Chapter 6/49: cell signaling and endocrine regulation

other endocrine glands

Kidneys Small intestine Ovaries Stomach Skin Placenta Liver Heart Testes

cell junctions

Review from K101 gap, tight, desmosomes

calmodulin

a calcium binding protein

paracrine signaling

a hormone (or other signal molecule) diffuses through interstitial fluid and acts on nearby target cells local regulators: - some are considered hormones - they use autocrine or paracrine signaling Types of local regulators - growth factors: * peptides that stimulate cell division and development - histamine: * causes blood vessel dialation and capillary permeability * in cold medication - nitric oxide: * gas that relaxes smooth muscle in blood vessel walls * increases oxygen delivery in the circulation - prostaglandins: * a group of local hormones that help regulate many metabolic processes * smooth muscle contraction, cause fever, induce labor * many different functions

autocrine signaling

a hormone (or other signaling molecule) is secreted into the interstitial fluid and then acts on the very cell that produced it eX: estrogen - stimulates additional estrogen secretion by the cell - bumps up the concentration of the estrogen in that area which stimulates development

portal system

a specialized region in the circulatory system consisting of a venous capillary bed in one region being connected to the arterial capillary bed in another region by a portal vein

lipophilic signaling molecules

activators: - lipid soluble - diffuse across membranes of the target cell - small hydrophobic (no gases) - steroid or thyroid hormones - receptor is located inside the cell - hormone depended on where the receptor is in the cell - pathway always ends up at the nucleus receptor location: - cytosolic = in the cytosol * binds ligand and then moves to the nucleus * aldosterone - intranuclear = in the nucleus * travels and binds to the receptor * thyroid hormones

hormone actions and effects

agonist: hormone that turns a pathway on or off, stimulates antagonist: does opposite additive: effect of having two hormones is sum of the effect of each one individually - two hormones in system at the same time and the cell being stimulated is being stimulated by both hormones at the same level as they would individually - 3 + 2 = 5 synergistically: effect of one hormone is increased by the presence of another but not fully additive - stimulates beyond what they would be - two hormones there, one hormones activity (2), with the other hormone there, the original one now transports 3

G linked receptors

also called g protein coupled receptors ligand binding - first messenger - receptor causes something else to happen - signaling molecules sets up a pathway to get the results change in conformation: - intracellular inactive g protein binds to intracellular domain and is activated - g protein becomes the signaling molecule to set up an event inside the cell action of activated g protein - opening of the ion channel (EX: smell/sight) - alter enzyme activity there are two major amplifier enzymes: - adenylyl cyclase - phospholipase c

ion channel linked receptors

also called ligand gated channels ligand binding - single molecule activation change in conformation: - channel opens or closes action: - ions move in or out of the cell ex: acetylcholine - its a neurotransmitter that binds to and opens a ligand gated sodium channel

grave's disease

an autoimmune disease involving the thyroid

peptide proteins

antidiuretic hormone (ADH) and glucagon ex: insulin - protein hormone, neuropeptides - ex: ADH length varies from very short to very long peptide chains

adenylyl cyclase

causes formation of cyclic amp which becomes the intracellular messenger as the levels of cAMP change, the activity in the cell chagnes ex: phosphorylate protein kinases

chemical signals

chemicals, including hormones, released into body fluid (blood or interstitial fluid)

down-regulation

decrease in the number of receptors on a cell

metabolic disturbances in diabetes

decreased use of glucose: cells have difficulty taking up glucose - glucose in the urine dehydration: water follows glucose osmotically into urine increased fat mobilization: energy source needed - ketone bodies may accumulate electrolyte imbalance: ketones take sodium calcium and other ions with them into the urine increased protein use: another energy source and often = thin and emaciated

down-regulation

decreases number of cell receptors

hypoglycemia

development: - low blood glucose concentration - sometimes occurs in people who alter develop diabetes hypoglycemia and insulin shock: - delayed response to carbohydrate glucose intake followed by overreaction of islets - insulin hypersecretion causes glucose levels to fall and individual becomes drowns, uncoordinated or unconscious - serous hypoglycemia can develop if diabetics receive too much insulin (insulin shock)

