Ch.10 Endocrine System

Ch.10 Endocrine SystemBy: Tyler Longmore, Alhi Leconte, & Christian khawly

Endocrine GlandsThe Endocrine System consists of glands and tissues that secrete hormonesHormones: Chemical signals that affect the glands or tissues .Endocrine glands: ductless; they secrete their hormones directly into tissue fluid and from there go to the bloodstream to spread through the body.

How Hormones FunctionTheyre two different types of hormones: Peptide and steroid.Along with fundamental differences in structure they both function differently.Peptide hormones bind to a receptor protein in the plasma membrane and activate the second messenger systemThe second messenger causes the cellular changes for which the hormone is credited4How Hormones Function Cont.Peptide acts like the boss hormone that stays outside the cell and directs activities Steroid hormones are lipids and diffuse across membranes only after they are inside the cell they produce hormones such as estrogen and progesterone that bind into receptor proteins

Hormones and HomeostasisThe release of hormones is usually controlled by one or more of three mechanisms Negative feedback controls hormone releaseHormone release is controlled by actions of other hormones Hormone release is controlled by the nervous system The majority is from negative feedback Hormone release may also be controlled by specific stimulating or inhibiting hormones

Hormones and Homeostasis Cont.The nervous is an important controller of the endocrine system upon receiving sensory information from the body, the brain can make appropriate adjustments to hormone secretion to ensure homeostasis. For example when you eat a meal the brain signals parasympathetic neurons (controls rest and digest functions) to release the hormone insulin. 8Hypothalamus And Pituitary Gland The hypothalamus regulates the internal environment by controlling heartbeat body temperature and water balance as well as the pituitary gland. The pituitary gland is about 1 cm in diameter and is connected to the hypothalamus. (has two portions: posterior and anterior)

Posterior Pituitary The back portion of the pituitary gland which secretes the hormone of oxytocin (increases uterine) and anti diuretic hormone (ADH; increases absorption of water by kidneys) The lack of ADH results in a disorder called diabetes and insipidus which is the inability to concentrate the urine (overly dilute) potentially leading to dehydration. Anterior Pituitary The front portion of the pituitary gland. The anterior produces hormones that influence growth, sexual development, skin pigmentation, thyroid function, and adrenocortical function. The effects of under function of the anterior pituitary gland include dwarfism and a rare case of overfunction include overgrowth (Gigantism) Thyroid And Parathyroid Gland The thyroid gland is a gland located in the neck where it is attached to the trachea. The thyroid gland is composed of a large number of follicles each small spherical structures made of thyroid cells. These cells are filled with Triiodothyronine(T3) and Thyroxine(T4) which are two forms of the thyroid hormone; T3 is thought to have greatest effect on body.Thyroid hormones increase the matbolic rate. They do not specify on one organ, therefor they stimulate all cells in the body.Thyroid And Parathyroid Gland Cont.If the Thyroid fails to develop properly, a condition called Congenital Hypothyroidism results.Congenital Hypothyroidism: can lead togrowth failureand permanentintellectual disability. Treatment consists of a daily dose of thyroid hormone (thyroxine) by mouth. Because the treatment is simple, effective, and inexpensive, nearly all of the developed world practicesnewborn screeningto detect and treat congenital hypothyroidism in the first weeks of life. Manufactured by Iodine.

Thyroid And Parathyroid Gland Cont.2Hyperthyroidism: Over secretion of thyroid hormone, makes muscles swell, patients become hyper active, nervous, irritable, and suffer from insomnia.Graves disease is a condition caused by excessive thyroid hormone.CalcitoninCalcium plays a significant role in the nervous conduction and muscle contraction as well as clotting of blood. Calcitonin is a hormone secreted by the Thyroid glands when blood calcium levels rise. Its main job is to bring and deposit calcium to the bones.

Parathyroid GlandsParathyroid Hormone(PTH): a polypeptide hormone, produced in the parathyroid glands, that helps regulate the blood levels of calcium and phosphate.

