Body Coordination

Menopause is when the ovaries stop producing ova, usually in women aged 45 to 55 years, and hormone replacement therapy (HRT) replaces the decreasing hormones p. 143.

7.1 Human Endocrine System

The endocrine system is one of the systems in the body that coordinates body functions that involve chemical substances p. 144. When a snake is seen, the endocrine gland secretes hormones that increase the heartbeat, rate of breathing, blood pressure, blood glucose level and rate of metabolism, so you can run away p. 144. Hormone is a type of chemical substance secreted by special glands known as the endocrine glands p. 144. These are ductless glands, because the hormone is secreted directly into the blood circulatory system to be distributed to the whole body p. 144. A type of hormone can have more than one target organ p. 144. Hormones are secreted in small quantities, give a slow response with a prolonged effect, and act on target organs that have a suitable receptor p. 145.

The pituitary gland is located below the cerebrum and is known as the master gland because it produces hormones that control other endocrine glands p. 146. Women have a pair of ovaries in the pelvic space p. 146. The thyroid gland is in front of the trachea, the adrenal glands are above the kidneys, the pancreas is at the back of the stomach, and men have a pair of testes protected by a scrotum p. 147.

The pituitary gland secretes antidiuretic hormone (ADH), which controls the quantity of water reabsorbed by the kidneys, and growth hormone (GH), which stimulates growth in children p. 148. Thyroxine from the thyroid gland controls the rate of metabolism and the physical and mental development in children p. 148. Adrenaline prepares the body for an emergency by increasing the rate of metabolism, heartbeat and blood glucose level and dilating the pupil p. 148. Insulin from the pancreas controls the blood glucose level by converting excess glucose into glycogen to be stored in the liver p. 148. Oestrogen controls female secondary sexual characteristics and prepares the uterus, progesterone maintains the thickness of the uterine wall, and testosterone controls male secondary sexual characteristics and stimulates sperm production p. 148.

Over secretion and under secretion of hormone by the endocrine glands cause hormonal imbalance that leads to diseases, which could be due to an unhealthy lifestyle or exposure to dangerous rays p. 149. Thyroxine deficiency causes a low rate of metabolism, cretinism in children, myxedema in adults and goitre p. 150. Excessive thyroxine causes a high rate of metabolism, a tendency to become thin and protruding eyeballs p. 150. Testosterone deficiency causes delay in reaching puberty and low sperm count, and progesterone deficiency causes menstrual problems and miscarriage p. 150. Growth hormone deficiency causes dwarfism, and excessive growth hormone causes acromegaly (gigantism) p. 151. ADH deficiency causes excessive production of urine and diabetes insipidus p. 151. Insulin deficiency causes an increase in blood glucose level and diabetes mellitus, while excessive insulin causes hypoglycaemia p. 151.

7.2 Disruptions to Body Coordination

Drugs are chemical substances that can disrupt the neuron function by delaying the impulse transmission in the neuron, and uncontrolled drugs cause addiction p. 152. Morphine and steroid need to be taken under a doctor’s supervision p. 153. Depressants such as barbiturates and alcohol slow down impulse transmission, while stimulants such as amphetamine and methamphetamine speed it up p. 153. Inhalants are inhaled and damage the brain, lungs and kidneys, and hallucinogens such as ketamine and LSD change the path of impulses in the brain p. 153.

Addicts experience withdrawal symptoms such as shivering, nausea, anxiety and depression if they cease to take drugs p. 154. The factors that cause drug abuse are curiosity, peer influence, seeking pleasure and the desire to overcome sadness or to forget a problem p. 154. Most drugs influence body coordination through the nervous system, and alcohol slows the flow of nerve impulses p. 155. Excessive alcohol affects the cerebrum and causes unclear speech p. 155. Psychoactive chemical substances in drugs and ethanol in alcohol block impulse transmission between the afferent neurons and interneurons, causing slow reflex action p. 155. Drugs and alcohol cause weak muscle coordination, staggering and loss of balance p. 155.

Continuous consumption of alcoholic drinks and drug abuse can cause liver cirrhosis, where the liver undergoes chronic damage, scarring and hardening p. 156. Alcohol causes the stomach to produce more acid than normal, which can cause stomach ulcer p. 157. Amphetamine can make a user violent and aggressive, and marijuana can cause hallucination and paranoia p. 157.

7.3 Healthy Mind

The mind is the brain function that relates to our consciousness, personality, thinking, memory, judgement, intellect and emotion p. 158. A healthy mind can reason and make logical judgements before an action is taken, and shows positive behaviour, independence, care for others and responsibility p. 158. Hormonal imbalance before or during the menstrual cycle and during menopause can cause headache, depression and irritability p. 159. Excessive alcohol disrupts the ability to think, reason and control emotions, and drug abuse can cause serious mental problems p. 159. Mental stress can affect a healthy mind, and brain injury can cause a person to lose memory or intellectual ability p. 159. Each individual must have a healthy mind because each has a responsibility towards family, place of work, society and country p. 160.