Paper 1 Cards Flashcards
(23 cards)
How do animals increase chance of survival
By adapting and responding to internal and external environments to make sure all metabolic reactions are happening at the correct rate
What is a change in an environment called
A stimulus
Role of receptors and effectors and how do they communicate
Receptors detect the stimuli whilst the effectors bring about a response. They do this through the Nervous system or the hormonal system
Structure of nervous system
- The two main parts are the CNS ( made from brain and spine) and the peripheral nervous system(made of neurones that connect rest of body to CNS)
- The peripheral splits into 2 parts the somatic (which controls conscious thought) and the autonomic( which controls unconscious thought)
- The autonomic splits again into the parasympathetic ( rest and digest) and sympathetic (fight or flight)
Parts of brain and their functions
- Cerebrum largest part of brain split into 2 and controls vision, learning and thinking.
- hypothalamus controls body temperature, water levels and it produces hormones that control pituitary gland
- medulla oblongata controls breathing and heart rate
- cerebellum controls muscle coordination and balance
- pituitary gland controlled by hypothalamus and it releases hormones and stimulates other glands
Reflex pathway
Stimulus- receptor-sensory neurone-relay neurone- motor nuerone- effector- response
Blinking reflex
- Stimulus is something touching your eye
- receptor is the sensory nerve endings in your cornea and a nerves impulse is sent along sensory neurone to relay neurone
- goes to the motor nuerone and the effector ( orbicularis oculi muscle muscles) will move your eyelids and makes them close
Knee jerk reflex
- stimulus is that quad is stretched
- stretch receptors detect change and send message down sensory neurone
- sensory neurone communicates directly with motor neurone
- motor carries impulse the quad muscles
- response is the lower leg moves forward quickly
Control of heart rate
- The SAN controls the heart rate as it depends entirely on how often it fires
- adapting your heart to conditions such as low BP and different O2 and CO2 amounts is key to survival
High blood pressure response
Baroreceptors detect high blood pressure and send impulse along sensory nuerone to cardio vascular centre which send impulse to parasympathetic pathway which will then secrete acetylcholine which binds to receptors on SAN which slows heart down to reduce BP
Low blood pressure response
Baroreceptors detect change in BP and send nervous impulse down sensory nuerone to cardio vascular centre. This the. secretes Nora adrenaline which will bind to receptors on SAN allowing it to increase the speed at which it contracts increasing the heart rate
High blood oxygen and low CO2
Chemoreceptors detect change and send message via sensory nuerone to cardiovascular centre. These secrete acetylcholine which binds to SAN receptors and puts all oxygen and CO2 levels back to normal
Low blood O2 levels
Chemoreptors detect change and send message down sensory nuerone to cardiovascular centre which secretes noradrenaline which binds to receptor on SAN which increases heart rate to return things to usual levels
Skeletal muscle structure
- Cell membrane called sarcolemma
- Transverse T tubules are flooded sarcolemma and help spread electrical impulse across the whole muscle fibre
- Sarcoplasmic reticulum stores and release calcium ions for muscle contraction
Myofibril structure
Contain thick( made of protein myosin) and thin filaments( made of protein actin)
Structure of sarcomere
Sarcomere is a section of a myofibril
- has Z line at both ends
- dark part À band light part I band
- M line is middle of it
- H zone contains only myosin
What happens as a muscles contracts
As a muscle contracts the H zone gets smaller due to the actin overlapping the myosin and Z line get close together
Myosin filament
-Myosin filament has a globular head which has a binding sight for actin and ATP
Muscle contraction mechanism
- action potential from motor nuerone stimulates a muscle cell
- it will depolarise the sarcolemma and will eventually depolarise the sarcoplasmic reticulum which will the release Calum ions into sarcoplasm
-calcium ion attach to troponin and makes it change shape which the pulls down the attached tropomyosin and unblocks the binding site
-this allows myosin head to form actin myosin cross bridge with actin filament - the calcium ion also activate ATPase, the energy from the ATP moves myosin head to the side which pulls along the actin filament whilst also providing enemrgy to break the actin myosin cross bridge
-cycle repeats
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How do muscle return to resting state
Calcium ions leave their binding site on tropinin so then the tropomyosin returns to its original place blocking the binding site calcium leaves sartoplasmic reticulum via active transport
How is atp produced
Aerobic respiration, aneroobic respiratio, ATP creatine phosphate system
Types of muscle
-Skeletal muscle is voluntary muscle (needs conscious thought to control it)
Smooth muscle is involuntary muscle (unconsciously controlled)
-cardiac muscle is myobenic and contracts on its own
Nueromusculsr junctions
- Synapse between motor nuerone and muscle cell
- synapse releases nuerotransmitters acetylcholine which triggers depolarisation
- acetylcholine binds to post synaptic receptors making it release ACHE stored in clefts which breaks down the acetylcholine after the action potential has passed
