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Flashcards in Responding to the environment: Humans Deck (241)
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What does the pupillary reflex do?

regulates the amount of light that enters the eye


What is astigmatism?

An irregular curvature of the CORNEA or LENS of the eye


What is the retina?

inner layer of the eye

contains light-sensitive rod and cone cells


What makes up the PNS?

12 pairs of cranial nerves

31 pairs of spinal nerves


How do organisms respond to stimuli in the environment allowing us to survive?

in a series of events


How do sesory recpeptors respond to simuli?

They initiate the transmission of nerve impulses via the sensory nerves


What are nerotransmitters released from?

Vesicles in the pre-synaptic neuron


What does a damaged spinal cord result in?

paralysis (immediate loss of the ability to move)

loss of feeling below the fracture


What is a synapse?

A gap between the two neurons over which an impulse is transmitted


The brain is the ___ of the spinal cord

large anterior end


Expliain, in detail, the process of how one hears sound

  1. pinna collects sound waves
  2. passed down auditory canal
  3. cause eardrum to vibrate
  4. cause the hammer anvil and stiuup to vibrate (amplifying vibrations)
  5. pass from stirrup through oval window
  6. pass into the inner ear (cochlea)
  7. create waves in the fluid within the inner ear
  8. waves stimulate hair cells of organ of Corti
  9. stimulus converted into a nerve impulse
  10. impulses transmit along auditory nerve to cerebrun
  11. cerebrum interprets nerve impulses as sound
  12. waves travel out round window into eustachian tube (which eases pressure in cochlea)


What is the leading cause of visual lloss amoung adults aged 55 years and older?



What kind of matter makes up the outer layer of the spinal cord?

White matter


What are reflex actions?

Actions that the body has no voluntary control over.

This includes sneezing an blinking


What is the structure of a sensory neuron?

One branch which acts as a dendrite and another branch that acts as an axon


What is the middle ear filled with?



What can the ANS be divided into?

The symapathetic nervous system


the parasympathetic nervous system


What is the most important function of the PNS?

Reflex actions


What is the conjunctiva?

thin transparent membrane lining cornea and eyelids

protects the front of the eye


What is the cornea?



allows light into the eye

refracts light rays so they focus on the retina


Explain the 5 stages of a reflex arc

  1. The receptor detects stimulus and generates a nerve impulse
  2. The sensory neuron conducts impulses from receptor to CNS
  3. The connector neuron conducts impulses from sensory neuron to motor neuron
  4. The motor neuron conducts impulses from CNS to effector
  5. The effector brings about an action in response to the stimulus


What can motor neurons also be called?

Efferent neurons


If you are short-sighted, is light focused in front of or behind of the retina?

In front of


What happens to the eye in dim light?

circular muscle relaxes

pupil dilates


What is the optic nerve

Sends electrical impulses from the rods and cones of the retina to the cerebrum

Here, interpretation of the image will take place


What are axons often immediately surrounded by?

A fatty myelin sheath


What is a connector neuron?

A neuron that uccurs between sensory and motor neurons in the CNS.

Connector neurons are found in reflex arcs


Does the parasympathetic nervous system increase or decrease blood pressure?

decreases blood pressure


Why does the myelin sheath break down when someone has MS (multiple sclerosis)?

The body's immune system attacks the meylin sheath, causing it to break down


How are impulses conducted across a synapse?

  1. Nerve impulses travel along axon to synaptic knob
  2. Vesicles release neurotransmitter into synaptic cleft
  3. neurotransmitter becomes attached to membrane of adjacent dendrite
  4. neurotransmitter is broken down by enzymes atttached to post-synaptic membrane
  5. neurotransmitter diffuses across synaptic cleft