8. metabolism and exercise

aerobic exercise

aerobic exercise

exercise which increases heart rate/breathing rate for at least 20 mins, improves function and use of oxygen

recommended exercise

moderate activity 150 mins a week

adrenaline

causes initial increase in heart rate when you start exercising

divert blood flow

adrenaline causes vasodilation of arterioles in muscles and skin and vasoconstriction of arterioles in gut and non essential organs

nitric acid

secreted when oxygen levels drop in muscles causing vasodilation

stroke volume

increases as more blood returns to heart, therefore increases cardiac output

breathing

rate and depth increases allowing more carbon dioxide to be removed

carbon dioxide concentration increase

reacts with water forming carbonic acid which lowers blood pH

chemoreceptors

located in brain and aortic arch, they detect falling pH and trigger in increase in breathing via sympathetic nervous system

training

repeated short bouts of exercise over long term allowing the body to adapt to it

systems which adapt to long term exercise

circulatory system, respiratory system, muscular system

lower heart rate

effect of long term exercise as more blood returns to heart (vein compression), ventricles stretched more and contract more forcefully (sterlings law), ventricle muscle increases, higher stroke volume

recovery time

Time for heart to return to resting state

skeletal mucles

increase in cross sectional area, increase in number and size of mitochondria, more blood capillaries, more glycogen and myoglobin

aerobic fitness

how efficiently oxygen is used

contribute to aerobic fitness

age, gender, smoking, exercise program, nutrition

FITT factors

frequency, intensity type and intensity/duration of exercise

frequency of exercise

3-6 per week, strength and resilience training training for less to allow recovery

intensity of exercise

the effort put into et eg speed, distance, weight. moderate to high causes heart to increase to heart max

type of exercise

eg cardiovascular, running, swimming, cycling, aerobics, weightlifting

time/duration of exersise

shorter but more frequent or longer but less frequent, maintain elevated heart rate fir 20mins+

VO2 max

maximum rate which oxygen can be taken in, transported and utilised in exercise

VO2 max expressed

absolute rate eg litres of oxygen per min dm3 min-1

or relative rate eg millimetres of oxygen per kilogram of body mass per minute ml kg-1 min-1

measure VO2 max

undertake graded exercise whilst ventilation oxygen and CO2 concentration of inhaled and exhaled air is measured, its reached when O2 consumption remains the same despite intensity increasing

precautions of carrying out VO2 max test

risk assessment of to determine existing health conditions, death suitable clothing, check equipment is in working order

measure aerobic fitness

indicated by time for heart rate to return to resting after exercise

Harvard step test

used to assess effect of FITT factors on aerobic fitness and indicate VO2 max

1, 5, 3, 4, 2, 6

order statements

1. using a 30-50cm high step, step up placing both feet on the step and step down placing both feet on floor

2. Convert pulse rates to beats per minute and add together

3. Wait 1 minute after stepping then measure pulse rate

4. Repeat pulse rate measurement at 2 minutes and 3 minutes after stepping

5. Each step cycle should take 2s and stepping is carried out for 300s

6. Calculate a score using the equation 100 x 300 / total beats per minute since 300s was the duration of stepping

measure pulse rate

use radial artery (wrist) or carotid artery (neck), use 2 fingers (not thumb) count for 30 seconds and multiply

measure effect of exercise

measure heart rate/pulse rate before, during and after, breathing rate, blood pressure, reaction times cognitive tasks

ethical and health safety issues for deciding someone can precipitate

give informed consent and know any potential health issues

factors to control when investigating activity

age, time of day, type and duration of exercise, sex, weight, height, fitness, BMI

oxygen deficit

when oxygen supply doens’t meet demand

excessive post-exercise oxygen consumption (EPOC)

period of increased oxygen consumption following vigorous exercise

oxygen dept

additional oxygen required to metabolise lactate

processes requiring oxygen after exercise

re-oxygenation of haemoglobin and myoglobin

oxidising lactate to pyruvate

regeneration of ATP and creatine phosphate

replenishing glycogen stores In muscle

meet increased metabolism rate due too been warmer and increased heart rate

cell repair

balancing hormones

oxygen deficit builds up at a start of exercise

takes time for heart rate and breathing rate to increase to meet demand

EPOC decreases with increased aerobic fitness

due to increased VO2 max due to increased stoke volume, more myoglobin and creatine phosphate

carbohydrate loading

aims to increase glycogen stores which can be hydrolysed to glucose for respiration

benefit from carbohydrate loading

endurance athletes not sprinters as it allows muscles to work for longer

carbohydrate loading regime

carbodepletion- less carbohydrates and more proteins/lipids from 10 days prior

carbohydrate loading- high carbohydrate diet diet 2-3 days prior to event

recovery- eat carbohydrates to replenish glycogen stores

athletic performance depends on

oxygen availability

carbohydrate availability

mass of muscles §

blood doping

artificial increase in red blood cell concentration

methods of blood doping

use recombinant erythropoietin (RhEPO)

autologous blood doping

erythropoietin

protein secreted by cells surrounding capillaries in renal correct of kidney in response to low oxygen levels or reduced blood volume

train at high altitude

low partial pressure of oxygen stimulates production of erythropoietin which increases number of red blood cells- legal

