Animal responses Module 5 Flashcards
What does the nervous system split up into?
The central nervous system - made up of the brain and the spinal cord
The peripheral nervous system - made up of the nuerons that connect the CNS to the rest of the body
What does the peripheral nervous system split up into?
The somatic nervous system - controls conscious activities such as running
The autonomic nervous system - controls unconscious activities such as digestion
What does the autonomic nervous system split up into?
The sympathetic nervous system - gets the body readu for “fight or flight” by sympathetic neurons releasing the neurotransmitter noradrenaline
The parasympathetic nervous system - Calms the body down “rest and digest” by parasympathetic neurons releasing the neurotransmitter acetlycholine
Where it’s found and it’s functions for the hypothalamus?
Found just beneath the middle part of the brain
Automatically maintains body temperature at the normal level, and produces hormones that control the pituitary gland
Where it’s found and it’s functions for the Pituitary gland?
Found just beneath the hypothalamus
It is controlled by the hypothalamus, and it releases hormones and stimulates other glands such as the adrenal glands
Where it’s found and it’s functions for the Cerebrum?
Largest part of the brain (all of the top) and is split into the 2 halves called the cerebral hemispheres
Has a thin outer layer called the cerebral cortex which is highly folded
It is involved in vision, hearing, learning and thinking
Where it’s found and it’s functions for the medulla oblongata?
Found at the base of the brain, and at the top of the spinal cord
It automatically controls breathing rate and heart rate
Where it’s found and it’s functions for the Cerebellum?
It is found beneath the back of the cerebrum and it also has a folded cortex
It’s important for muscle coordination, posture and coordination of balance
What’s a reflex?
Where the body responds to a stimulus without making a conscious decision to respond
Describe the blinking reflex?
Sensory nerve endings in the cornea are stimulated by touch
A nerve impulse is sent along the sensory nuerone to a relay neuron in the CNS
The impulse is then passed from the relay neurons to motor neurons
The motor nuerons send impulses to the effectors - the orbicularis oculi muscles that move your eyelids
These muscles contract causing eyelid to shut quickly and prevent eye being damaged
Describe the knee jerk reflex?
Stretch receptors in the quadricep muscle detect that the muscle is being stretched
A nerve impulse is passed along a sensory neuron which communicates directly with a motor neuron in the spinal cord
The motor neuron carries the nerve impulse to the effector (the quadricep muscle), causing it to contract so the lower leg moves forward quickly, so you maintain balance
Describe how the nervous system and hormonal system coordinate in the fight or flight response?
Nerve impulses from sensory neurons arrive at the hypothalamus activating both the hormonal system and the sympathetic nervous system
The pituitary gland is stimulated to release a hormone called ACTH, this causes the cortex of the adrenal to release steroidal hormones
The sympathetic nervous system is activated, triggering the release of adrenaline from the medulla region of the adrenal gland
Effects of the sympathetic nervous system and adrenaline in the fight of flight response?
Heart rate increased so blood pumped around body faster
Muscles around the bronchioles relax, so breathing is deeper
Glycogen is converted into glucose, so more glucose is available for muscles to respire
Muscles in the arterioles supplying the skin and gut constrict, and muscles in the arterioles in the supplying the heart lungs and skeletal muscles dilate - so blood is diverted from the skin and gut to the heart lungs and skeletal muscles
Erector pilli muscles in the skin contract - this makes hairs stand on end so the animal looks bigger
How does the nervous system help to control heart rate?
The sinoatrial node (SAN) generates electrical impulses that cause the cardiac muscle to contract
The rate at which the SAN fires is unconsciously controlled by a part of the brain called the medulla
Stimuli of high and low pressure are detected by baroreceptors (pressure receptors) in the aorta and vena cava
Oxyen level (Co2 and pH aswell help), is detected by chemorecptors in the aorta, the carotid artery and in the medulla
Steps that occur if a high blood pressure is present/ or high blood O2, low CO2 conc, and high pH level?
