Sensory organs Flashcards
look at diagrams on PowerPoint
1
Q
Where is the olfactory organ found and what doe it do here?
A
- olfactory mucosa in dorsocaudal nasal cavity
- Covers lateral wall and ethmoidal conchae here
2
Q
How can the olfactory organ be distinguished histologically?
A
- by presence of olfactory neuronal cells
3
Q
Why is sense of smell better in domestic animals?
A
- there are more neuronal cells = larger SA
4
Q
What do concha do?
A
- divide up areas
5
Q
What type of epithelium covers concha?
A
- Pseudostratified columnar epithelium
6
Q
Normal respiration is directed through …
A
- respiratory pathways
7
Q
Sniffing to try and smell something is directed through ….
A
= olfactory pathways
– dorsal caudal nasal area so it can go to olfactory area
8
Q
Olfactory neurone dendrites reach what? and do what?
A
- epithelium
- Present cilia (hair-like projections) into cavity beyond epithelium and mucosa
9
Q
Axons combine to form what (olfactory)?
A
- combine to form the fascicles of the olfactory nerve
10
Q
Where does the olfactory nerve pass through?
A
- Pass through cribriform plate to connect directly to olfactory bulb on brain
11
Q
Olfactory (bowman’s) glands are below what?
A
- epithelium
12
Q
What do olfactory glands contain?
A
- Lipid-rich fluid mucus to bind odorants
13
Q
What happens after odorants dissolve in the olfactory gland?
A
- reach sensory receptors
- Wash away odour particles (to nasopharynx to be swallowed) so new smells can be sensed
14
Q
If there is humidify epithelium what happens?
A
= more intense smells
15
Q
What is expressed per olfactory neurone cell?
A
- only one receptor is expressed per olfactory neurone cell
16
Q
What are receptors like in olfactory cells?
A
- not very specific to odour molecules (different molecules can all trigger same receptor infinity,).
- There is an infinity so some have a preference
17
Q
Olfactory cells from synapses with what?
A
- with mitral cells in olfactory bulb
18
Q
What are there multiple of in a mitral cell?
A
- multiple olfactory neurones per mitral cell in a tuft (glomerulus) of nerve endings coming together
19
Q
What do mitral cells do?
A
- Mitral cell links to one type of olfactory receptor
20
Q
What does the brain compare to distinguish the overall odour?
A
- Brain compares signal frequency from different mitral cells to distinguish the overall odour
21
Q
What is the vomeronasal organ? (Jacobson’s)
A
- accessory olfactory system
22
Q
Where is the vomeronasal organ found?
A
- the nasal cavity
23
Q
Describe the structure of the vomeronasal organ?
A
- Two narrow parallel ducts
- Embedded in hard palate
- End blindly (caudally)
- Open into incisive ducts (rostrally)
- Part-lined by olfactory mucosa
24
Q
What connects the oral and nasal cavities through hard palate?
A
- Incisive ducts
25
What is absent in equids?
- oral opening
26
What does the vomeronasal organ do?
- Detects pheromones
= ‘sexual nose’
- role in reproductive and social behaviours
27
What is the flehmen reaction?
- detection of oestrus by males
following birth and interaction with newborn
- interesting smells
28
Taste receptor cell only have a single type of what?
- receptor type
29
Where are sensory cells derived from?
- epithelium cells
30
What is taste receptors innervated by?
- Innervated by sensory nerve fibres from CN VII and IX (facial and glossopharyngeal nn.)
31
What do gustatory inputs link to?
- cerebral cortex
- brain stem
- limbic system
32
What role does the cerebral cortex have?
- conscious perception of taste and smell
33
What role does the brainstem have?
- unconscious reflexes e.g. salivation, digestive juices, pre-absorptive insulin release
34
What is the limbic system responsible for?
- emotional response
35
What is aroma?
= Taste + smell
- Including olfactory input from nasopharynx as food chewed
36
What does the eye detect?
- light info
37
How is light info sent from the eye to the brain?
- Sent to brain via CN II (optic n.)
38
How is light focused onto the retina?
- Light passes through transparent parts (the refractive media) which focus light onto retina at back of eye
- Cornea -> aqueous humour -> lens -> vitreous humour
39
What are the three layers of the eye called?
- tunicae
40
What is the innermost layer (tunica) of the eye?
- the retina
41
What does the retina do?
- Connected to brain
- Converts light information to nerve signal
42
What is the middle layer of the eye?
- vascular tunic
43
What does the vascular tunic contain?
- Contains blood vessels
- Also structures that hold the lens, regulate pupil size, and produce fluid that fills the eyeball
44
What is the outer layer of the eye called?
