Week 11 Flashcards
is there more water in the extracellular fluid or the intracellular fluid
intracellular fluid
2/3 of the body’s water
Do obese or lean people have more water per % body weight
Lean bodies have more water as % of body weight than obese individuals
how does the sodium-potassium pump help keep the water balanced in the body?
its moves ions against their concentration gradients by active transport. water moves into the area of greater concentration of Na+
where is there a greater concentration of K and Na+ ions, inside the cell or outside the cell
Higher concentration of Na+ outside the cell
Higher concentration of K inside the cell
If 3 Na+ ions are actively transported across the membrane into the cell how many K+ ions move out of the cell?
2
Define electrolytes
elements that separate into ions in water make the water able to conduct electrical current.
what are 5 functions of water in the body?
- helps maintain blood volume
- solvents for many reactions
- precursor for body fluids
- temperature regulation
- waste product removal
What is the AI for water?
15 cups for men
11 cups for women
what is the water AI based off?
80% from fluid intake, 20% from food
intake
what happens when there water deficiency? how does the body react?
dehydrations
body reacts by
- release of anti diuretic hormone
- renin-antiogension system
- aldosterone pathway
What happens in water toxicity?
Concentration of electrolytes is diluted, especially sodium = hyponatremia
Water from diluted blood is pulled into cells by osmosis
Diluted blood and swollen cells can cause headache, blurred vision, muscle cramps
What is hyponatremia?
Low sodium levels in blood
what is the functional unit of the kidneys?
the Nephron
what are the different parts of the nephron?
afferent arteriol glomerular capilaries bowmans capsule efferent arteriol Proximal convoluted tubule Distal convoluted tubule Collecting duct loop of henle
when and where is renin secreted?
secreted by the kidneys when sodium or blood volume is decreases (low blood pressure)
what is the function of renin?
converts angioteniogen to angiotensin 1
where is angioteniogen produced?
liver
how is angiotensin 1 (inactive) converted to angiotensin 2 (active form)?
by angiotensin converting enzyme (ACE)
what is the functionof angiotensin 2?
restriction of small blood vessels leading to a increased BP
promotes relsease of aldosterone
What is the function of aldosterone?
stimulates Na+ reabsorption increasing the ECF osmorality and thus fulid retention as water follows Na+
Anti-diuretic hormone (ADH) also known as vassiopressin is secreted from where?
posterior pituritary gland
When is ADH released?
when blood pressure is low
What is the function of ADH?
increases water permeablility and thus promotes water reabsorption, reducing urine output and increasing the blood pressure
when and where are Atrial natriuretic factor (ANF) released?
release by atrial myoctyes (heart) in response to raised blood pressure
what is the function of atrial natriuretic factor (ANF)?
to reduce sodium and water retention in the body by promoting sodium secretion. Thus reducing the blood volume and decreasing blood pressure.
what does alcohol consumption do to water balance in the body?
inhibits the action of ADH and thus causing dehydration
what is the difference between major minerals and trace (minor) minerals?
need:
>100mg per day = major minerals
<100mg per day = trace (minor) minerals
Which of the follow are major minerals and minor (trace) minerals?
calcium, iron, magnesium, zinc, chloride, sodium, sulfur, seleium, chromium, potassium, molybdem, flurine, iodine, copper, manganese, phosphorus
major
calcium, phospherus, potassium, sulfur, sodium, chloride, magnesium
Minor
iron, manganese, copper, iodine, flurine, molybdem, chromium, seleium, zinc
what factors impair the bioavailablity of minerals?
excess fibre oxlic acid polyphenols and tannis (phytochemicals) high doses of minerals antacids: because of reduced stomach acidity
how does excess fibre affect bioavailablity of minerals?
Phytic acid found in fibre (phytate in legumes and whole grains): binds to minerals & leads to excretion. decrease bioavailability
Leavened breads with yeast may break the bonds between the phytates and the minerals: ↑ bioavailability of minerals
how does oxlic acid decrease bioavailablity of minerals?
oxlic acid in dark green leafy vegetables: binds minerals and makes them less bioavailable
how does high dosage affect bioavailablity of minerals?
High dosage in supplements minimise absorption and interfere with with other minerals
What factors aid the bioavalibilty of minerals?
how do these factors help?
vitamin C: improves non-haem iron absorption within the same meal
Vitamin D: facilitates dietary calcium absorption
Stomach acidicity: assists in converting minerals from 3+ to 2+: helps their absorption, as 2+ is the absorption form
How do minerals travel in the blood?
travel free in the blood or bound to proteins
Define blood pressure?
the force against the arteriol wall
what is hypertension?
chronic elevation of blood pressure
what are the consequences of hypertension?
Increased pressure on heart
Can lead to heart, kidney and eye disease, as the arterial wall thickens, narrowing the lumen, making the blood vessels less elastic
Causes damage particularly in organs with small vessels
what is the difference between systolic and diastolic blood pressure?
Systolic blood pressure = as the heart contracts
Diastolic blood pressure = as the heart relaxes
what are the risk factors associated with primary hypertension?
- high LDL cholesterol levels
- Diabetes
- overweight and obesity
- high sodium diet (water retension)
- lifestyle: inactivity, smoking, alcohol
- idiopathic, genetics, ethencity, ageing
What are some treatment options for hypertension?
sodium reduction
improve lipid profile (LDL/HDL)
DASH: Dietary approach to stop hypertension
reduced alcohol consumption and reduce weight (where relevant)
Describe the DASH diet
High in potassium, magnesium, calcium, fiber through high vegetable and fruit intake, whole grain, and lean dairy products
Low in sodium (2300mg or 1500mg /day)
High ratio of potassium to sodium (~4000mg / 1500mg)
Low total fat, saturated fat, dietary cholesterol
Moderate protein intake: lean poultry, fish, nuts and low fat dairy, low amounts of red meat
Avoid added sugar: control of blood sugar level for endothelial health
What are the nutritional characteristics of DASH, Targets in numbers?