cell-cell contact

direct contact cells releasing signaling molecules to turn other cells on immune system t cell b cell interactions

abnormal secretion of growth hormones

dwarfism: extrene GH difficiency during childhood giantism: ecessivve amounts of GH during childhood acromegaly: - hypersecretion of GH during adulthood - connective tissue thickens - changes in ears and nose - bones in hands, feet, and face may increase in diameter - released at a higher rate than normal even in adults

neurohormones and metamorphosis in vertebrates

ex: frog development - tadpole to frog there is some environmental influence

chemical groups of hormones include

fatty acid derivatives, steroids, amino acid derivatives, and peptides and proteins

phospholipase C

g protein activates different enzymes in the membrane works on a specific phospholipid in the membrane causing a breakdown of the phospholipid into two separate signaling molecules - diasoglycerol and phosphorilated head group

endocrine glands

glands without ducts that secrete hormones into the interstitial fluid (endocrine system) release product directly into the surrounding or into the blood so it circulates direct release into the environment

diabetes mellitus

group of related disorders characterized by high blood glucose level most common endocrine disorder

antidiuretic hormone

hormone that acts on water channels in the kidney

human endocrine system

hormone: - chemical signal that regulate physiological processes - regulate growth and development - reproduction - salt and fluid balance - and many aspects of metabolism and behavior - signaling molecule between cells components: - endocrine glands, cells, and tissues (table 49-1) - specialized nerves product: hormones (chemical signals or messengers) tropic and releasing hormones: target other endocrine structures - have an impact on another endocrine structure - the second structure releases the hormone abnormalities: - hyposecretion * abnormally reduced output * above normal * more hormones than needed - results in exagerated impact from that hormone - really tall - hypersecretion * abnormally increased output * below normal * under secreting * less than normal impact with hormone - really short

steroids

hormones secreted by the adrenal cortex, ovary, and testis, as well as the molting hormone of insects enter into the cell - can cross the membrane into the cytoplasm or the nucleus cholesterol is the main backbone structure ex: cortisol, testosterone, estrogens, progesterone

affinity

how easily and tightly a receptor binds a hormone

affinity

how easily/tightly a hormone binds to the receptor

water soluble peptides

hydrophilic transport: - dissolved in plasma - move out of plasma into interstitial fluid - may or may not need transporter receptors: - surface of the cell as opposed to the inside of the cell

Reception

hydrophilic signaling molecules: - receptors on the surface of target cells - eX: peptide hormones hydrophobic signaling molecules: - move through plasma membrane and bind - intracellular receptors (cytoplasmic or nuclear) - receptor can be in the cytoplasm or in the nucleus cell response may vary: - ligand binding triggers a response associated with that individual receptor - different cell types may respond differently to same signal (ligand) - response depends upon which cell is being stimulated

thyroid disorders

hyposecretion: hypothyroidism - infancy and childhood: low metabolic rate *cretinism - may occur (slowed mental and physical development - adults: * myxedema - characterized by slowing down of physical and mental activity hypersecretion: hyperthyroidism - most common form - over secretion - graves' disease: an autoimmune disease causing high metabolism, weight loss, and irritability enlarged thyroid: - goiter: result is either hyposecretion or hypersecretion of hormones

phytochromes

in plants sense red light

rhodopsin

in vertebrate eyes sense light

up-regulation

increased in the number of receptors on a cell

up-regulation

increases number of cell receptors

hormones and insect development

initiating events: - environmental factors that stimulate the brain to release brain hormone brain hormone: - brain neuroendocrine cells: produce BH - stimulates prothoracic gland: to produce molting hormone molting hormone: type of steroid hormone - stimulates growth and molting juvenile hormone: - effect: causes metamorphasis - changes in hormone levels: * if it is high - remain in molting stage - mh down * if it is low - mh goes up - move from larvae to adult

hormone function

insulin function: - stimulates glucose uptake form the blood - inhbits liver cells form releasing glucose - free glucose level reduced glucagon function: - stimulates liver cells to convert glycogen to glucose (glycogenolysis) - production of glucose (gluconeogenesis) from non carbs - glucose level rises

