Science Assessment task 1

• Sensory neuron

  Transmits impulses from sense organs to other neurones in the CNS
• Interneuron (also called connector neuron)

  Connect sensory neurons with motor neurons. Mainly found in brain and spine
• Motor neuron


  Transmit impulses from CNS to effectors (muscles and glands)
• A nerve consists of a bundle of nerve cells(neurons)
• • Nerve impulses travel along a neuron in one direction only — from one neuron to another.
• The junction between two nerve cells is called a *synapse.
• The gap between two nerve cells is called the *synaptic cleft.
• When an impulse reaches the axon terminals of a neuron, it causes chemical compounds called neurotransmitter to be released into the *synapse.
• • When a neurotransmitter locks onto receptors in the membrane of the cell on the other side of the synapse, this causes the cell to fire.
• Receptor cells detect a change in the environment (a stimulus) and start electrical signals along neurons. These move towards the central nervous system (spinal cord and brain) where it coordinates the responses. Messages are then sent back along different neurones to muscles which contract or relax and glands which secrete hormones. Muscles and glands are called effectors.
• Effectors produce a specific response to a detected stimulus. For example:

  • a muscle contracting to move an arm
  • muscle squeezing saliva from the salivary gland
  • a gland releasing a hormone into the blood.
• sensory

  Detect changes in environment via receptor and send signals to brain
• interneuron


  Nerve cells that connect sensory neurons to motor neurons
• motor

  Send messages from brain to muscles of glands that carry out a response
• cell body

  Contains cytoplasm and nucleus - required for cell function
• dendrite


  Short projects or extensions that stretch out of the cell body - receive external input signals(nerve impulses) from brain
• axon

  Long thread like projection of the neuron - sends out information
• myelin sheath

  Insulating and protective sheath( the axon ) - to encase the electrical signals ; made of fats and proteins + Increases the speed of the nerve signals
• The nerves carry messages in the form of electrical signals called nerve impulses.

  Neurons are bundled together to form a nerve
• Motor neuron

  A) dendrites

  B) axon

  C) Myelin Sheath

  D) Axon terminal

  
• Receptor


  Component which detects environmental changes from stimuli
• Effector


  Takes action of signal sent from brain.
• Stimuli

  Triggers receptor(creates changes in environment)
• A disease could come from different sources, whether it is genetics, environmental or pathogenic based.
• A micro-organism is any organism that is of microscopic or submicroscopic size.
• What is a physical barrier?

  Physical barriers stop pathogens from entering the body by blocking or trapping them. Examples include skin and mucus. Some physical barriers, like cilia, actively push pathogens out.
• What are chemical barriers?

  Chemical barriers kill pathogens before they can enter the body. They include stomach acid as well as enzymes in tears, saliva and mucus.
• Explain the role of the first line of defense

  The first line of defence prevents pathogens from entering the body. The skin is a major barrier that keeps pathogens out. Special defences are needed to protect the mouth, airways, eyes and urinary tract.
• In biology, the definition of disease is

  a disorder of structure or function of an organism that is not a direct result of physical injury
• A disease could come from different sources, whether it is genetics, environmental or pathogenic based.
• A pathogen is a disease causing agent and pathology is the study of disease.

  A prion is another microorganism(not really considered that) - like a virus.

  A mis-folded protein influencing other proteins to mis-fold