Week 20 Flashcards
(25 cards)
How many hair cells are present in the cochlea?
16,000 hair cells
Each hair cell has 30-100 stereocilia.
What is the function of the tectorial membrane?
It overlaps the spiral organ of Corti and is involved in the sense of hearing.
Where do the basal sides of inner hair cells synapse?
With 1st order sensory neurons in the spiral ganglion.
What are the three main regions of the ear?
- Outer ear
- Middle ear
- Inner ear
What is the role of the outer ear?
Collects sound waves and passes them inwards.
What occurs in the inner ear when pressure changes in fluid?
Stimulates the release of neurotransmitters.
What type of light do rods and cones transduce?
Rods: shades of grey in dim light; Cones: sharp, colour vision.
What are the three layers (tunics) of the eyeball?
- Fibrous Tunic (outer layer)
- Vascular Tunic (middle layer)
- Nervous Tunic (inner layer)
What is the function of the fovea?
Area of sharpest vision due to the high concentration of cones.
What is the structure of the lens?
Avascular, made of crystallin proteins, arranged like layers in an onion.
What muscles control the iris?
- Constrictor pupillae (circular)
- Dilator pupillae (radial)
What is the role of the external auditory canal?
Directs sound waves towards the eardrum.
What do ceruminous glands secrete?
Cerumen, which prevents entry of foreign particles.
What is the function of the auditory ossicles?
Transmit sound waves via vibrations.
What is the composition of the bony labyrinth in the inner ear?
Set of tube-like cavities filled with perilymph.
What is the function of hair cells in the cochlear duct?
Convert mechanical deformation into electrical signals.
What happens when microvilli are bent in hair cells?
Mechanically-gated channels let in K+ ions, causing depolarization.
What is the primary auditory pathway?
- Vestibulocochlear nerve (CNVIII)
- Medulla oblongata
- Midbrain
- Thalamus
- Temporal lobe
What is the purpose of the lacrimal apparatus?
Produces and drains lacrimal fluid.
What is the average amount of tears produced per day?
About 1ml.
What is contained in tears that provides protection?
Bactericidal enzymes called lysozyme.
What are the components of the macula region in the saccule and utricle?
- Hair cells with stereocilia and one cilia (kinocilium)
- Supporting cells that secrete gelatinous layer
What does the movement of stereocilia or kinocilium result in?
Release of neurotransmitter onto vestibulocochlear nerve.
What does the cerebellum do with sensory information?
Receives constant updates to adjust signals to maintain balance.