Biology: The Nervous System and Senses

The Nervous System - Senses

• General sensation receptors include:
  • Mechanoreceptors (respond to mechanical stimuli)
  • Thermoreceptors (respond to temperature changes)
  • Nociceptors (respond to pain stimuli)
  • Chemoreceptors (respond to chemical changes)
• Special senses include:
  • Vision
  • Hearing
  • Taste
  • Smell
  • Balance
• Receptive field: the specific area of the body that a particular sensory receptor is responsible for detecting stimuli from
• Gustation: the sense of taste
• Olfaction: the sense of smell
• Inner ear structures and functions:
  • Cochlea: converts sound waves into electrical signals
  • Vestibule: detects head position and movement
  • Semicircular canals: detect rotational movement
• Eustachian tube: connects the middle ear to the back of the throat, helping to equalize air pressure
• The three layers of the eye from most superficial to deepest:
  • Sclera (white, outer layer)
  • Choroid (middle layer with blood vessels)
  • Retina (inner layer with light-sensitive cells)

The Endocrine System

• Hypothalamic releasing hormones: stimulate the release of other hormones from target glands
• Hypothalamic inhibiting hormones: inhibit the release of other hormones from target glands
• Target glands affected by hypothalamic hormones include:
  • Pituitary gland
  • Adrenal glands
  • Thyroid gland
• "Releasing" means stimulating the release of another hormone
• "Inhibiting" means blocking the release of another hormone
• The two "thyroid hormones" are:
  • Triiodothyronine (T3)
  • Thyroxine (T4)
• The three major categories of the adrenal cortex and their examples are:
  • Mineralocorticoid hormones (e.g., aldosterone)
  • Glucocorticoid hormones (e.g., cortisol)
  • Androgen hormones (e.g., DHEA)
• The two hormones that are also neurotransmitters and secreted from the adrenal medulla are:
  • Epinephrine (adrenaline)
  • Norepinephrine
• The three general categories of hormones based on chemical structure are:
  • Steroid hormones
  • Amino acid-derived hormones
  • Peptide hormones
• Up-regulation of receptors: an increase in the number of receptors on a target cell, making it more responsive to hormone signals
• Down-regulation of receptors: a decrease in the number of receptors on a target cell, making it less responsive to hormone signals
• The four ways for hormones to be eliminated from the body are:
  • Metabolism by enzymes
  • Excretion by the kidneys
  • Excretion by the liver
  • Degradation by proteases