SAFOLO — 2e.2 — Nutrition in humans Flashcards
Balanced diet?
A diet in which all components needed to maintain health are present in appropriate proportions
Why do humans need a balanced diet?
To ensure the body is provided with components to maintain good health
What does a balanced diet contain?
- Carbohydrates (starch, glucose)
- Protein
- Vitamins
- Lipids (fat & oil)
- Dietary fibre
- Minerals
- Water
Function of carbohydrates?
Direct energy source
Deficiency: Lack of energy
Source: Meat, starch
Car(bohydrates) give out energy with meat
Function of protein?
Growth and repair
Deficiency: Marasmus - poor growth
Source: Meat
Pro-teens frow and repaire while Marasmus - who doesn’t grow - eats meat
Function of Vitamin A?
Healthy eyesight
Deficiency: Night blindness
Source: Carrots
A carrot A day keeps night blindness Away
Function of Vitamin C?
Heal wounds and rebuilds tissue
Deficiency: Scurvy - bleeding gums
Source: Lemon
(vitamin) SEA captain Wounds and Tissue screams BLEEDING SCURVY LEMONS
Function of Vitamin D?
Strengthen teeth and bones
Deficiency: Rickets - curved bones
Source: Margarine
Dentists Rick(et)roll with Margarine
Function of Lipids?
Insulation and Energy storage
Deficiency: Weak immunity, hair loss
Source: Meat, oil
Lips(ids) insulate the energy storage until our hair falls out and we have weak immunity with meat and oil
Function of dietary fibres?
Lowers Cholesterol
Deficiency: Constipation
Source: Vegetables
Fi(bres)ve low cholesterols had constipation with vegetables
Function of calcium?
Strengthen teeth and bones
Deficiency: Rickets - curved bones
Source: Milk
Cal(cium) has strong teeth and bones because his friend Rick(ets) told him to drink milk
Function of iron?
Promote Haemoglobin
Deficiency: Anaemia - poor Oxygen transport
Source: Meat
Iron (hea)Man(globin) and his girlfriend Anaemia (poor oxygen transport) eat meat
Function of water?
Allows chemical reactions to occur
Deficiency: Dehydration, kidney failure
Source: Water
Factors that affect energy requirements?
- Age
- Activity levels
- Pregnancy
How does age affect energy requirements?
- Amount of energy required increases towards adulthood for growth and muscle development
How do activity levels affect energy requirements?
- Amount of energy required increases with activity level as more energy is needed to allow muscle contractions to facilitate exercise via respiration
How does pregnancy affect energy requirements?
- Amount of energy required by females during pregnancy increases since more energy is needed to support growth of developing fetus, and the large mass that the Mother will cary
Mouth?
- Mechanical digestion occurs
- large food is turned into a bolus to provide large SA:V ratio for amylase to break down starch in food into glucose
- Saliva lubricates bolus for easy swallow
Oesophagus?
- Tube connecting mouth to stomach
- Peristalsis (wave-like contractions) occur to push bolus down the tube towards the stomach
Stomach?
- Peristalsis continues mechanical digestion, and enzymes begin chemical digestion
- Hydrochloric acid maintains optimum pH to increase rate of enzyme activity and metabolic reactions
Small intestine?
- Lined with Villi to absorb digested soluble molecules into blood
- duodenum is the first part, helps further digest food coming from stomach and absorbs nutrients to be used by the body
- ileum is the last part, connects to cecum and helps further digest food
Large intestine?
- Absorbs water from undigested food to produce faeces (stored in rectum and removed through anus)
- colon removes water and nutrients
- rectum is at end of large intestine where faeces are held before moving to anus
Pancreas
- Synthesises pancreatic enzymes (Amylase, protease and lipase)
- Secretes pancreatic enzymes into the stomach and small intestine for digestion
Peristalsis?
Wave-like muscle contractions that push food bolus down the Oesophagus from the mouth to anus. Occurs in the stomach and gut
How does peristalsis occur?
- Circular muscles change radius of oesophagus, longitudinal muscle change length of oesophagus
- Contraction of circular muscles behind food constricts gut to prevent bolus from being pushed back to mouth
- contraction of longitudinal muscle where food bolus is located moves it along gut (intestines)
- as a result, wave-like muscle contractions occur which push food down
What are the digestive enzymes?
Amylase/maltase, Protease, Lipase
Amylase breaks down starch (big molecule) to glucose
Protease breaks down protein to amino acids
Lipase breaks down lipids to fatty acids and glycerol
Bile?
Alkaline substance produced in the liver and stored in the gall bladder.
Emulsifies lipid molecules into droplets with larger SA:V ratio to increase the rate of digestion
How does bile neutralise small intestine acid?
- Enzymes in small intestine function optimally in alkaline conditions (optimum pH of 8-14)
- However churning food in stomach by HCL acid creates acidic environment
- Bile will neutralise HCl to maintain Alkaline conditions, allowing optimum enzyme activity and increasing the rate of metabolic reactions
How does bile emulsify lipids?
- As the breakdown and digestion of lipid molecules requires a long period of time, bile is used to emulsify large lipid molecules into small droplets
- lipid droplets will have larger SA:V ratio, allowing faster breakdown by lipase in fatty acids and glycerol, hence increasing rate of lipid digestion
Villus?
Small finger-like projections lining the intestine wall that absorb digested soluble food molecules
How are villi adapted for absorption?
- Thin cell wall
- Large SA:V ratio
- Dense capillary network
- Lacteal
How does a thin cell help villus?
Thin cell wall (one cell thick) to minimise distance of diffusion of digested soluble molecules, increasing rate of absorption
How does a large SA:V ratio help villus?
Folded to increase SA:V ratio for diffusion of digested soluble molecules, increasing rate of absorption
How does a dense capillary network help villus?
Dense capillary networks nearby to provide rich blood supply, creating strong concentration gradient for the diffusion of digested soluble molecules, increasing rate of absorption
How does a lacteal help villus?
Absorb and transport fatty acids and glycerol from intestine to lymphatic system
How is the small intestine adapted for absorption
- Very long
- Have villi and microvilli to increase surface area
muscular contractions to move food - Digestive enzymes
