The two regulatory systems involved in maintenance of homeostasis are the nervous system and the endocrine system Remember: homeostasis: the condition in which the body’s internal environment remains relatively constant Neural control is quick, brief and generally results muscle contractions or glandular secretions

Endocrine Hormones Is made up of ductless glands that secrete directly into the blood. Affects cell activities by releasing chemical messengers ( hormones) directly into the bloodstream, the target cells are varied (may be all over body) Hormones control generally takes from minutes to hours to occur and the changes are long lasting, usually due to changes in the metabolic activity of the target cell

Endocrine glands Remember: exocrine glands: secrete products by way of ducts onto a surface. Ex sweat glands, digestive glands, oil glands Endocrine glands: secrete produces into extracellular spaces where they are picked up and transported by the circulatory system

Hormones A secretion of endocrine tissue that is transported in the blood and its signaling influences a wide variety of body functions ranging from bone growth and muscle grow to the concentration of glucose in the blood.

2 major types of hormones 1. Amino acid based : molecules: range from small amino acids to huge proteins Are water soluble Include majority of hormones 2. Steroids: ( derivatives of cholesterol) Are lipid soluble so can cross cell membranes Includes only gonads and some adrenal hormones

Mechanisms of hormone action: Since hormones are released into the circulatory system, virtually all tissues are exposed to them. The ability of a cell to respond to a hormone depends on the presences of large protein molecules called receptors which are very specific ( lock and key analogy)

Mechanisms of hormone action: They bind with specific hormones and not others. The combination of a hormone and receptor activates a chain of events resulting in the hormonal effect A single type of hormone can have different effects on different cells because they might be either different types of receptors, or varying quantities of receptors producing varying magnitudes of effects

2 major types of receptors are: 1. Plasma membrane receptors: found on cell membrane 2. Intracellular receptors: found within cell. React with hormones that enter cell membrane and generally initiate or stop protein synthesis

In General, A hormones effect is one of the following: 1. Change in membrane permeability 2.Start or stop protein synthesis 3.Activate or deactivate enzymes 4.Induce or stop secretory activites

The endocrine glands Are pockets of hormones producing tissue found in the : stomach, heart, small intestines and placenta Additionally there are “local hormones” called prostaglandins

Prostaglandins are membrane associated lipids produced by possibly all cells. Some characteristics: 1. have a hormone-like effect but are not true hormones 2. have local effect only if not produced by endocrine glands. Ex of their functions is influencing blood clotting to effect inflammation

Pituitary gland (hypophysis) Located in the sella turcica of sphenoid bone and is attached to the hypothalamus of the brain by the stalk-like infundibulum Regulates so many bodily activities ( especially glands) that it is called the master gland of the body The pituitary gland is stimulated/inhibited by factors produced in the hypothalamus of the brain

Pituitary gland Is divided into: Anterior pituitary gland: adenohypophysis which makes up 75% of mass of the pituitary gland and releases 7 different hormones Posterior pituitary gland: Neurohyphysis which is not really a gland, it stores and secretes hormones which are produced in the hypothalamus

Hypophysis  Know 2 division:  Adenohypophy sis ( anterior ½) H/F  Neurohpophysis ( posterior ½) H/F it has fibers and is lighter

The anterior pituitary synthesizes and secretes the following important endocrine hormones: 1. FSH ( follicle stimulating hormone): regulates hormonal activities of gonads such as sperm or egg production, (ovulation), estrogen and progesterone release and testosterone 2.Luteinizing hormone (LH): same as above 3.ACTH (adrenocorticotropic hormone) regulates endocrine activity of adrenal gland (cortex)

The anterior pituitary synthesizes and secretes the following important endocrine hormones: 4.TSH (thyoid stimulating hormone) (thyrotropic hormone): functions ingrowth and activity of thyroid gland 5.Growth hormone (SRH) (somatotropin): functions in metabolism/body size, stimulates growth via protein synthesis, deficiency causes dwarfism 6.LTH (leuteotropic hormone) (prolactin): lactation of mammary glands

The anterior pituitary synthesizes and secretes the following important endocrine hormones: 7.MSH ( meloancyte stimulating hormone) not significant in humans, may be a precursor to several other hormones

Hormones of posterior pituitary gland 1.oxytocin: functions in uterine contraction and mammalary gland due to smooth muscle contractions 2.ADH (antidiuretic hormone) (vasopresin) functions in increasing blood volume and pressure, also constricts blood vessels and affects the kidney tubules causing them to reabsorb water

Thyroid gland Located below the larynx and is composed of spherical bags called follicles The follicle walls are simple cuboidal epithelium and are called follicular cells The follicular cells produce and store the thyroid hormones in the follicles as thyroblobin in a gelatin state called a colloid

Thyroid gland Cells outside of the follicle walls are called parafollicular cells

Thyroid Gland  Know  Thyroid follicle  Thyroid colloid  Follicular cells H/F  Parafollicular cells H/F

Thyroid hormones 1.Thyroxin: produced by follicular cells and affects body metabolism 2.Calcitonin: produced by parafollicular cells and decreases calcium levels. It is antagonistic against parathyroids attempt to increase calcium

