B5- Homeostasis & response

• Homeostasis


  Regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes
• Conditions controlled by homeostasis

  • Blood glucose concentration
  • Body temperature
  • Water levels
• Stimulus

  A change in the environment
• Receptor


  Structures that detect a change in the environment
• Sensory neurone


  Neurones that send electrical impulses from the receptor to the CNS
• CNS

  Central nervous system
• Relay neurone


  Neurones found within the CNS
• Motor neurone


  Neurone that takes electrical impulses from the CNS to the effector
• Effectors

  • Muscle
  • Gland
• Synapse


  The gap between 2 neurones
• Glands


  Where hormones are released from
• Hormones

  Travel around the body in the blood
• Pituitary gland

  The master gland
• Blood glucose concentration is too high

  Insulin is released
• Insulin


  Released from the pancreas
• Blood glucose concentration is too low

  Glucagon is released
• Glucagon


  Released from the pancreas
• How insulin lowers blood glucose concentration

  1. Stimulates glucose to move from the blood into cells

  2. Causes excess glucose to be converted into glycogen to be stored in the muscle and liver cells
• How glucagon increases blood glucose concentration


  Causes glycogen to be converted into glucose and released into the blood
• Type 1 diabetes

  Pancreas fails to produce insulin
• Treatment for type 1 diabetes

  Insulin injection
• Type 2 diabetes


  Body cells no longer respond to insulin
• Treatment for type 2 diabetes

  Carbohydrate controlled diet and exercise
• Ovulation


  Egg release from the ovaries
• FSH


  Causes maturation of an egg in the ovaries
• LH


  Stimulates the release of an egg from the ovaries (ovulation)
• Oestrogen and progesterone


  Hormones involved in maintaining the uterus lining
• Oestrogen and progesterone

  Inhibit (stop) the production of LH and FSH
• Hormones in hormonal contraceptives

  Oestrogen - Prevents FSH production and stops egg maturation and release

  Progesterone - Stimulates the production of thick sticky cervical mucus. It can stop egg maturation and release
• Hormonal methods of contraception

  • Oral contraceptive pill, injection, IUD, patch
• Barrier methods of contraception

  • Condom and diaphragm
• IVF process

  Mother injected with FSH and LH to stimulate the maturation of many eggs

  1. The eggs are collected and fertilised by sperm
  2. The fertilised eggs develop into embyros
  3. Embryos are inserted into the mother's uterus
• Adrenaline is not controlled by negative feedback
• Thyroxine

  Released from the thyroid gland
• Thyroxine is controlled by negative feedback
• Adrenaline

  Released from the adrenal gland
• explain the importance of sugars, amino acids, fatty acids and glycerol in the synthesis and breakdown of carbohydrates, proteins and lipids.

  Sugars are important for providing energy in the synthesis of carbohydrates. Amino acids are the building blocks of proteins, crucial for growth and repair. Fatty acids and glycerol are essential for the synthesis of lipids, which are important for energy storage and cell structure. In the breakdown process, these molecules are broken down to release energy for various cellular functions. 
• what is metabolism?


  Metabolism is the sum of all the reactions in a cell or the body.
• The energy transferred by respiration in cells is used by the organism for the continual enzyme controlled processes of metabolism that synthesise new molecules.
• Metabolism includes:

  • conversion of glucose to starch, glycogen and cellulose

  • the formation of lipid molecules from a molecule of glycerol and three molecules of fatty acids

  • the use of glucose and nitrate ions to form amino acids which in turn are used to synthesise proteins

  • respiration

  • breakdown of excess proteins to form urea for excretion.