Adrenal GlandsSit atop the kidneysEach adrenal gland consists of an adrenal medulla (inner portion) and an adrenal cortex (outer portion)The adrenal medulla is under nervous control, and the adrenal cortex is under the control of corticotropin (ACTH), an anterior pituitary hormone.

The Adrenal Medulla & Adrenal CortexThe adrenal medulla produces epinephrine (adrenaline) and norepinephrine (non-adrenaline), which rapidly bring about all the body changes that occur when an individual reacts to an emergency situationThe adrenal cortex produces Mineralocorticoids: regulate salt and water balance, leading to increases in blood volume and blood pressureGlucocorticoids: regulate carbohydrate, protein, and fat metabolism, leading to an increase in blood glucose level

GlucocorticoidsCortisol is a biologically significant glucocorticoid produced by the adrenal cortexCortisol promotes the breakdown of muscle proteins to amino acids, which are taken up by the liver from the bloodstreamCortisol promotes the metabolism of fatty acids, which spares glucose for the brainCortisol counteracts the inflammatory response that leads to the pain and swelling of joints in arthritis and bursitisMineralocorticoidsThe most important mineralocorticoid is aldosteroneAldosterone primarily targets the kidney where it promotes renal absorption of sodium and water, and a renal excretion of potassiumAtrial natriuretic hormone (ANH) is a hormone released by cardiac cells and it hibits the secretion of aldosterone from the adrenal cortexMalfunction of the Adrenal CortexA malfunction of the adrenal cortex can lead to a syndrome, a set of symptoms that occur togetherAddison disease and Cushings syndrome are commonly associated with the adrenal cortex

Addison Disease & Cushing SyndromeA person develops Addison disease when their adrenal cortex levels are low due to hyposecretionA person develops Cushing syndrome when their adrenal cortex levels are high due to hypersecretion

Addisons diseaseCushings syndromePancreasPancreatic islets, endocrine tissue, produce and secrete insulin and glucagon directly into the bloodInsulin is secreted when the blood glucose level is high, which occurs after eating Glucagon is usually secreted between meals, when the blood glucose level is low

Diabetes MellitusDiabetes mellitus is a hormonal disease in which insulin-sensitive body cells are unable to take up and/or metabolize glucoseThat causes the blood glucose level to elevate, which is called hyperglycemiaThe person becomes extremely hungry due to a condition called polyphagiaFat metabolism leads to the build up of ketones in the blood and the excretion of ketones in the urineThe build up of ketones in the blood could cause acidosis (acid blood), which can lead to coma and deathDiabetes Mellitus (continued)There are 2 forms of diabetes mellitusInsulin-dependent diabetes mellitus (IDDM): the pancreas does not produce insulin and the exposure to an environmental agent takes part in thisNoninsulin-dependent diabetes (NIDDM): usually occurs in people of any age who are obese and can be prevented or controlled by exercising regularly and maintaining a healthy weightOther Endocrine GlandsThe human body has many other endocrine glands, for example the gonads (testes/in males and ovaries/in females)Hormones are also produced in lesser-knows glands, such as the thymus gland and the pineal glandProstaglandins are local messenger chemicals that individual body cells produceTestesTestes are located in the scrotumThey produce androgens (testosterone), the male sex hormonesTestosterone brings about and maintains the male secondary sex characteristics that develop during pubertySome athletes take supplemental amounts of anabolic steroids, which are either testosterone or related chemicals Ovaries Ovaries are located in the pelvic cavityThey produce estrogen and progesterone, the female sex hormonesEstrogen is necessary for ovum maturation and for the secondary sex characteristics in femalesEstrogen and progesterone take part in the development of females body

