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83 Cards in this Set
- Front
- Back
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What is the exocrine function of the pancreas?
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Acini produce pancreatic juice for the small intestine.
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What is the endocrine function of the pancreas?
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Islets of Langerhans secrete hormones.
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Where is the pancreas located?
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Between the greater curvature of the stomach and the duodenum
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What are the three types of cells that secrete hormones from the Islets of Langerhans?
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Alpha cells
Beta cells Delta cells |
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What do alpha cells secrete?
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glycogon
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What do beta cells secrete?
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insulin
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What do delta cells secrete?
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somatastatin
this also inhibits alpha and beta secretions |
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Where is the Islets of Langerhans innervated?
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by the parasympathetic and the sympathetic nervous system
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Where does insulin target?
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Skeletal muscle, liver, adipose tissue and satiety center
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Where does glycagon target?
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mainly the liver but also skeletal muscle and adipose tissue
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What is the effect of insulin?
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To increase glucose and amino acid uptake by target cells from blood and to overall decrease blood glucose.
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Where does insulin bind to?
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Membrane receptors
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When insulin binds to membrane receptors what happens?
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Stimulates phosphorulation of intracellular side of receptor & phosphorulates some intracellular proteins. Proteins produce a cell response.
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What is the cell response to insulin?
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To increase number of glucose and amino acid transport proteins on membrane surface.
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What happens after binding of insulin and membrane receptor?
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-Insulin and receptor complex brought into cell
-Insulin and receptor seperate -Insulin broke down and receptor moves back to cell membrane to be used again |
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Glucose Uptake
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Some used for energy then the excess is put in storage
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What is glucose stored as in the liver and skeletal muscles?
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Stored as glycogen
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What is glucose stored as in the adipose tissue?
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Stored as adipose tissue or fat
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What can amino acids be used as?
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Energy
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What are amino acids used to make?
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Glucose and proteins
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What happens when there is too little insulin or when insulin receptors don't work?
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-severe hypoglycemia
-decrease in amino acid uptake in cells -satiety center has decrease in uptake so increases hunger -causes increase in thirst and urine volume |
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Type I Diabetes Mellitus
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-Insulin dependent Diabetes
-typically in young people -don't make insulin or not enough -3% of people in US with diabetes have this type |
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Type II Diabetes Mellitus
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-None insulin dependent Diabetes
-typically develops in older people -cause by decrease response by insulin receptors -controlled with diet and exercise |
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What happens when there is too much insulin?
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-insulin shock: hypoglycemia- severe and rapid decrease in BG
-problems with NS functions -lead to disorientation,confusion, convulsions, loss of consciousness and even death |
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What does insulin cause a cell to do?
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increase number of transport proteins and bring in more glucose and amino acids
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What is the response of the liver and the skeletal muscles to glucagon?
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-Increases glycogen breakdown
-release glucose to blood |
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What is the response of the adipose tissue to glucagon?
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-Increase fat break down which releases fatty acids to blood
- fatty acids can be used as energy |
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Regulation of Insulin by fasting
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- Inhibits insulin secretion
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Regulation of insulin by blood glucose levels
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-hyperglycemia stimulates secretion of insulin
-hypoglycemia inhibits secretion of insulin |
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Regulation of insulin by amino acids
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- increase level of some amino acids stimulates secretion of insulin
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Regulation of insulin by autonomic nervous system
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-Parasympathetic NS stimulation= stimulation insulin secretion
-Sympathetic NS stimulation= inhibits insulin secretion |
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Regulation of glucagon by blood glucose levels
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-Hyperglycemia inhibits secretion of glucagon
-Hypoglycemia stimulates secretion of glucagon |
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Regulation of glucagon by autonomic nervous system
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-Sympathetic NS stimulates secretion of glucagon
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Thyroid Gland
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- 2 lobed gland
-located anterior to trachea |
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Follicle
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-a sphere with walls made from simple cuboidal epithelial.
-this stores thyroid hormones |
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Thyroglobulin
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- a protein in the middle of the follicle
-its also a colloid |
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Colloid
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- a substance that suspends other substances
-prevents settling -T3 and T4 are stored in one of these |
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Parafollicular cells
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-AKA "C cells"
-located between follicles -secrete calcitonen |
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What are the two main hormones secreted by the thyroid gland?
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1.T3 (Triiodothyronine) hormone
2. T4 (Tetraiodothyronine) hormone |
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What is the third hormone secreted from the thyroid gland?
-less important |
Calcitonin
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What hormone increases the synthesis and secretion of T3 and T4?
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-TSH (thyroid stimulating hormone)
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TSH causes the cells of the thyroid gland to do what?
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-Hyperplasia (cells increase in number)
-Hypertrophy of thyroid (enlargement of cells) |
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This substance is REQUIRED for T3 and T4.
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Iodine
-this is the only place in the body that it is required |
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How are T3 and T4 transported?
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-bound to plasma proteins
-this increases half life -and creates a reserve of T3 and T4 in blood |
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What happens when T3 and T4 levels decrease in interstitial spaces?
