Class Notes (838,386)
Canada (510,872)
HLTH 230 (50)
Lecture 6

Lecture 6 - Water and Water Soluble Vitamins.doc

18 Pages
111 Views
Unlock Document

Department
Health Studies
Course
HLTH 230
Professor
Jeffery Lalonde
Semester
Winter

Description
Lecture 6 - Water and Water Soluble Vitamins • an essential nutrient - more important than any other nutrient • needed in larger quantity/day than any other nutrient survival without water is only a few days compared to weeks, months, years for other nutrients • Water and the body fluids -approximately 60% of an adult’s body weight is water -water makes up: -approx. 3/4 of the weight of lean tissue -less than 1/4 the weight of fat -> generally percentage of water is lower in females, elderly, and obese people athletic/muscular people = lots of water Roles of water in body fluids • carries waste products and nutrients maintains structure of large molecules such as proteins and glycogen • • participates in metabolic reactions -condensation and hydrolysis reactions • serves as a solvent for vitamins, minerals, a.a., glucose to participate in metabolic rxns • acts as a lubricant and cushion around joints, inside the eyes, spine • aids in regulation of body temperature • maintains blood volume • body must actively maintain an appropriate water balance to support all vital functions Water Balance • water intake and excretion quickly adjusted to ensure composition of intracellular fluid and interstitial fluid is maintained intracellular fluid (fluid within the cells) -accounts for 2/3 of body’s water -usually high in potassium and phosphate interstitial fluid (between the cells) -largest component of extracellular fluid -usually high in sodium and chloride -> interstitial (between cells) -> intravascular (inside blood vessels) Water Intake thirst: a conscious desire to drink • thirst lags behind the body’s need -if you feel thirsty, you are already dehydrated! • influences water intake in response to changes sensed by mouth, hypothalamus, and nerves hypothalamus initiates drinking when: • -blood becomes concentrated -mouth becomes dry • excessive water intake stopped by: (signal you to stop drinking) Lecture 6 - Water and Water Soluble Vitamins -stretch receptors in stomach and volume receptors in heart dehydration: the condition in which body water output exceeds water input • symptoms: -thirst, dry mouth -dry skin and mucous membranes -weakness -rapid heart beat -low blood pressure -exhaustion, delirium, death Body Weight Lost (%) Symptoms 1-2 thirst, fatigue, weakness, vague discomfort, loss of appetite 3-4 impaired physical performance, dry mouth, reduction in urine, flushed skin, impatience, apathy 5-6 difficulty in concentrating, headache, irritability, sleepiness, impaired temperature regulation, increased respiratory rate 7-10 dizziness, spastic muscles, loss of balance, delirium, exhaustion collapse 1L of water = 2.2 lbs ex. someone weighs 200 lbs, losing 1L of water is 1-2% of body weight water intoxication: body water contents are too high in all the body fluid compartments • is rare, but may occur with: -excessive water consumption (10-20L in a few hours) -ex. trying to flush out toxins, recreational drugs -can lead to hyponatremia - a decreased Na+ conc. in blood -ex. endurance athletes lose a lot of sodium from sweat, end up with low blood sodium, taking in water after a race will dilute symptoms -> confusion, convulsions (only in intoxication, not dehydration!), death Water Sources & Percentage of Water water • • beverages = 80-100% water • fruit and vegetables = 70-99% water • meats and cheese = 30-69% water butter and oils = 0-20% water (fats are low in water) • • we also produce water during metabolism = 200-300ml/day -energy yielding nutrients producing CO2 and H20 with their breakdown (condens.rxn) Lecture 6 - Water and Water Soluble Vitamins Water Losses • body must excrete at least 500ml of urine/day to carry away waste products more usually excreted to adjust for intake (drinking water) • • water lost in urine, lungs as vapour (breath), skin as sweat, GI tract with feces • insensible water loss - via lungs and skin make up for about half the daily water loss -> foods and beverages provide the most water TABLE 12-3 - THIS IS IMPORTANT! -in order to balance this, kidneys produce urine, skin sweats, lungs excrete from breathing, GI tract loses water from feces -> liquids and foods are the main water sources! -> kidneys and skin are the main causes of water losses! Water Recommendations • 1.0 -1.5ml/kcal of energy expended for adults • 1.5ml/kcal of energy expended for infants and athletes • AI total water -3.7L/day for men -2.7L/day for women *according to DRI committee, total water intake includes caffeinated and non caffeinated beverages and food! What beverages are best? • beverages account for more than 20% of energy intake in US • obesity is a major concern - drink more water (no calories) • any