neuronal communication *5

• what is the role of receptors in homeostasis ?

  to detect changes in a specific stimulus involved in a physiological process
• Why are receptors described as transducers ?

  they convert a stimulus into a nerve impulse
• give a specific example of a mechanoreceptor which responds to pressure in the skin.

  pacinian corpuscle
• what stimulus do rods and cones respond to ?

  Light
• what is the name of the sleeve of protein and fatty material which covers some neurones?

  Myelin sheath
• state the name of the cell which produces the sleeve of protein and fatty material which covers some neurones.

  schwann cell
• what effect does the insulating layer of protein and fatty material have on the impulse conduction speed of neurones?

  nerve impulses are conducted at a faster speed
• what is the name of the gaps found in the sleeves of protein and fatty material which covers some neurones ?

  Nodes of Ranvier
• what term is used to describe the period of time when a neurone is unable to repeat an action potential?

  Refractory period
• describe how voltage gated channels and the movement of sodium ions prevent the generation of action potential during the refractory period.

  voltage-gated NA channels are shut, meaning NA+ cannot go into the axon, stopping the generation of an action potential
• give two reasons why a refractory period should follow an action potential.

  makes sure action potential is one way and occurs as discrete impulses
• generated action potentials by neurones are always the same no matter how large the stimulus as long as threshold minimum is reached. what is the name of this response ?

  the all or nothing response
• what method of conduction in myelinated axons involves action potentials jumping from one node of Ranvier to the next?

  Saltatory conduction
• list three factors that affect the speed of conduction along an axon.

  myelination, temperature, axon thickness
• what name is given to the swollen end of a presynaptic neurone?

  Synaptic knob
• which neurotransmitter is found in cholinergic synapses?

  Acetylcholine
• name the two categories synapses can be placed in, based on how they affect the likelihood of an action potential occurring.

  excitatory or inhibitory
• what effect do inhibitory synapses have on the postsynaptic membrane?

  hyperpolarisation
• what term describes the process in which more than one impulse is needed to generate an action potential at synapse ?

  Temporal summation
• name the process by which an action potential is generated from a single presynaptic neurone releasing neurotransmitters a number of times

  temporal summation
• name the process by which an action potential is generated from multiple presynaptic nerurones releasing neurontransmitters

  spatial summation
• which part of the brain controls learning, memory and conscious thoughts?

  cerebrum
• which part of the brain controls unconscious actions including posture and balance ?

  Cerebellum
• which part of the brain controls breathing rate and heart rate?

  Medulla oblongata
• which part of the brain is the regulatory centre for temperature and water balance?

  Hypothalamus
• which part of the brain stores and secretes hormones ?

  Pituitary gland
• what are the three types of muscle found in the body?

  Skeletal, smooth, cardiac
• which type of muscle is under voluntary control?

  Skeletal muscles
• which type of muscle has the slowest contraction speed?

  Smooth muscles
• what two types of muscles are striated?

  Skeletal and cardiac.
• which type of muscle is branched?

  Cardiac
• which type of muscle is mutinucleated?

  Skeletal
• which type of muscle is capable of remaining contracted for relatively long periods of time?

  smooth muscle
• what is actin?

  molecule that forms the thin protein filaments in myofibrils in muscle fibre
• what is myosin?

  myosin is a molecule which forms the thick protein filaments in myofibrils in muscle fibre
• what is a sacromere?

  distance between adjacent Z-lines on a myofibril
• what is the name of the band on a sarcomere where actin and myosin do not overlap?

  light band
• what is the name of the band on a sarcomere where actin and myosin do overlap?

  dark band
• which protein filament is present in the H zone of a sarcomere?

  Myosin
• what is the neuromuscular junction?

  where a motor neurone meets a skeletal muscle fibre