Nervous System - Sense Organs Flashcards

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1
Q

What is a receptor?

A

Specialised cells that detect stimuli and and convert them into nerve impulses

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2
Q

What is a sense organ?

A

A concentration of receptors with the same function

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3
Q

Functions of the ear

A

Hearing and balance

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4
Q

Location of the ear

A

Pinnae positioned outside the skull on opposite sides of the head, rest of the ear embedded in the temporal bone

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5
Q

Three parts of the ear

A

Outer ear
Middle ear
Inner ear

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6
Q

Parts which make up the outer ear

A

Pina

External auditory canal

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7
Q

Structures making up the middle ear

A
Tympanic membrane (eardrum)
Ossicles
Oval window
Round window
Opening to the Eustachian tube
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8
Q

Parts which make up the inner ear

A

Bony labyrinth (perilymph filled)
Membranous labyrinth
Vestibular apparatus
Cochlea

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9
Q

The vestibular apparatus consists of…

A

The utriculus and the sacculus

Three semicircular canals

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10
Q

What are maculae?

A

Special receptors found in the sacculae and utriculae

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11
Q

The function of the maculae

A

Generate impulses when stimulated by gravity during a change in position of the head

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12
Q

The impulses from the maculae go to…

A

The cerebellum (which coordinates muscles to restore balance)

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13
Q

What are cristae?

A

Sensory organs of rotation found in the ampullae of the semi-circular canals

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14
Q

Cristae are stimulated by…

A

Movement of the endolymph of the semi-circular canals due to movement of the head

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15
Q

Impulses from the cristae go to…

A

The cerebellum (which coordinates muscles to restore balance)

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16
Q

The type and location of receptors which detect light stimuli

A

Photoreceptors in the eye

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17
Q

The shape of the eye

A

Pretty spherical

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18
Q

Purpose of the eyelids and eyelashes

A

Protect the eye from foreign objects

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19
Q

Describe the conjunctiva

A

Thin mucous membrane containing pain receptors that are stimulated by dust/other particles and trigger blink reflex

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20
Q

Location of the conjunctiva

A

Covers the front of the eye and the inner surface of the eyelid

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21
Q

Position and function of the tear gland

A

Above the eyeball secretes antiseptic tears that protect the conjunctiva from bacteria and dehydration

22
Q

The eye has how many muscles for movement

A

6

23
Q

Three layers of the internal structure of the eye

A

Outer fibrous layer
Middle vascular layer
Inner light-sensitive retina

24
Q

The outer fibrous layer consists of the…

A

Sclera

Cornea

25
Q

Structure of the sclera

A

Strong, white, inelastic layer of connective tissue forming the outer layer of the eyeball and extending to the cornea at the front

26
Q

Function of the sclera

A

Protects internal parts of the eye
Helps maintain spherical shape
Serves for muscle attachment

27
Q

Structure of the cornea

A

Transparent front part of the sclera, which is more convex than the rest of the eyeball

28
Q

Function of the cornea

A

Allows light rays through to the inner layers of the eye

Causes refraction of incoming light

29
Q

The middle vascular layer consists of the…

A

Choroid
Ciliary body
Iris
Lens

30
Q

Structure of the choroid

A

Thin, darkly pigmented vascular layer

31
Q

Function of the choroid

A

Pigment absorbs excess light which prevents internal reflection and blurred images
Blood vessels supply oxygen and nutrients to cells

32
Q

Structure of he ciliary body

A

Thickening of the front part of the choroid, consisting of ciliary muscles
Connected to the lens by suspensory ligaments

33
Q

Function of the ciliary body

A

Contracts and relaxes to control the curvature of the lens during accommodation

34
Q

Structure of the iris

A

Round, coloured continuation of the choroid situated in front of the lens
Has an opening in the middle, the pupil

35
Q

Function of the iris

A

Regulates the amount of light that enters the eye by controlling the size of the pupil with radial and circular muscles

36
Q

Structure of the lens

A

Rubbery, elastic, transparent, biconvex structure that can change shape
Kept in position by suspensory ligaments attached to the ciliary body

37
Q

Function of the lens

A

Changes shape to refract light rays from near and far objects to form a clear image on the retina

38
Q

The inner light-sensitive retina consists of the…

A

Pigment layer

Nervous tissue layer

39
Q

Structure and function of the pigment layer

A

Outer layer that is in contact with the choroid

Absorbs light rays and prevents internal reflection

40
Q

Two types of photoreceptors that make up the nervous tissue layer

A

Rods and cones

41
Q

Function of rods and cones

A
Detect and convert light stimuli into nerve impulses
Rods:
Stimulated in low light intensity
Black and white vision
Cones:
Stimulated in high light intensity
Colour vision
42
Q

Name the area of the retina that contains mostly cones and very few rods

A

The yellow spot

43
Q

Function of the yellow spot

A

Clearest, most accurate image is formed here

44
Q

Function of the optic nerve

A

Conducts nerve impulses to the cerebral cortex where they are interpreted

45
Q

The two internal cavities of the eye divided by the lens

A

Anterior cavity in front of the lens

Posterior cavity behind the lens

46
Q

Contents and parts of the anterior cavity

A

Filled with a fluid - aqueous humour

Divided into anterior chamber (between cornea and iris) and posterior chamber (between iris and lens)

47
Q

What fills the posterior cavity?

A

The vitreous humour

48
Q

Function of the vitreous humour

A

Maintains shape of the eyeball
Holds retina in place against choroid
Refracts light rays to form a sharp image

49
Q

The automatic reflex action to the amount of light that enters the eye

A

Pupillary mechanism

Or pupil reflex

50
Q

Which parts of the eye refract light entering the eye?

A

The cornea, aqueous humour, lens and vitreous humour

51
Q

What is accommodation?

A

Process during which the eye adapts for the observation of objects at different distances

52
Q

The ability to see in 3D (depth of field)

A

Stereoscopic vision