Animal responses

Question 1

Define central nervous system

Answer 1

Consists of your brain and spinal cord

Question 2

Define peripheral nervous system

Answer 2

1. This consists of all the neurones that connect the CNS to the rest of the body.
2. These are sensory neurones which carry nerve impulses from the receptors to the CNS, and the motor neurones which carry nerve impulses away from the CNS to the effectors

Question 3

Define somatic nervous system

Answer 3

1. This system is under conscious control- used when you voluntarily decide to do something
2. E.g. when you decide to move a muscle to move your arm
3. It carries impulses to the body’s muscles

Question 4

Define autonomic nervous system

Answer 4

1. This works constantly
2. It is under subconscious control and is used when the body does something automatically without you deciding to do it- it is involuntary
3. E.g to cause the heart to beat or to digest food
4. The autonomic nervous system carries nerve impulses to glands, smooth muscle and cardiac muscle

Question 5

Define sympathetic nervous system

Answer 5

1. Division of the autonomic nervous system
2. Initiates flight or fight responses
3. Neurotransmitter - noradrenaline

Question 6

Define parasympathetic nervous sytem

Answer 6

1. Division of the autonomic nervous system
2. Relaxing responses
3. Neurotransmitter- acetylcholine

Question 7

State 4 differences between the autonomic nervous system and the somatic nervous system.

Answer 7

1. Somatic is voluntary and autonomic is involuntary
2. Somatic most neurones are myelinated, autonomic most are unmyelinated or lightly myelinated
3. Somatic carry impulses to skeletal but autonomic cary it to cardiac, smooth muscle and glands
4. Somatic- 1 neurones to connect CNS to effector but autonomic- at least 2 neurones to connect CNS to effector

Question 8

Define the term “antagonistic system” in relation to the sympathetic and parasympathetic nervous systems, and outline how they co-ordinate responses.

Answer 8

1. The sympathetic and parasympathetic have antagonistic effects on the organs
2. The action of ones system opposes the action of the other.
3. Under normal conditions impulses are passing along the neurones of both systems at a relatively low rate
4. Changes to conditions lead to an altered balance between the two systems which leads to an appropriate response

Question 9

Draw a table to compare the structure and function of the sympathetic and parasympathetic nervous systems.

Answer 9

1. PNS is most active in sleep and relaxation, SNS is most active in times of stress
2. SNS- neurones of a pathway are linked at a ganglion just outside the spinal cord (long post-ganglionic neurones, short pre-ganglionic neurones). PNS- neurones of a pathway are linked at a ganglion within the target tissue (long pre-ganglionic neurones and short post-ganglionic neurones)
3. SNS- neurotransmitter is noradrenaline, PNS- uses acetylcholine

Question 10

Label a diagram of the human brain showing the location of the cerebrum, cerebellum, medulla oblongata, hypothalamus and pituitary gland

Answer 10

p362 look and practice labelling

1. Main top bit is the cerebrum
2. Skull surrounds it all
3. Located just underneath the cerebrum is the corpus callosum which is worm shaped ish
4. Pituitary gland comes of the hypothalamus
5. Hypothalamus comes from the medulla oblongata
6. Cerebellum is a leaf shaped part under cerebrum
7. Spinal cord comes from comes down from the cerebellum

Question 11

Describe the structure of the cerebrum.

Answer 11

1. It is highly convoluted which increases its surface area considerably and therefore it capacity for complex activity
2. It is split into right and left hemispheres which control one half of the body.
3. The outer layer of the cerebral hemispheres is known as the cerebral cortex
4. Six areas- frontal lobe, parietal lobe, occipital lobe, cerebellum, medulla oblongata, temporal lobe

Question 12

Describe the role of sensory areas, association areas and motor areas of the cerebral cortex.