Baroreceptors detect high blood pressure, chemoreceptors detect chemicals
Impulses are sent to the medulla oblongata, which sends impulses along the vagus nerve. This secretes acetlycholine, which binds to receptors on the SAN.
Effector is the cardiac muscle- heart rate slows down to reduce blood pressure back to normal
Steps that occur if low blood pressure is present/ or low O2 blood conc, high CO2 or low pH?
Baroreceptors detect low blood pressure/ or chemoreceptors detect chemicals
Impulses are sent to the medulla, which sends impulses along the accelerator nerve. This secretes noradrenaline, which binds to receptors on the SAN
Effector is the caridac muscle, Heart rate speeds up to increase blood pressure back to normal
How to use the student’s t test to compare heart rate before and after exercise?
Identify null hypothesis , that the means for the 2 sets of data are the same
Calculate the mean and standard deviation for both sets of data
Calculate the t test by using the formula (Mean 1 - Mean 2) / The square root of (standard deviation(1)^2/number of values in that table) + (standard deviation(2)^2/number of values in that table)
So all of bottom row is square rooted
Calculate the degrees of freedom by doing the total value of n then - 2
Look up values for t crit in a table of critical values at the 95% confidence level, if the t test is larger than the t crit we can be 95% sure there has been a significant change, so it’s not down to chance
What does skeletal muscle (striated, striped, voluntary) do?
Allows movement
What is skeletal muscle made up of?
Large bundles of long cells called muscle fibres
What is the cell membrane of a muscle fibre cell called?
Sarcolemma
Function of the sarcolemma?
Parts of it fold inwards across the ,muscle fibre and stick into the sarcoplasm ( a muscle cells cytoplasm), these folds are called transverse tubules
They help spread electrical impulses throughout the sarcoplasm, so they reach all parts of the muscle fibre
What’s sacroplasmic reticulum?
Network of internal membranes that runs through the sarcoplasm, and stores and releases calcium ions which are required for muscle contraction
Why do muscle fibres have a lot of mitochondrion?
To provide a lot of ATP required for muscle contraction
Muscle fibres are multi nucleated what does this mean?
They contain many nuclei
Muscle fibres contain lots of long cylindrical organelles which are highly specialised for contraction?
Myofibrils
What do myofibrils contain?
Thick or thin myofilaments
What are thick myofilaments made up of?
The protein myosin
What are thin myofilaments made up of?
The protein actin
If you look at a myofibril under a microscope what will you see?
An alternating pattern of dark and light bands
Dark bands contain the thick myosin filaments and some overlapping thin actin filaments = these are called A bands
Light bands that contain thin actin filaments only = I bands
A myofibril is made up of many short units called?
Sarcomers
What are the ends of each sacromere marked with?
Z line
Which line is in the middle of each sacromere so in the middle of the myosin filaments?
M line
What does the H zone contain?
Only myosin filaments
Generally what is the sliding filament theory?
Myosin and actin filaments slide over each other to make the sarcomers contract, the simultaneous contraction makes the myofibrils and muscle fibres contract
The sarcomers return to their original length after the contraction
What happens to band length when during muscle contraction?
A band stays the same
I band gets shorter
H zone gets shorter
Describe the globular heads and binding sites on myosin filaments
They have globular heads that are hinged so they can move back and forward
Each myosin head has a binding site for actin and for ATP
Actin filaments have a binding sites for myosin heads called actin-myosin binding sites
2 other proteins called tropomyosin and troponin are found between actin filaments, they are attached to each other and help myofilaments move past each other
What is the actin-myosin binding site in resting muscles blocked by?
Tropomyosin, which is held in place by troponin
Describe the whole process of muscle contraction being triggered by an action potential?
