Topic 11 - Coordination and Response

• adrenal glands

  pair of endocrine glands situated above the kidneys. Secretes adrenaline.

  
• adrenaline


  hormone secreted by the adrenal glands. Stimulates several organs in the 'fight or flight' response

  
• dendrites

  fine extensions of the dendrons of a neurone

  
• diabetes

  disease where the blood glucose concentration cannot be properly controlled. Caused by a lack of insulin

  
• effector


  organ that brings about a response (a muscle or gland)

  
• endocrine gland


  gland secreting a hormone into the bloodstream

  
• excretion


  removal from the body of the waste products of metabolism
• glucagon


  hormone released by the pancreas. Action of glucagon causes an increase in the concentration of glucose in the blood

  
• glycogen

  polysaccharide of glucose that acts as a storage carbohydrate in animals and fungi. Found in liver and muscles

  
• homeostasis

  maintaining constant conditions in the body. Maintaining a constant internal environment buy, a constant internal environment

  
• hormone

  In animals: chemical messenger that travels in the blood. In plants: chemical messengers affecting growth

  
• insulin hormone

  produced by the pancreas. Action of insulin results in a decrease in the concentration of glucose in the blood

  
• motor neurone


  nerve cell that transmits impulses from the central nervous system to an effector organ

  
• myelin sheath


  covering made of a lipid material that surrounds an axon. Nerve cells that have a myelin sheath are described as myelinated

  
• negative feedback

  process where a change in the body is detected and brings about events that return conditions to normal

  
• nerve impulse


  tiny electrical signal that passes down a nerve cell. Caused by movements of ions in and out of the axon

  
• neurone


  nerve cell

  
• neurotransmitter


  chemical released at the end of a neurone by the arrival of a nerve impulse. The neurotransmitter diffuses across a synapse causing a new impulse in the following neurone

  
• receptor

  cell or organ that detects a stimulus. Can also refer to a channel/protein in the membrane of a cell e.g. post-synaptic receptor.
• reflex action

  rapid/automatic/involuntary response to a stimulus

  
• reflex arc

  nerve pathway of a reflex action

  
• relay neurone


  short neurone that connects a sensory neurone with a motor neurone in the CNS

  
• response

  reaction by an organism to a change in its surroundings

  
• sensory neurone


  nerve cell which carries impulses from a receptor into the CNS

  
• shivering

  rapid, involuntary contractions of skeletal muscles which generates heat when a person is cold

  
• stimulus

  change in the surroundings of an organism that produces a response

  
• sweat gland

  structure in the dermis of the skin that secretes sweat

  
• synapse


  junction between two neurones

  
• vasoconstriction

  narrowing of blood vessels in the skin. Decreases the blood flowing through the skin to reduce heat loss

  
• vasodilation

  widening of blood vessels in the skin. Increases the blood flow through the skin to increase heat loss

  
• hair erector muscle

  muscle attached to the base of

  each hair in the skin. The muscle contracts to pull the hair upright