Answer 12

1. Each sensory area within the cerebral hemispheres receives information from receptor cells located in sense organs
2. The size of the sensory area allocated is in proportion to the relative number of receptor cells present in the body part.
3. The information is then passed on to other areas of the brain known as association areas, to be analysed and acted upon.
4. Impulses come into the motor areas where motor neurones send out impulses, e.g to move skeletal muscles
5. The size of the motor area allocated is in proportion to the relative number of motor endings in it.
6. The main region which controls movement is the primary motor cortex located at the back of the frontal lobe

Question 13

Describe the role of the cerebellum in coordinated muscular movement.

Answer 13

1. This area of the brain is concerned with the control of muscular movement, body posture and balance- it does not initiate movement but coordinates it.
2. If this area of the brain is damaged, a person suffers from jerky, uncoordinated movement.
3. The cerebellum receives information from the organs of balance in the ears and information about the tone of muscles and tendons.
4. It then relays this information to the areas of the cerebral cortex that are involved in motor control

Question 14

Describe which side of the brain controls which side of the body

Answer 14

1. In the base of the brain, impulses from each side of the body cross
2. Therefore the left hemisphere receives impulses from the right-hand side of the body and the right hemisphere receives impulses from the left-hand side of the body

Question 15

Describe the structure and location of the pituitary gland.

Answer 15

1. This is found at the base of the hypothalamus and controls most of the glands in the body.
2. It is divided into two sections.
   - Anterior pituitary- produces 6 hormones including follicle-stimulating hormone (FSH), which is involved in reproduction and growth hormones
   - Posterior pituitary (back section)- stores and releases hormones produced by the hypothalamus, such as ADH involved in urine production

Question 16

Describe the structure and location of the hypothalamus

Answer 16

1. This is the main controlling region for the autonomic nervous system.
2. It has two centres- one of the parasympathetic and one for the sympathetic nervous system.
3. It has a number of functions:
   - Controlling complex patterns of behaviour such as feeding, sleeping and aggression
   - Monitoring the composition of blood plasma, such as the concentration of water and blood glucose- therefore it has a very rich blood supply
   - Producing hormones- it is an endocrine gland, that is, it produces hormones

Question 17

Describe the structure and location of the medulla oblongata

Answer 17

1. It contains many important regulatory centres of the autonomic nervous system
2. These control relex activities such as ventilation (breathing rate) and heart rate.
3. It also controls activities such as swallowing, peristalsis and coughing

Question 18

Define the term reflex action

Answer 18

Involuntary response to a sensory stimulus

Question 19

Define the term reflex arc

Answer 19

The pathway of neurones involved in a reflex action is known as a reflex arc

Question 20

Define stimulus

Answer 20

A detectable change in the internal or external environment

Question 21

Define receptor

Answer 21

Extrinsic glycoproteins that bind to chemical signals triggering a response by the cell

Question 22

Define effector

Answer 22

Muscle or gland which carries out bodies response to a stimulus

Question 23

Define response

Answer 23

The way a body reacts to a stimulus

Question 24

Draw, label and annotate a diagram to show the arrangement of neurones in the “withdrawal of the hand from a heat stimulus” reflex arc and the actions that occur in the stimulus-response pathway

Answer 24

1. Stimulus heat from candle flame
2. Thermoreceptor in skin detects heat
3. Sensory neurone passes nerve impulses to spinal cord
4. Relay neurone passes impulses across the spinal cord
5. Motor neurone passes impulses to the muscle
6. Effectory contracts
7. Response hand is moved quickly away from flame

Question 25

Describe the characteristics of reflex actions and the survival value of them.

