Histology presentation- ear and organs

1. The organ of hearing
Kartik karwasara

14. The Organ of Balancing
Lokendra beniwal

15. Introduction
The organ of balancing, also known as the vestibular
system, is located in the inner ear. It is responsible for
detecting changes in head position and movement,
and for helping to maintain balance and equilibrium.
The vestibular system is made up of two main parts:
the semicircular canals and the otolith organs.

16. Diagram of the
vestibular system:
This diagram shows the
overall structure of the
vestibular system, including
the semicircular canals,
otolith organs, and vestibular
ganglia. The vestibular
ganglia contain the cell
bodies of the neurons that
carry signals from the hair
cells to the brain

17. (1)Semicircular canals
The semicircular canals are three fluid-filled tubes that are
arranged in three perpendicular planes. The ends of the canals
are enlarged into ampullae, which contain sensory hair cells.
The hair cells are embedded in a gelatinous substance called
cupula.
When the head moves, the fluid in the semicircular canals
moves too. The movement of the fluid bends the cupula, which
stimulates the hair cells. The hair cells send signals to the brain
about the direction and speed of the head movement.

18. Diagram of the
semicircular canals:
This diagram shows the three
semicircular canals and the
ampullae at their ends. The
ampullae contain the cristae
ampullares, which are the
sensory organs of the
semicircular canals. The
cristae ampullares contain type
I hair cells, which are
responsible for detecting
angular acceleration.

19. (2) Otolith organs
The otolith organs are the utricle and saccule. They are two
small sacs that are located in the vestibule of the inner ear. The
otolith organs contain sensory hair cells that are embedded in a
gelatinous substance called the otolith membrane.
The otolith membrane contains tiny crystals of calcium
carbonate, called otoconia. When the head changes position,
the otoconia shift and bend the hair cells. The hair cells send
signals to the brain about the position of the head relative to
gravity and linear acceleration.

20. Diagram of the otolith organs:
This diagram shows the utricle and
saccule, the two otolith organs. The
otolith organs contain the maculae
utriculi and maculae sacculi, which
are the sensory organs of the otolith
organs. The maculae utriculi and
maculae sacculi contain type I and
type II hair cells, which are
responsible for detecting linear
acceleration and changes in head
position relative to gravity,
respectively

21. Histophysiology of the vestibular system:
The vestibular system is made up of a variety of tissues,
including:
1. Sensory epithelium
2. Supporting cells
3. Stroma
4. Nerve fibres

22. 1. Sensory epithelium:
The sensory epithelium is the layer of tissue that contains the hair
cells. The hair cells are the primary sensory receptors of the
vestibular system.
The sensory epithelium is made up of two types of hair cells: type I
hair cells and type II hair cells. Type I hair cells are the most
common type of hair cell in the vestibular system. They are
responsible for detecting angular acceleration (changes in head
rotation). Type II hair cells are responsible for detecting linear
acceleration (changes in head movement in a straight line).

23. Here are some more things about the sensory epithelium of
the vestibular system:
● The sensory epithelium is a highly regenerative tissue. This means
that hair cells can be replaced if they are damaged or lost.
● The sensory epithelium is also very sensitive to toxins and other
environmental insults. Exposure to toxins or other environmental
insults can damage the hair cells and lead to balance disorders.
● The sensory epithelium is also susceptible to age-related changes. As
we age, the number of hair cells in the sensory epithelium decreases.
This can lead to balance problems and dizziness.

24. Diagram of the hair cells:
This diagram shows the structure of
a hair cell. Hair cells are bipolar
neurons, meaning that they have
two processes: a dendrite and an
axon. The dendrite is located at the
apical end of the hair cell and
contains the kinocilium and
stereocilia, which are the sensory
organelles of the hair cell. The axon
is located at the basal end of the
hair cell and carries signals to the
brain.

