Upload
imogen-eaton
View
219
Download
4
Tags:
Embed Size (px)
Citation preview
Copyright © 2010 Pearson Education, Inc.
Endocrine system and nutrition;Nutrition and endocrine system
Copyright © 2010 Pearson Education, Inc.
Let’s define some more - Define Hormone
The term hormone is derived from a Greek verb meaning
– to excite or arouse Hormone is a chemical messenger that is released in one
tissue (endocrine tissue/gland) and transported in the
bloodstream to reach specific cells in other tissues Regulate the metabolic function of other cells
Have lag times ranging from seconds to hours
Tend to have prolonged effects
Hormone actions must be terminated – how?
Copyright © 2010 Pearson Education, Inc.
Intercellular communication types
• Autocrine - the cell signals itself through a chemical that it synthesizes and then responds to. Autocrine signaling can occur:
• solely within the cytoplasm of the cell or
• by a secreted chemical interacting with receptors on the surface of the same cell
• Paracrine - chemical signals that diffuse into the area and interact with receptors on nearby cells (cells within the same tissue).
• Endocrine - the chemicals are secreted into the blood and carried by blood and tissue fluids to the cells they act upon.
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/H/Hormones.html
Copyright © 2010 Pearson Education, Inc.
Bloodstream
Copyright © 2010 Pearson Education, Inc.
Endocrine versus Nervous system
• Released in synapse
• Close to target cells
• Signal to release by action potential
• Short live effect
• Crisis management
• Released to bloodstream
• Can be distant from target cells
• Different types of signal
• Long term effect
• Ongoing processes
Neurotransmitters Hormones
• Both use chemical communication
• Both are being regulated primarily by negative feedback
Copyright © 2010 Pearson Education, Inc.
Control of Hormone Release
Blood levels of hormones: Are controlled by negative feedback systems
Vary only within a narrow desirable range
Hormones are synthesized and released in response to: Humoral stimuli
Neural stimuli
Hormonal stimuli
Copyright © 2010 Pearson Education, Inc.
Humoral Stimuli
Secretion of hormones in direct response to changing blood levels of ions and nutrients
Example: concentration of calcium ions in the blood
Declining blood Ca2+ concentration stimulates the parathyroid glands to secrete PTH (parathyroid hormone)
PTH causes Ca2+ concentrations to rise and the stimulus is removed
Copyright © 2010 Pearson Education, Inc.
Neural Stimuli
• Neural stimuli – nerve fibers stimulate hormone release
• Preganglionic sympathetic nervous system (SNS) fibers stimulate the adrenal medulla to secrete catecholamines
Figure 16.5b
Copyright © 2010 Pearson Education, Inc.
Hormonal Stimuli
Hormonal stimuli – release of hormones in response to hormones produced by other endocrine organs
The hypothalamic hormones stimulate the anterior pituitary
In turn, pituitary hormones stimulate targets to secrete still more hormones
Copyright © 2010 Pearson Education, Inc.
Let’s define some more - Define nutrients
Nutrients are chemicals in foods that our bodies use for growth and function
Organic nutrients contain carbon, an essential component of all living organisms
Carbohydrates, lipids, proteins, vitamins
Inorganic nutrients: nutrients that do not contain carbon
Minerals and water
Macronutrients are nutrients required in relatively large amounts
Provide energy to our bodies
Carbohydrates, lipids, proteins
Copyright © 2010 Pearson Education, Inc.
• Two main classes
1.Amino acid-based hormones
Amino acid derivatives
• Structurally similar to amino acids
• Derivative of tyrosine : thyroid hormones catecholamines (Epinephrine, norepinephrin, dopamine),
• Derivative of tryptophan - melatonine.
Hormone structure - based on chemical structure
Copyright © 2010 Pearson Education, Inc.
• Peptide hormones – 2 groups
• Short polypeptides and small proteins – hormones secreted by heart, thymus, digestive tract, pancreas, hypothalamus (ADH and OT) and anterior pituitary (ACTH, GH, MSH, PRL)
• Glycoproteins – consist more than 200 amino acids and have carbohydrate side chains.
• anterior pituitary (TSH, LH and FSH), kidneys (erythropoietin), reproductive organs (inhibin)
Hormone structure
Copyright © 2010 Pearson Education, Inc.
2.Steroids (Lipid derivatives)
• Synthesized from cholesterol
• Gonadal and adrenocortical hormones
Hormone structure
Copyright © 2010 Pearson Education, Inc.
