Hormones as Regulators of Metabolic Activity

Structural Role of Protein

• Keratin: in hair and outer layer of the skin.
• Myosin: major protein in skeletal and cardiac muscle.

Metabolic Role of Protein

• Many proteins function as enzymes (specific biological catalysts).
• Some proteins function as hormones.

Carbohydrate

• Elements: CHO. General Formula: (CH₂O)n or C_X(H₂O)_Y
• Monosaccharides: single sugar unit
• Pentoses: C₅H₁₀O₅ Deoxyribose of DNA and Ribose of RNA
• Hexoses: C₆H₁₂O₆ Glucose, Fructose, Galactose — use for respiration
• Disaccharides: double sugars — two sugar units linked together
• Maltose: glucose + glucose — intermediate between glucose and starch
• Sucrose: glucose + fructose — food transported in the phloem of plants is a sucrose solution
• Lactose: glucose + galactose — the sugar present in milk
• Polysaccharides: multisugars — the three examples are multiglucoses
• Starch: plant glucose reserve
• Glycogen: glucose reserve of animals and fungi. Glycogen stored in skeletal muscle and liver
• Cellulose: plant cells walls and fibre in our diet

Dietary Sources of Carbohydrates

• Monosaccharides: fruit, honey and jam.
• Disaccharides: Sucrose - fruit, table sugar. Lactose - milk. Maltose - germinating seeds.
• Polysaccharides: Starch: bread, rice, pasta, potatoes, seeds.
• Cellulose: fruit, vegetables, wholegrain cereals, nuts.

Structural Role of Carbohydrate

• Cellulose walls of plant cells.
• Chitin in the cell walls of fungi.

Metabolic Role of Carbohydrate

• Energy Source: energy released by the respiration of glucose is used to make ATP.
• Energy Storage: starch in plants, glycogen in animals and fungi.

Lipid

• Elements: CHO – with more H but less O than carbohydrates.
• Composed of glycerol with three fatty acids linked to the glycerol.
• Fat – solid lipid at room temperature. Oil – lipid that is liquid at room temperature.
• Phospholipid: two fatty acids and a phosphate group linked to the glycerol.
• Good Dietary Sources: meat, milk, butter, cheese, plant oils, margarine.

Structural Role of Lipid

• Lipids and Phospholipids are very important in cell membrane structure.
• The protective wax cuticle on the outside of leaves.

Metabolic Role of Lipids

• Energy storage: more than twice the energy of carbohydrate or protein.
• Energy source: released during respiration.
• Storage of fat-soluble vitamins.
• Some lipids function as hormones.

Hormones as Regulators of Metabolic Activity

• Hormones are chemical messengers that cause their target cells or tissues to adjust or alter their activity.
• Hormones stimulate or inhibit specific metabolic reactions.
• The level of stimulation or inhibition depends on the concentration of hormone in the blood.
• Hormones play an important role in homeostasis.

Vitamins

A vitamin is an organic compound needed in small quantities in the diet for health.

Water-soluble Vitamin: Vitamin C (ascorbic acid)

• Obtained in fresh fruit and vegetables.
• Needed to make and maintain connective tissue and the absorption of iron by the gut.
• Long term deficiency of vitamin C causes a disease called scurvy.
• Scurvy symptoms: internal bleeding, bruising, bleeding gums, poor healing.

Fat-soluble Vitamin: Vitamin D (calciferol)

• Obtained from milk, eggs, liver, fish liver oils and produced in skin exposed to UV light.
• It is needed for bone and tooth formation, bone maintenance and the absorption of calcium from the gut.
• Long term deficiency cause diseases known as rickets and osteomalacia.
• Major deficiency symptoms: late teething and walking, deformed legs and arms, weak bones.

Minerals

Minerals or mineral nutrients are soluble inorganic salts that contain elements essential for metabolism.

Minerals are only needed in small quantities in comparison to protein, carbohydrate and lipid.

Plants obtain their minerals by absorbing them from external ‘water’ — soil water, freshwater and seawater.
Animals receive most of their minerals in the food they eat; some from the ‘water’ they drink.

Дата добавления: 2015-11-14