% of calories Total fat 27% Saturated fat 6% protein 18% carbohydrates 55%
goals: Cholesterol 150mg sodium 2300mg potassium 4700mg calcium 1250mg magnesium 500mg fibre 30g
where and how is sodium absorbed?
Small and large intestines: 98% efficient
Active transport: sodium-potassium pump
How is sodium excreted?
mostly urine and sweat
some lost in faeces
what are the functions of sodium?
- Maintenance of extracellular volume
- Assists in the absorption of glucose and amino acids in the small intestine
- Normal muscle and nerve function
- Membrane potential of cells
if you consume 5g of salt how much sodium have you consumed?
5g
= 5000mg
5000mg x 0.393
= 1965mg of sodium
What disease occurs with sodium deficiency?
Hyponatremia
what occurs with sodium toxicity?
Hypernatremia
>2g /day can increase urinary calcium losses
How much, where and now is postassium absorbed?
90% absorbed
Small & large intestines
Passive diffusion or Na-K-ATPase pump active absorption
where is potassium stored?
95% inside cells
how is potassium excreted?
mainly in urine
some in sweat and faeces
What are some functions of potassium?
Major cation in intracellular fluid
Responsible for changing the electrical potential during depolarisation/repolarisation of nerve/muscle cells for conduction of impulse
Contractility of smooth, skeletal and cardiac muscle
Excitability of nerve tissue
Cofactor of pyruvate kinase
What does high potassium intake result in?
reduces serum calcium excretion
promotes sodium + H20 excretion, resulting in reduced blood volume, and balanced blood pressure. This is a major mechanism of action of the DASH
What is being deficient in potassium lead to?
hypokalemia
in what disease may potassium toxicity occur and why?
chronic kidney disease, potassium is not excreted well
where does the absorption of chloride occur? what path might it follow?
In small and large intestines
Follows sodium absorption: electrical neutrality
What are the functions of chloride?
- Electrical neutrality: balancing sodium positive charge
- Main anion for ECF
- Fluid/electrolyte balance
- Acid/base balance
- Nerve impulse transmission
- Component of NaCl and HCL
Where is calcium absorbed?
Small and large intestines: most efficient in upper duodenum where the pH is slightly acidic; keeps calcium in 2+ form
what can increase calcium absorption?
Calcitriol (1,25(OH)2 vitamin D3)
Lactose and presence of protein in food
pregnancy and childhood, as there is an increased need
What are factors that may limit calcium absorption?
Phytic acid Oxalic acid Polyphenols and tannins Fat mal-absorption (calcium binds with unabsorbed fat in the intestine and gets excreted) Dietary phosphorous
How is calcium transported to cells?
Transported to cells as free ionised calcium or bound to proteins
Where is calcium stored?
Skeleton and teeth = 99%
All cells require calcium for function
How is calcium excreted?
sweat
urine
faeces
What two hormones is calcium regulated by?
calcitonin (when to high) and parathyroid hormone (when to low)
What are the functions of calcium?
- Bone development and maintenance
- Blood clotting
- Muscle contraction
- Transmission of nerve impulses to target cells
How is calcium used in muscle contraction?
Calcium ions released when nerve impulse reaches myocytes
Calcium triggers muscle proteins to contract
When calcium is transported back into the intracellular storage site: relaxation of muscle fiber
What is osteopenia?
Decreased in bone mineral density(BMD)
What is Osteoporosis?
Loss of both bone salts and collagen (organic) content
What is Osteomalacia/ Rickets?
Loss of mineral (inorganic) content but not the collagen (e.g low vitamin D status, which limits dietary calcium absorption)
How much, where and how is phosphorus absorbed?
70% of dietary source absorbed
in the upper small intestines
through active transport and diffusion
what are the function of phosphorus?
- Major component of bone and teeth
- Main ICF anion as HPO42- or HPO4-
– Buffer of acid
– Critical in energy production /storage: part of ATP & creatine phosphate
– All phosphorylation reactions, such as required to activate hormones
– Part of DNA and RNA, phospholipids in cell membranes, enzymes and cellular signaling pathways
What is Hyperphosphataemia?
toxicity of phospherus
what is Hypophosphataemia
deficiency of phospherus
How much, where and how is magnesium absorbed?
40-60% is absorbed
in the small instestine
by active and passive transport
where is magnesium stored?
50% found in bone: calcium-hydroxyapatite mineral
33% in muscles and soft tissue
Functions of magansium
12
- Second most abundant ICF cation
- Binds to phosphate of ATP to stabilise the molecule
- Required as cofactors in >300 enzymes and their reactions
- Energy production, CHO and Fat metabolism
- Insulin sensitivity
- DNA, RNA and protein synthesis
- Glutathione synthesis
- Sodium /potassium flux in membrane potential
- Nerve transmission
- Smooth muscle and heart contraction
- Calcium metabolism: role in bone structure and mineralisation
- Vasorelaxation: promotes healthy endothelium function and prevention of HTN
what happens where there is a deficiency in magnesium?
Irregular heartbeat, weakness, muscle spasms due to imbalance in the sodium/potassium pumping
Decrease in PTH and calcitriol activity: hypocalcaemia, and eventually osteoporosis
Associated with Hypertension and Type 2 diabetes
What are the functions of sulfure?
- Is part of vitamins and amino acids
- Required in the synthesis of sulfur containing compounds (glutathione peroxidase)
- Involved in the stabilisation of protein structure (collagen, nails, hair, skin)
- Participates in acid-base balance
