animal responses

• central nervous system

  • relay neurones
  • brain and spinal chord
  • grey matter - cell bodies
  • white matter - myelinated neurones
• peripheral nervous system

  • sensory and motor neurones
  • splits into - autonomic and somatic
• autonomic nervous system

  • involuntary
  • controls homeostasis
  • target tissue - cardiac muscle and smooth muscle
  • 2 neurones in pathway
  • splits into - sympathetic and parasympathetic
• somatic nervous system

  • voluntary
  • conscious activities
  • target tissue - skeletal muscle
  • excitatory effect on tissue
  • 1 neurone in pathway
  • mostly myelinated neurones
• sympathetic

  • more active at times of stress
  • controls flight/fight
  • ganglion outside spinal cord
  • pre-ganglionic neurone very short
  • nordarenaline at synapse
• parsympathetic

  • more active during sleep and relaxation
  • ganglion within target tissue
  • pre ganglion length varies
  • acetylcholine at synapse
• cerebrum - concious thought and imagination
• cerebellum - coordination, balance
• medulla oblongata - non skeletal muscle, involuntary movements, cardiac centre
• hypothalamus - controls body temperature, hunger, and regulates pituitary gland
• pituitary gland - releases and stores hormones e.g, ADH
• reflex is a rapid and involuntary response to a stimulus, does not involve the brain
• a reflex arc

  the stimulus is detected by receptors. impulse travels along sensory neurones, through the dorsal root ganglion into spinal cord. might pass into motor or relay neurone and then motor neurone.
• if a relay neurone is present then can inhibit some reflexes e.g, blinking and contact lenses
• knee jerk reflex

  sensory neurone directly stimulates a motor neurone
• fight/flight response

  1. cerebral understanding activates the hypothalamus
  2. activity increased in the sympathetic
  3. adrenaline released from adrenal medulla of adrenal gland
  4. hypothalamus released CRH and TRH which stimulate pituitary gland
• control of heart rate - heart is myogenic and required oxygen and glucose but also carbon dioxide to be removed
• heart rate too slow

  1. cardio vascular centre in medulla oblongata detects
  2. sympathetic nerve activates
  3. noradrenaline released at SAN
• heart rate too fast

  1. cardiovascular centre in medulla oblongata detects
  2. vagus nerve activates
  3. act released at SAN
• nervous control of the heart

  • stretch receptors - detects movement of limbs and if more oxygen is needed
  • baroreceptors - detect pressure changes
  • chemoreceptors - detect pH changes, from carbon dioxide
• hormonal control - adrenal glands secrete adrenaline and noradrenaline increase the frequency and strength of the heart beat
• voluntary (skeletal) muscle

  • striated
  • multinucleate
  • in limbs and attached to sketelon
• involuntary smooth muscle

  • non striated
  • uninucleate
  • spindle shaped
  • in bronchioles, arteries
  • controls diameter of: arteries, bronchioles and pupil size
• cardiac muscle

  • striated
  • branched
  • intercalated discs
  • uninucleate
  • heart
  • pump blood around the body and removal of waste products
• sarcolemma - cell surface membrane of skeletal muscle
• sarcoplasm - cytoplasm of muscle fibre
• sarcoplasmic reticulum - release of calcium ions
• t tubules - infolding of the sarcolemma
• events at a neuromuscular junction

  1. action potential causes voltage gated calcium ion channels to open and diffuse in
  2. synaptic vesicles move and fuse with pre-synaptic membrane
  3. acetylcholine released into cleft
  4. acth bind to receptors on sarcolemma causing sodium channels to open
  5. sodium ions flood in causing the t tubules to depolarise
  6. calcium ions diffuse out of the sarcoplasmic recticulum
  7. calcium ions bind to proteins in the muscle causing contraction
  8. acetylcholinesterase breaks down acth
• sarcomere - the region between two z lines
• z line holds together thin actin filaments
• m line holds thick myosin filaments
• a band remains the same in muscle contraction
• h zone decreases

  just myosin
• I band decreases

  light band
• thin actin filaments - globular proteins, coiled around fibrous protein tropomyosin
• sliding filament model

  1. tropomyosin covers the actin binding sites
  2. calcium ions released into sarcoplasm during impulse, binds to troponin, causing troponin to change shape and move the tropomyosin, exposing binding sites
  3. myosin head attaches forming cross bridges
  4. myosin heads bend causing the thick filament to overlap with the thin filament = power stroke
  5. atp attaches to myosin head detaching
  6. atp hydrolysed causing heads to move back and bind to new site
• atp also used for active transport of calcium ions back into the sarcoplasmic reticulum
• sources of atp

  1. creatine phosphate - held in the sarcoplasm
  2. aerobic respiration - 38 produced
  3. glycogen reserves and oxygen from oxygen-myoglobin
  4. anaerobic respiration - 2 produced