25. 2. Supporting cells:
The supporting cells provide structural support for the hair
cells and help to maintain the integrity of the sensory
epithelium.
The hair cells are connected to the supporting cells by
tight junctions. The tight junctions help to create a barrier
between the endolymph (the fluid that surrounds the hair
cells) and the perilymph (the fluid that surrounds the
cochlea). This barrier is important for protecting the hair
cells from damage.

26. Here are some more things about supporting cells in the vestibular
system:
● Supporting cells are columnar cells with microvilli on their apical
surface. Microvilli are small finger-like projections that help to
increase the surface area of the cell. This is important because
it allows the supporting cells to absorb more nutrients and
oxygen from the endolymph.
● Supporting cells are interconnected by tight junctions. Tight
junctions are specialized cell junctions that create a barrier
between the endolymph and the perilymph. This barrier is
important for protecting the hair cells from damage.

27. ● Supporting cells also contain a number of different channels and
transporters. These channels and transporters help to regulate the
flow of ions and other molecules into and out of the supporting cells.
This is important for maintaining the ionic composition of the
endolymph, which is essential for proper hair cell function.
● Supporting cells also play a role in the development and maintenance
of the vestibular system. During development, the supporting cells
provide a scaffold for the growth and organization of the sensory
epithelium. In adulthood, the supporting cells help to maintain the
structural integrity of the vestibular system and to protect it from
damage.

28. 3. Stroma
The stroma is the connective tissue that surrounds the sensory epithelium
and supporting cells of the vestibular system. It is made up of a variety of
cells, including fibroblasts, chondrocytes, and adipocytes.
The stroma plays a number of important roles in the vestibular system,
including:
1. Providing structural support for the sensory epithelium and supporting
cells.
2. Supplying the sensory epithelium with nutrients and oxygen.
3. Removing waste products from the sensory epithelium.
4. Helping to regulate the fluid pressure within the vestibular system.
5. Protecting the sensory epithelium from damage.

29. The stroma is also important for the development and maintenance of the
vestibular system. During development, the stroma provides a scaffold for the
growth and organization of the sensory epithelium and supporting cells. In
adulthood, the stroma helps to maintain the structural integrity of the vestibular
system and to protect it from damage.
Here are some more specific things about the stroma of the vestibular system:
1. The stroma of the vestibular system is highly vascularized, meaning that it
is well supplied with blood vessels. This is important because the sensory
epithelium needs a constant supply of oxygen and nutrients.
2. The stroma of the vestibular system also contains a number of lymphatic
vessels. Lymphatic vessels help to remove waste products from the
sensory epithelium.

30. 3. The stroma of the vestibular system also contains a number of
nerve fibers. These nerve fibers carry signals from the supporting
cells to the brain. The supporting cells play a role in regulating the
fluid pressure within the vestibular system.
● It provides structural support, nutrition, and protection for the
sensory epithelium and supporting cells. It is also important for
the development and maintenance of the vestibular system.

31. 4. Nerve fibers:
The nerve fibers carry signals from the hair cells to the brain.
The nerve fibers from the hair cells synapse with neurons in the
vestibular nuclei of the brainstem. The vestibular nuclei send
signals to a variety of other brain regions, including the cerebellum,
thalamus, and cortex. These brain regions work together to
coordinate balance, movement, and eye gaze.

32. Here are some more things about nerve fibers in the vestibular
system:
● There are two types of nerve fibers in the vestibular system:
type I and type II.
● Type I nerve fibers carry signals from type I hair cells. Type I
hair cells are responsible for detecting angular acceleration
(changes in head rotation).
● Type II nerve fibers carry signals from type II hair cells. Type
II hair cells are responsible for detecting linear acceleration
(changes in head movement in a straight line) and changes
in head position relative to gravity.

33. ● The nerve fibers in the vestibular system are very sensitive to
damage. Damage to the nerve fibers can lead to balance
problems, dizziness, and other vestibular disorders.

34. The organ of taste
Dharmendra

41. Thank you