CHAPTER 41 ~ Hormones Flashcards
endocrine cell
hormone secreting cell that releases these chemical signals to target cells that have receptors for those hormones
exocrine cells
secrete signals into ducts that are connected to the “outside” (i.e. into GI tract, sweat or salivary glands)
endocrine glands…
secrete hormones that circulate in blood
paracrines
affect cells nearby, in immediate vicinity
autocrine
affects the same cell that secreted it
3 groups of hormones:
- Peptides/proteins - water soluble, transported out of cell that made them through vesicles via exocytosis; their receptors must be on surface of target cells
- Steroid hormones - lipid-soluble = they diffuse across membrane of cell that made them, but need carrier proteins to travel through blood; receptors MOSTLY intracellular, in cytoplasm or nucleus
- Amine hormones - derived mostly from a.a. tyrosine, some water soluble, some lipid soluble.
3 parts of surface receptors (for polar hormones) :
binding domain, transmembrane, and cytoplasmic domain
binding domain:
of a surface hormone receptor
part that projects outside of plasma membrane for hormone molecule to bind to
transmembrane domain:
of a surface hormone receptor
anchors receptor IN membrane
cytoplasmic domain:
of a surface hormone receptor
part that juts out into cytoplasm, initiates target cell’s response-> activate enzymes: protein kinases or phosphatases through a secondary messenger activated cascade and activate or inactivated enzymes in cytoplasm, which are the cell’s response
pituitary gland
link between nervous system and many endocrine glands
posterior pituitary
releases 2 neurohormones: ADH (controls water retention in kidneys) and oxytocin (“cuddle hormone”)
anterior pituitary
releases 4 tropic hormones: thyrotropin, adrenocorticotropin, luteinizing hormone, and follicle stimulating hormone; AND some NON-tropic hormones: growth hormone, and endorphines, etc.
4 tropic hormones released by anterior pituitary:
thyropotin, adrenocorticotropin, luteinizing protein, and follicle-stimulating hormone
(all peptide and protein hormones)
growth hormone:
stimulates cells to take up amino acids, stimulates liver to produce IGFs which stimulate bone and cartilage growth
islets of Langerhans
endocrine portion of the pancreas (1-2%):
- produce insulin
- 3 types of cells produce hormones:
- Beta cells = produce/secrete insulin
- Alpha cells = produce/secrete glucagon
- Delta cells = produce somatostatin
Beta cells
produce/secrete insulin
Alpha cells
produce/secrete glucagon
Delta cells
produce somatostatin
After a meal…
blood glucose levels rise as glucose is absorbed from food in gut; increased blood glucose stimulates Beta cells to produce insulin; insulin binds to cell receptor on membrane–>GLUT-4 move from cytoplasmic vesicles to the cell membrane = easier glucose uptake; if glucose concentration falls, beta cells of islets stop releasing insulin; cells shift to use glycogen and fat rather than glucose; if glucose falls way below normal, alpha cells release glucagon = stimulates liver to break down stored glycogen to release glucose into blood.
cellular effects of insulin
binding of insulin to insulin receptors triggers response cascade resulting in exocytosis of intracellular vesicles containing GLUT-4 –>more GLUT-4 on plasma membrane = increased glucose uptake
Diabetes Mellitus
affects 285 million worldwide, 5-10% in North America = type I, rest are type II
TYPE I Diabetes
~10% of all cases, previously “juvenile diabetes”; due to auto-immune destruction of pancreatic Beta cells –>the insulin producing cells.
TYPE II Diabetes
(adult-onset), ~90% of all cases, insulin resistance caused by lack sufficient functional insulin receptors in target cells; linked to obesity 90% of TYPE II are obese.
symptoms of diabetes
weakness, lethargy, dramatic loss of body size/mass. with no insulin, glucose builds up in blood=water drawn out of cells through osmosis to counteract pH funkiness, = dehydration and more peeing.
Acute complications of Diabetes
Ketoacidosis, and diabetic Hypoglycemia
Ketoacidosis
an acute complication of diabetes, wherein liver switches to “starvation” mode and makes ketone bodies. Glucose and the ketone bodies cause raised blood osmolarity, water rushes into blood which leads to dehydration, and acidic ketone bodies lower blood pH, resulting in the diabetic Ketoacidosis
Diabetic Hypoglycemia
occurs if insulin treatment is “overshot” –> lack of blood glucose results in coma and death
Diabetic Retinopathy
severe vision loss/blindness resulting from diabetes
Diabetic Neuropathy
kidney damage that can lead to chronic kidney failure, needing dialysis
Diabetic Foot
combo of neuropathy and arterial damage cause skin ulcers, infection, necrosis, and gangrene, usually results in amputation
heterotrophs
derive their nutrition from eating other organisms –> use food to obtain energy as well as building blocks for complex molecules
calorie
amount of energy needed to raise the temp of one gram of water by 1ºC.
metabolic rate
the measure of an animal’s overall energy needs that must be met by the animal’s food.
basal metabolic rate
meabolic reate resulting from all of the essential physiological functions that take place in a resting state –> physical activity adds to basal energy requirement
carbs stored in _____ and _____ as ______
carbs are stored in muscle cells and liver as glycogen
_____ is the most important form of energy storage.
Fat is the most important form of energy storage; more energy/gram than glycogen and is stored more compactly
when undernourished…
start “self-consumption” - metabolize glycogen (1 day) and fat stores (4-5 weeks); protein metabolization staved off for as long as possible
Kwashiorkor
disease caused by chronic protein defficiency, when proteins start to be metabolized, blood plasma are first to be sacrificed = decrease in osmotic concentration of plasma, resulting in loss of fluid from blood to interstitial spaces = edema, or swelling occurs. accumulation of fluid in extremities and abdomen. Leads to organ damage and death
when over-nourished…
glycogen reserves built up first, then excess carbs, fats, and proteins are converted to fat. = obesity = increased risk of high blood pressure, heart attack, and diabetes
