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Equilibrium (balance)

Along with audition, the inner ear is responsible for encoding information about equilibrium    , the sense of balance. A similar mechanoreceptor—a hair cell with stereocilia—senses head position, head movement, and whether our bodies are in motion. These cells are located within the vestibule of the inner ear. Head position is sensed by the utricle    and saccule    , whereas head movement is sensed by the semicircular canals    . The neural signals generated in the vestibular ganglion    are transmitted through the vestibulocochlear nerve to the brain stem and cerebellum.

The utricle and saccule are both largely composed of macula    tissue (plural = maculae). The macula is composed of hair cells surrounded by support cells. The stereocilia of the hair cells extend into a viscous gel called the otolithic membrane    ( [link] ). On top of the otolithic membrane is a layer of calcium carbonate crystals, called otoliths. The otoliths essentially make the otolithic membrane top-heavy. The otolithic membrane moves separately from the macula in response to head movements. Tilting the head causes the otolithic membrane to slide over the macula in the direction of gravity. The moving otolithic membrane, in turn, bends the sterocilia, causing some hair cells to depolarize as others hyperpolarize. The exact position of the head is interpreted by the brain based on the pattern of hair-cell depolarization.

Linear acceleration coding by maculae

This diagram shows how the macula orients itself to allow for equilibrium. The top left panel shows the inner ear. The bottom left panel shows the cellular structure of the macula. In the top right panel, a person’s head is shown in the side view along with the orientation of the macula. In the bottom right panel, a person’s head is shown with the head tilted forward and depicts the orientation of the macula to account for the tilt.
The maculae are specialized for sensing linear acceleration, such as when gravity acts on the tilting head, or if the head starts moving in a straight line. The difference in inertia between the hair cell stereocilia and the otolithic membrane in which they are embedded leads to a shearing force that causes the stereocilia to bend in the direction of that linear acceleration.

The semicircular canals are three ring-like extensions of the vestibule. One is oriented in the horizontal plane, whereas the other two are oriented in the vertical plane. The anterior and posterior vertical canals are oriented at approximately 45 degrees relative to the sagittal plane ( [link] ). The base of each semicircular canal, where it meets with the vestibule, connects to an enlarged region known as the ampulla    . The ampulla contains the hair cells that respond to rotational movement, such as turning the head while saying “no.” The stereocilia of these hair cells extend into the cupula    , a membrane that attaches to the top of the ampulla. As the head rotates in a plane parallel to the semicircular canal, the fluid lags, deflecting the cupula in the direction opposite to the head movement. The semicircular canals contain several ampullae, with some oriented horizontally and others oriented vertically. By comparing the relative movements of both the horizontal and vertical ampullae, the vestibular system can detect the direction of most head movements within three-dimensional (3-D) space.

Rotational coding by semicircular canals

The left panel of this image shows a person’s head in a still position. Underneath this, the ampullary nerve is shown. The right panel shows a person rotating his head, and the below that, the direction of movement of the cupula is shown.
Rotational movement of the head is encoded by the hair cells in the base of the semicircular canals. As one of the canals moves in an arc with the head, the internal fluid moves in the opposite direction, causing the cupula and stereocilia to bend. The movement of two canals within a plane results in information about the direction in which the head is moving, and activation of all six canals can give a very precise indication of head movement in three dimensions.

Questions & Answers

In what time stomach empty it's content in to doudemun? what is chyme?
Sneha Reply
write the chemical and mechanical digestion which occurs in stomach?
Does absorption take place in stomach? what are absorption in the stomach by which cell?
Chemical digestion---Mixtures of the food with the gastric acid Mechanical digestion--- churning of the food in the stomach making it become more involved into chyme
absorption takes place in the small intestine because of the presence of the villi
name the muscles supplied redina nerve
Appu Reply
mechanism of hormone releasing by gland
said Reply
why is muscle tissue not considered to be a type of connective tissue?
Ezel Reply
A Skeletal muscles consist of numerous muscles cells called Muscle Fibers . Three layers of connective tissues surrounded these fibers to make the muscles tissues
that's wny connective tissues is not considered as muscles fibers
there are 4 types of tissues : epithelial, connective tissue, nervous tissue and muscle tissue, each one has its own properties. The main function of connective tissue is nutrition, it supplies nutrientes to epithelial tissues that are responsible for protection.
Muscle tissue has properties that allow movement, the function here is movement and not nutrition like connective tissue.
In what time stomach empty it's content in to doudemun?
write the chemical and mechanical digestion which occurs in stomach?
Does absorption take place in stomach? what are absorption in the stomach by which cell?
Does absorption take place in stomach? what are the absorption in the stomach by which cell?
mechanism of hormone controlling releasing by gland
please can someone explain renin angiotensin aldosteron system for me
name the joint present between epichysif and diachysif
what is arteries
oxygenated blood carrying vessels
I think oxygenated blood carrying pulmonary vein
ya this stetment is right 4 pulmonary vein carrying the oxygenated blood
What is the relation between cold and clammy skin and disorders that cause poor perfusion?
Tyrone Reply
name the instruments used to measure the gas volume and flow in pulmonary function test
Preethi Reply
In a spirometry test, While you are sitting, you breath into a mouthpiece that is connected to an instrument called a spirometer . The spirometer records the amount and the rate of air that you breath in and out over a period of time. When standing, Some numbers might be slightly different.
tq soo much
u most wlcm
what is signal transduction?
Signal Transduction (Also know as cell signaling) is the transmission of molecular signal from a cell exterior to its interior.Signals receive by cells must be transmitted effectively into the cell to ensure an appropriate response. This step is initiated by cell - surface receptors.
i know now didn't know
that's great respond
what is histological anatomy?
Thelma Reply
what is histological anatomy?
the study of form of structure seen under the microscope
is the branch of biology which studies the microscopic anatomy of biological tissues.
it's the study of the microscopic anatomy of cells and tissues in the plants and it's carried out by examining a thin slice of tissues under a microscope light / or an electronic microscope
is the study of anatomy in a microscopic level
thank you
what are the significance differrences can be donated between the female and male skeleton..
What is Ions and Ionic bonds
Ravi Reply
2 less stable atoms
Ionic bonding is the complete transfer of valence electron(s) between atoms. It is a type of chemical bond that generates two oppositely charged ions. In ionic bonds, the metal loses electrons to become a positively charged cation, whereas the nonmetal accepts those electrons to become a negatively
what is osmosis
Brown Reply
it's out Body Fluid.
high pressure to low pressure flow
Osmosis is the movement of solvent from a region of lower solute concentration to a region of higher solute concentration through a semi- permeable membrane.
how many types of tissue
4, that is muscle tissue, connective, nerve and epithelial tissue
We have four types of tissue these are ,epithelial tissue,nerve tissue,muscle tissue and connective tissue
function of labia minora
why is a graph of plasma [glucose] superimposed
Sefai Reply
what is biosphere
Jenessa Reply
supporting life
it is the part of the earth and its atmosphere capable of supporting life
what is the function of villus?
Grant Reply
absorption of nutrients
They have a large surface area so there will be more efficient absorption of fatty acids and glycerol into the blood stream.
what is the relationship between heart and lungs
when blood inter the rihgt ventricle the blood is inpure through the pumps blood rich the luns there blood exchange pure
blood ( inpure blood exchange in to pure blood
I don't understand what these messages are about.
I gave you all the information I could think of. What is next?
if you were to poke a pin in the greater omentum how many layers of simple squamous epithelium would it pass
MrLinear Reply

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