YEAR 2 PHYSIOLOGY

The science of how humans’ function in an integrated way and is the basis for many biological and clinical sciences

The branch of the biological sciences that is concerned with the way that the body responds to exercise and training

• Maintenance of a constant and normal internal environment - All variables of physiological mechanisms must operate within a narrow range of values

• Physiological variable (HR) is unchanging but not necessarily normal, plateau on graph • Balance between demands placed on body and the body’s response to those demands • Eg; HR, Body temp, Arterial BP

fluctuates

stays constant due to baroreflex responses and kidney function

• protein breakdown and synthesis • energy production • maintenance of stored nutrients

• pulmonary and circulatory systems - replenish oxygen and remove carbon dioxide

detects change in a variable

asses input and initiates the response

changes internal environment back to normal

• Acts to reduce an effect. When a change occurs in a system it opposes that change and restores the controlled variable back to its usual value • Eg; respiratory systems control of CO2 conc in extracellular fluid 1. Increase in extracellular CO2 triggers a receptor 2. Sends info to respiratory control centre 3. Respiratory muscles are activated to increase breathing 4. CO2 conc returns to normal Most control systems work via negative feedback

• Acts to increase an effect. When a change occurs, it becomes amplified • Eg; childbirth 1. Initiation of childbirth stimulates receptors in cervix and sends message to brain to release oxytocin from pituitary gland 2. Oxytocin promotes increased uterine contractions

sensitivity of the response • Degree to which a control system maintains homeostasis • Pulmonary and cardiovascular systems have large gains (thus more capable of maintaining homeostasis)

• Exercise disrupts homeostasis by changes in pH, PO2, PCO2 and temperature in cells • Inability to maintain steady state = fatigue and end of exercise

o Changes in structure and function of cell or organ system o Results in improved ability to maintain homeostasis o Many adaptive changes occur within cells

o Adaptation to environmental stresses (e.g. heat or hypoxic stress) o Results in improved function of existing homeostatic system

process in which a low to moderate dose of a potentially harmful stress (for example a chemical agent or environmental stress) results in a beneficial adaptive response on the cell or organ system.

-communication between cells using chemical messengers -coordinates cellular activities -important for maintaining homeostasis five different cell signalling pathways exist in cells

Chemical messengers inside cell triggers response

chemical messengers passed between 2 CONNECTED cells

chemical messengers acts on that same cell

chemical messengers acts on nearby cells

chemical messengers (that is hormones) released into blood. (affects cells with specific receptor to the hormone)