Exercise and feedback mechanisms (7.11-7.16)

Question 1

Homeostasis

Answer 1

Maintenance of a stable internal environment

Question 2

Hypothalamus

Answer 2

The region of the brain located near the pituitary gland that is involved in homeostatic control including thermoregulation

Question 3

Negative feedback

Answer 3

The process where effectors counteract the change that has occurred to bring the level back to its normal value

Question 4

Positive feedback

Answer 4

A process which causes an increase in change away from the normal level

Question 5

Thermoregulation

Answer 5

The homeostatic process of maintaining a constant body temperature.

Question 6

Vasoconstriction

Answer 6

​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.

Question 7

Vasodilation

Answer 7

​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.

Question 8

Receptors

Answer 8

Detect deviation from the norm

Question 9

Effectors

Answer 9

Muscles or glands that are turned on by receptors to bring the condition back to the norm value

Question 10

Mechanisms which reduce body temp

Answer 10

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

Question 11

Mechanisms which increase body temp

Answer 11

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

Question 12

Stages of thermoregulation

Answer 12

• 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

Question 13

Narrow limits of negative feedback

Answer 13

Blood temp
Glucose conc in blood
Blood PH
Water potential of blood

Question 14

Natural killer cells

Answer 14

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

Question 15

Disadvantages of vigorous exercise

Answer 15

Activity of natural killer cells, T and B lymphocytes and phagocytes decreases

Question 16

Knee problems

Answer 16

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

Question 17

Benefits of keyhole surgery

Answer 17

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

Question 18

Prosthetic knee joint

Answer 18

Can replace damaged cartilage and bone

Smooth knee joint with cushioning to reduce impact on knees

Question 19

Advantages of physical activity

Answer 19

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

Question 20

Anabolic steroids

Answer 20

Increase strength and stamina by increasing muscle size

Question 21

Stimulants

Answer 21

Speed up reactions to reduce fatigue

Question 22

Narcotic analgesis

Answer 22

Reduce pain so injuries don’t affect performance

Question 23

Transcription factors

Answer 23

Bind to DNA sites near start of genes and increase/decrease rate of transcription
Activators and repressors