Answer 25

1. Reflexes are essential for survivla as they avoid the body being harmed or reduce severity of any danger 2. Reflexes increase your chances of survival by: 1. Being involuntary responses- the decision-making regions of the brain are not involved, therefore the brain is able to deal with more complex responses. It prevents the brain from being overloaded with situations in which the response is always the same 2. Not having to be learnt- They are present at birth and therefore provide immediate protection 3. Extremely fast- The reflex arc is very short. It normally only involves one or two synapses, which are the slowest part of nervous transmission 4. Many reflexes are what we would consider everyday actions, such as those which keep us upright and those which control digestion

Question 26

Draw, label and annotate a diagram to show the arrangement of neurones in the “knee jerk” reflex arc and the actions that occur in the stimulus-response pathway

Answer 26

1. It is a spinal reflex- the neural circuit only goes up to the spinal cord, not the brain 2. When the leg is tapped just below the kneecap, it stretches the patellar tendon and acts as a stimulus 3. This stimulus initiates a reflex arc that causes the extensor muscle on top of the thigh to contract 4. At the same time, a relay neurone inhibits the motor neurone of the flexor muscle, causing it to relax 5. This contraction, coordinated with the relaxation of the antagonistic flexor hamstring muscle, causes the leg to kick

Question 27

Explain the “survival value” of the knee jerk reflex.

Answer 27

1. The absence of this reflex may indicate nervous problems and multiple oscillation of the leg may be a sign of a cerebellar disease 2. This reflex is used by the body to help maintain posture and balance, allowing you to remain balanced with little effort or conscious thought.

Question 28

Draw, label and annotate a diagram to show the arrangement of neurones in the “corneal blinking” reflex arc and the actions that occur in the stimulus-response pathway.

Answer 28

1. It is a cranial reflex- occurs in the brain not the spinal cord When the cornea of the eye is irritated by a foreign body, the stimulus trigger an impulse along a sensory neurone. 2. The impulse then passes through a relay neurone in the lower brain stem. 3. Impulses are then sent along branches of the motor neurone to initiate a motor response to close the eyelids. 4. The reflex initiates a consensual response- both eyes are closed in response to the stimulus.

Question 29

What are the different stimuli for the different types of blinking reflex

Answer 29

1. The blinking reflex is an involuntary blinking of the eyelids 2. It occurs when the cornea is stimulated e.g by being touched. Its purpose is to keep the cornea safe from damage due to foreign bodies such as dust or flying insects entering the eye. -corneal reflex 3. It alsos occurs when loud sounds 4. It also occurs as a result of very bright light- optical reflex

Question 30

Explain the “survival value” of the blinking reflex.

Answer 30

1. It this reflex is present, it indicated that the lower brain stem is functioning. 2. This is used as part of an assessment to determine whether a patient is brain dead. 3. Protects retina and lens from damage

Question 31

State the two systems which coordinate mammalian responses to stimuli

Answer 31

1. Nervous system | 2. Endocrine system

Question 32

Define the term “fight or flight response”

Answer 32

A series of physical responses intended to help mammals survive by preparing the body to either run or fight.

Question 33

Draw a diagram showing how the hypothalamus uses both the nervous system and the endocrine system to coordinate the physiological responses associated with the “fight or flight” response.

Answer 33

1. The hypothalamus activates both the sympathetic nervous system and the adrenal-cortical system by releasing CRF (corticosteroid releasing factor) into the pituitary gland 2. The sympathetic nervous system impulses activate glands and smooth muscles 3. The sympathetic nervous system activates the adrenal medulla so it produces noradrenaline and adrenaline into the bloodstream 4. The pituitary gland (stimulated by CRF) secretes the hormone ACTH (adrenocorticotropic hormones) which stimulates the adrenal cortex to release a number of different corticosteroid hormones into the bloodstream 5. Combination of above responses result in the physiological responses in the flight or fight response.

Question 34

List 7 physiological changes that occur during the “fight or flight” response and describe the purpose of each

Answer 34

1. Heart rate increases- to pump more oxygenated blood around the body 2. Pupils dilate- to take in as much as possible for better vision 3. Arterioles in skin constrict- more blood to major muscle groups, brain, heat and muscles of ventilation 4. Blood glucose level increases- increase respiration to provide energy for muscle contraction 5. Smooth muscle of airways relaxes- to allow more oxygen into lungs 6. Non-essential systems shut down (like digestion)- to focus resources on emergency functions 7. Difficulty focusing on small tasks- brain solely focused only on where threat is coming from.

Question 35

Define first messanger

Answer 35

An extracellular substance (hormone) that binds to a cell-surface receptor and initiates intracellular activity

Question 36

Define second messanger

Answer 36

Molecules that relay signals received at receptors at the cell surface to target molecule

Question 37

State the two types of hormone and identify which type adrenaline is.

Answer 37

1. Steroid hormones- lipid soluble. e.g. oestrogen - Pass through lipid component of cell membrane and bind to steroid hormone receptors to form a hormone-receptor complex. - Receptors may be present in cytoplasm or nucleus depending on hormone. - Hormone-receptor complex formed acts as a transcription factor which facilitates or inhibits the transcription of a specific gene 2. Non steroid hormones- adrenaline - hydrophillic so cannot pass directly through cell membrane - bind to specific receptors on the cell surface membrane of the target cell. - Triggers a cascade reaction mediated by chemicals called second messengers

Question 38

Draw a flow chart to show how adrenaline has its effect on cells.

Answer 38

1. The hormone fuses to the receptor site and in doing so activates an enzyme inside the membrane 1. When adrenaline binds to its receptor, the enzyme adenylyl cyclase is activated 2. Adenylyl cyclase triggers the conversion of ATP into cyclic adenosine mono-phosphate cAMP on the inner surface of the cell membrane in the cytoplasm 4. The increase in cAMP levels activates specific enzymes called protein kinases which phosphorylate and hence activate other enzymes. In this example enzymes are activated which trigger the conversion of glycogen and glucose

Question 39

Explain why the second messenger system is said to have a “cascade effect”, and explain the usefulness of this effect.

Answer 39

1. The hormone is known as the first messenger and cAMP the second messenger 2. One hormone molecule can cause many cAMP molecules to be formed 3. At each stage the number of molecules involved increases so the process is said to have a cascade effect

Question 40

Describe the main features and function of adrenaline

Answer 40

1. One of its main function during flight or fight is to trigger liver cells to undergo glycogenolysis so that glucose is released into the bloodstream. This allows respiration to increase so more energy is available for muscle contraction 2. It is hydrophilic so cannot pass through cell membranes 3. It binds with receptors on the surface of liver cell membrane and triggers a chain reaction inside the cell

Question 41

Suggest how adrenaline can have different effects on different tissue types.

Answer 41

1. cAMP activates different molecules in different cells | 2. Different types of interactions between the receptor protein adenylyl cyclase

Question 42

Explain why there is a need to be able to alter heart rate in humans.

Answer 42

1. When you exercise or in times of danger, it is essential that the heart rate increases to provide that extra oxygen required for increased respiration

Question 43

Describe two ways in which the heart’s action changes in order to supply more oxygen and glucose to cells.

Answer 43

1. Increase frequency of impulses sent by the sympathetic nervous

Question 44

Define heart rate

Answer 44

The number of heartbeats per unit of time, usually per minute.

Question 45

Define stroke volume

Answer 45

The amount of blood pumped by the left ventricle of the heart in one contraction.

Question 46

Define cardiac output

Answer 46

The amount of blood the heart pumps through the circulatory system in a minute.

Question 47

How can you work out cardiac output

Answer 47

Cardiac output = stroke volume * heart rate

Question 48

State which part of the brain controls heart rate, and describe how is role of controlling heart rate is divided into two centres.

Answer 48

1. The medulla oblongata in the brain is responsible for controlling heart rate. 2. There are two centres within the medulla oblongata, linked to the sinoatrial node in the heart by motor neurons 3. One centre increases heart rate by sending impulses through the sympathetic nervous system, these impulses are transmitted by the accelerator nerve 4. One centre decreases heart rate by sending impulses through the parasympathetic nervous system, these impulses are transmitted by the vagus nerve.

