Equilibrium.

Question 1

What is the sense of equilibrium?

Answer 1

The sense of balance.

Question 2

What organ is responsible for the sense of equilibrium?

Answer 2

The vestibular organ of the ear.

Question 3

What is static equilibrium?

Answer 3

Maintaining body position in relation to gravity.

Question 4

What is dynamic equilibrium?

Answer 4

Maintaining body position in response to sudden movements.

Question 5

What are 2 major areas of the vestibular organ of the ear?

Answer 5

The utricle.

The saccule.

Question 6

What are the utricle and saccule of the vestibular organ filled with?

Answer 6

Fluid.

Question 7

What is the name of the sensitive spot in the utricle and saccule?

Answer 7

The macula.

Question 8

What kind of equilibrium are the utricle and saccule involved in?

Answer 8

Static equilibrium.

Question 9

What is found in the semi-circular canals of the inner ear?

Answer 9

A sensitive area called a crista.

Question 10

What is the crista of the circulae canals of the inner ear involved in?

Answer 10

Dynamic equilibrium.

Question 11

Can dynamic and static equilibrium be used at the sane time?

Answer 11

Yes.

Question 12

What are the sensitive spots that help to control static equilibrium?

Answer 12

The maculae of the saccule and utricle.

Question 13

What is located within the maculae of the saccule and utricle?

Answer 13

Hair cells.

Question 14

What are the hair cells of the maculae of the saccule connected to?

Answer 14

Each hair is connected to a neuron that belongs to cranial nerve 8.

Question 15

How do the hair cells of the maculae of the saccule contribute towards static equilibrium?

Answer 15

Each hair is surrounded by a gelatine mass.

When we move the head the gelatine mass moves and this stretches the hair cells.

As the hairs move it activates tip links and this the depolarises the neurons.

Question 16

How are the hair cells of the maculae affected if we tip our head to the left?

Answer 16

The hair cells in the left vestibular organ will be stretched.

The hair cells in the right vestibular organ will be compressed.

Question 17

What does compression of the hair cells of the maculae lead to?

Answer 17

Hyperpolarisation.

Question 18

What does stretching of the hair cells of the maculae lead to?

Answer 18

Depolarisation.

Question 19

How does the body detect linear acceleration?

Answer 19

The otolithic membrane lags behind the movement and the hairs bend in the opposite way.

Question 20

What are the hair cells of the maculae embedded into?

Answer 20

The otolithic membrane.

Question 21

What is found in the ampulla of the semicircular ducts of the inner ear?

Answer 21

A crista.

Question 22

What is found in the cristae of the semicircular ducts of the inner ear?

Answer 22

Hair cells that are embedded into a gelatinous mass called the cupula.

Question 23

What happens to the hair cells of the cristae when there is no movement?

Answer 23

They are in their normal position.

Question 24

What happens to the hair cells of the cristae when we perform a rotational movement with the head?

Answer 24

The semicircular ducts move followed by the endolymph.

The lymph pushes against the crista causing it to bend.

This bends the cilia and the transduction channels open for depolarisation.

Question 25

What part of the brain is involved in all coordinated activities?

Answer 25

The cerebellum.

Question 26

What will be the effects of a lesion in the equilibrium system?

Answer 26

It affects the muscles that maintain balance and this leads to ataxia.

Question 27

What happens to the hair cells in the right crista if the hair cells in the left crista have depolarised?

Answer 27

They will be hyperpolarised.

Question 28

What happens to the hair cells in the left crista if the hair cells in the right crista have depolarised?

Answer 28

They will be hyperpolarised.

Question 29

What nerve transmits information about balance to the brain?

Answer 29

The vestibulocochlear nerve.

Question 30

How will the eyes react to a rotational movement of the head?

Answer 30

They move against the rotational movement and then they jump forward in the same direction as the movement.

Question 31

What exams do we do to look for balance problems within an animal?

Answer 31

Physiological nystagmus tests.

Question 32

How will the animals eyes react if it has pathological nystagmus?

Answer 32

The eyes will roll in the animals head when the head performs a rotational movement.

Question 33

When does pathological nystagmus occur?

Answer 33

When one of the vestibular organs is destroyed.

Question 34

Why does damage to the vestibular organs cause pathological nystagmus?

Answer 34

The brain thinks the head is tilted at a particular angle and it tries to compensate even though the head is straight.

Question 35

What characterises pathological nystagmus?

Answer 35

Eye movement without head rotation.

Question 36

What is a common sign of pathological nystagmus?

Answer 36

The animal will have a head tilt towards the side where the lesion is present.

Question 37

Will an animal with physiological nystagmus be ataxic?

Answer 37

Yes, and it will typically stumble on the same side that the lesion is present on.

Question 38

What is vestibular ataxia?

Answer 38

When the animal stumbles on the same side that the lesion to the vestibular region is.

Question 39

What 3 things can we use to distinguish vestibular ataxia from proprioceptive ataxia?

Answer 39

The head tilt.

The one sided stumbling.

The pathological nystagmus.