Three types of receptors on the cell surface

ion channel linked g-linked receptors enzyme linked receptors

endocrine function:

islets of langerhans: - endocrine function - alpha and beta cells present in this specific part of the pacreatic tissue alpha cells: glucagon beta cells: insulin

local signaling

local regulators: molecule diffuses through interstitial fluid and acts on nearby cells two types of local signaling: - autocrine signaling - paracrine signaling

pituitary gland

location: - connected to hypothalamus function: - secretions control several other endocrine glands and tissues - MASTER GLAND structure: - human pituitary gland has two lobes: anterior and posterior

pancreas

location: - curvature of small intestine near stomach and below the liver function: (mixed) - endocrine - insulin and glucagon (secondary function) - exocrine - digestive enzymes (primary function) pancreatic cancer is very hard to treat because not very many

adrenals

location: above the kidneys structure: tissue regions that carry out different functions - cortex: - medulla: - adrenal cortex: * androgens: precursors to sex hormones testosterone and estradiol * aldosterone: acts on kidneys to regulate salt balance to maintain blood volume and pressure * cortisol: stimulates glucose production by liver cells during stress - stress hormone - medulla: * control - sympathetic nervous system ^ during stress hypothalamus signals sympathetic neurons triggering hormone release * hormones - epinephrine and norepinephrine * effect of adrenal medulla hormones ^ increased metabolic rate, circulation of the brain muscles and heart, conversion of glycogen to glucose

hypothalamus

location: brain - connects to pituitary and extends down the brain function: regulates the activity of the pituitary gland - link nervous and endocrine systems anatomically and physiologically control most endocrine activity

thyroid gland

location: front of trachea, below larynx hormones: - synthesized form tyrosin and iodine - t3 / t2 * increase metabolic rate * regulate proteins for cell differentiation * calcium metabolism - calcitonin - later * regulation of calcium levels heat production: - with exposure to very cold temps, the hypothalamus increases secretion of TSH - releasing hormone, which increases heat production - reason why you get used to certain temps

cell signaling

mechanism for communication between cells and organisms

Endocrine and nervous systems interact

nervous system: - response: rapid, shorter lasting, transmits electrical and chemical signals * relatively quick - even if it is unmyelinated * quicker than hormones * impact on other cells and neurons * main function = cellular interaction - effectors: * endocrine system: - response: slow, but longer lasting * slower than nervous system - effectors: many cells and systems * can effect individual cells and systems across the board - digestion, transport, uptake, etc. systems are linked by the hypothalamus and the pituitary connection

neuroendocrine signaling

neurohormones in vertebrates, the hypothalamus produces neurohormones that link the nervous system with the pituitary gland and the endocrine gland that secrete several hormones neurohormone production: - neurons secrete neurohormones - nerve cells release: - these neurohormones are transported down axons and then secreted - released at the axon terminal just like a neurotransmitter transport: - they are typically transported in the blood (or interstitial fluid) - has an effect just like any other hormone the dif is they are made by nerves

electrical signals

neurotransmission within the nervous system could be by synapse or through gap junctions between neighboring cells

acromegaly

occurs as the result of hypersecretion of growth hormones in adults resulting in an increase in the amount of connective tissue

autocrine signaling

occurs when a cell produces signaling molecules that when released stimulate the cell that released them

paracrine signaling

occurs when released signaling molecules act on nearby cells rather than on some distant cells

steroid hormone

one that is not soluble in plasma, requires a transport protein, and crosses the lipid bilayer and binds an intracellular receptor

hydrophilic hormone

one that is soluble in the plasma and binds a receptor on the cell's surface

secondary endocrine organ

one whose primary function is nonendocrine, however hormones are produced by specific cells within the organ

