homeostasis, adaptation and fitness testing- week 1 Flashcards
what is homeostasis?
fundamental principle of body function
maintenance of constant and normal internal environment
what is steady state?
balance between demands placed on the body and the body’s responses to those demands
e.g. HR, body temp
explain changes in arterial blood pressure at rest ? (3)
arterial BP oscillates
BP mean stays constant
stretch receptors in the aorta signal to brain to change BP depending on the stretch
what is an example of steady state ?
core body temperature
what are the intracellular control systems ?
protein breakdown
energy production
maintenance of stored nutrients
why is a biological control system ?
series of interconnected components that maintain a physical or chemical parameter at a near constant value
what are the components of biological control systems ? (3)
sensor receptor
control centre
effector
where is the control centre usually located ?
brainstem
what is role of sensor/receptor?
detects change in environment
what is role of control centre ?
assesses input and initiates response
what is role of effector ?
changes internal environment back to normal
what type of feedback reverses initial disturbance in homeostasis ?
negative
what type of feedback increases the original stimulus ?
positive feedback
give example of negative feedback in homeostasis (5)
control of CO2 concentration in extracellular fluid
- detects increase in CO2
- sends info to respiratory control centre
- respiratory muscles activated to increase breathing
- CO2 concentration returns to normal
give example of positive feedback in homeostasis
childbirth stimulates receptors in cervix
sends message to brain to release oxytocin from pituitary gland
oxytocin promotes increase uterine contractions
what is gain (sensitivity of response)?
the degree to which control system maintains homeostasis
how does exercise change homeostatic control ?
changes pH, PCO2 and temperature in cells
if unable to maintain steady state = fatigue
what is adaptation in relation to homeostasis?
improved ability to maintain homeostasis
change in structure and function pf cells/organ
what is acclimation ?
adaptation to environmental stresses
e.g. heat or hypoxic stress
what is hormesis?
low to moderate dose of stress can result in a beneficial adaptive response on the cell/organ system
regular exercise is required to adapt
what is intracrine signalling?
chemical messengers (CM) triggers response
what is juxtacrine signalling ?
CM passed between 2 connected cells
what is autocrine signalling ?
CM acts on the same cell
hat is paracrine signalling ?
CM acts on nearby cells
what is endocrine signalling ?
CMs (hormones) related into blood
what is a reflex arc ? (3)
when receptors detect change in the conditions of the body
send afferent info to the brain
efferent info is sent from brain centre to nullify the variation
how is temperature controlled in homeostasis ? (5)
temperature is at set point
thermoreceptors send afferent info to hypothalamic brain centre
this detects change in temp
effector response sent to tissues and organs
skin blood vessels, sweat glands and skeletal muscle responds
give examples of how negative feedback is used in homeostasis
control of body temp
control of BP
resting HR
give an example on how positive feedback is sued in homeostasis
blood clotting after we cut ourself
what is meant by feed forward ?
physiological responses in anticipation of a change in variable
what is meant by VO2 max ?
maximal rate of O2 consumed
if a person has a high VO2 max ….
the greater the ability to sustain work st high intensity fo rlong time
what is the primary indicator that someone hit their VO2 max ?
plateau in O2 consumption even when work rate increase
what are secondary indicators that show VO2 max ? (4)
reached age predicted HR
blood lactate 8mmol/L or higher
RER - respiratory exchange ratio of 1.15 or higher
what is anaerobic capacity ?
ability to produce, tolerate and sustain maximal/supramaximal work rates through anaerobic energy production