A Structural Classification of Hormones
Copyright © 2010 Pearson Education, Inc.
Distribution of Hormones in bloodstream
• Hormones that are released into the blood are being transported in one of 2 ways:
• Freely circulating
• Bound to transport protein
Copyright © 2010 Pearson Education, Inc.
Distribution of Hormones in bloodstream
• Freely circulating (most hormones)
• Hormones that are freely circulating remain functional for less than one hour and some as little as 2 minutes
• Freely circulating hormones are inactivated when:
* bind to receptors on target cells
* being broken down by cells of the liver or kidneys
* being broken down by enzymes in the plasma or interstitial fluid
• Bound to transport proteins – thyroid and steroid hormones (>1% circulate freely)
• Remain in circulation longer
Copyright © 2010 Pearson Education, Inc.
Target Cell Specificity
Hormones circulate to all tissues but only activate cells referred to as target cells
Target cells must have specific receptors to which the hormone binds
These receptors may be intracellular or located on the plasma membrane
Copyright © 2010 Pearson Education, Inc.
Interaction of Hormones at Target Cells
• Three types of hormone interaction
• Permissiveness – one hormone cannot exert its effects without another hormone being present
• For example, thyroid hormone increases the number of receptors available for epinephrine at the latter's target cell, thereby increasing epinephrine's effect at that cell. Without the thyroid hormone, epinephrine would only have a weak effect
• Synergism – more than one hormone produces the same effects on a target cell
• Antagonism – one or more hormones opposes the action of another hormone
Copyright © 2010 Pearson Education, Inc.
Target Cell Activation
Hormone exert their effects on target cells at very low blood concentrations (ng-10-9 gr; pg-10-12 gr)
Target cell activation depends on three factors
Blood levels of the hormone
Relative number of receptors on the target cell
The affinity of those receptors for the hormone
The time required to effect target cells depends on the hormone - some influence immediately and some (steroids; why?) require hours or days
Hormone effect duration also varies and can range between seconds to hours
Copyright © 2010 Pearson Education, Inc.
• down regulation – the presence of the hormone induces a decrease in the receptors concentration;
• high levels of hormone – cell less sensitive
• Up regulation – absence of the hormone induces the increase in receptors concentration;
• Low levels of hormone – cell more sensitive
• In most systems the maximum biological response is achieved at concentrations of hormone lower than required to occupy all of the receptors on the cell (spare receptors).
• Examples:
• insulin stimulates maximum glucose oxidation in adipocytes with only 2-3% of receptors bound
• LH stimulates maximum testosterone production in Leydig cells when only 1% of receptors are bound
Receptors number on target cell
Copyright © 2010 Pearson Education, Inc.
• The hormone must interact with a specific receptor in
order to affect the target cell
• In the cell membranes of target cells
• In the cytoplasm or nucleus
Receptors for hormones are located:
Copyright © 2010 Pearson Education, Inc.
Mechanisms of Hormone Action• Two mechanisms, depending on their chemical nature
1. Water-soluble hormones (all amino acid–based hormones
except thyroid hormone)
• Cannot enter the target cells
• Act on plasma membrane receptors
• Coupled by G proteins to intracellular second
messengers that mediate the target cell’s response
2. Lipid-soluble hormones (steroid and thyroid hormones)
• Act on intracellular receptors that directly activate genes
Copyright © 2010 Pearson Education, Inc.
Indirect effect – through G-protein and 2nd messenger
Copyright © 2010 Pearson Education, Inc.
Figure 16.2 1
The actions of second messengers for hormones that bind toreceptors in the plasma membrane
Effects on cAMP Levels Effects on Ca2+ LevelsMany G proteins, once activated, exert their effects by changing theconcentration of cyclic-AMP, which acts as the second messenger withinthe cell.
Some G proteins use Ca2+ as a secondmessenger.
Hormone Hormone Hormone
Proteinreceptor
Proteinreceptor
Proteinreceptor
G proteinactivated
G proteinactivated
G proteinactivated
Acts assecond
messenger
Increasedproduction
of cAMP
cAMP cAMP AMPATP
Opens ionchannels
Activatesenzymes
If levels of cAMP increase,enzymes may be activatedor ion channels may beopened, accelerating themetabolic activity of thecell.
In some instances, G proteinactivation results in decreasedlevels of cAMP in thecytoplasm. This decrease hasan inhibitory effect on the cell.
