human response

• sensory neurone?

  starts at receptor and ends at spinal cord and relay neurone
• relay neurone?

  found in spinal cord and joins the sensory and motor neurones
• motor neurone?

  starts in spinal cord and relay neurone and ends at an effector
• an effector?

  a muscle or gland that carries out the response
• reflex arc?

  R: electrical impulse created by receptor

  S: travels through sensory neurone

  R: joins the relay neurone in the spinal cord

  M: travels along motor neurone

  E: reaches an effector that starts a response
• advantages of reflex?

  quick response = less damage to body
• dendrites?

  Branch-like structures on a neuron that receive signals from other neurons.
• retina?

  have 2 types of photoreceptors - rod cells to see black and white, dima and bright - cone cells to see red blue and green
• bright light?

  see less light = circular muscles contract, radial muscles relax
• dim light?

  see more light = circular muscles relax and radial muscles contract
• distance objects?

  ciliary muscles relax, suspensory ligaments taut, lens becomes long and thin = less convex (light refract less)
• near objects?

  ciliary muscles contract, suspensory ligaments slackened, lens becomes short and fat = more convex (light refract more)
• accommodation?

  the lens ability to change shape to focus
• homeostasis?

  process of the body maintaining a constant internal environment

  controlled by the hypothalamus (used to keep at correct level)
• how does homeostasis work?

  use receptors to monitor levels = if levels are wrong brain sends electrical impulses along nerves to the part of the body that can fix it = negative feedback
• vasodilation?

  blood vessel diameter increase, increase in sweat, hair follicles lie flat, blood closer to skin, more heat lost via radiation
• The function of dendrites in a neuron is to receive incoming signals from other neurons.
• vasoconstriction?

  blood vessel diameter decrease, shivering, hairs raised to trap air between skin and hair, blood lower from skin, sweat less
• hormones?

  chemical messengers that travel in blood plasma from the glands made at to their target organ
• hormone system = endocrine system
• nerves: fast response, lasts short time, affects a specific area
• hormones: slower response, lasts longer, affects larger area
• adrenaline?

  from adrenal gland

  makes body ready to run away

  increases: heart rate, breathing rate, blood flow to muscles, blood sugar levels, respiration rate
• insulin?

  from pancreas

  stored in liver

  reduces blood sugar levels

  turns glucose into glycogen
• testosterone?

  made in testes

  causes male secondary sexual characteristics
• progesterone?

  made in the ovaries

  helps support pregnancy by keeping uterus lining thick
• oestrogen?

  made in the ovaries

  controls menstrual cycle

  repairs uterus lining
• ADH (triple)?

  made in pituitary gland in brain

  affects kidneys

  controls osmoregulation = water content in the blood - released when dehydrated to reabsorb water from urine to blood
• FSH (triple)?

  made in pituitary gland in brain

  affects the ovaries

  causes an ovum to mature once a month

  stimulates oestrogen production
• LH (triple)?

  made in pituitary gland in brain

  affects ovaries

  causes an ovum to be released once a month = ovulation
• • Sensory neurones are long and have a cell body branching off the middle of the axon

  
• Relay neurones are short and have a small cell body at one end with many dendrites branching off it

  
• • Motor neurones are long and have a large cell body at one end with long dendrites branching off it

  
• • Neurones have a cell body (where the nucleus and main organelles are found) and cytoplasmic extensions from this body called axons and dendrites
  • The axon is the main long fibre of the neurone