Exercise and feedback mechanisms (7.11-7.16) Flashcards
Homeostasis
Maintenance of a stable internal environment
Hypothalamus
The region of the brain located near the pituitary gland that is involved in homeostatic control including thermoregulation
Negative feedback
The process where effectors counteract the change that has occurred to bring the level back to its normal value
Positive feedback
A process which causes an increase in change away from the normal level
Thermoregulation
The homeostatic process of maintaining a constant body temperature.
Vasoconstriction
The narrowing of the blood vessels that supply capillaries at the skin surface to decrease heat loss to the environment which acts to maintain the core body temperature by keeping warm blood in central blood vessels.
Vasodilation
The widening of the blood vessels that supply capillaries at the skin surface to increase heat loss to the environment which results in a decrease in body temperature.
Receptors
Detect deviation from the norm
Effectors
Muscles or glands that are turned on by receptors to bring the condition back to the norm value
Mechanisms which reduce body temp
Sweating - Sweat is secret from sweat glands and water evaporates to take heat away
Hairs lie flat - Erector pili muscles relax so less air is trapped and less insulated
Vasodilation - Arterioles near surface dilate so more blood flows to capillaries on surface to lose heat via radiation
Mechanisms which increase body temp
Shivering - Muscles contact in spasms so more heat is produced from increased respiration
Less sweat - Reduced heat loss from evaporation
Hairs stand up - Erector pili muscles contract to trap more air and insulate
Vasoconstriction - Arterioles near surface constrict, so less blood flows to capillaries
Hormones - Adrenaline and thyroxine released which increase metabolism so more heat is produced
Stages of thermoregulation
- Thermoreceptors detect temp is too high
- Impulse sent to hypothalamus
- Hypothalamus sends impulse to effectors
- Mechanisms for decreasing temp (sweating, vasodilation) occur
- More heat is lost and returns back to normal body temp
Narrow limits of negative feedback
Blood temp
Glucose conc in blood
Blood PH
Water potential of blood
Natural killer cells
Moderate exercise increases number in the body and offer non specific protection against pathogens
Release the protein perforin which makes pores in the target cell membrane to allow proteases to enter
Disadvantages of vigorous exercise
Activity of natural killer cells, T and B lymphocytes and phagocytes decreases
Knee problems
Articular cartilage covering the surface of the bones wears away so bones grind
Patellar tendonitis occurs when patella doesn’t glide smoothly across the femur due to damage of the article cartilage on the femur
Bursea fluid sacs can swell up with extra fluid and may posh against other tissues in the joint
Damage to ligaments
Benefits of keyhole surgery
Small incision is made so less blood is lost and there is less scarring
There is less damage to patient recovers quicker and can leave hospital sooner
Prosthetic knee joint
Can replace damaged cartilage and bone
Smooth knee joint with cushioning to reduce impact on knees
Advantages of physical activity
Increasing arterial vasodilation lowers blood pressure, reducing risk of CVD
Increases HDLs which transport cholesterol to the liver
Blood glucose regulation improves due to increased sensitivity of muscle cells to insulin
Increases bone density
Anabolic steroids
Increase strength and stamina by increasing muscle size
Stimulants
Speed up reactions to reduce fatigue
Narcotic analgesis
Reduce pain so injuries don’t affect performance
Transcription factors
Bind to DNA sites near start of genes and increase/decrease rate of transcription
Activators and repressors