The calcium ions themselves serve asmessengers, generally in combinationwith an intracellular protein calledcalmodulin.
Enhancedbreakdown
of cAMP
Reducedenzymeactivity
Activatesenzymes
Ca2+
Ca2+Ca2+
Ca2+
Openingof Ca2+
channelsRelease ofstored Ca2+
from ERor SER
Ca2+ acts assecond messenger
Calmodulin
Hormone
Proteinreceptor
G protein(inactive)
G proteinactivated
Links the firstmessenger
(hormone) and thesecond messenger
Copyright © 2010 Pearson Education, Inc.
Receptors on the cell membrane
• Hormones do not induces changes in cell activity directly but via the induction of the appearance and action of other agents
• Hormones are referred to as first messengers and the agents that are activated by the hormones are called second messengers.
• All amino-acid hormones (with exception of the thyroid hormone) exert their signals through a second messenger system:
• cAMP
• PIP
Copyright © 2010 Pearson Education, Inc.
Receptors on the cell membrane
• Second messengers function as enzyme activator, inhibitor or cofactor
• A small number of hormone molecules induce the appearance and activity of many 2nd messenger molecules – amplification
• one single hormone can induce the activation of more than one 2nd messenger
• Activation of a 2nd messenger can start a chain of reactions – receptor cascade
Copyright © 2010 Pearson Education, Inc.
Amino Acid-Based Hormone Action: cAMP Second Messenger
• Hormone (first messenger) binds to its receptor, which then binds to a G protein
• The G protein is then activated
• Activated G protein activates the effector enzyme adenylate cyclase
• Adenylate cyclase generates cAMP (second messenger) from ATP
• cAMP activates protein kinases, which then cause cellular effects
Copyright © 2010 Pearson Education, Inc.
• Hormone binds to the receptor and activates G protein
• G protein binds and activates phospholipase
• Phospholipase splits the phospholipid PIP2 into diacylglycerol (DAG) and IP3 (both act as second messengers)
• DAG activates protein kinases; IP3 triggers release of Ca2+ stores
• Ca2+ (third messenger) alters cellular responses
Amino Acid-Based Hormone Action: PIP-Calcium
Copyright © 2010 Pearson Education, Inc.
Intracellular Receptors and Direct Gene Activation
• Steroid hormones and thyroid hormone
1. Diffuse into their target cells and bind with intracellular receptors
2. Receptor-hormone complex enters the nucleus
3. Receptor-hormone complex binds to a specific region of DNA
4. This prompts DNA transcription to produce mRNA
5. The mRNA directs protein synthesis
Copyright © 2010 Pearson Education, Inc.
Location of Receptor
Classes of Hormones
Principle Mechanism of Action
Cell surface receptors (plasma membrane)
Proteins and peptides, catecholamines and eicosanoids
Generation of second messengers which alter the activity of other molecules - usually enzymes - within the cell
Intracellular receptors (cytoplasm and/or nucleus)
Steroids and thyroid hormones
Alter transcriptional activity of responsive genes
http://arbl.cvmbs.colostate.edu/hbooks/pathphys/endocrine/moaction/change.html
Copyright © 2010 Pearson Education, Inc.
What Are Carbohydrates?
One of the three macronutrients
Important source of energy for all cells
Preferred energy source for nerve cells
Composed of carbon, hydrogen, oxygen
Good sources: fruits, vegetables, grains
Important component of the glycoprotein hormones (gondotrophins, Thyroid-stimulating hormone, erythropoietin to name few)
Copyright © 2010 Pearson Education, Inc.
Different types of carbohydrates
Simple carbohydrates
Contain one or two molecules
Commonly referred to as sugars
Monosaccharides contain one molecule
Glucose, fructose, and galactose
Disaccharides contain two molecules
Lactose, maltose, and sucrose
Copyright © 2010 Pearson Education, Inc.
What Are Carbohydrates?
Glucose
The most abundant carbohydrate
Produced by plants through photosynthesis
Copyright © 2010 Pearson Education, Inc.
Different types of carbohydrates - Complex carbohydrates
Oligosaccharides contain 3 to 10 monosaccharides
Most polysaccharides consist of hundreds to thousands of glucose molecules (Starch, glycogen, most fibers)
Copyright © 2010 Pearson Education, Inc.