inject recombinant erythropoietin

artificially increase number of red blood cells and therefore oxygen by a substance produced from genetically modified bacteria. illegal and may lead to kidney failure and increased chance of thrombosis

autologous blood doping

remove 1 dm3 of blood, which their body replenishes the inject their packed blood cells back into their body

anabolic

synthesise complex molecules from simple molecules

group of macromolecules with steroids

lipids

steroids synthesised form

cholesterol

steroids are able to pass through cell surface

due to them been non polar lipids

steroids cause

transcription and synthesis of new muscle protein

transcription factor

molecule which binds to DNA and determines which genes are expressed

anabolic steroids

eg nandrolone and stanozolol, are artificially produced and injected into muscles to music action of hormones like testosterone which increase protein synthesis

anabolic steroids effet

promote growth and repair allowing more muscle building, train for longer and recover faster. also increase erythrocyte production and therefore VO2 max

why anabolic steroids are banned

enhance perforce giving an unfair advantage, health risks

health risks of anabolic steroids

altered behaviour eg aggression and mood swings

liver dammage

infertility and altered sexual characteristics

creatine phosphate

legal performance enhancer found in many foods and naturally synthesised by the body

creatine phosphate

can lose its phosphate group to phosphorylate ADP to ATP

respiratory pigments

haemoglobin

myoglobin

haemoglobin

found in erythrocytes to transport oxygen

myoglobin

found in muscle tissue to store oxygen

haemoglobin structure

quaternary protein containing 4 polypeptide chains with a haem prosthetic group (Fe2+ which binds to oxygen)

saturated

when 4 oxygen bind to haemoglobin

associate

when oxygen bind to haemoglobin

dissociation

release of oxygen from haemoglobin

oxygen realsed

haemoglobin response to increase of carbon dioxide and drop in oxygen in respiring tissues

myoglobin structure

a tertiary protein containing one ham group

haemoglobin function

carry oxygen (oxyghaemoglobin HbO8)

carry carbon dioxide (carboaminohaemoglobin)

act as a buffer

partial pressure of oxygen

pO2 is a measure of relative pressure oxygen contributes to a mixture of gases

lungs

area with high partial pressure where haemoglobin becomes fully saturated

respiring tissues

low partial pressure where haemoglobin becomes half saturated

s shaped curve

oxygen dissociation curve, due to co-operative binding, once one oxygen binds it is easier for more to, hard to achieve 100 saturation

myoglobin oxygen affinity

higher affinity for oxygen than Hb so only releases oxygen at low pO2

fetal haemoglobin

able to bind to oxygen at a lower affinity where adult haemoglobin dissociates. this is due to its higher affinity for oxygen

fetal haemoglobin

quaternary structure made of 2 alpha and 2 gamma globin chains

adult haemoglobin

quaternary structure made of 2 alpha and 2 beta chains

carbon dioxide transport in blood

5% dissolves in plasma

10% combines with Hb to form carbaminohaemoglobin

85% transported as HCO3- in plasma

carbonic anhydrase

enzyme which catalyses reaction of CO2 and water to form carbonic acid. within red blood cells

carbonic acid

produced from CO2 and dissociates to H+ and hydrogencarbonate (HCO3)-

chloride ions

inward movement of ions to balance outward movement of hydrogencarbonate into plasma from red blood cells

H+ ions

cause oxyhemoglobin to dissociate and release oxygen, due to it binding and forming haemoglobinic acid, this prevents a change in pH

greater affinity for oxygen

dissociation curve shifts to left

lower affinity for oxygen

dissociation curve shifts to right

Bohr effect

increase in CO2 causes dissociation curve to shift to right, due to more H+ ions causing dissociation of oxygen

pH

decrease causes dissociation curve to shift to right, due to anaerobic respiration producing lactic acid and therefore H+

temperature

raise causes dissociation curve to shift to right, due to it effecting H and ionic bonds in haemoglobin and association between oxygen and haemoglobin

types of muscle

cardiac muscle

skeletal muscle

smooth muscle

smooth muscle

involuntary, found in walls of arteries and intestines and controls blood flow, moves food and controls pupil size, contracts slowly without fatigue, spindle unstriped fibre appearance.

cardiac muscle

forms part of heart, contracts continuously to pump blood, connected to intercalated disks to allow transmission of action potential, some are myogenic, contracts rhythmically without fatigue, striated

skeletal muscle

voluntary muscle, attached to skeleton via tendons, contracts to move bones at joints, striated, contracts rapidly and powerfully but fatigues quickly

cause of striped muscles

due arrangement of protein filaments in myofibrils

thick protein filamnet

composed of myosin, surrounded by 6 other filaments

think protein filament

composed of actin, troponin and tropomyosin, around 1 filament

z line

are the thin filaments anchor to with the distance between been called a sarcomere, move closer together with muscle contraction

sarcomere

distance between 2 z lines, approximately 2.5µm in length when relaxed, and shortens when muscles contract as the filaments slide past each other,

G actin

2 chains of globular subunits twisted together

tropomyosin

hides a myosin binding site on the actin subunits

troponin

found at intervals with 3 subunits, one binds to tropomyosin, one to actin, one to Ca2+