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-T3 and T4 in blood will release plasma proteins and diffuse into interstitial spaces of tissue.
-Blood levels of T3 and T4 stay constant |
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What is the major thyroid gland that interacts with targets?
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T3
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In the blood what is 33-40% of T4 converted to?
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T3
-excess T4 is excreted into urine or bile -T3 is the more potent form |
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What is the action of T3 and T4 in the body?
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-targets every cell
-binds to intracellular receptors -Initiate protein synthesis in target -Protein synthesized depends on target cell type. -slower response can take up to a week |
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What does T3 and T4 effect?
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-metabolism, growth, and maturation
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How does T3 and T4 effect metabolism?
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- increase metabolism rate by increasing breakdown of glycogen, fat, proteins
-increase rate of aerobic respiration and plays a role in maintaining body temp |
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How does T3 and T4 effect normal growth and maturation?
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-T3 and T4 are required by all tissues in body for normal growth
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Hypothyroidism
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-decrease metabolic rate
-weight gain -decrease appetite -weak muscles |
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Hyperthyroidism
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-increase in metabolic rate
-weight loss -increase in appetite -enlarged thyroid (goiter) |
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Hypothyroidism may have a goiter it is caused by what?
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Iodine deficiency
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Cretinism
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Before maturity: decrease in mental development and bone growth.
-iodine deficiency |
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Iodine deficiency during fetal development can be a problem with what?
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T3 and T4 synthesis or TSH synthesis
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Some causes of hyperthryoidism is?
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-grave's disease
-autoimmune disease-starts attacking self -immunoglobulin-structure is close to TSH structure. can bind to TSH receptors -pituitary tumor-increase in TSH secretion |
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Calcitonen
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-this hormone has nothing to do with T3 and T4
-secreted and synthesized by parafollicular cells. |
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What is calcitonen stimulated by?
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-increase in blood calcium levels
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Where does calcitonen target?
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-bone
-increase osteoblast activity and decrease osteoclast activity -stores more calcium |
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What is the overall effect of calcitonen?
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-to decrease blood calcium levels by putting excess calcium into storage in bone.
-as we age, calcitonen secretion decreases more in females then in males |
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Parathyroid Gland
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-embedded in posterior part of thyroid
-consists of 2 types of cells *Cheif cells *Oxyphils |
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Cheif cells
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-cells that secrete parathryoid hormone (PTH)
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Oxyphils
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- cell in the the parathyroid that has an unknown function
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Parathyroid hormone
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-small peptide
-targets bone,kidney,and intestines -binds to membrane receptors |
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What is the effect of the parathyroid hormone?
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-Regulates blood calcium levels
-Overall increases blood calcium levels |
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What is the effect of PTH on the bone?
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-increase osteoclast activity
-breakdown bone and release calcium and phosphate into blood |
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What is the effect of PTH on the intestines?
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-mainly the small intestine
-increase vitamin D synthesis which causes increase in synthesis of calcium and phosphate transport proteins -this increases calcium and phosphate absorption in blood |
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What is the effect of PTH on the kidneys?
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-increase calcium reabsorption to blood
-less calcium lost into urine but increase in phosphate excretion in urine. -Overall PTH decreases phosphate level in blood |
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Hypoparathyroidism
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-Hypocalcemia-decrease in blood calcium levels
-causes nervousness, muscle spasms, convulsions, muscles can go into tetany |
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Hypoparathyroidism
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-muscles are hyperexcitable
-decrease in extracellular fluid -calcium levels cause sodium channels to open which causes depolarization -can cause tetany of resp muscles= death |
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Hyperparathyroidism
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-Hypercalcemia= increase in blood calcium levels
-causes weak bones, muscles, and low excitability -can cause possible cardiac-increase in conctraction force |
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Adrenal Glands
(suprarenal glands) |
-located superior to the kidneys
-consists of 3 parts 1.capsule 2.cortex 3.medulla |
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Part of the adrenal gland made of connective tissue
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Capsule
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Part of the adrenal gland made of 3 different layers.
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Cortex
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The 3 layers of the cortex
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1. Zona Glomerulosa
2. Zona Fasciculata 3. Zona Reticularis |
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The most center part of the adrenal gland
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Medulla
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Medulla
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Develops from neural cells
-part of autonomic nervous system -made of chromaffin cells that are part of sympathetic nervous system -secrets epi and norepi |
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The 2 neurohormones secreted from the adrenal gland
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-epinephrine (adrenaline)
-norepinephrine (noradrenaline) -epi can be made from norepi |
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What do epinephrine and nor epinephrine bind to?
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adrenergic receptors
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What are the two main categories of adrenergic receptors?
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-alpha adrenergic receptors
-beta adrenergic receptors |
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Alpha adrenergic receptors
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-open calcium channels and cause calcium to be released from ER.
-open potassium channels and cause synthesis decrease of cAMP |
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Beta adrenergic receptors
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-causes increase in cAMP synthesis
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