either out of the body or directly into the digestive system. �sweat, tears, digestive enzymes Endocrine glands – release their secretions (hormones) directly into the blood.

Hormones & Glands �Prostaglandins The glands of the endocrine system were once thought to be the only organs that produced hormones. However, nearly all cells have been shown to produce small amounts of hormonelike substances called prostaglandins.

Hormones & Glands �Prostaglandins �Sometimes called “local hormones” because they affect only nearby cells and tissues. Ex: some cause smooth muscles (uterus, bronchioles, and blood vessels) contract. One group causes the sensation of pain during most headaches. • Aspirin inhibits the synthesis of these prostaglandins

Hormone Action �Steroid Hormones Steroid hormones act by entering the nucleus of a cell and changing the pattern of gene expression.

Hormone Action �Produced from a lipid called cholesterol. �Steroid hormones help control metabolism, inflammation, immune functions, salt and water balance, development of sexual characteristics, and the ability to withstand illness and injury.

Hormone Action Some examples of synthetic steroid hormones: �Glucocorticoids: prednisone, dexamethasone, triamcinolone �Mineralocorticoid: fludrocortisone �Vitamin D: dihydrotachysterol �Androgens: oxandrolone, testosterone, nandrolone (also known as anabolic steroids) �Oestrogens: diethylstilbestrol (DES) �Progestins: norethindrone, medroxyprogesterone acetate.

Hormone Action �Nonsteroid Hormones Nonsteroid hormones bind to receptors on a target cell membrane and cause the release of secondary messengers that affect cell activities

Hormone Action �Non-steroid hormones include: Choleckystokinin Epinephrine Dopamine Insulin Norepinephrine Serotonin Vasopressin

The Human Endocrine Glands �Pituitary Gland Bean shaped structure that dangles on a slender stalk of tissue at the base of the brain. It secretes hormones that directly regulate many body functions or control actions of other endocrine glands � Too much growth hormone during childhood results in gigantism � Too little GH causes pituitary dwarfism Can be treated with GH produced by genetically engineered bacteria

The Human Endocrine Glands �Hypothalamus Attached to the posterior pituitary, it is the link between the CNS and the endocrine system. Controls the secretions of the pituitary gland � The hypothalamus contains the cell bodies of neurosecretory cells whose axons extend into the posterior pituitary. When cell bodies are stimulated, axons in the posterior pituitary release hormones into the blood.

The Human Endocrine System �Hypothalamus Indirect control of the anterior pituitary. Produces releasing hormones, which is secreted into blood vessels leading to the anterior pituitary. � Produces a specific releasing hormone that controls the secretion of each anterior pituitary hormone. Follicule-stimulating Hormone (FSH) – Luteinizing hormone (LH) - Thyroid-stimulating Hormone (FSH) Adreno-corticotropic hormone (ACTH) Growth Hormone (GH) Prolactin Melanocyte-stimulating hormone (MSH)

The Human Endocrine Glands �Adrenal Glands Pyramid shaped structures that sit on top of the kidneys. Release hormones that help the body prepare for – and deal with – stress. Adrenal Cortex (outer part) produces more than two dozen steroid hormones ca called corticosteroids. � Aldosterone regulates blood volume and pressure � Cortisol regulates helps control the rate of metabolism of carbohydrates, fats and proteins. Released during physical stress such as intense exercise.

The Human Endocrine Glands Adrenal Medulla (inner part) releases hormones that produce the heart pounding, anxious feeling you get when excited or frightened (fight or flight). Sympathetic nervous system stimulate cells to release large amounts of. . . � Epinephrine (adrenaline) and norepinephrine. Increase heart rate and blood pressure Cause air passageways to widen for increase O 2 uptake Stimulate the release of extra glucose

The Human Endocrine Glands �Pancreas Both an endocrine AND exocrine gland. Exocrine: releases digestive enzymes to break down food Endocrine: “islets of Langerhans” � Blood Glucose Regulation: Insulin – stimulates cells to take glucose out of the blood Glucagon – stimulates the liver and skeletal muscle cells to break down glycogen and release glucose into the blood • Diabetes Mellitus

The Human Endocrine Glands �Thyroid & Parathyroid Glands Thyroid wraps around trachea and has a major role in regulating metabolism. Thyroid � Produces thyroxine which increases the metabolic rate of cells throughout the body. Iodine needed to produce thyroxine. � Calcitonin signals the kidneys to reabsorb less calcium and promotes absorption into bones. � Parathyroid hormone increases calcium levels in the blood. Promotes proper nerve and muscle function and proper bone structure.

The Human Endocrine Glands �Reproductive Glands Gonads (ovaries and testes) are reproductive glands. Two important functions: � Produce gamtes � Secrete sex hormones Ovaries – produces eggs and secrete estrogens. Testes – produce sperm and secrete testosterone.

Control of the Endocrine System �The Endocrine System is regulated by feedback mechanisms that function to maintain homeostasis. Feedback inhibition occurs when an icrease in any substance “feeds back” to inhibit the process that produced the substance in the first place.

Control of the Endocrine System �Maintaining Water Balance Hypothalamus detects concentration of water in blood. As you lose water, concentration of dissolved materials in blood rises. Hypothalamus signals posterior pituitary to release antidiurect hormone A water deficit stimulates the release of ADH, causing the kidneys to conserve water; Later you experience thirst – a signal that you should drink to restore lost water. An oversupply of water causes the kidneys to eliminate the excess water in urine.

Control of the Endocrine System �Controlling Metabolism

The Reproductive System

Sexual Development

The Male Reproductive System �Sperm Development �Sperm Release �Sperm Structure

The Female Reproductive System �Female Reproductive Structures �The menstrual cycle �Pregnancy

Sexually Transmitted Diseases

Fertilization and Development �Fertilization �Multiple Embryos �Implantation �Gastrulation �Neurulation �The Placenta

Later Development �Months 4 -6 �Months 7 -9 �Childbirth �Infant and Maternal Health