• 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

•

HypophysisHypophysis Know 2 Know 2

division:division: AdenohypophyAdenohypophy

sis (sis ( anterior ½) anterior ½) H/FH/F

Neurohpophysis Neurohpophysis

((posterior ½) H/F posterior ½) H/F it has fibers and it has fibers and

is lighteris 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 GlandThyroid Gland KnowKnow Thyroid Thyroid

folliclefollicle Thyroid Thyroid

colloidcolloid Follicular Follicular

cells H/Fcells H/F Parafollicular Parafollicular

cells H/F 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:Thyroid disorders: hyperthyroidism:

Characteristics:Characteristics: Abnormal metabolic rateAbnormal metabolic rate Sensitive to heatSensitive to heat Restless, overactiveRestless, overactive Appears mentally alertAppears mentally alert Eyes protrude (exophthalms)Eyes protrude (exophthalms) Irritable de to sensitive nervous systemIrritable de to sensitive nervous system Enlarged thyroid ( goiter) Enlarged thyroid ( goiter)

Thyroid disorders: hypothyroidismThyroid disorders: hypothyroidism

Characteristics:Characteristics: Low metabolic rateLow metabolic rate Abnormal sensitivity to coldAbnormal sensitivity to cold Physical sluggishnessPhysical sluggishness Poor appetitePoor appetite Appears mentally dullAppears mentally dull Swelling of body tissueSwelling of body tissue Tendency to gain weight 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 GlandParathyroid Gland

Just Identify it and know Just Identify it and know H/FH/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

PANCREASPANCREAS

KnowKnow Acini cellsAcini cells Islet of Islet of

Langerhans Langerhans Alpha cells Alpha cells

( found at edges ( found at edges H/F)H/F)

Beta cells Beta cells ( ( found in found in center H/F)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 mellitusDiabetic mellitus 2 types:2 types:

Type I:Type I: juvenile onset, lack insulin activity juvenile onset, lack insulin activity insulin dependentinsulin dependent

Something destroys insulin producing capacity Something destroys insulin producing capacity of of beta cellsbeta cells

Type IIType II: 90%, maturity onset ( after age 40), : 90%, maturity onset ( after age 40), alpha cellsalpha cells

Strong genetic link??? Unable to use insulin Strong genetic link??? Unable to use insulin produced by body due to abnormal receptors in produced by body due to abnormal receptors in cell membrane cell membrane

Hormones released by PancreasHormones released by Pancreas

1.1. InsulinInsulin: released by beta cells : released by beta cells functions to decrease glucosefunctions to decrease glucose

2.2. GlucoseGlucose: released by alpha cells : released by alpha cells which secrete glucagon that which secrete glucagon that increases sugar levelsincreases sugar levels

• HyperinsulinismHyperinsulinism: rare, usually tumor : rare, usually tumor of islet cellsof islet cells

Adrenal GlandAdrenal Gland

Located on the superior surface of each Located on the superior surface of each kidney,kidney,

composed of 2 distinct layers: composed of 2 distinct layers: adrenal adrenal cortex and adrenal medullacortex and adrenal medulla

Adrenal medullaAdrenal medulla is the central portion of is the central portion of the glandthe gland

Adrenal cortexAdrenal cortex is the outer layer of the is the outer layer of the gland and has 3 zonesgland and has 3 zones

Adrenal GlandAdrenal Gland

Know: Know: Adrenal cortex and its sublayers:Adrenal cortex and its sublayers:

1.1. Zona glomerulosa (loops and circles _ H/F)Zona glomerulosa (loops and circles _ H/F)

2.2. Zona fasiculata (widest H/F) Zona fasiculata (widest H/F)

3.3. Zona reticularis ( netlike with brown spots H/F)Zona reticularis ( netlike with brown spots H/F) Adrenal medulla H/FAdrenal medulla H/F CapsuleCapsule

Adrenal hormonesAdrenal hormones

Adrenal MedullaAdrenal Medulla: central portion: central portion Hormones:Hormones: Epinephrine: Epinephrine: fight or flight , increase fight or flight , increase

respiratory and metabolic rates and respiratory and metabolic rates and constrict blood vesselsconstrict blood vessels

Norepinephrine: sameNorepinephrine: same

Adrenal hormonesAdrenal hormones

Adrenal cortex: outer layer has 3 zonesAdrenal cortex: outer layer has 3 zones 1. 1. Zona glomerulosaZona glomerulosa (outer layer): hormone is (outer layer): hormone is

aldosteronealdosterone (mineralocorticoid) which regulates (mineralocorticoid) which regulates sodium ion reabsorption by kidneyssodium ion reabsorption by kidneys

2. 2. Zona fasiculataZona fasiculata (middle) (middle) Hormone isHormone is cortisone cortisone (glucocorticoid) functions (glucocorticoid) functions

in increasing blood glucose levelsin increasing blood glucose levels

Adrenal hormonesAdrenal hormones

3. 3. zona reticularis: (zona reticularis: (inner layer)inner layer) Hormone is Hormone is sex hormonessex hormones

(gonadocorticoids)(gonadocorticoids)

Adrenal GlandAdrenal Gland

Adrenal disorders: hyposecretions Adrenal disorders: hyposecretions

Causes Addison’s diseaseCauses Addison’s disease Characteristics:Characteristics: Low sodium, high potassiumLow sodium, high potassium Low blood glucoseLow blood glucose DehydrationDehydration Low blood pressureLow blood pressure Increased skin pigmentation (ACTH mimics MSH)Increased skin pigmentation (ACTH mimics MSH) Mental lethargyMental lethargy Muscular weaknessMuscular weakness Weight lossWeight loss Death in a few days if untreatedDeath in a few days if untreated

Adrenal disorders: hypersecretionsAdrenal disorders: hypersecretions

Causes Cushing’s DiseaseCauses Cushing’s Disease CharacteristicsCharacteristics Decrease in protein Decrease in protein wasting of muscle and loss of bone tissuewasting of muscle and loss of bone tissue Blood glucose elevatedBlood glucose elevated Puffy skin due to water retentionPuffy skin due to water retention Sodium highSodium high Fat deposits between shoulders and in face making Fat deposits between shoulders and in face making

buffalo hump and moon facebuffalo hump and moon face Spindly arms and legsSpindly arms and legs Poor wound healingPoor wound healing

GonadsGonads OvariesOvaries: primary source of female sex : primary source of female sex

hormoneshormones HormonesHormones EstrogenEstrogen: secondary sex characteristics: secondary sex characteristics ProgesteroneProgesterone: menstrual cycle: menstrual cycle

TestesTestes: primary source of male sex hormones: primary source of male sex hormones Hormones:Hormones: TTestosteroneestosterone: secondary sex characteristics of : secondary sex characteristics of

malemale MORE LATERMORE LATER