Homeostasis

• feedback loop

  a circular process in which a system's output serves as input to that same system
• Pancreas

  An organs in the abdominal cavity with two roles. The first is an exocrine role: to produce digestive enzymes and bicarbonate, which are delivered to the small intestine via the pancreatic duct. The second is an endocrine role: to secrete insulin and glucagon into the bloodstream to help regulate blood glucose levels.
• Nervous system

  the body's speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems
• Hormones

  chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues
• endocrine system


  Consists of glands that control many of the body's activities by producing hormones.
• Homeostasis

  relatively constant internal physical and chemical conditions that organisms maintain
• Receptor

  Detects a change or stimulus
• Control centre

  Located in the brain and compares change to the set point
• Effectors

  A bodily structure such as organs, glands or muscle that direct an appropriate response to correct the change
• Why is homeostasis so important to cells?

  Some cells only use glucose as energy, so a constant and sufficient supply of glucose is required for them to function properly.
• Examples of homeostatic control systems in the body

  body temperature, blood pressure, blood glucose, volume of body water, ion concentrations
• How does the endocrine system differ from the nervous system?

  The endocrine system uses chemical messengers, while the nervous system uses electrical signals
• Parasympathetic Nervous System

  The medulla communicates with various organs and glands through the vagus nerve to conserve energy for the resumption of digestion, rest etc.
• Sympathetic Nervous System

  Thoracic and lumbar regions of the spinal cord control the body's response to an emergency, the "fight" or "flight" response, which speeds up heart rate and slows digestion
• Central nervous system

  brain and spinal cord acts as the main control centre in most systems
• Peripheral nervous system

  nerves which travel to and from the central nervous system
• Autonomic nervous system

  involved in automatic/involuntary and subconscious responses
• Somatic nervous system

  All voluntary actions
• Glands

  a series of small organs that release specific hormones into the bloodstream
• Pituitary gland

  the master gland in the brain produces hormones that control other endocrine glands
• Nervous system traits

  -fast response

  -Short-lived effect

  -brain, spinal cord
• Endocrine system traits

  -Slower

  -longer effects

  -glands and hormones
• Insulin

  Type of hormone released by Beta cells when they detect high blood glucose levels. Signals the liver to convert glucose into glycogen and stimulates body cells to uptake glucose for cellular respiration
• Glucagon

  Type of hormone released by alpha cells when they detect low blood glucose levels. Stimulates the liver to convert glycogen into glucose and release it in the bloodstream.
• Which organ needs the most glucose?

  The brain
• Where do the alpha and beta cells reside?

  in the Islet of Langerhans
• What type of sugar is glucose?

  Monosaccharide
• What type of sugar is sucrose?

  Disaccharide
• What does the body do when it needs to store carbohydrates?

  The body converts excess carbohydrates into glycogen and stores it in the liver and muscles. Or converts monosaccharides into polysaccharides.
• How is insulin released from beta cells?

  Exocytosis
• Why does insulin take a long time to work?

  Insulin takes 30 minutes to an hour for the insulin gene to be switched on and for the insulin protein to be made
• Glucogen synthase

  Enzyme catalysing the formation of glycogen polymers
• Glucogen phosphorylase

  Enzyme catalysing the breakdown of glycogen polymers back into glucose
• Gluconeogenesis

  New glucose is created using fats and amino acids
• Glycogenesis

  The formation of glycogen from glucose
• Glycogenolysis

  Splitting of glycogen into glucose
• Glycogen Synthase

  Catalyses the formation of glucose polymers
• Glycogen phosphorylase

  Catalyses the breakdown of glycogen polymers back into glucose
• Transduction

  Hormones outside of the cell regulate functions inside the cell to stimulate a cellular response