Session 1 Homeostasis,PH,temp,body fluids Flashcards
Define the word ‘homeostasis’ with respect to water, temperature and pH balance
Homeostasis is the dynamic balance that is maintained in our body tissues and organs. It is dynamic because it is constantly adjusting any changes detected by our body systems. Our body systems monitor and respond to any changes around the set point. This keeps our temperature, water balance and pH at just the right level and within a normal range, for our physiology to work well, ensuring all of our cells, body tissues and organs can function optimally.
Explain the concepts behind positive and negative feedback loops
Feedback loops are biological mechanism whereby homeostasis is maintained. This occurs when the product or output of an event or reaction changes the response to that reaction.
Positive feedback occurs to increase the change or to output：the result is amplified to make it occur more quickly.
Negative feedback occurs to decrease the change: result is reduced
Importance of feedback loop
When a body system detects a change that takes our body system out of balance, our system responds to the feedback to maintain that balance . Homeostasis is occurring to keep the environment in our tissues and organs optimal for cell function.
State a positive feedback loop
Blood clotting
Example of negative feedback loop
Temperature and osmoregulation
Four basic parts of negative feedback loop(temperature regulation)
Stimulus: when the body temperature exceed 37 degrees
Sensors: nerve cells with endings in the skin and brain
Control: temperature regulatory sensor in the brain
Effector: sweat glands through out the body
State the normal range for core body temperature.
36.5 -37.5
State the normal range for pH in tissues including blood
7.35-7.45
Explain the importance of acid-base balance for normal human physiology
Acid- base balance is the level of acids and bases in the blood at witch the body functions best.
(a great importance for enzyme to work efficiently)
Recall the mechanisms that regulate pH
Acid-base buffering system(lungs and kidneys ) are in dynamic equilibrium with the same hydrogen ion concentration in the blood, maintaining homeostasis.
Lungs: remove CO2. Change the rate and depth of ventilation.
Kidneys:reabsorb HCO3- from the urine and secrete H+ into the urine. Adjusting the amounts reabsorbed and secreted.
Recall the mechanism that regulate body temperature.
Negative feed back loop
Too hot: vasodilation, sweating, hairs lie flat
Too cold: vasoconstriction, shivering, hairs stand up
Compare and contrast water balance in males and females, and in early life and in old populations
Male: 60% of body weight
Female: 55% of body weight
Infants:70%
Children:65%
Adult:60%
Old:50%
Recall the percentage of water in a standard 70kg male
60%(42liters)
State the body compartments where fluids accumulate, describe the process of odema
Body water:
Intracellular2/3
Extracellular1/3
Interstitial 3/4
Plasma1/4
Because of the increased capillary fluid pressure
or decreased plasma oncotic pressure
or increased capillary permeability
or increased interstitial fluid colloid osmotic pressure,
the fluid builds up in the interstitium of surrounding tissues and cavities, leading to swelling.
Outline the differences between dehydration and water toxicity
Water toxicity: the concentration of solutes is high inside cells as compared to the extra cellular space. The amount of intracellular water increases, causing the cell to swell.
Dehydration: this occurs when you use or lose more fluid than you take in, and your body doesn’t have enough water and other fluids to carry out its normal functions.
