In this video you will be learning about: The Endocrine System, The Nervous System, Hormones, Receptors, and The hypothalamus and pituitary gland and their roles. How can the body parts communicate with each other to detect and counteract changes from the normal? By pathways in 2 interacting body systems. Endocrine System (Hormonal system). The endocrine system is made up of glands that secrete chemical hormones into blood and target tissues. Endocrine glands make hormones. These are chemicals that travel in the blood to cause an effect in other parts of the body – to maintain a balance. The Nervous System which is made up of the: central nervous system (CNS) or control centre (brain and spinal cord), peripheral nervous system (PNS) with branching nerves (neurons) covering the entire body. Our body knows how to respond in each environment due to receptors in our body. Receptors are cells that are on our skin and within our body to be able to detect change and send the message by our nerves to the brain. There are different receptors within our body and on the surface of our skin. Receptors depend on the body senses – sight, hearing, taste, smell and touch. Eyes – photoreceptors, light sensitive. Ears – mechanoreceptors, detects vibrations in sound. Tongue – chemoreceptors receptors (detect chemicals). Nose – chemoreceptors (detect chemicals). Skin – mechanoreceptors that are sensitive to touch and pressure. There are multiple receptors in the skin to detect external stimuli. For temperature there are thermoreceptors and for pain there are nociceptors. Most internal vital organs are protected by fluid and ultimately by the skin. Without the skin, our vital organs would be exposed to many harsh environments which they wouldn’t be able to cope. Our senses work together to maintain a stable internal environment despite external conditions. It is to protect our body’s vital organs and activities by keeping a constant internal environment. The nerves cells change their rate of impulses according to the temperature of the body. They communicate with a part of the brain called the hypothalamus. The hypothalamus is the control centre of homeostasis and is linked to the endocrine (hormonal) system by the pituitary gland. The pituitary gland releases hormones when signaled by the hypothalamus. Plants and other organisms without nervous systems secrete hormones to make changes based on their external environment. Plants will respond to changes in temperature sunlight, water and nutrients available in the environment. These are much slower than a nervous system response. The hormone is moved from cell to cell along the plant until it reaches the target area, however animals use their blood as a transport of hormones and therefore an animal’s hormonal responses are much faster. Hormones are released in glands in the body in response to the activity of tissues and organs. Some hormones are released into target areas by ducts; examples include salivary glands, milk glands and digestive glands. Some hormones are released directly into the blood to be transported to target cells. There are around 50 different types of hormones in the human body. Some glands and hormones are mentioned below. ADH – water concentration regulation, Prolactin – controls milk production and secretion, Growth hormone – stimulates growth and cell reproduction, Thyroxine – controls the regulation of the body’s metabolic Functions. The role of hormones is the control of the internal environment to maintain homeostasis by regulating the amounts and types of body chemicals. Hormones are chemical messengers which are secreted by glands in order to bring about (usually) relatively gradual changes in the body. For example, insulin is released by the pancreas to encourage the liver to absorb glucose from the blood (and then convert it to glycogen). Hormones allow the body to cope with stress, physical and emotional. Blood sugar, water and waste levels are other internal stimuli. Blood glucose levels are maintained by the hormone of insulin released by the pancreas. When there is insufficient insulin, blood sugar levels remain high, this results in diabetes. Anti-diuretic hormone (WATER regulation) (ADH or vasopressin) controls water reabsorption in the nephron. When levels of fluid in the blood drop, the hypothalamus causes the pituitary to release ADH. Aldosterone (SALT regulation) is a steroid hormone secreted by the adrenal gland. Its function is to regulate the transfer of sodium and potassium ions in the kidney. Aldosterone (SALT regulation) and the Anti-diuretic hormone (water reabsorption regulation) are two hormones that are vital to the body and you should know these for your course.