Chapter 7

Question 1

2 divisions of the nervous system

Answer 1

Central and Peripheral

Question 2

Central Nervous System includes..

Answer 2

brain and spinal cord

Question 3

Peripheral Nervous system includes..

Answer 3

peripheral nerves(cranial and spinal nerves)

Question 4

Describe spinal nerves

Answer 4

• Spinal nerves from the spinal cord are paired (sensory and motor nerves)
  -The amount varies with the number of vertebrae in the vertebral column:
• Rock Pigeon (Columba livia) has 39 pairs of spinal nerves; Ostrich (Struthio camelus) has 51

Question 5

How are spinal nerves attached to the spine?

Answer 5

• They have a ventral root containing motor neurons and a dorsal root containing sensory neurons
• it attaches to the Arachnoid Dura Pia

Question 6

Meninges

Answer 6

• protect the brain and spinal cord

Question 7

Describe the avian eye

Answer 7

• large relative to the size of the head and brain
• has anterior chamber (between iris and cornea) and posterior chamber ( between iris and lens)

Question 8

Nictitating membrane

Answer 8

• in many birds; has a cartilaginous-like connective tissue fold along the leading edge of the membrane called the marginal plait
• Sweeps the surface of the eye to keep it clean

Question 9

What 2 glands lubricate the surface of the eye

Answer 9

lacrimal gland and Harderian gland

Question 10

3 types of avian eyes

Answer 10

• flattened
• globose
• tubular

Question 11

flattened avian eye

Answer 11

• wide angle lens

Question 12

globose avian eye

Answer 12

• zoom lens
• in swallows, most raptors

Question 13

tubular avian eye

Answer 13

• adapted for low light levels
• in owls

Question 14

Name the layers of the eye

Question 15

Sclera

Answer 15

• layer that includes the sclerotic ring, cornea, Crampton’s muscle and Bruckner’s muscle

Question 16

Sclerotic ring

Answer 16

• made up of approx. 12-15 small bones called scleral ossicles

Question 17

cornea

Answer 17

• change their curvature to focus light on the light-sensitive cells of the retina
• this happens in the lens of the eye as well

Question 18

Crampton’s muscle

Answer 18

muscle increases the corneal curvature
striated muscle
helps focus on objects

Question 19

Bruckner’s muscle

Answer 19

• change the shape of the lens
• helps focuses on objects
• striated muscle

Question 20

Choroid

Answer 20

• layer 2 of the avian eye
• includes the iris, pupil, and lens

Question 21

iris

Answer 21

• thin layer of tissue that controls the size and shape of the pupil
• The underlying mechanisms that determine eye coloration follow the same general principles as feather coloration
• Iris color can differ among individuals within the same species, either between sexes or among the same species at different ages

Question 22

lens

Answer 22

• lens change their curvature to focus light on the light-sensitive cells of the retina

Question 23

The retina

Answer 23

• layer 3 of the avian eye
• includes the fovea, pecten, and optic nerve

Question 24

Optic nerve

Answer 24

• intertwined with blood vessel
• has a blind spot
• blind spot where optic nerve and retinal blood supply exit the eye orbit
• eyes on side have narrow sigh/wideron sides t while eyes of the front provide wider range of vision forward but with huge blind spot

Question 25

pecten

Answer 25

• Source of nutrition and oxygen for the retina
• Allowed birds to increase the density of light receptors in the retina while entirely eliminating retinal vasculature
• This evolutionary innovation has greatly advanced the visual acuity of birds

Question 26

Foveae

Answer 26

• concave depressions of high cone density
• has temporal and central fovea

Question 27

temporal fovea

Answer 27

• forward-directed eyes with good binocular vision (fast-flying birds and aerial or diving predators
• owls

Question 28

Central fovea

Answer 28

• located in the center of the retina near the optic nerve - images the portions of the visual field on either side of the bird

Question 29

Tapetum lucidum

Answer 29

• A structural color produced by light scattering from an array of lipid spheres in the last layer of the retina (the retinal pigmented epithelium)
• in barred owls

Question 30

binocular vs monocular vision

Answer 30

• Monocular vision refers to the ability to see with one eye, while binocular vision is the ability to see with both eyes
• monocular vision can give a wider range of sight but binocular vision can focus on objects better