Exercise And Feedback Mechanisms 7.11-7.16 Flashcards
What is homeostasis?
The mainetanance of a stable internal environment using control systems
What happens if body temperature becomes too high?
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
What types of things does homeostasis control?
Temperature - vital for enzyme function
Blood glucose concentration - falls after exercise - monitored by pancreas
Water - monitored by kidneys
What is negative feedback
Where a change from a set point in one direction leads to a counteractive change in the opposite direction, returning to the set point
How does negative feedback work in homeostasis?
Receptors detect when level is too high or low
Communicated by nervous/hormonal system to effectors
Effectors counteract the change restoring normal level
What is positive feedback?
Where a change from a set point in one direction leads to further change in the same direction
How does positive feedback work?
Rapidly activates something
Eg. Platelets become activated and release a chemical that triggers more platelets
Why is a positive feedback mechanism not part of homeostasis?
Doesn’t keep your internal environment stable
What is thermoregulation?
Thermoregulation is a process that allows your body to maintain its core internal temperature
Describe mechanisms used to reduce body temperature x3:
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
Describe mechanisms used to increase body temperature x5:
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
What part of the brain regulates body temperature?
The hypothalamus
How does the hypothalamus control body temperature?
- Thermoreceprors send nerve impulses along sensory neurones to the hypothalamus
- Hypothalamus sends impulses along motor neurones to effectors
What are transciption factors?
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
What affects the activity of transcription factors?
Hormones
Describe steroid and thyroid hormones
Work inside cells by crossing cell membrane, entering the nucleus and binding to transcription factors
Describe what happens with the thyroid hormone in regulation of body temperature
- 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
Why can steroid and thyroid hormones cross the cell membrane?
They are lipid-soluble
Describe protein hormones:
Cannot cross the cell as they are not lipid soluble, so work from cell membrane
How do protein hormones work?
- 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
For analysis and data interpretation questions om exercise and health, see page 170-171
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Describe keyhole surgery:
Surgeons make a small incision into patient and insert a video camera and specialised medical instrunments through the incision into the body
Advantages of keyhole surgery:
- 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
What ligament is commonly treated with keyhole surgery + where are they found?
Cruciate ligaments - found in the middle of the knee, connecting thigh bone to lower leg bone
