Animal responses

Question 1

Peripheral nervous system

Answer 1

Made up of the neurones that connect the cns to the rest of the body. It also has two functional systems.

Question 2

CNS (Central nervous system)

Answer 2

Made up of the brain and spinal cord

Question 3

Somatic nervous system

Answer 3

Controls conscious activities eg running and video games

Question 4

Autonomic nervous system

Answer 4

Controls unconscious activities eg digestion- it had two divisions that have opposite effects on the body.

Question 5

Parasympathetic nervous system

Answer 5

Calms the body down- The ‘rest and digest’ system. Parasympathetic neurones release the neurotransmitter acetylcholine

Question 6

Sympathetic nervous system

Answer 6

Gets body ready for action. Its the fight or flight system. Sympathetic neurones release the neurotransmitter noradrenaline.

Question 7

Hypothalamus

Answer 7

Controls body temperature

• Found beneath middle part of brain
• Automatically maintains body temperature at the normal level
• Produces hormones that control the pituitary gland

Question 8

Cerebrum

Answer 8

Allows you to hear see learn and think.

• Largest part of brain
• Two halves called cerebral hemispheres

Question 9

Pituitary gland

Answer 9

Controls hormone release by the bodies glands.

• Found beneath hypothalamus
• Controlled by the hypothalamus
• Releases hormones and stimulates other glands.

Question 10

Medulla oblongata

Answer 10

Controls breathing rate and heart rate automatically

Question 11

Cerebellum

Answer 11

Coordinates muscles, balance and posture.

Question 12

Reflex

Answer 12

Help organisms avoid damage to the body because they are rapid.

Question 13

Blinking reflex

Answer 13

• Sensory nerve endings in the cornea are stimulated by touch.
• A nerve impulse sent along the sensory neurone to a relay neurone in the CNS
• Impulse passed from relay neurone to motor neurone
• Motor neurones send impulses to effectors- orbicularis oculi muscles contract causing eye lid to shut

Question 14

Knee jerk reflex

Answer 14

• Stretch receptors in the quadriceps muscle detect that the muscle is being stretched.
• Nerve impulse is passed along a sensory neurone which communicates directly with a motor neurone in the spinal cord.
• Motor neurone carries nerve impulse to effector causing it to contract and the leg to move forward quickly.

Question 15

Flight or fight response- What happens?

Answer 15

Nerve impulses from sensory neurones arrive at the hypothalamus activating both the hormonal system and sympathetic nervous system.

• Pituitary gland is stimulated and releases ACTH causes the cortex of the adrenal gland to secrete steroidal hormones.
• Sympathetic nervous system is activated, triggering the release of adrenaline from the medulla region of the adrenal gland.

Question 16

Sympathetic nervous system and adrenaline effects on the body

Answer 16

• Heart rate increased
• Muscles around bronchioles relax- breathing deeper
• Glycogen converted into glucose
• Muscles in arterioles going to the skin and gut contract restricting blood flow so its sent to the Heart, lungs and skeletal muscles
• Erector pili muscles in skin contract- hair stands up.

Question 17

How does the nervous system control heart rate?

Answer 17

-SAN generates electrical impulses that cause the cardiac muscles to contract rate the SAN fires is controlled by the medulla.

Question 18

How do animals alter there heart rate in response to internal stimuli?

Answer 18

Pressure receptors called baroreceptors in aorta and vena cava get stimulated by high or low blood pressure.
- Chemical receptors called chemoreceptors in aorta, carotid artery and the medulla monitor O2 level in blood and CO2 and pH.

Question 19

Stimuli High blood pressure

Answer 19

Baroreceptors sense and impulses sent to medulla sends impulses down the vagus nerve which secretes acetylcholine which binds to receptors in the SAN.
- Cardiac muscles get effected and heart rate is slowed down to lower blood pressure.

Question 20

Stimuli low blood pressure

Answer 20

Baroreceptors detect impulses sent to the medulla the down the accelerator nerve and noradrenaline is secreted and binds to SAN which effects the cardiac muscles making the heart beat quicker to raise blood pressure.

Question 21

Stimuli high blood O2 Low C02 `

Answer 21

Chemoreceptors sense Impulses sent to medulla sends impulse down vagus nerve secrets acetylcholine which binds to receptors on the SAN and effects cardiac muscles. Heart rate slows down to lower O2 and increase CO2 and return it to normal

Question 22

Stimuli High CO2 low O2

Answer 22

Chemoreceptors sense and send impulses along accelerator nerve and noradrenaline is secreted and binds to receptors on the SAN and effects cardiac muscles and heart rate increases to return it to normal levels.

Question 23

What coordinates muscle movement?

Answer 23

The CNS controls and coordinates muscle movement- it receives sensory information and decides what response is needed if movement is needed CNS sends it down neurones to the skeletal muscles to contract.

Question 24

How do skeletal muscles work and what is it made from?

Answer 24

• They are made up of large bundles of long cells called muscle fibres- cell membrane of these fibres called sarcolemma.
• Parts of sarcolemma fold inwards across muscle fibre and stick into the sarcoplasm- folds called transverse tubules and help spread electrical impulses throughout the muscle fibre to reach all parts.

Question 25

Myofibrils

Answer 25

Contain bundles of thick and thin myofilaments that move past each other in order to contract.

• Made up of small units called sarcomeres ends of each one marked with a Z Line
• Middle of each sarcomere is a M line
• Around M Line there is a H zone which only contains myosin filaments.

Question 26

Thick myofilaments

Answer 26

Made up off the protein myosin

- Dark bands contain these myosin filaments and are called A bands

Question 27

Thin myofilaments

Answer 27

Made up of the protein actin

- Light bands only contain thin actin filaments only and are called I bands

Question 28

Sliding filament theory

Answer 28

Myosin and actin filaments slide over each other one another to make the sarcomere contract myofilaments themselves don’t contract.
- Simultaneous contraction of lots of sarcomeres means the myofibrils and muscle fibres contract.

Question 29

What does myosin filaments have that makes them able to bind and move?

Answer 29

• They have globular heads that are hinged, so they can move back and forth.
• Myosin head has binding site for ATP and actin.
• Actin filaments have binding sites for myosin head called actin-myosin binding site.
• Tropomyosin and troponin are found between actin filaments- These are attached to each other and help myofilaments move past each other.

Question 30

What happens when the muscle is resting

Answer 30

The actin-myosin binding site is blocked by tropomyosin which is held in place by troponin
- So myofilaments cant slide past each other because the myosin head cant bind to the actin-myosin binding site on the actin filaments.

Question 31

How does muscle contraction take place?

Answer 31

• Triggered by action potential which triggers a calcium influx- when a action potential from a motor neurone stimulates a muscle cell, it depolarises the sarcolemma which spreads down the t tubules to the sarcoplasmic reticulum which causes it to release stored calcium ions into the sarcoplasm

Question 32

Muscle contract continued

Answer 32

Calcium ions bind to troponin causing it to change shape. This pulls the attcahed tropmyosin out of the actin-myosin binding site on the actin filament

• This exposes the binding site which allows the myosin head to bind
• Bond formed is called an actin-myosin cross bridge.

Question 33

What does ATP do in muscles

Answer 33

It provides energy for contraction and to move the myosin head.

• Calcium ions activate the enzyme ATPase which breaks down ATP to provide energy for contraction.
• Energy moves the myosin head pulling the actin filament along like a rowing action