Topic 7 Flashcards
What are ligaments?
- Hold bone to bone
- Strong connective tissue to control and restrict movement in the joint
What are tendons?
- Hold muscle to bones
- Strong connective tissue to enable the muscles to power joint movement
What are antagonistic muscles?
- Muscles that work in pairs
- Move in opposition directions
What is an extensor muscle?
- A muscle that straightens a joint during contraction
What is a flexor muscle?
- A muscle that bends a joint during contraction
What is a skeletal muscle?
- Muscles in the body that are attached to a skeleton
How are muscle fibres specialised?
- each fibres contain an arrangement of contractile proteins in the cytoplasm
- each fibre is surrounded by cell surface membrane (sarcolemma)
- each fibre contains many nuclei
What is the cytoplasm, cell surface membrane and endoplasmic reticulum called in a muscle fibre?
- Sarcoplasm
- Sarcolemma
- Sarcoplasmic reticulum
What are T tubules?
- Deep tube projections that fold from the sarcolemma
- Spreads electrical impulses through muscle fibres
What are myofibrils?
- Inside muscle fibres
- Bundles of actin and myosin filaments
What is a sarcomere?
- Short repeating units of myofibrils
- Distance between adjacent Z lines
How are actin and myosin filaments organised in myofibrils?
- I band, A band, H zone, M line, Z line
What is the I band made of?
- only has thin actin filaments
What is the A band made of?
- Both actin and myosin filaments
What is the H band made of?
- In the A band
- Only thick myosin filaments present
What is the M line made of?
- Attachment for myosin filaments
What is the Z line made of?
- Attachment for actin filaments
How is the structure of a muscle fibre related to its function?
- Many mitochondria to supply ATP via aerobic respiration
- Sarcolemma contain voltage gated channels to allow depolarisation of muscle fibres
- Myofibrils allow contraction of muscles
What are the two types of muscle fibres?
- Fast twitch
- Slow twitch
What is a fast twitch muscle?
- Muscles contract rapidly and produce powerful contractions
- Anaerobic respiration for ATP
- Fatigue quickly
What is a slow twitch muscle?
- Muscles contact slower and work at endurance
- Aerobic respiration for ATP
- Fatigue slower
What are the adaptations of fast twitch muscles?
- Large store of myoglobin
- Rich blood supply to deliver oxygen + glucose quickly
- high density of mitochondria to provide ATP
What are the adaptations of slow twitch muscles?
- Thicker myosin filaments
- High conc of glycogen
- Phosphocreatine to replenish ATP
- Less conc of myoglobin so pale colour
What is myoglobin?
- Red molecule storing oxygen in muscles
- Increases rate of oxygen absorption from capillaries
How do muscles contract?
- Sliding filament theory
What is the sliding filament theory?
- Acton potential arrives at neuromuscular junction, calcium ions are released from sarcoplasmic reticulum
- Bind to troponin causing tropomyosin to move.
- Exposes myosin binding sites on actin filament
- Myosin attached forming cross bridges.
- Myosin head bends, pulling actin filament over myosin
- ATP binds to myosin head causing them to detach and move back to original position.
How is the conc of calcium ions around a myofibril controlled?
- Released in response to nerve impulse
- Channels open to allow ions to cross membrane
- Taken back in via active transport
What is tropomyosin?
- Fibrous protein intertwined on the actin filaments
What is troponin?
- Globular protein found on tropomyosin
What is aerobic respiration?
- Breaking down a respiratory substrate in order to produce ATP using oxygen
What is the equation for aerobic respiration?
- Glucose + oxygen –> carbon dioxide + water + energy
What are the 4 stages of aerobic respiration?
- Glycolysis
- Link reaction
- Krebs cycle
- Oxidative phosphorylation
Where does each stage of respiration take place?
- Glycolysis - cytoplasm
- Link reaction - matrix
- Krebs cycle - matrix
- Oxidative phosphorylation - inner membrane of mitochondria
What happens in glycolysis?
- Glucose broken down to 2 molecules pyruvate
- Producing 2 NADH and 2 ATP
What are the products of glycolysis?
- 2 pyruvate
- 2 NADH
- 2 ATP
What happens in the Link reaction?
- Pyruvate oxidised (dehydrogenated) to produce acetate
- Pyruvate decarboxylated to form CO2
- reduced NAD formed from hydrogen released
- Acetate combines with coA to form acetyl coenzyme A
What are the products of the Link reaction?