primary endocrine organ

one whose primary function is the production and secretion of hormones

regulation of calcium homeostasis

parathyroid hormone: surround the thyroid gland - secrete parathyroid hormone (PTH) - works antagonistically to calcitonin calcitonin (thyroid): negative feedback cycle with PTH

anterior pituitary

portal system structure: - connection with the hypothalamus - capillary bed, vein, capillary bed - hormones enter capillaries in the hypothalamus - portal system = capillary bed on one end, drained by a group of veins that expand in to another region with another capillary bed - travel via portal vein to capillary bed in AP - from AP capillary bed diffuse out and contact cells neurohomrones affect anterior pituitary hypothalamus produces several releasing and inhbiting hormones A.P. products: - look at figure in the book

exocrine glands

primary: - main function: organs whose major function is to produce the hormones - examples: hypothalamus and pituitary secondary: - main function: produce hormones but have other things as their primary function: digestion, etc. - examples: heart, skin, stomach

fatty acid derivatives

prostaglandins and the juvenile hormone of insects long carbon hydrogen atom chains - can be branched or mult. chains - must be carbon hydrogen and some significant length

neurohormones regulate the following:

regeneration in hydras, flatworms, and annelids color changes in crustaceans growth, development, metabolism, gamete production, and reproduction in other groups in insects, hormones and neurohormones interact with one another to regulate metabolism, growth, and development

cretinism

retarded mental and physical development as a result of hypothyroidism in infancy and childhood

Receptors may respond to the following non chemical signals

rhodopsin, phytochromes, hearing organ, and the pacinian coruscles

pacinian coruscles

sense pressure in skin

hearing organ

sense sound waves

Cell signaling involves 4 main processes

signaling molecule: - cell releases hormone or other molecule receptor on target cell: - binding signaling molecule - hormones signal transduction: - occurs after receptor binding - receptor acts as a transducer -> when it is activated we have to get the pathway to go inside the cell to have a response - conversion of an extracellular to intracellular signal target cell response: - cellular process altered - cells with receptors on them = target cells

specificity

similarity in hormone structure and receptor binding site

classical endocrine signaling

steroid and thyroid hormones transport: - discrete endocrine glands secrete hormones into the interstitial fluid - hormones are transported by the blood - bound to plasma proteins - no transporter needed receptors: - they bind with receptors on or in specific target cells - intracellular (cytoplasmic or nuclear)

posterior pituitary:

structure: - connection with hypothalamus - axons from neuron in hypothalamus extend into pituitary - release hormone directly into circulation or posterior pituitary hormones released: - neurohormones (peptide) from hypothalamus - EX: * ADH: stimulates reabsorption of water by the kidney tubules * oxytocin: contractions of the uterus and stimulation of milk by the mammary glands ^ role in some social behaviors ^ helps facilitate mood and recognition

medulla

the central specialized tissue region of some organs such as the adrenal glands and kidney

cortex

the outer specialized tissue region of some organs such as the adrenal glands and kidney

amino acid derivatives

thyroid hormones and epinephrine use amino acid as the main synthesizing molecule T3/T4 = thyroid hormones - tyrosine is the main amino acid in the structure

Enzyme linked receptors

two main types: - tyrosine kinases - guanylyl cyclases common ligands are insulin and growth factors

two types of diabetes

type one: - insulin dependent - decline in number of beta cells - treated by injections of insulin - autoimmune disorder type two: - often begins as type one - non insulin dependent - lack functional receptors on target cells - regulation by exercise and diet

specificity

whether a receptor binds only one or more than one hormone base upon hormone structure and the receptor binding site

regulating reception and response

whole cell level: - change number of receptors to alter the effect - regulates the amounth of stimulus - up regulation and down regulation Receptor level: - includes affinity and speciificity Extracellular level: - concentration of a signal molecule Intracellular level: - response determined by intracellular molecules activated, altered membrane permeability, altered metabolism, or altered gene activity - turns on or off pathways