Nutrition and energy reaction in cells Flashcards
Define and give approximate values to the components of your daily energy expenditure
Daily energy expenditure is split into 3 components:
* BMR - Measure of the basal energy required to maintain life i.e., the functioning of various tissues (30% skeletal 20% CNS 20% liver 10% heart). Rough estimate of BMR for people who are not obese is 100 times the body weight in KG.
* Voluntary physical activity - In addition to BMR, energy required by skeletal and cardiac muscle for voluntary activity contributes to daily expenditure (BMR + 30% for an inactive person, BMR + 70% for someone who does 2hr exercise a day, BMR + 100% for someone who does several hours a day
* DIT (Diet-Induced Thermogenesis) - Following the ingestion of food, our metabolic rate increases because energy is required to digest, absorb, distribute and store nutrients
(about 10% of the energy content of the food).
Define cell metabolism and explain its functions
Metabolism is the set of processes which derive energy and raw materials from food stuffs and use them to support repair, growth and activity of the tissues of the body to sustain life
Describe the relationship between catabolism and anabolism
Catabolism - Break down larger molecules into smaller ones (intermediary molecules). Release large amounts of free energy. Oxidative so it releases H atoms (reducing power).
Anabolisms - Synthesis larger important cellular components from intermediary metabolites. Use energy released from catabolism (ATP). Reductive (use H released in catabolism.
Why do cells need a continuous supply of energy
Cells require a constant supply of energy to power the constant metabolic reactions that sustain life, and to replenish the ones that were used up.
Explain the roles of redox reactions and H-carrier molecules in metabolism
Redox Reactions - The summation of oxidation and reduction provides cellular energy as the flow of electrons between molecules produces usable energy.
H-carrier molecules - These transport hydrogen atoms to the electron transport chain which will change ADP to ATP by adding a phosphate. They participate in oxidation-reduction reaction by getting reduced due to the acceptance of a hydrogen
Explain the role of creatine phosphate
Creatine phosphate is an energy store that can be used when cells need to increase metabolic activity very quickly e.g., skeletal muscles.
When ATP concentrations are high, creatine phosphate is formed. If ATP concentration falls suddenly, the reaction reverses providing short boost to ATP.
Explain the roles of high and low energy signals in the regulation of metabolism
Catabolic pathways tend to activate when the concentration of ATP and the concentration of AMP rises.
Anabolic pathways tend to be activated when the concentration of ATP rises.
High energy signals activate anabolic pathways, and they include: ATP, NADH, NADPH, FAD2H
Low energy signals activate catabolic pathways, and they include: ADP, AMP, NAD+, NADP+, FAD
List the essential components of the diet and explain why they are essential
Carbohydrates - A source of glucose which is used by tissues
Fats - Not an absolute requirement as an energy source however produces 2.2 times the energy yield, necessary for the absorption of fat-soluble vitamins. Also, some polyunsaturated fatty acids, which are components of the cell membrane aren’t synthesised in the body sands must be consumed in the diet
Proteins - Amino acids are used for the structure of the body and are used in the synthesis of essential N-containing compounds. Some (35g) of amino acids are lost by further degradation and must be replaced from the diet. Also, there are 9 essential amino acids which cant be synthesised from the body.
Water - 50-60% of the body. Constantly lost (2.5L per day) and must be replenished
Dietary fibre - Non-digesitble plant material such as cellulos is necesssary for normal bowel function
Minerals and Vitamins - Either water soluble or lipid soluble and some have important antioxidant properties.
Explain the clinical consequences of protein and energy deficiency in humans
Malnutrition is caused by damage from low energy intake, deficiency diseases of other nutrients and low protein intake. Some protein-energy malnutrition diseases include:
Marasmus - Type of protein-energy malnutrition mainly seen in children under 5. Signs of muscle wasting and loss of body fat although no oedema. Thin, dry hair, with diarrhoea being common
Kwashiorkor - Occurs in young children when given a diet low in protein. Generalised oedema, enlarged liver, accumulation of fluid in peritoneal cavity, low serum albumin and anaemia is common
Determine the Body Mass Index of a patient and interpret the value
BMI is Weight (KG)/ height^2 (m^2)
Underweight = <18.5
Desirable = 18.5-24.9
Overweight = 25-29.9
Obese = 30-34.9
Severely obese = >35
Define obesity and describe the factors involved in the regulation of body weight.
Obesity is excessive fat accumulation in adipose tissue which impairs health. Measured as a BMI >30.
If energy intake = expenditure the body weight will be stable. If there is an imbalance, it will either cause energy stores (fats) to increase or decrease.
Increased risk of:
Insulin resistance, Hypertension, Hyperlipidaemia, Type 2 diabetes, Hyperinsulinism, Stroke.
What are the 9 essential amino acids
- Isoleucine
- Lysine
- Threonine
- Histidine
- Leucine
- Methionine
- Phenylalanine
- Tryptophan
- Valine
What is the energy content per gram for:
Fat, Carbohydrates, Proteins, Alcohol
Fats - 37KJ/g
Alcohol - 29KJ/g
Protein - 17KJ/g
Carbohydrate - 17KJ/g
What produces serum albumin and why can a lack of it cause oedema and swelling
Amino acids are required to produce the albumin proteins. If there is low serum albumin in the blood, the osmotic pressure will be low as a result. Less water is attracted, Water leaves the blood and enters the interstitial space which causes swelling. Fluid makes the abdomen swell up.
What is refeeding syndrome and why is it bad
The rapid feeding of energy rich food in starved or inadequately nourished patients will rapidly increase blood sugar and insulin resulting in glycogen, fat and protein synthesis. This will utilise phosphate, magnesium and potassium from body stores that are already depleted and therefore result in electrolyte abnormalities such as hypophosphatemia. As a result, it is important to feed the with gradual reintroduction of protein and energy.