Thymus GlandThe lobular thymus gland lies just beneath the sternum It reaches its largest size and is most active during childhoodLymphocytes are white blood cells that originate in bone marrow and defend against a particular invaderAfter passing complete development in the thymus, lymphocytes are transformed into thymus-derived lymphocytes (T-lymphocytes)The lobules of the thymus are lined by epithelial cells that secrete hormones called thymosins Pineal GlandThe pineal gland is located in the brainIt produces the hormone melatonin, which is involved in the daily sleep-wake cycleCircadian rhythms are daily 24-hour cycles that are controlled by an internal timing mechanism called a biological bookHormones from Other TissuesLeptin is a protein hormone produced by adipose tissue and it acts on the hypothalamus, where it signals that the individual has had enough to eatA number of different types of organs and cells produce peptide growth factors, which stimulate cell division and mitosisProstaglandins are potent chemical produced within cells from arachidonate, a fatty acidThey are not distributed in the blood, they act locally and close to where they were producedOther Endocrine GlandsThe body has a number of other glandsSuch as the gonadsTestes in males And the ovaries in femalesLesser-known glandsThymus glandPineal gland Testes and ovariesTestes are located in the scrotumProduce androgens(testosterone)Ovaries are located in the pelvic cavityProduce estrogens and progesteroneThe hypothalamus and pituitary gland control the hormonal secretions of these organs

AndrogensPuberty is the time when sexual maturation occurs meaning greatly increased testosterone secretion during this time period which also stimulates the growth of the penis, testes, growth of a beard, underarm hair and pubic hair.It prompts the larynx and the vocal cords to enlarge and is also partially responsible for the muscular strength of males.This is why some athletes take supplemental amounts of anabolic steroid which are either testosterone or related chemicals.37Estrogen and ProgesteroneThe female sex hormones have many effects on the bodyThe estrogen secreted during puberty stimulate the growth of the uterus and vagina.Estrogen is necessary for ovum maturation and is responsible for female body hair and fat distribution.Both Estrogen and Progesterone are required for beast development and for regulation of the uterine cycle which includes monthly menstruation.Thymus glandLies beneath the sternumReaches its largest size and is most active during childhood.Lymphocytes are white blood cells that originate in the bone marrow and are responsible for specific defense against a particular invaderWhen lymphocytes pass complete development in the thymus they are transformed into thymus derived lymphocytesThe lobules of the thymus are lined by epithelial cells that secrete hormones called thymosinsAlthough the hormones secreted by the thymus ordinarily work only in the thymus researches hope that these hormones could be injected into AIDS or cancer patients where they would enhance T-lymphocyte function

Pineal Gland Located in the brainProduce the hormone melatonin primarily at night.Involved in our daily sleep-wake cycle When melatonin levels increase we grow sleepy and reverse when levels become low.Daily 24 hour cycles such as this are called circadian rhythms, which are controlled by an internal timing mechanism called a biological clockGrowth FactorsGranulocyte and macrophage colony-stimulating factor-secreted by many different tissues . Causes bone marrow stem cells to form either granulocyte or macrophage cells depending on whether the concentration is high or low.Platelet derived growth factor and nerve growth factor is released from platelets and form many other cell types. It helps in wound healing and causes an increase in the number of fibroblasts, smooth muscle cells, and certain cells of the nervous system.Epidermal growth factor and nerve growth factor stimulate the cells indicated by their names as well as many other. These growth factors are also important in wound healing.Tumor angiogenesis factor stimulates the formation of capillary networks and is released by tumor cells. One treatment for cancer is to prevent the activity of this growth factor

ProstaglandinsPotent chemical signals produced within cells from arachidonate, a fatty acid.Not distributed in the blood, instead they act locally, close from where they are produced In the uterus they cause the muscles to contract and may be involved in the pain and discomfort of menstruation.

Chemical SignalsIn the human body some chemical signals such as traditional endocrine hormones and secretions of neurosecretory cells, act at a distance. Others such as prostaglandins, growth factors and neurotransmitters, act locallyWhether humans have pheromones is understudy

Effects of agingTwo concerns often seen in the elderly are thyroid malfunctioning and diabetes mellitus.HomeostasisHormones particularly help maintain homeostasis in several ways:Help maintain level of nutrientsHelp maintain blood volume and pressure by regulating the sodium content of the bloodHelp maintain the blood calcium levelHelp regulate fuel metabolism And help regulate our response to the external environment.