beverage can meet water needs, with or without energy • water is best choice for most people • Canada’s Food Guide: “Satisfy your thirst with water!” -“Drink water regularly. It’s a calorie-free way to quench your thirst” Lecture 6 - Water and Water Soluble Vitamins Situations where water needs above the norm • fever, diarrhea, vomiting, runny nose • blood donation, surgery • exercise - increased loss via skin and respiration • pregnancy, breastfeeding • environmental conditions (extreme heat) Health Effects of Water • not only do fluid needs have to be met, but water intake can have health benefits -may protect against urinary stones and constipation -even mild dehydration can interfere with physical and mental performance hard water -high concentrations of calcium and magnesium -water that leaves dark rings around sinks -some people have water softners where you add sodium/potassium soft water -high sodium or potassium -generally sodium is added to water -prevent rings in the bathtub, toilet, and laundry tub -produces more bubbles when soap is added -more easily dissolves contaminants like cadmium and lead Blood Volume and Blood Pressure • fluid maintains blood volume -> directly related to blood pressure • kidneys play a major role in regulating blood pressure and blood volume -are filters that reabsorb needed nutrients and excrete waste products • volume concentration of urine is adapted by kidneys based on food and beverage intake • instructions on whether to retain/release substances come from: -ADH, renin, angiotensin, aldosterone ADH (Antidiuretic hormone) and water retention • hypothalamus signals pituitary gland to release ADH when: -BV or BP drops low -extracellular fluid becomes too concentrated • ADH stimulates kidneys to reabsorb water • thirst is triggered - drinking water and retaining fluids help restore blood volume *ADH is a water conserving hormone -consequently, the more water you need, the less water your kidneys would excrete Renin and Sodium Retention • renin released by kidney cells when BP is low Lecture 6 - Water and Water Soluble Vitamins • release of renin -> chain of events -> Na+ reabsorption by kidneys -> H20 reabsorption -> increase in blood pressure and volume Angiotensin and blood vessel constriction • renin also initiates activation of angiotensinogen -> angiotensin I • Angiotensin I is inactive until converted to angiotensin II • Angiotensin II: vasoconstrictor (narrows blood vessels => increase blood pressure) Aldosterone and Na+ retention • Angiotensin II also stimulates release of hormone aldosterone from adrenal glands • aldosterone signals kidneys to retain more Na+ -> more water FIGURE 12-3 IN TEXT Fluids help maintain body temperature -water can help us keep cool through 2 factors: 1) Water has a high heat capacity -takes a lot of heat to raise the temperature of water 2) Body fluids are our primary coolant -too cool: increase blood flow to vessels just under the skin -too hot: secrete more sweat, evaporates and releases heat Fluids protect and lubricate other tissues -water protects tissues and organs from injury -cerebrospinal fluid -amniotic fluid -synovial fluid -tears -saliva Fluid and Electrolyte Balance • balance of water inside and outside cell is essential -approx. 2/3rd of body water is inside cell -1/3rd outside the cells -movement of major minerals plays essential role in maintaining this balance -ex. water follows salt! dissociation of salt in water -mineral salt dissociates into positively and negatively charged particles (Na+ and Cl-) -Cations - positively charged (ex. Na+) -Anions - negatively charged (ex. Cl-) -pure water => poor conductor of electricity -ions dissolved in water => carry electric current -(+) and (-) charges inside and outside cells are perfectly balanced even though numbers of different kinds of ions may be different Lecture 6 - Water and Water Soluble Vitamins -ex. if there are 1000 (-) charges, there must also be 1000 (+) charges -when an Na+ leaves the cell, a K+ is entering electrolytes attract water -water molecules each have a net charge of zero -O side: (-) slightly negative -H side: (+) slightly positive -this attraction dissolves salts in water and enables body fluids to move into appropriate compartments water follows electrolytes -sodium and chloride are typically outside the cell -potassium, magnesium, phosphate, and sulphate are typically inside cell -cell membranes are selectively permeable -whenever electrolytes move across the membranes, water follows -osmosis: movement of water towards the more concentrated solute water moves to make sure concentration is the same so concentration in both sides is the same Lecture 6 - Water and Water Soluble Vitamins proteins regulate flow of fluids and ions -protein can act as a pump regulating crossing of a membrane -ex. Na/K pump (exchanges sodium for potassium) uses ATP for energy regulation of fluid and electrolyte balance -amounts of various minerals in the body must remain constant -steady state maintained by: -GI tract -minerals in digestive juices and food are reabsorbed in large intestine as needed -kidneys -control body water with ADH -electrolyte content is regulated by aldosterone Fluid and Electrolyte Imbalance • ex. prolonged diarrhea, vomiting, heavy sweating, burns, medications -ex. potassium wasting diuretics sodium and chloride most easily lost -principle extracellular cation and anion in the body, they are lost via sweater, blood, or excretion -easier to lose because they are outside the cell different solutes lost by different routes -vomiting and diarrhea causes sodium to be lost indiscriminately -too much K+ may be excreted if tumor develops, causing adrenal glands to secrete too much aldosterone -person with uncontrolled diabetes may lose glucose in urine -dehydration may occur in all situations, but water alone will not restore electrolyte balance -electrolytes are lost too, need electrolytes as well as water replacing fluid and electrolyte loss -drinking water and eating regular food -medical attention (ex. IVs) sometimes required Lecture 6 - Water and Water Soluble Vitamins Acid-Base Balance • body must maintain blood pH between 7.35 and 7.45 • wrong pH can denature proteins -prevents enzymes from working -> stops reactions -> serious consequences • pH primarily regulated by -Buffers -bicarbonate (base) and carbonic acid (acid) found in body fluids protect body against changes in acidity by neutralizing acids and bases -some proteins act as buffers -Lungs -control concentration of carbonic acid by changing respiration rate -if carbonic acids build up -> respiration rate increases -> increase in CO2 exhaled -Kidneys -role in long term acid base balance -> selecting ions to retain and secrete -urine acidity fluctuates to help body pH remain constant Sodium AI: 1500mg UL: 2300mg 1 teaspoon of salt = approx. 2300mg Na very common in processed foods reducing sodium in the diet has been linked to reduced blood pressure WATER - SOLUBLE VITAMINS • vitamins -> powerful substances discovered in early 1900s • vitamins can fight certain diseases, absence can cause dreadful conditions like scurvy, blindness, dementia support nutritional health but do not cure all • • supplements do not offer many benefits of vitamin-rich foods • are “organic, essential nutrients required in small amounts by body for health. they regulate processes that support and maintain life.” • “vita” - life “amin” - nitrogen containing Vitamins differ from carbs, protein, and fat in 3 main ways: Structure -vitamins are individual units (not linked together) where as carbs and proteins generally are Function -vitamins DO NOT YIELD USABLE ENERGY!!!! -often play an important role in metabolism Food Contents -measured in micrograms and milligrams, not grams • similar to energy yielding nutrients in the way that they are essential to life, organic and available from foods Bioavailability Lecture 6 - Water and Water Soluble Vitamins bioavailability: rate and extent to which a nutrient is absorbed and used • amount of vitamins available from food is dependent on: 1) amount in the food (quantity) 2) amount that can be absorbed and used by the body • food may be high in a particular vitamin but amount absorbed and used be very little bioavailability depends on: -efficacy of digestion and time of transit through GI tract -previous nutrient intake and nutritional status -other foods consumed at the same time -ex. vitamin C assists absorption of iron phytates assists absorption of calcium -method of food preparation (raw, cooked, processed) -source of nutrient (synthetic, fortified, naturally occurring) • provitamin is a precursor of a vitamin -ex. some vitamins in food are in their inactive form and are converted to active form within body (ex. beta carotene is converted to vitamin A in the body) • vitamins are organic and can be destroyed during handling and cooking -ex. oxygen destroys vitamin C, prolonged heating may destroy thiamin, UV light can destroy riboflavin Minimizing nutrient losses 10-1 • refrigerate most fruits and veg • store fruits and vegetables (that have been cut) in airtight containers (limit oxidation) • to prevent losses during washing, cut fruits and vegetables after washing • to minimize losses during cooking: -use microwave or steam vegetables in small amount of water -put vegetables in soup after water is boiling -avoid high temp and long cooking times *less cooking time = more nutrients! Solubility -hydrophilic vitamins referred to as water soluble vitamins -these 9 vitamins are dissolvable in water -water soluble vitamins include -Thiamin -Riboflavin -Niacin -Biotin -Vitamin B12 -Pantothenic Acid -Vitamin B6 -Folate -Vitamin C water soluble vitamins generally found in watery compo
More Less

Related notes for HLTH 230

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit