Animal responses Module 5

Question 1

What does the nervous system split up into?

Answer 1

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

Question 2

What does the peripheral nervous system split up into?

Answer 2

The somatic nervous system - controls conscious activities such as running

The autonomic nervous system - controls unconscious activities such as digestion

Question 3

What does the autonomic nervous system split up into?

Answer 3

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

Question 4

Where it’s found and it’s functions for the hypothalamus?

Answer 4

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

Question 5

Where it’s found and it’s functions for the Pituitary gland?

Answer 5

Found just beneath the hypothalamus

It is controlled by the hypothalamus, and it releases hormones and stimulates other glands such as the adrenal glands

Question 6

Where it’s found and it’s functions for the Cerebrum?

Answer 6

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

Question 7

Where it’s found and it’s functions for the medulla oblongata?

Answer 7

Found at the base of the brain, and at the top of the spinal cord

It automatically controls breathing rate and heart rate

Question 8

Where it’s found and it’s functions for the Cerebellum?

Answer 8

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

Question 9

What’s a reflex?

Answer 9

Where the body responds to a stimulus without making a conscious decision to respond

Question 10

Describe the blinking reflex?

Answer 10

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

Question 11

Describe the knee jerk reflex?

Answer 11

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

Question 12

Describe how the nervous system and hormonal system coordinate in the fight or flight response?

Answer 12

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

Question 13

Effects of the sympathetic nervous system and adrenaline in the fight of flight response?

Answer 13

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

Question 14

How does the nervous system help to control heart rate?

Answer 14

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

Question 15

Steps that occur if a high blood pressure is present/ or high blood O2, low CO2 conc, and high pH level?

Answer 15

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

Question 16

Steps that occur if low blood pressure is present/ or low O2 blood conc, high CO2 or low pH?

Answer 16

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

Question 17

How to use the student’s t test to compare heart rate before and after exercise?

Answer 17

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

Question 18

What does skeletal muscle (striated, striped, voluntary) do?

Answer 18

Allows movement

Question 19

What is skeletal muscle made up of?

Answer 19

Large bundles of long cells called muscle fibres

Question 20

What is the cell membrane of a muscle fibre cell called?

Answer 20

Sarcolemma

Question 21

Function of the sarcolemma?

Answer 21

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

Question 22

What’s sacroplasmic reticulum?

Answer 22

Network of internal membranes that runs through the sarcoplasm, and stores and releases calcium ions which are required for muscle contraction

Question 23

Why do muscle fibres have a lot of mitochondrion?

Answer 23

To provide a lot of ATP required for muscle contraction

Question 24

Muscle fibres are multi nucleated what does this mean?

Answer 24

They contain many nuclei

Question 25

Muscle fibres contain lots of long cylindrical organelles which are highly specialised for contraction?

Answer 25

Myofibrils

Question 26

What do myofibrils contain?

Answer 26

Thick or thin myofilaments

Question 27

What are thick myofilaments made up of?

Answer 27

The protein myosin

Question 28

What are thin myofilaments made up of?

Answer 28

The protein actin

Question 29

If you look at a myofibril under a microscope what will you see?

Answer 29

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

Question 30

A myofibril is made up of many short units called?

Answer 30

Sarcomers

Question 31

What are the ends of each sacromere marked with?

Answer 31

Z line

Question 32

Which line is in the middle of each sacromere so in the middle of the myosin filaments?

Answer 32

M line

Question 33

What does the H zone contain?

Answer 33

Only myosin filaments

Question 34

Generally what is the sliding filament theory?

Answer 34

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

Question 35

What happens to band length when during muscle contraction?

Answer 35

A band stays the same
I band gets shorter
H zone gets shorter

Question 36

Describe the globular heads and binding sites on myosin filaments

Answer 36

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

Question 37

What is the actin-myosin binding site in resting muscles blocked by?

Answer 37

Tropomyosin, which is held in place by troponin

Question 38

Describe the whole process of muscle contraction being triggered by an action potential?

Answer 38

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

Question 39

Describe what happens in muscle contraction when excitation stops?

Answer 39

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

Question 40

What are the 3 ways energy is created for muscle contraction?

Answer 40

Aerobic respiration
Anaerobic respiration
ATP-Creatine Phosphate (CP) system

Question 41

Describe briefly how aerobic respiration generates energy for muscle contraction?

Answer 41

Most ATP is generated via oxidative phosphorylation in the cells mitochondria
Aerobic respiration only works when oxygen is available

Question 42

Describe briefly how anaerboic respiration generates energy for muscle contraction?

Answer 42

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

Question 43

Describe briefly how the CP system generates energy for muscle contraction?

Answer 43

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)

Question 44

Describe 4 features of skeletal (voluntary) muscle?

Answer 44

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

Question 45

5 Featues of smooth muscle (involuntary)?

Answer 45

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

Question 46

What does smooth muscle do in the gut?

Answer 46

Contracts to move food along (peristalsis)

Question 47

What does smooth muscle do in blood vessels?

Answer 47

Contracts to reduce the flow of blood

Question 48

4 Features of cardiac muscle?

Answer 48

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

Question 49

How can you analyse electrical signals to monitor muscle fatigue?

Answer 49

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

Question 50

Describe the neuromuscular junctions ( the synapses between neurones and muscles?

Answer 50

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