- the fibrous tunic
45
what is the fibrous tunic?
- Dense, tough collagen tissue
- Protects and holds the eyeball’s shape
- Extraocular muscles attach here to move eye
46
What is within the fibrous tunic?
- Scalera
- cornea
47
What is within the vascular tunic?
- iris
- ciliary body
- choroid
48
What is within the retina?
- pigmented layer
- neural layer
49
What does the innermost eye layer grow directly from?
- the neural tube
50
The retina has two layers - what are they and what do they do?
- Pigmented layer (prevents light scattering)
- Nervous layer (contains photoreceptors, neurones)
51
What doe incoming light stimulate in the retina?
- stimulates opsin proteins in receptor cells (rods & cones)
52
What are rods used for?
- night vision
- B&W (Rhodopsin)
53
What are cones used for?
- day vision
- colour (Photopsins)
54
Signals from receptor cells are transmitted back through retinal sub-layers to what?
- the ganglionic cell layer
55
What converge in the optic nerve?
- axons
56
What does the optic nerve do?
- takes info to brain
57
The ear is composed of what?
- outer ear
- middle ear
- inner ear
58
The outer ear is located where?
- mostly outside of skull
59
What makes up the outer ear?
- The pinna (aka auricle) – skin and cartilage
- Auricular muscles
- Ear canal (external auditory meatus)
60
Where does the outer ear end?
- Ends at ear drum (tympanic membrane)
61
What is the function of the outer ear?
- Directs and transmits sound to the middle ear
62
How is the middle ear separated from the outer ear?
- by the tympanic membrane
63
What do sound waves in the middle ear cause?
- cause the membrane to vibrate and transmits vibrations to middle ear ossicles (3 middle bones)
64
What are ossicles?
- a chain of 3 small bones
65
What do ossicles do?
Transmit and amplify vibrations to oval window of inner ear
66
What do equids have that is unique to their ear?
- have outpouchings of the auditory tubes connecting middle ear to pharynx
67
What is the function of equid outpouching?
- may function in brain cooling
68
How are guttural pouches divided into a medial and lateral compartments?
by the stylohyoid bone
69
Where is the inner ear housed?
- within the temporal bone of the skull
70
What is the inner ear?
- its a membranous labyrinth is filled with endolymph
- Surrounded by bony labyrinth, filled with perilymph
71
What are the two functions of the inner ear?
- Hearing by the cochlea (and cochlear duct)
- Balance by the vestibular system (saccule, utricule, and semicircular ducts)
72
The cochlear canal is divided into three parts - what are these?
- The cochlear duct
- The scala vestubuli
- The scala tympani
73
Where do the two scala communicate?
- at the tip of the cochlea’s spiral (the helicotrema)
74
As the stapes vibrates in the oval window what happens?
- it compresses the perilymph in the scala vestibuli
75
How do pressure waves travel in the cochlea?
- The pressure wave travels through the scala vestibuli and continues into the scala tympani
76
What do pressure waves travelling in the ear cause?
- This causes part of the basilar membrane to vibrate, moving the hair cells relative to the tectorial membrane
77
Hair cells in the ear send impulses how and where?
- send impulses along the (vestibulo) cochlear nerve to the brain
78
What part of the inner ear is responsible for sensing balance and movement?
- the vestibular
79
What is found within the inner ear?
- Three semicircular canals
- Enlargements of the membranous labyrinth: saccule and utricle
80
What do the semi-circular canals detect?
- rotations of the head
81
What do the saccule and utricle detect?
- linear accelerations
82
How is information carried from the vestibular to the brain?
- Information is carried by the vestibular part of the vestibulocochlear nerve to the brain
83
How are the three canals structured?
- roughly perpendicular to one another
84
Each canal can detect rotation around a directional axis - what are these?
- Pitch
- Roll
- Yaw
85
Why can an animal sense 3D rotations of its head?
- Because there are 3 canals at right angles
86
Rotations cause what current inside canal?
- endolymph current
87
What is found in the ampulla of the canal?
- moving hair cells
88
What are the saccule and utricle?
- they are are expansions of the membranous labyrinth
89
What do the saccule and utricle contain?
- They contain hair cells in thickened patches (maculae)
- Covered with a gel-like layer containing otolith crystals
90
What movement happens in the saccule and utricle and what does this do?
- endolymph movement bends the hairs and information about movement is transmitted via the vestibulocochlear nerve
91
What can the saccule and utricle do?
- Detect linear accelerations
- E.g. Gravity, longitudinal and vertical movements
