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level: Exercise 2

Questions and Answers List

level questions: Exercise 2

QuestionAnswer
H bandwhere only thick myosin filaments are found
I bandwhere only thin actin filaments are found
A bandwhere both actin and myosin are found actin and myosin overlap
M lineattachment for myosin filaments
Z lineattachment for actin filaments
properties of fast twitch fibrescontract quickly fewer capillaries fewer mitochondria large store of calcium ions in the sarcoplasmic reticulum large amounts of glycogen fatigues faster due to greater lactate formation white - little myoglobin
slow twitch fibrescontract slowly large network of capillaries lots of mitochondria small store of calcium ions in the sarcoplasmic reticulum fatigues slower due to less lactate formation red - lots of myoglobin
define negative feedbackthe product of a process that counteracts change to maintain an equilibrium around a normal level
define positive feedbacka process that causes an increase in change away from the normal level
homeostasismaintenance of a constant internal environment changes are detected by receptors controlled by negative feedback controls temp, salt, water and CO2
how does homeostasis maintain dynamic equilibrium during exercise?changes cardiac output changes breathing rate balances temp
why is homeostasis important in mammals?metabolic reactions are controlled by enzymes enzymes work best at a narrow range of pH and temp so it is important to maintain a steady environment
what is dynamic equilibrium?when the rate of the forward reaction is equal to the reverse reaction it is dynamic because the molecules react continuously it is in equilibrium because there is no overall net change
role of the hypothalamus in homeostasishas thermoreceptors which detect changes in blood temp stimulates effectors to decrease or increase the body temp
mechanisms of thermoregulation during exercisevasodilation of skin capillaries sweating hairs lay flat
what are the two methods of medical technology that allows those with injuries/disabilities to do sport?keyhole surgery prosthesis
keyhole surgerynon invasive uses fibre optics repairs damaged joints quickly recovery time is shorter cheaper than conventional methods
prosthesisartificial body part allows people to regain the appearance/function of a particular body part can be connected internally or externally
the effects of moderate exercise on the immune systemincreases the number and activity of natural killer cells found in the blood and lymph increases blood HDL and reduces LDL helps maintain a healthy weight reduces the risk of CHD, diabetes and some cancers improves mental wellbeing
the effects of vigorous exercise on the immune systemreduces number and activity of: natural killer cells, phagocytes, B cells, T helper cells, cytokines and antibodies
the effects of little exercise on the immune systemleads to obesity increased risk of CVD and diabetes immune system suppressed increased levels of LDL's
the effects of vigorous exercise on the joints/skeletal musclesdamage to muscle fibres articular cartilage can wear away the kneecap may stop gliding across the femur bursae can swell up with extra fluid damage to ligaments
why would athletes take testosterone?increases protein synthesis in muscle cells to increase the size and strength of the muscle testosterone is easily broken down so the chemically modified anabolic steroid nandrolone was made to overcome the problem urine tests to find the ratio of testosterone to epitestosterone
why would athletes take blood transfusions?increases the number of blood cells so more oxygen can be transported to the blood athletes can use their own blood or someone else's with the same blood type increased risk of blood clot, heart attack, stroke
why would athletes take EPO's?a peptide hormone naturally produced by the kidneys stimulates the formation of new red blood cells in the bone marrow increased risk of thrombosis when EPO levels are too high it is hard detecting EPO doping because EPO naturally occurs in the body however scientist have found a way to distinguish between synthetic and natural EPO
why would athletes take HGH?human growth hormone increases lean body mass and decreases fat mass blood test to distinguish between the natural and synthetic HGH
why would athletes take creatine?amino acid derived naturally found in meat and fish carried in the blood to tissues helps build lean muscle mass and reduce recovery time creatine is not banned from athletes use
examples of peptide hormonesEPO, insulin, human growth hormone
examples of steroid hormonestestosterone, estrogen, progesterone
what is a hormone?a chemical substance produced by the endocrine gland transported in the blood they alter the activity of tissues
how do peptide hormones reach their target cell?binds to receptors on the cell surface membrane this activates a second messenger the second messenger will activate the enzymes or transcription factors that will alter the function of the cell
how do steroid hormones reach their target cells?the hormone pass through the membrane via simple diffusion it binds to the receptors in the cell the hormone-receptor complex acts as a transcription factor switching enzyme synthesis on or off
what are transcription factors?proteins binds to specific base sequences of DNA stimulates or prevents the transcription of a gene
why can steroid hormones go across the membrane but peptide hormones can't?steroid hormones are made of lipids so they can enter via simple diffusion peptide hormones are charged
what is the promoter region?enable the binding of RNA polymerase promoting transcription
what is the enhancer sequence?regulates DNA activity by changing chromatin structure makes it more or less open to RNA polymerase open means active gene expression closed means gene inactivity
how do transcription factors work?most transcription factors will be made by hormones transcription factors and RNA polymerase bind to DNA forming a transcription initiation complex the transcription initiation complex attaches to the promoter region transcription can happen now