Question 49

Which nervous system is heart rate controlled by

Answer 49

1. Heart rate is involuntary and controlled by the autonomic nervous system

Question 50

Which nervous system is heart rate controlled by

Answer 50

1. Heart rate is involuntary and controlled by the autonomic nervous system

Question 51

State the two receptors that detect changes in the blood

Answer 51

1. Chemoreceptors (chemical receptors) | 2. Baroreceptors (pressure receptors)

Question 52

What do chemoreceptors detect and how does this affect heart rate

Answer 52

1. They are located in the aorta, carotid artery and the medulla 2. Chemoreceptors are sensitive to changes in the pH level of the blood. 3. If the CO2 level in the blood increases, the pH of the blood decreases because carbonic acid formed when the CO2 interacts with water in the blood. 4. If chemoreceptors detect a decrease in pH, a response is triggered to increase heart rate- blood therefore flows more quickly to the lungs so the CO2 can be exhaled 5. When the CO2 level in the blood decreases, the pH of the blood rises. This is detected by the chemoreceptor in the wall of the carotid arteries and the aorta. 6. This results in a reduction in the frequency of the nerve impulses being sent to the medulla oblongata, which in turn reduces the frequency of impulses being sent to the SAN via the sympathetic nervous system and thus heart rate is back to normal

Question 53

What do baroreceptors detect and how does this affect heart rate

Answer 53

1. Baroreceptors present in the aorta and carotid artery wall detect changes in pressure. 2. If blood pressure is too high, impulses are sent to the medulla oblongata centre which decreases heart rate. 3. The medulla oblongata sends impulses along the parasympathetic neurones to the SAN which decreases the rate at which the heart beats. This reduces blood pressure back to normal 4. If blood pressure is too low, impulses are sent to the medulla oblongata centre which increases heart rate 5. The medulla oblongata sends impulses along sympathetic neurones to SAN which increases the rate at which the heart beats. This increases blood pressure back to normal.

Question 54

What factor other than pressure and pH affects heart rate and how does this affect it

Answer 54

1. The presence of hormones 2. In times of stress adrenaline and noradrenaline are released 3 These hormones affect the pacemaker region of the heart itself- they speed up your heart rate by increasing the frequency of impulses produced by the SAN

Question 55

Draw a flow chart to show the effect of exercise on cardiac output.

Answer 55

1. Increased muscular/metabolic activity 2. More carbon dioxide produced by tissues from increased respiration 3. Blood pH is lowered 4. Centre in medulla oblongata that speeds up heart rate, increases frequency of impulses to SAN via the sympathetic nervous system 5. SAN increases heart rate 6. Increased blood flow removes carbon dioxide faster 7. Carbon dioxide levels return to normal

Question 56

Describe when a “Student’s t-test” would be used to analyse data.

Answer 56

1. Used to compare the mean values of two sets of data 2. To use this test the data collected must be normally distributed and enough data should be collected to calculate a reliable mean. 3. Different sample sizes may be used

Question 57

Describe when a paired t-test would be used and when an unpaired t-test would be used to analyse data.

Answer 57

1. Unpaired t-test compares two different subjects- two independent groups 2. Paired - compares the same subject/ the same group measured before and after and event/manipulation

Question 58

Describe the meaning of each of the symbols in the equation for calculating the t-value (the test statistic) from an unpaired Student’s t-test.

Answer 58

1. x̄1 -mean of sample one x̄2- mean of sample 2 2. σ1- standard deviation of sample one σ2 -standard deviation of sample two 3. n1- population of sample one, n2- population of sample two

Question 59

Describe the steps to carry out an unpaired student's t-test

Answer 59

1. Work out the t-value by using the formula 2. Calculate degrees of freedom df= (n1+n2)-2 3. Then look at corresponding probability values. 4. For the data to be considered significantly different from chance alone, the probability must be 5% or less 5. The calculated statistic needs to be less than the t-value at 5% at the degree of freedom to be significant. Otherwise you accept the null hypothesis. 6. 95% it is significant 7. 99% highly significant 8. 99.9% very highly significant