- 2 Acetyl coA
- 2 CO2
- 2 NADH
What happens in the krebs cycle?
- 2C acetyl coA combine with 4C oxaloacetate to form 6C citrate
- Citrate decarboxylated (CO2 released) and dehydrogenated (NADH) to form 5C compound
- 5C decarboxylated (CO2 released) and dehydrogenated (2 NADH and 1 FADH) 3 times
- Dephosphorylated (ADP to ATP) to produce oxaloacetate.
What are the products of the Krebs cycle?
- 3 NADH
- 2 CO2
- 1 ATP
- 1 FADH
2x for each pyruvate
What happens in oxidative phosphorylation?
- H atoms from reduced NAD and reduced FAD from krebs cycle
- Split into protons and electrons
- electrons move down ETC and release energy which transports protons from matrix into intermembrane space
- Chemiosmotic gradient of protons
- Return to matrix via facilitated diffusion via ATP synthase
- Causes synthesis of ATP
- Oxygen is the final electron acceptor combining with protons and electrons to form water
What is the role of carrier molecules in ETC?
- Receive H atoms from reduced NAD and FAD
- Split into e- and H+
- Transferred via series of redox reactions
- Energy released pumps H+ ions into intermembrane space
How many ATP molecules are produced from each red NAD/FAD?
- 3 ATP for every NADH
- 2 ATP for every FADH
How many molecules of ATP can be produced per molecule of glucose?
- 2 ATP in glycolysis
- 2 ATP in Krebs cycle
- 30 NADH and 4 FADH in oxidative phosphorylation
= 38 ATP
What happens if there is no oxygen available in respiration?
- No final acceptor of electrons from ETC
- ETC stops functioning
- No more ATP produced
- No oxidised NAD and FAD available from dehydrogenation
- Krebs cycle stops
- Link reaction stops
Why is oxygen so important for aerobic respiration?
- It is the final electron acceptor
- ETC cannot continue
What are the two different anaerobic pathways?
- Lactate pathway in animals
- Ethanol pathway in yeast
What happens in the lactate pathway of anaerobic respiration?
- Reduced NAD transfers hydrogen to pyruvate to form lactate
- NAD can be reused in glycolysis
- Pyruvate is a hydrogen acceptor
- Lactate can be further metabolised and a small amount of ATP is produced
What is lactate?
- Acidic (low pH)
- Inhibits enzyme action
- Transported to liver where it is converted to pyruvate
What does myogenic mean?
- Muscle which can initiate its own contractions without nervous stimulation
How does electrical activity in the heart stimulate the contraction of atria/ventricles?
- Sinoatrial node becomes depolarised, initiating wave causing atria to contract
- Non conducting septum tissue prevents wave of passing to ventricles
- Depolarisation carried to AV node
- Stimulation passed along the bundle of His, which divides into 2 conducting fibres called the Purkyne tissue
- Purkyne fibres initiate wave of depolarisation causing ventricles to contract
What is an ECG?
- Electrocardiogram
- Shows electrical waves produced by activity of heart
What is the P wave on an ECG?
- Caused by depolarisation of atria
- Atrial systole
What is the QRS complex on an ECG?
- Peak cause by depolarisation of ventricles
- Ventricular systole
What is the T wave on an ECG?
- Repolarisation of ventricles
- Diastole
What are some heart problems which are diagnosed by ECGs?
- Tachycardia - heart beats too fast
- Bradycardia - heart beats too slow
- Fibrillation - irregular rhythm
- Ectopic heartbeat - pause in heart beat
What is homeostasis?
- Maintaining a constant internal environment at dynamic equilibrium despite internal/external changes
Why is homeostasis of temperature important?
- Ensures maintenance of optimal conditions for enzyme action and cell function.
What happens when temp increases?
- Denature enzymes
- Break bonds in tertiary structure
- Change in active site so enzyme-substrate complex cannot form
Why is homeostasis of blood glucose important?
- Cells need a constant supply of energy in the form of ATP
- Glucose is respired to supply ATP
Why is homeostasis of water in the body important?
- Cells to function optimally.
- Takes up metabolic reactions
What is thermoregulation?
- Maintenance of internal body temperature
How are thermoregulatory responses generated?
- Thermoreceptors in hypothalamus/skin detect changes
- Thermoregulatory centre in hypothalamus is stimulated
- Sends impulses to effector
What are the body’s cooling mechanisms?