Complex Carbohydrates - Starch
Plants store carbohydrates as starch
Amylose—straight chain of glucose
Amylopectin—branched chain of glucose
Resistant starch (fiber)—glucose molecules linked by beta bonds are largely indigestible
Sources: grains, legumes, fruits, vegetables
Copyright © 2010 Pearson Education, Inc.
Complex Carbohydrates - glycogen
Storage form of glucose for animals (humans)
Not found in food and therefore not a source of dietary carbohydrate
Stored in the liver and muscles
Copyright © 2010 Pearson Education, Inc.
Complex Carbohydrates - fiber
Composed of long polysaccharide chains
Dietary fibers are non-digestible parts of plants
Functional fibers are non-digestible forms of carbohydrates extracted from plants or manufactured in a laboratory and have known health benefits
Total fiber = Dietary fiber + Functional fiber
Copyright © 2010 Pearson Education, Inc.
Complex Carbohydrates - Soluble fibers
Dissolve in water; viscous and gel-forming
Fermentable, digested by intestinal bacteria
Associated with risk reduction of cardiovascular disease and type 2 diabetes
Examples: pectin, gum, mucilage
Found in citrus fruits, berries, oats, beans
Copyright © 2010 Pearson Education, Inc.
Complex Carbohydrates – insoluble fibers
Do not dissolve in water, nonviscous
Cannot be fermented by bacteria in the colon
Promote regular bowel movements, alleviate constipation, and reduce diverticulosis
Examples: lignins, cellulose, hemicelluloses
Good sources: whole grains, seeds, legumes, fruits, and vegetables
ABC Video Whole Grains
Copyright © 2010 Pearson Education, Inc.
The Role of Carbohydrates – Energy
Each gram of carbohydrate: 4 kcal
Red blood cells use only glucose for energy
Both carbohydrates and fats supply energy for daily activities
Glucose is especially important for energy during exercise
Copyright © 2010 Pearson Education, Inc.
The Role of Carbohydrates – prevent ketosis
Fat breakdown during fasting forms ketones
Excess ketones increase blood acidity and cause ketoacidosis
Sufficient energy from carbohydrates prevents ketone production as alternate energy source (will be discussed later in the course)
Fad Diets
Copyright © 2010 Pearson Education, Inc.
The Role of Carbohydrates - Spare Protein
Gluconeogenesis occurs when a diet is deficient in carbohydrate
The body will make its own glucose from protein
Amino acids from these proteins cannot be used to make new cells, repair tissue damage, support the immune system, or perform any of their other functions
Copyright © 2010 Pearson Education, Inc.
Complex Carbohydrates Have Health Benefits
Fiber
May reduce the risk of colon cancer
Helps prevent hemorrhoids, constipation, and other intestinal problems
May reduce the risk of diverticulosis
May reduce the risk of heart disease
May enhance weight loss
May lower the risk of type 2 diabetes
Diverticulosis and Fiber
Copyright © 2010 Pearson Education, Inc.
How Much Carbohydrate?
Recommended Dietary Allowance (RDA) is 130 grams/day to supply adequate glucose to the brain
Acceptable Macronutrient Distribution Range (AMDR) is 45% to 65% of daily calories
Focus on fiber-rich carbohydrate foods
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
Simple Carbohydrates
Diets high in simple sugars:
Can cause tooth decay
May increase “bad cholesterol”
May decrease “good cholesterol”
May contribute to obesity
ABC Video Sugar and Processed Food
Copyright © 2010 Pearson Education, Inc.
Complex Carbohydrates
Most Americans eat too little complex carbohydrates
Enriched foods are foods in which nutrients that were lost during processing have been added back so the food meets a specified standard
Fortified foods have nutrients added that did not originally exist in the food (or existed in insignificant amounts)
Copyright © 2010 Pearson Education, Inc.
Complex Carbohydrates
Adequate Intake (AI) for fiber
25 g per day for women
38 g per day for men, or
14 g of fiber for every 1,000 kcal per day
It is best to get fiber from food (also a source of vitamins and minerals)
An adequate fluid intake (at least 8 oz/day) with high-fiber diets is recommended
Copyright © 2010 Pearson Education, Inc.
http://www.medbio.info/Horn/Time%203-4/homeostasis_2.htm
Copyright © 2010 Pearson Education, Inc.
