animal responses ( module 5 : section 3 )

The nervous system splits into two main structural systems explain what those structural systems are?

( CNS ) the central nervous system - is made up of the brain and the spinal cord

The peripheral nervous system - is made up of neurones that connect the CNS to the rest of the body

Explain the two functional systems the peripheral nervous system is divided into

• the somatic nervous system controls conscious activities e.g ) running

• the autonomic nervous system controls unconscious activities e.g ) digestion

Explain the two divisions the autonomic nervous systems further divide into

• the sympathetic nervous system gets the body ready for action

• It’s the fight or flight system

• The sympathetic neurones release a neurotransmitter called noradrenaline

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• the parasympathetic nervous system calms the body down

• It’s the rest and digest system

• Parasympathetic neurones releases a neurotransmitter called acetylcholine

State the function of the hypothalamus in the brain

• The hypothalamus automatically maintains body temperature at the normal level

• The hypothalamus produces hormones that controls the pituitary gland

Describe and Explain the role of the cerebrum

• the cerebrum is the largest part of the brain

• its divided into two halves called cerebral hemispheres

• The cerebrum has a thin outer layer called the cerebral cortex which is highly folded

• The cerebrum is involved in vision, hearing, learning and thinking

Explain where the pituitary gland is and its function

• the pituitary gland is found beneath the hypothalamus

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• It is controlled by the hypothalamus

• it releases hormones and stimulates other glands ( e.g ) adrenal glands to release their hormones

Explain where the medulla oblongata is located and its function

• the medulla oblongata is at the base of the brain at the top of the spinal cord

• it automatically controls breathing rate and heart rate

Explain where the cerebellum is located and explain its function

• the cerebellum is underneath the cerebrum and it also has a folded cortex

• it’s important for muscle coordination, posture and coordination of balance

Explain what a reflex is and why a reflex is fast

• A reflex is where the body responds to a stimulus without making a conscious decision to respond

• This is because the pathway of communication doesn’t involve conscious parts of the brain y

• You don’t have to spend time deciding how to respond - information travels really fast from receptors to effectors

What does a knee jerk reflex work to do

• Works to quickly straighten your leg if the body detects your quadriceps is suddenly stretched

• It helps to maintain posture and balance

Explain how the knee jerk reflex works to ensure an individual remains upright

• stretch receptors in the quadriceps muscle detect that the muscle is being stretched

• A nerve impulse is passed along a sensory neurone which communicates directly with a motor neurone in the spinal cord ( there is no relay neurone involved )

• The motor neurone carries the nerve impulse to the effector ( the quadriceps muscle ) causing it to contract so the lower leg moves forward quickly

Label the parts of the brain

A - hypothalamus

B - pituitary gland

C - medulla oblongata

D - cerebrum

E - cerebrum

When an organism is threatened it responds by preparing the body for action this response is called the fight or flight response explain what occurs during this response

• nerve impulses from sensory neurones 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 gland to release steroidal hormones

• The sympathetic nervous system is activated, triggering the release of adrenaline from the medulla region of the adrenal gland

explain the following effects the sympathetic nervous system and adrenaline have during the fight or flight response

• heart rate is increased —- so blood is pumped around the body faster

• The muscles around the bronchioles relax —- so breathing so 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 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 Pili muscles in the skin contract — this makes hairs stand on end so the animal looks bigger

Explain the two ways the nervous system helps to control heart rate

• the Sinoatrial node (SAN) generates electrical impulses that causes the cardiac muscles to contract

• the rate at which the SAN fires (i.e the heart rate) is unconsciously controlled by the medulla

Give examples into why animals need to alter their heart rate to respond to internal stimuli

• to prevent fainting due to low blood pressure

• or to make sure the heart rate is high enough to supply the body with enough oxygen

What are the two types of receptors that detect stimuli

• pressure receptors

• Chemical receptors

How does the body detect changes that affect heart rate

• there are pressure receptors called baroreceptors in the aorta and the vena cava they’re stimulated by high and low blood pressure

• There are chemical receptors called chemoreceptors in the aorta, the carotid artery ( a major artery in the neck ) and In the medulla. They monitor the oxygen level in the blood and also carbon dioxide and pH

Explain what happens when the baroreceptors detect high blood pressure and in addition what’s the effector muscles and response after

• impulses are sent to the medulla which sends impulses along the vagus nerve

• This secretes acetylcholine which binds to receptors on the SAN

Effector muscle - cardiac muscle

Response - heart rate slows down to reduce blood pressure back to normal

Explain what happens when the baroreceptors detect low blood pressure and what’s the effector muscle and response

• impulses are sent to the medulla which sends impulses along the accelerator nerve

• This secretes noradrenaline which binds to receptors on the SAN

effector muscles - cardiac muscles

Response - heart rate speeds up to increase blood pressure back to normal

Explain what happens when the chemoreceptors detect High oxygen levels low CO2 or high pH levels & what’s the effector muscle and response

• impulses are sent to the medulla which sends impulses along the vagus nerve

• This secretes acetylcholine which binds to receptors on the SAN

muscle - cardiac muscle

Response - heart rate decreases to return O2 , CO2 and pH levels back to normal

Explain what happens when the chemoreceptors detect low oxygen in blood, high CO2 or low pH levels

• impulses are sent to the medulla which sends impulses along the accelerator nerve.

• This secretes noradrenaline which binds to receptors on the SAN

Effector - cardiac muscle

Response - heart rate increases to return O2 , CO2 and pH levels back to normal

( PRACTICAL SKILLS )

Describe how you would carry out an investigation to find out if regular exercise affects resting heart rate and explain how you would analyse the results

The practical method

• find your pulse count ( count beats per minute )

• Measure your heart rate at rest and record it in a table

• Do some gentle exercise e.g) stepping on and off a step —→ immediately after measure you’re heart rate again

• Return to a resting position. Measure your heart rate every minute until it’s back to its resting state

• Record how long it takes to return back to normal

The t-test explanation

• the student t - test is used to find out whether there is a significant difference in the means of the two sets of data the value obtained is compared to a critical value

• Identify the null hypothesis - the difference is not significant —→ probably just chance

• Calculate the mean and standard deviation for each set of data

• Use the formula to calculate the t value ( usually ignore the minus sign if there is one )

• Calculate the degrees of freedom [ ( number of values data set 1 ) + ( number of values of data set 2) - 2 ] always gonna be 2

• Identify the critical value

• T - value > critical value = difference is significant ( reject the null hypothesis)

• T value < critical value = difference is NOT significant ( accept the null hypothesis)

For movement which muscle does the CNS send signals to

Skeletal muscles

What are the Skeletal muscles made up of?

• large bundles of long cells called muscle fibres

What is the cell membrane of muscle fibre cells called?

Sarcolemma

Explain how sarcolemma spread electrical impulses to all the muscle fibres

•