Thyroid disorders: hyperthyroidism:  Characteristics:  Abnormal metabolic rate  Sensitive to heat  Restless, overactive  Appears mentally alert  Eyes protrude (exophthalms)  Irritable de to sensitive nervous system  Enlarged thyroid ( goiter)

Thyroid disorders: hypothyroidism  Characteristics:  Low metabolic rate  Abnormal sensitivity to cold  Physical sluggishness  Poor appetite  Appears mentally dull  Swelling of body tissue  Tendency to gain weight

Parathyroid gland Tiny glands located on posteror surface of the thyroid gland Hormone secreted is: Parathrormine: which increases calcium levels by increasing absorption in the kidneys and intestines. If this hormone functions improperly the result is weak brittle bones

Disorder of parathyroid gland Hypoparathyroidism: Characteristics Blood calcium drops Nervous system excitable Muscles undergo tetanic contractions (cramps and seizures) Can die due to respiratory failure Treatment large does of vitamin D and calcium

Disorder of parathyroid gland Hyperparathyroidism: Characteristics Blood calcium is high Nervous system depressed Muscle contractions weak and sluggish Usually caused by tumors Bones deformed and soft due to osteoclast

Parathyroid Gland  Just Identify it and know H/F

Thymus gland Located below the thyroid gland, superficial to the heart Is a large gland in infants which diminishes in size with age Hormone produced: Thymosin: for production and programming of T cells (immunity) is gone by age 35

Pineal gland Found in center of brain, Its function is mostly a mystery Hormone produced: Melatonin: may be involved in circadian rhythems

Pancreas Located behind and inferior to the stomach Has both endocrine and exocrine functions ( called a mixed gland) Endocrine portion consists of clusters of cells called islets of Langerhan which consist of 2 types of cells: 1: alpha cells: in middle 2. beta cells: outer edge

Pancreas Exocrine section is the acini cells which secrete various enzymes for digestive purposes

PANCREAS  Know  Acini cells  Islet of Langerhans  Alpha cells ( found at edges H/F)  Beta cells ( found in center H/F)

Diabetes Any of a various disorders having in common the abnormal amounts of urine produced Diabetic insipidus: pituitary disorder resulting in insufficient ADH and excess fluid loss Diabetic mellitus: collection of diseases grouped together because they result in excessive sugar levels in blood (hyperglycemia) Hypoglycemia: low blood sugar

Diabetic mellitus  2 types:  Type I: juvenile onset, lack insulin activity insulin dependent  Something destroys insulin producing capacity of beta cells  Type II: 90%, maturity onset ( after age 40), alpha cells  Strong genetic link??? Unable to use insulin produced by body due to abnormal receptors in cell membrane

Hormones released by Pancreas 1. Insulin: released by beta cells functions to decrease glucose 2. Glucose: released by alpha cells which secrete glucagon that increases sugar levels Hyperinsulinism: rare, usually tumor of islet cells Hyperinsulinism: rare, usually tumor of islet cells

Adrenal Gland  Located on the superior surface of each kidney,  composed of 2 distinct layers: adrenal cortex and adrenal medulla  Adrenal medulla is the central portion of the gland  Adrenal cortex is the outer layer of the gland and has 3 zones

Adrenal Gland  Know:  Adrenal cortex and its sublayers: 1. Zona glomerulosa (loops and circles _ H/F) 2. Zona fasiculata (widest H/F) 3. Zona reticularis ( netlike with brown spots H/F)  Adrenal medulla H/F  Capsule

Adrenal hormones  Adrenal Medulla: central portion  Hormones:  Epinephrine: fight or flight, increase respiratory and metabolic rates and constrict blood vessels  Norepinephrine: same

Adrenal hormones  Adrenal cortex: outer layer has 3 zones  1. Zona glomerulosa (outer layer): hormone is aldosterone (mineralocorticoid) which regulates sodium ion reabsorption by kidneys  2. Zona fasiculata (middle)  Hormone is cortisone (glucocorticoid) functions in increasing blood glucose levels

Adrenal hormones  3. zona reticularis: (inner layer)  Hormone is sex hormones (gonadocorticoids)

Adrenal Gland

Adrenal disorders: hyposecretions  Causes Addison’s disease  Characteristics:  Low sodium, high potassium  Low blood glucose  Dehydration  Low blood pressure  Increased skin pigmentation (ACTH mimics MSH)  Mental lethargy  Muscular weakness  Weight loss  Death in a few days if untreated

Adrenal disorders: hypersecretions  Causes Cushing’s Disease  Characteristics  Decrease in protein  wasting of muscle and loss of bone tissue  Blood glucose elevated  Puffy skin due to water retention  Sodium high  Fat deposits between shoulders and in face making buffalo hump and moon face  Spindly arms and legs  Poor wound healing

Gonads  Ovaries: primary source of female sex hormones  Hormones  Estrogen: secondary sex characteristics  Progesterone: menstrual cycle  Testes: primary source of male sex hormones  Hormones:  Testosterone: secondary sex characteristics of male  MORE LATER