Animal responses Flashcards
Peripheral nervous system
Made up of the neurones that connect the cns to the rest of the body. It also has two functional systems.
CNS (Central nervous system)
Made up of the brain and spinal cord
Somatic nervous system
Controls conscious activities eg running and video games
Autonomic nervous system
Controls unconscious activities eg digestion- it had two divisions that have opposite effects on the body.
Parasympathetic nervous system
Calms the body down- The ‘rest and digest’ system. Parasympathetic neurones release the neurotransmitter acetylcholine
Sympathetic nervous system
Gets body ready for action. Its the fight or flight system. Sympathetic neurones release the neurotransmitter noradrenaline.
Hypothalamus
Controls body temperature
- Found beneath middle part of brain
- Automatically maintains body temperature at the normal level
- Produces hormones that control the pituitary gland
Cerebrum
Allows you to hear see learn and think.
- Largest part of brain
- Two halves called cerebral hemispheres
Pituitary gland
Controls hormone release by the bodies glands.
- Found beneath hypothalamus
- Controlled by the hypothalamus
- Releases hormones and stimulates other glands.
Medulla oblongata
Controls breathing rate and heart rate automatically
Cerebellum
Coordinates muscles, balance and posture.
Reflex
Help organisms avoid damage to the body because they are rapid.
Blinking reflex
- 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
Knee jerk reflex
- 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.
Flight or fight response- What happens?
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.
Sympathetic nervous system and adrenaline effects on the body
- 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.
How does the nervous system control heart rate?
-SAN generates electrical impulses that cause the cardiac muscles to contract rate the SAN fires is controlled by the medulla.
How do animals alter there heart rate in response to internal stimuli?
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.
Stimuli High blood pressure
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.
Stimuli low blood pressure
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.
Stimuli high blood O2 Low C02 `
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
Stimuli High CO2 low O2
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.
What coordinates muscle movement?
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.
How do skeletal muscles work and what is it made from?
- 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.
Myofibrils
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.
Thick myofilaments
Made up off the protein myosin
- Dark bands contain these myosin filaments and are called A bands
Thin myofilaments
Made up of the protein actin
- Light bands only contain thin actin filaments only and are called I bands
Sliding filament theory
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.
What does myosin filaments have that makes them able to bind and move?
- 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.
What happens when the muscle is resting
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.
How does muscle contraction take place?
- 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
Muscle contract continued
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.
What does ATP do in muscles
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