Endocrine organs: Pancreas Pancreas structure
Exocrine pancreas (99% of volume)
Cells (pancreatic acini) forming glands and ducts that secrete pancreatic fluid and enzymes with digestive function
Endocrine pancreas (1%)
Small groups of cells scattered in clusters (pancreatic islets) that secrete hormones
Copyright © 2010 Pearson Education, Inc.
Pancreas – islets of Langerhans cells• The islets contain two major cell types:
• Alpha () cells that produce glucagon
• Beta () cells that produce insulin
• The islets also contain
• Delta cells – produce a peptide hormone identical to GH
inhibiting hormone (GH-IH). That hormone suppresses the
release of glucagon and insulin and slows food absorption and
digestive enzyme secretion
• F cells – Produce the hormone pancreatic polypeptide (pp) that
inhibits gallbladder contractions and regulate the production of
some pancreatic enzymes
Copyright © 2010 Pearson Education, Inc.
Pancreas
Copyright © 2010 Pearson Education, Inc.
Pancreas
Copyright © 2010 Pearson Education, Inc.
Pancreas and blood glucose levels
• Blood Glucose Levels are controlled by insulin and glucagon
• When levels rise
• Beta cells secrete insulin, stimulating transport of glucose across plasma membranes
• When levels decline
• Alpha cells release glucagon, stimulating glucose release by liver
Copyright © 2010 Pearson Education, Inc.
HOMEOSTASISDISTURBED
Rising bloodglucose levels
Beta cellssecreteinsulin.
Ris
ing
blo
od
glu
cose
lev
els
Fal
lin
g b
loo
d g
luco
se l
evel
s
Falling bloodglucose level
HOMEOSTASISDISTURBED
Alpha cellssecrete
glucagon
HOMEOSTASISRESTORED
HOMEOSTASISRESTORED
Blood glucoselevels decrease
Blood glucose levels increase
Increased breakdown ofglycogen to glucose (inliver, skeletal muscle)
Increased breakdown of fat to fatty acids (inadipose tissue)
Increased synthesisand release of glucose(in liver)
HOMEOSTASIS
Normal bloodglucose levels(70-110 mg/dL)
Increased amino acidabsorption and proteinsynthesis
Increased triglyceridesynthesis in adiposetissue
Increased conversionof glucose to glycogen
Increased rate ofglucose utilization andATP generation
Increased rate ofglucose transport intotarget cell
Copyright © 2010 Pearson Education, Inc.
• A 51-amino-acid protein consisting of two amino acid chains linked by disulfide bonds
• Insulin is released when glucose levels exceed normal levels (70-110 mg/dl)
Insulin
http://www.chemistryexplained.com/images/chfa_02_img0437.jpg
Copyright © 2010 Pearson Education, Inc.
• Insulin facilitates entry of glucose cells by binding to a membrane receptor
• The complex insulin-receptor make a specific carrier protein (GLUT4) available
• Once at the cell surface, GLUT4 facilitates the passive diffusion of circulating glucose down its concentration gradient into cells.
• Receptors for insulin are present in most cell membranes (insulin-dependant cells)
• Cells that lack insulin receptors are cells in the brain, kidneys, lining of the digestive tract and RBC (insulin-independent cells).
• Those cells can absorb and utilize glucose without insulin stimulation.
Effects of Insulin Binding to its receptors
Copyright © 2010 Pearson Education, Inc.
Effects of Insulin
• Acceleration of glucose uptake as a result from an increase of the number of glucose carrier proteins
• Acceleration of glucose utilization and increased ATP production
• Stimulation of glycogen formation in the liver and muscle cells
• Inhibits glycogenolysis (break down of glycogen) and gluconeogenesis (glucose building)
• Stimulation of amino acid absorption and protein synthesis
• Stimulation of triglyceride formation in adipose tissue
• As a result glucose concentration in the blood decreases
Copyright © 2010 Pearson Education, Inc.
• Released by alpha cells
• A 29-amino-acid polypeptide hormone that is a potent hyperglycemic agent (what does it mean?)
• it promotes:
• Glycogenolysis – the breakdown of glycogen to glucose in the liver and skeletal muscle
• Gluconeogenesis – synthesis of glucose from lactic acid and noncarbohydrates in the liver
• Release of glucose to the blood from liver cells
• breakdown of triglycerides in adipose tissue
Glucagon
Copyright © 2010 Pearson Education, Inc.
Other hormones that control glucose levels
Glucocorticoids
Copyright © 2010 Pearson Education, Inc.
