Communication is essential for the survival of organisms as they must detect and respond to changes in their internal and external environments
In multicellular organisms, changes necessary for survival are triggered by the nervous and endocrine systems
Cell signalling involves communication between cells through electrical signals carried by neurones or with the help of hormones
Neuronal cell signalling is faster and short term, while chemical signalling is slower and long term
Endocrine signalling can be used for long-distance signalling, carried by the circulatory system
Examples of signalling include paracrine signalling between cells in close proximity and autocrine signalling where a cell stimulates its own receptors
Homeostasis ensures a constant internal environment is maintained despite changes in the external environment
Achieved through negative feedback which counteracts changes in internal conditions
Elements needed for negative feedback pathway: sensory receptors to detect changes, effectors like muscles and glands for response
Positive feedback increases the original change in conditions, e.g., dilation of the cervix during childbirth
Ectotherms regulate body temperature with external sources, while endotherms maintain a constant body temperature
Endotherms use thermoreceptors to monitor core body temperature changes and coordinate responses through the hypothalamus
Actions taken by endotherms for temperature control include shivering, sweat production, hair position changes, and arteriole dilation/constriction
Excretion is essential for removing waste products produced during metabolism
Liver plays a crucial role in excretion by breaking down harmful substances and converting them into less harmful forms
Liver is involved in detoxification, breakdown of excess amino acids, and conversion of ammonia to urea
Kidneys excrete waste products like urea in the form of urine
Ultrafiltration in the kidneys involves the Glomerulus, Bowman’s Capsule, and selective reabsorption in the nephrons
Control of water potential in the blood involves negative feedback and the role of hormones like antidiuretic hormone (ADH)
ADH makes walls of DCT and collecting duct more permeable to water, increasing reabsorption to produce concentrated urine
Kidney failure can be caused by infections, high blood pressure, leading to toxic waste build-up and fluid accumulation
Treatment for kidney failure includes renal dialysis and kidney transplant
Dialysis can be haemodialysis or peritoneal dialysis, while kidney transplant is a long-term solution requiring a suitable donor
Patients may need to wait for a suitable donor with the same blood type and tissue type to minimize the risk of rejection
Immunosuppressants are still required by the patient to prevent rejection
In most cases, a family member is the donor due to the degree of similarity
Only one kidney is required for survival
Urine samples can be used for diagnostic tests such as pregnancy testing using monoclonal antibodies to detect human chorionic gonadotropin
Urine samples can also be used to test for the presence of anabolic steroids
Anabolic steroids are used to build muscle mass and are banned due to their dangerous side effects as well as to ensure fair competition among athletes
Detection of stimuli involves receptors which are specialized cells that convert one form of energy into another form
Pacinian corpuscles are pressure receptors found in the skin that convert mechanical energy into electrical energy
All action potentials have the same magnitude, and the brain interprets the strength of the stimulus based on the frequency of action potentials
Hormones are signaling molecules secreted by ductless endocrine glands that affect target cells with complementary receptors on their plasma membrane
Adrenal glands secrete adrenaline in response to danger, stress, or excitement, and the adrenal cortex produces mineralocorticoids and glucocorticoids
The pancreas functions in both an endocrine and exocrine way, with the Islets of Langerhans secreting insulin and glucagon directly into the blood
Blood glucose regulation is important to maintain essential processes such as brain cell respiration
Insulin secretion is controlled by beta cells through a series of actions involving adenyl cyclase and cAMP
Diabetes mellitus is a disease where the body cannot control blood glucose levels, with Type I being an autoimmune disease and Type II resulting from cells becoming less responsive to insulin
Genetically engineered bacteria can produce insulin for the treatment of diabetes