When an action potential from a motor neuron stimulates a muscle cell it depolaries the sarcolemma
Depolarisation spreads down the t tubules to the sarcoplasmic reticulum
This causes the sarcoplasmic reticulum to release stored Ca2+ ions into the sarcoplasm
Ca 2+ ions bind to troponin, causing it to change shape, this pulls the attached tropomyosin out of the actin-myosin binding site on the actin filament
This exposes the binding site, which allows the myosin head to bind = actin-myosin crossbridge
Calcium ions also activate the enzyme ATPase which breaks down ATP (into ADP +Pi) to provide the energy required for muscle contraction. The energy released from ATP moves the myosin head, which pulls the actin along in a rowing action
ATP also provides energy to break the actin-myosin crossbridge, so the myosin head detaches from the actin filament after it’s moved
The myosin then reattaches to a different binding site further along the actin filament, a new actin-myosin cross bridge is formed and the cycle is repeated
Overall this effect causes the sarcomere to shorten and the muscle to contract
Describe what happens in muscle contraction when excitation stops?
When the muscle stops being stimulated, calcium ions leave their binding sites on the troponin molecules and are moved back to sarcoplasmic reticulum via active transport
The troponin molecules return to their original shape, pulling the attached tropomyosin molecules with them, this means the tropomyosin molecules block the actin-myosin binding sites again
Muscles aren’t contracted and the actin filaments slide back into their relaxed positions lengthening the sarcomere
What are the 3 ways energy is created for muscle contraction?
Aerobic respiration
Anaerobic respiration
ATP-Creatine Phosphate (CP) system
Describe briefly how aerobic respiration generates energy for muscle contraction?
Most ATP is generated via oxidative phosphorylation in the cells mitochondria
Aerobic respiration only works when oxygen is available
Describe briefly how anaerboic respiration generates energy for muscle contraction?
ATP is made via glycolysis
The end product of glycolysis is pyruvate, which is converted to lactate via lactate fermentation
Lactate can quickly build up in the muscles and cause muscle fatigue
Describe briefly how the CP system generates energy for muscle contraction?
ATP is made by phosphorylating ADP - adding a phosphate group taken from creatine phosphate
CP is stored inside cells and this system generates ATP very quickly
CP runs out very quickly so is used for short burts of exercise (eg. tennis serve)
This system is anaerobic and alactic (no lactic acid formed)
Describe 4 features of skeletal (voluntary) muscle?
Contraction is caused consciously
It’s made up of many muscle fibres that have many nuclei - fibres can be many cm long
Can see cross striations under a microscope ( striped pattern)
Some muscle fibres contract very quickly and fatigue very quickly, whilst others contract slowly and fatigue slowly
5 Featues of smooth muscle (involuntary)?
Contraction is caused unconsciously
It’s called smooth muscle as doesn’t have striped appearance
Found in the walls of hollow internal organs such as the gut or the blood vessels
Each muscle fibre is spindle shaped, have one nucleus and about 0.2mm long
They contract slowly and don’t fatigue
What does smooth muscle do in the gut?
Contracts to move food along (peristalsis)
What does smooth muscle do in blood vessels?
Contracts to reduce the flow of blood
4 Features of cardiac muscle?
Contracts on it’s own so it’s myogenic
Found in walls of heart and is made of muscle fibres connected by intercalated discs and branched, which have low electrical resistance so nerve impulses pass easily between cells
Cylinder shaped, 1 nucleus and about 0.1mm long
Muscle fibres contract rhythmically and don’t fatigue
How can you analyse electrical signals to monitor muscle fatigue?
Attach 2 electrodes to a muscle, a 3rd electrode will go on inactive point eg/ bony wrist area to act as a control
Connect electrodes to an amplifier and computer
When muscle is at rest it’s a straight line
When it’s flexed the amplitude of waves will increase, and keep on increasing as muscle fatigues as more motor units are being activated
Describe the neuromuscular junctions ( the synapses between neurones and muscles?
They use the neurotransmitter acetlychloine, which binds to receptors called nicotinic cholinergic receptors
Work in the same way as synapses between neurones- causing depolarisation in muscle cell which always leads to a contraction (if threshold level is reached)
Acetlycholinesterase stored in clefts on the postsynaptic membrane is released to breakdown acetlycholine after use
