Exercise And Feedback Mechanisms 7.11-7.16

Question 1

What is homeostasis?

Answer 1

The mainetanance of a stable internal environment using control systems

Question 2

What happens if body temperature becomes too high?

Answer 2

Enzymes become denatured - enzymes molecules vibrate too much which breaks hydrogen bonds holding them together so shape of aftive site is changed so no longer a catalyst = metabloic reactions are less efficient

Question 3

What types of things does homeostasis control?

Answer 3

Temperature - vital for enzyme function
Blood glucose concentration - falls after exercise - monitored by pancreas
Water - monitored by kidneys

Question 4

What is negative feedback

Answer 4

Where a change from a set point in one direction leads to a counteractive change in the opposite direction, returning to the set point

Question 5

How does negative feedback work in homeostasis?

Answer 5

Receptors detect when level is too high or low
Communicated by nervous/hormonal system to effectors
Effectors counteract the change restoring normal level

Question 6

What is positive feedback?

Answer 6

Where a change from a set point in one direction leads to further change in the same direction

Question 7

How does positive feedback work?

Answer 7

Rapidly activates something

Eg. Platelets become activated and release a chemical that triggers more platelets

Question 8

Why is a positive feedback mechanism not part of homeostasis?

Answer 8

Doesn’t keep your internal environment stable

Question 9

What is thermoregulation?

Answer 9

Thermoregulation is a process that allows your body to maintain its core internal temperature

Question 10

Describe mechanisms used to reduce body temperature x3:

Answer 10

Sweating: sweat secreted from sweat glands, water evaporates from surface of skin removing heat

Hairs lie flat: erector pili muscles relax so hairs lie flat, less air is trapped so skin is less insulated and heat can be lost more easily

Vasodilation: arterioles near the surface of the skin dilate so more blood flows through the capillaries in surface layer of dermis, more heat is lost by radiation and temp lowered

Question 11

Describe mechanisms used to increase body temperature x5:

Answer 11

Shivering: muscles contract in spasms so more heat produced from increased respiration

Less sweat: less secreted so less heat lost

Hairs stand up: erector pili muscles contract which traps more air so prevents heat loss

Vasoconstriciton: arterioles near surface of skin constrict so less blood through capillaries in surface layers of dermis so less heat loss

Hormones: adrenaline and thyroxine release which increases metablosim so more heat produced

Question 12

What part of the brain regulates body temperature?

Answer 12

The hypothalamus

Question 13

How does the hypothalamus control body temperature?

Answer 13

• Thermoreceprors send nerve impulses along sensory neurones to the hypothalamus
• Hypothalamus sends impulses along motor neurones to effectors

Question 14

What are transciption factors?

Answer 14

Proteins that control the trasncription of genes by binding to DNA sites near the start of genes and either increase (activator) or decrease (repressor) the rate of transcription

Question 15

What affects the activity of transcription factors?

Answer 15

Hormones

Question 16

Describe steroid and thyroid hormones

Answer 16

Work inside cells by crossing cell membrane, entering the nucleus and binding to transcription factors

Question 17

Describe what happens with the thyroid hormone in regulation of body temperature

Answer 17

• at normal body temp, thyroid hormone receptor binds to DNA at start of gene
• decreases the transcription of a gene coding for a protein that increases metabolic rate
• at cold temp, throxine released which binds to thyroid hormone receptor causing it to act as an activator
• trasncription rate increases, more protein produced, increased metabkoc rste, increased body temperature

Question 18

Why can steroid and thyroid hormones cross the cell membrane?

Answer 18

They are lipid-soluble

Question 19

Describe protein hormones:

Answer 19

Cannot cross the cell as they are not lipid soluble, so work from cell membrane

Question 20

How do protein hormones work?

Answer 20

• bind to receptors in cell membrane
• activate messenger molecules in cytoplasm of the cell
• messengers activate enzymes callaed protein kinases which trigger a cascade inside cell
• during cascade transcription factors are activated which effects trasncription of genes

Question 21

For analysis and data interpretation questions om exercise and health, see page 170-171

Answer 21

:)

Question 22

Describe keyhole surgery:

Answer 22

Surgeons make a small incision into patient and insert a video camera and specialised medical instrunments through the incision into the body

Question 23

Advantages of keyhole surgery:

Answer 23

• patient loses less blood and less scarring
• recovery time is quick due to less pain and less damage to body
• hospital time is shorter so quicker return time to normal activities

Question 24

What ligament is commonly treated with keyhole surgery + where are they found?

Answer 24

Cruciate ligaments - found in the middle of the knee, connecting thigh bone to lower leg bone

Question 25

What can be done to damaged cruciate ligaments?

Answer 25

It can be removed and replaced with a graft - likely to be a tendon in the patients leg

Question 26

What do prostheses do?

Answer 26

Replace whole limbs eg. artificial leg

Replace part of limbs eg. artificial hip joints

Question 27

How do lectronic prstheses work?

Answer 27

They pick up info sent from nervous system

Question 28

How can a damaged knee joint be replaced by prosthetic joints?

Answer 28

• metal device inserted into knee to replace damaged cartilage and bone
• cushioning in new joint helpe to reduce impact on knee

Question 29

Name three types of perfromance-enhancing drugs:

Answer 29

• anabolic steroids
• stimulants
• narcotic analgesics

Question 30

What are anabolic steroids?

Answer 30

Deugs that increase strength, speed, stamina and agression by increasing muscle size

Question 31

What are stimulants?

Answer 31

Drugs that speed up reactions, reduce fatigue and increase agression

Question 32

What are narcotic analgesics?

Answer 32

Drugs that reduce pain so that injuries don’t affect performance

Question 33

What are absolutists?

Answer 33

People that believe performance enhancing drugs should be banned from ALL sports as it is morally wrong

Question 34

What are rationalists?

Answer 34

People that believe performance enhancing drugs can be justified in certain circumstances

Question 35

What are the arguments AGAINST performance-enhancing drugs?

Answer 35

• some are illegal
• unfair advantage
• serious health risks eg. high blood pressure
• athletes not fully informed of risks

Question 36

What are the arguments FOR performance-enhancing drugs?

Answer 36

• athletes have right to make own decision
• drug free sports isn’t fair anyway, access to different training facilities, coaches, equipment
• drugs allow for a higher level of performance