Maintaining the Internal Environment

Key Issues

Titles

Chapters

• Also temperature receptors in the skin send impulses to the centre giving information about skin temperature
• Body temperature is monitored and controlled by the thermoregulatory centre in the brain
• Controlling Fertility
• Diabetes is a disease in which a person's blood glucose concentration may rise to a fatally high level because the pancreas does not produce enough of the hormone insulin
• Diabetes may be treated by careful attention to diet and by injecting insulin into the body
• explain how one way in which insulin reduces blood sugar levels is by converting excess blood glucose to glycogen in the liver
• explain that people deficient in insulin suffer from diabetes, where there is fluctuation in blood sugar levels
• explain that the dosage of insulin depends upon diet and activity
• explain the term homeostasis and how, in blood sugar regulation, it is achieved by negative feedback mechanisms
• Homeostasis
• Hormones
• Hormones are secreted by glands and are transported to their target organs by the bloodstream
• Hormones regulate the functions of many organs and cells
• If the core body temperature is too high blood vessels supplying the skin capillaries dilate so that more blood flows through the capillaries and more heat is lost
• If the core body temperature is too low blood vessels supplying the skin capillaries constrict to reduce the flow of blood through the capillaries muscles may 'shiver' - their contraction needs respiration which releases some energy as heat
• Information from receptors passes along cells (neurones) in nerves to the brain
• Internal Conditions
• Internal conditions which are controlled include: blood sugar levels - to provide the cells with a constant supply of energy
• Internal conditions which are controlled include: temperature - to maintain the temperature at which enzymes work best
• Internal conditions which are controlled include: the ion content of the body - ions are lost via the skin when we sweat and excess ions are lost via the kidneys in the urine
• Internal conditions which are controlled include: the water content of the body - water leaves the body via the lungs when we breathe out and via the skin when we sweat, and excess water is lost via the kidneys in the urine
• Many processes within the body are coordinated by chemical substances called hormones
• NERVOUS SYSTEM
• Neurones and Reflex Actions
• Organs and Cells
• recall that treatment of diabetes is controlled by diet or insulin injection
• Receptors
• Receptors detect stimuli which include light, sound, changes in position, chemicals, touch, pressure, pain and temperature
• Reflex actions are automatic and rapid
• Reflex actions often involve sensory, relay and motor neurones
• Removal of carbon dioxide by the lungs
• Removal of urea by the kidneys
• Several hormones are involved in the menstrual cycle of a woman
• state that the pancreas produces a hormone called insulin that controls levels of blood sugar
• state the function of insulin
• Structure of a nephron
• sweat glands release more sweat which cools the body as it evaporates
• Sweating and shivering - maintenance of body temperature
• Sweating helps to cool the body. More water is lost when it is hot, and more water has to be taken as drink or in food to balance this loss
• The blood glucose concentration of the body is monitored and controlled by the pancreas
• The Body's Waste Products
• The brain coordinates the response
• The harmful effects of solvents, alcohol and tobacco
• The Menstrual Cycle
• the monthly release of an egg from a woman's ovaries and the changes in the thickness of the lining of her womb are controlled by hormones secreted by the pituitary gland and by the ovaries
• The Nervous System
• The nervous system enables humans to react to their surroundings and coordinate their behaviour
• The pancreas produces the hormone insulin which allows glucose to move from the blood into the cells
• The role of ADH in regulating water content of blood
• The role of motor neurones in simple reflex actions
• The role of receptors in simple reflex actions
• The role of relay neurones in simple reflex actions
• The role of sensory neurones in simple reflex actions
• The role of synapses and effectors in simple reflex actions
• The role of the mucous membrane in defence against infection
• The roles of skin, stomach acid and blood in defence against infection
• the thermoregulatory centre in the brain has receptors sensitive to the temperature of blood flowing through the brain
• The use and misuse of drugs - antibiotics, pain killers, stimulants and sedatives
• The uses of hormones in controlling fertility include giving FSH as a 'fertility drug' to a woman whose own level of FSH is too low to stimulate eggs to mature
• The uses of hormones in controlling fertility include giving oral contraceptives which contain hormones to inhibit FSH production so that no eggs mature
• Those hormones involved in promoting the release of an egg include FSH which is secreted by the pituitary gland and causes eggs to mature in the ovaries, and also stimulates the ovaries to produce hormones including oestrogen
• Those hormones involved in promoting the release of an egg include Oestrogen which is secreted by the ovaries and inhibits the further production of FHS as well as stimulating the pituitary gland to produce a hormone called LH
• Ultrafiltration in Bowman's capsule and reabsorption
• Vasodilatation and vasoconstriction in temperature regulation
• Water and Ions