Animal responses : OCR a-level biology : 5.1.5.2

• what does the CNS consist of

  brain and spinal cord
• what is the peripheral nervous system system made of

  nerves that connect the CNS to the rest of the body
• describe the structure of the cerebrum and its function

  - larest part of the brain

  - 2 hemispheres

  - language processing, vision, thinking and emotion
• what are 2 hemispheres connected by

  the corpus callosum
• role of hypothalamus

  - maintaining body temp

  - producing hormones

  - control pituitary gland
• function of the cerebellum in the brain

  - movement and balance

  - in the back of the brain
• cerebral cortex

  - thin outer layer of cerebrum

  - folded for lager SA

  - language processing, thinking and emotions
• medulla oblongata


  - base of the brain

  - unconscious processes ( breathing rate )
• Reflexes

  rapid, unconscious actions

  - protects body from harm

  - blinking
• eye reflexe

  > cornea is stimulated

  > sends electrical impulses along a sensory neurone to CNS

  > in CNS relay neurone passes impulse between sensory and motor neurone

  > passes impulse to orbicularis oculi muscles
• stretch receptors


  receptors that sense muscle stretch and contraction
• muscle contaction

  > in quadriceps muscle detect muscle being stretched

  > electric impulse along sensory neurone to spinal cord

  > then to motor neurone

  > to quadriceps muscle

  > muscle contracts
• hormones during flight or fight respond

  - pituitary gland releases ACTH

  -ACTH acts on adrenal gland

  - stimulating release of steroid hormones from adrenal cortex
• nervous system during flight or fight response

  - sympathetic branch of the autonomic nervous system is activated

  - signals adrenal gland to release adrenalin from the adrenal medulla
• effects of released steroid hormones and adrenaline

  - breakdown of glycogen

  - blood flow towards brain and muscles

  - increased heat rate and breathing

  - erector pili muscles contact > hair stands
• cardiovascular control centre


  changes heart rate

  - sends impulses along sympathetic or parasympathetic neurones

  - releases different neurotransmitters onto SAN

  - SAN modifies rate of firing
• 2 types of receptors responsible for detecting stimuli in blood and signalling the medulla oblongata

  baroreceptor and chemoreceptors
• Baroreceptors


  detect changes in blood pressure
• Chemoreceptors

  detects oxygen concentration in blood

  - sensitive to pH causing CO2 to dissolve in blood = carbonic acid
• Where are chemoreceptors and baroreceptors located?

  aortic and carotid bodies
• what happens to the medulla oblongata when it receives a signal from baroreceptors and chemoreceptors


  it changes the rate at which the SAN fires
• if blood pressure or oxygen concentration is low

  the cardiovascular control centre increases the rate of SAN firing through activation of the sympathic nervous system
• How does the sympathetic nervous system increased heart rate?

  by releasing a neurotransmitter called noradrenaline which binds to receptors on SAN
• Is blood pressure or oxygen concentration is high

  The cardiovascular control centre reduces the rate of SAN firing by activating the parasympathetic nervous system
• How does the parasympathetic nervous system decrease heart rate?

  by releasing in your transmitter called acetylcholine which binds to the receptors on the SAN slowing the rate of firing
• Three. Different types of muscles

  skeletal, cardiac, smooth
• What is skeletal muscle used for?

  physical movement
• Skeletal muscle is made up of bundles of long muscle cells. What are they called?

  muscle fibres
• sarcolemma


  muscle cell membrane
• Sacroplasm


  cytoplasm of a muscle cell
• Transversetubules (T tubules)


  when the sarcolemma folds into the sarcoplasm
• purpose of T tubules

  helps spread electrical impulse throughout the cell
• sarcoplasmic reticulum

  stores calcium ions for muscle contraction
• How do muscle cells differ from other cells?

  - contain more nuclei

  - Lot of mitochondria to generate ATP for muscle contraction.

  - Contain long cylinders of proteins called microfibrils enabling muscle fibre to contract
• Sacomeres


  short units that make up the myofibril
• The two types of myofilament that make up myofibrils

  myosin and actin
• Myosin


  - thick myofilament

  - Dark band ( A band )
• Actin

  - thin myofilament

  - Light band ( I band)
• Z-line

  end of sarcomere

  - where sarcomeres join
• M-line


  middle of sarcomere