- Vasodilation of blood vessels so more blood flow to skin
- Sweating cools skin via evaporation
- Flattening of hairs stops hair from forming an insulation
What are the body’s warming mechanisms?
- Vasoconstriction of blood vessels so less blood flow
- Shivering causes muscles to contract generating heat
- Hairs stand up creating insulating layer
- Less sweat to reduce heat loss via evaporation
How does the hypothalamus help to regulate body temperature?
- Detects via thermoreceptors
- Monitors temperature of blood
- Homeostatic response via motor neurons to effectors
What is negative feedback?
- Loop that reverses the effect of the original stimulus back to optimum
What is the process of negative feedback?
- Receptors detect change and signal to coordinator
- Sends signals to effectors to make changes and return internal conditions
- Linked by efficient communication systems
What is positive feedback?
- Loop where the stimulus responds to change by deviating away from optimum
How can hormones alter events inside a cell?
- Gene expression
- Transcription factors to alter gene expression
How do steroid hormones cause changes inside a cell?
How do protein and peptide hormones cause changes inside a cell?
What is a neuronal system?
- Passes neurones via synapses through nervous system
- Short term response
What is a hormonal system?
- Carry signals through blood where endocrine glands release hormones
- Long term response
What are target cells?
- Have specific receptors for each hormone
What is cardiac output?
- The volume of blood pumped out the heart per unit of time
How does cardiac output vary?
- Fitter individuals have higher cardiac output
- Thicker and stronger ventricles
What is heart rate and stroke volume?
- Heart rate = beats per minute
- Stroke volume = volume of blood pumped out the heart during once cardiac cycle
What happens to the body during exercise?
- More aerobic respiration due to more frequent muscle contraction
- Cells require more O2 and produce more CO2 as a waste product
What are two ways the body responds to changes during exercise?
- Increased rate of breathing so more O2 enters and more CO2 is removed via gaseous exchange
- Increased heart rate which transports more O2 and removes CO2 due to high rate of respiration
How is breathing rate controlled?
- By medulla oblongata
- Transfers nerve impulses from brain to spinal cord
What is inspiration?
- Sends nerve impulses along motor neurones to intercostal muscles and diaphragm
- CONTRACT
- Volume of chest increases, pressure lowers
What is expiration?
- Nerve impulses to intercostal muscles and diaphragm
- RELAX
- Volume of chest decreases, pressure increases
What effect does exercise have on blood pH?
- Decrease in pH of blood
- Extra CO2 in blood due to increase in respiration
How does exercise stimulate changes in breathing rate?
- Chemoreceptors in medulla oblongata detect change
- Nerve impulse sent to medulla oblongata which then sends more frequent nerve impulses to intercostal and diaphragm
- Increases breathing rate
- Restoring blood pH to return to normal
How does heart rate change with high blood pressure?
- High BP detected by baroreceptors who send impulses to CV control centre
- Impulses sent along parasympathetic neurones, secrete acetylcholine
- Bind to SAN receptors causing HR to slow
How does heart rate change with low blood pressure?
- Low BP detected by baroreceptors who send impulses to CV control centre
- impulses sent along sympathetic neurones, secrete noradrenaline
- Binds to SAN receptors causing it to increase
What are the 4 ways that breathing can be scientifically measured?
- Tidal volume
- Breathing rate
- Oxygen consumption
- Respiratory minute ventilation
What is keyhole surgery?
- Minimally invasive surgery
- Small incision inserted into knee
What are the benefits of keyhole surgery?
- Less blood loss
- Less chance of infection
- Quicker recovery
What is the impact of overexercising?
- Immune suppression
- Damage to joints
- Bone and joint inflammation
What is the impact of underexercising?
- Obesity
- Diabetes
- High blood pressure
What are anabolic steroids and their side effects?
- Acts as a transcription factor to switch on genes for protein synthesis
- Increase muscle size and stamina
- Side effects: organ damage, aggression, liver dysfunction, cancer
What are stimulants and their side effects?
- More alert and react faster
- Side effects: aggression
What is erythropoietin and its side effects?
- Produces enzymes for red blood cell production so more produced for aerobic respiration
- Side effects: Serious health problems, blood thickening
What are the arguments for the use of performance enhancing drugs?
- Freedom to choose
- May overcome inequality
- May be only possible to compete at high levels
What are the arguments against the use of performance enhancing drugs?
- Many are illegal
- Unfair advantage
- Serious health risks
- Not fully informed
