Homeostasis

Name: __________________ Topic: Homeostasis Concepts Summary Notes Nan Hua High School Biology 1 LO: Define homeostasis as the maintenance of a constant internal environment Homeostasis is the maintenance of a constant internal environment. Eg. Regulation of blood glucose level (insulin and glucagon) Regulation of water potential in blood plasma (ADH) Regulation of body temperature LO: Explain the basic principles of homeostasis in terms of stimulus resulting from a change in the internal environment, a corrective mechanism and negative feedback ● A stimulus is a change from the normal condition of the internal environment. ● Receptors detect these changes in the internal environment and are stimulated. Nerve impulses generated from the receptors are transmitted to the control centre or regulator, triggering an appropriate response (corrective mechanism) to restore internal environment back to the norm. ● A response counteracts the changes and returns the internal environment back to the norm. ● This response to return the internal environment to its normal levels is known as negative feedback. Negative feedback is a set of corrective mechanism triggered due to a change in the internal environment detected by receptor to bring about the reverse effect of the stimulus to restore normal conditions. Examples; ● Regulation of blood glucose level Stimulus – Change in the blood glucose level Receptor – Islets of Langerhans of the pancreas Corrective mechanism – Secretion of more insulin/ glucagon

Name: __________________ Topic: Homeostasis Concepts Summary Notes Nan Hua High School Biology 2 ● Regulation of water potential in blood plasma Stimulus – Change in water potential in blood plasma Receptor – Hypothalamus Corrective mechanism –Secretion of more or less anti-diuretic hormone (ADH) from pituitary gland to reabsorb more/less water from collecting duct into the blood capillaries. LO: Identify on a diagram of the skin: hairs, sweat glands, temperature receptors, blood vessels and fatty tissue Layers of skin Layers of cells Type of cells/ structure Function of cells Epidermis Cornified layer • Flattened and dead keratinised cells • Protects body from water loss • Protects body from invasion by microbes • Protects body from mechanical, thermal & chemical damage Granular layer • New cells undergo cell division Malpighian layer • Pigment cells • To replace dead cells from the cornified layer

Name: __________________ Topic: Ho