• Adrenal glands – paired, pyramid-shaped organs atop the kidneys
• Structurally and functionally, they are two glands in one
• Adrenal medulla – neural tissue; part of the sympathetic nervous system
• Adrenal cortex - three layers of glandular tissue that synthesize and secrete corticosteroids
Adrenal (Suprarenal) Glands
Copyright © 2010 Pearson Education, Inc.
Adrenal Cortex
• Synthesizes and releases steroid hormones called corticosteroids
• Different corticosteroids are produced in each of the three layers
• Zona glomerulosa – glomerulus- little ball. Secretes mineralocorticoids – main one aldosterone
• Zona fasciculata – glucocorticoids (chiefly cortisol)
• Zona reticularis – gonadocorticoids (chiefly androgens)
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
Zona glumerulosa – Mineralocorticoids
• Aldosterone secretion is stimulated by:
• Rising blood levels of K+
• Low blood Na+
• Decreasing blood volume or pressure
• Effects will be discussed in details with the urinary system
Copyright © 2010 Pearson Education, Inc.
Zona fasciculata - Glucocorticoids (Cortisol/hydrocortisone)
• This adrenal layer responds to ACTH (which endocrine glands secretes ACTH?)
• Main hormone secreted are the Cortisol/hydrocortisone and small amounts of corticosterone
• Glucocorticoids accelerate the rates of glucose synthesis and glycogen formation – especially in the liver
• Adipose tissue responds by releasing fatty acids into the blood and the tissues start to utilize fatty acids as source of energy - glucose-sparing effect (GH has similar effect and will be discussed later)
• Clucocorticoids also have anti-inflammatory effect – inhibit the activities of WBC (use?)
Copyright © 2010 Pearson Education, Inc.
Zona reticularis Gonadocorticoids (Sex Hormones)
• Most gonadocorticoids secreted are androgens (male sex hormones), and the most important one is testosterone
• Androgens can be converted into estrogens after menopause
• Both hormones from the kidney origin do not effect sexual characteristics
Copyright © 2010 Pearson Education, Inc.
Diabetes Mellitus (DM)
• Two types:
• Type I results from the destruction of beta cells and the complete loss of insulin (hypoinsulinemia)
• Type II is the most common type (90%) and is a result of decrease sensitivity of cells to insulin (insulin resistance). Type II is accompanied by hyperinsulinemia (what is that? Why?).
• Type II is associated with excess weight gain and obesity but the mechanisms are unclear.
• Other reasons that were associated with type II diabetes: pregnancy, polycystic ovary disease, mutations in insulin receptors and others
Copyright © 2010 Pearson Education, Inc.
Diabetes Mellitus (DM) effects• Increase in blood glucose due to diabetes causes
• Increase in glucose loss in urine
• Dehydration of cells – since glucose does not diffuse through cell membrane and there is an increase in osmotic pressure in the extracellualr fluid.
• In addition, the loss of glucose in the urine causes osmotic diuresis - decrease in water reabsorption in the kidney.
• The result is
• Polyuria – huge urine output and dehydration.
• Polydipsia – excessive thirst
Copyright © 2010 Pearson Education, Inc.
Diabetes Mellitus (DM) effects
• Polyphagia – excessive hunger and food consumption because cells are starving
• Damage to blood vessels and poor blood supply to different tissues
• Increase use of lipids as a source of energy by the cells and increase release of keto bodies – ketosis and changes of blood pH (acidosis). That leads to increased respiratory rate
Copyright © 2010 Pearson Education, Inc.
http://www.medbio.info/Horn/Time%203-4/homeostasis_2.htm
Copyright © 2010 Pearson Education, Inc.
Carbohydrate metabolism disorders
Copyright © 2010 Pearson Education, Inc.
Hypoglycemia
Low blood glucose may cause shakiness, sweating,
anxiety, weakness
Reactive hypoglycemia: pancreas secretes too much
insulin after a high-carbohydrate meal
Fasting hypoglycemia: pancreas produces too much
insulin, even when someone has not eaten
Copyright © 2010 Pearson Education, Inc.
Blood glucose levels in normal and hypoglycemia
Copyright © 2010 Pearson Education, Inc.
Lactose Intolerance
Insufficient enzyme lactase to digest the lactose-
containing foods
GI symptoms: gas, cramping, diarrhea
Variations in extent of intolerance
Not to be confused with milk allergy
Need alternate sources of calcium