Senses

Question 1

1. What do the senses provide?
2. What are the main senses?

Answer 1

1. The senses provide vital information about the environment.
2. The senses of sight, sound, smell, taste and touch are included.

Question 2

The body receives various _______ from the ________ environment, e.g. sight, sound, taste, touch and smell. Due to the presence of ______ ________, either on the surface of the relevant organ or within its tissues, these stimuli can be received and translated into meaningful information. The body can then respond accordingly.

Answer 2

The body receives various stimuli from the external environment, e.g. sight, sound, taste, touch and smell. Due to the presence of sensory receptors, either on the surface of the relevant organ or within its tissues, these stimuli can be received and translated into meaningful information. The body can then respond accordingly.

Question 3

The eyes are the organs that allow visual information to be received.

Each eye is a _________ organ, encased in a ____ ______ on the anterior surface of the face. It is held in place by six _______ that allow the eye to perform many thousands of movements per day. The _______ arteries and veins provide the blood supply.

Answer 3

The eyes are the organs that allow visual information to be received.

Each eye is a spherical organ, encased in a bony cavity on the anterior surface of the face. It is held in place by six muscles that allow the eye to perform many thousands of movements per day. The retinal arteries and veins provide the blood supply.

Question 4

The wall of the eye consists of three layers. Name & Describe them….

Answer 4

The wall of the eye consists of three layers.

1. The outside layer is the sclera.

• This is tough and fibrous.
• The sclera is white, except at the front where there is a transparent area called the cornea.
• The cornea allows light into the eye and is covered by the conjunctiva.

2. The middle layer is the choroid,

• which contains many blood vessels.
• At the front of the eye the choroid forms the iris.
• The iris contains pigment that gives the eye its colour.
• It also contains bands of muscle. The contraction and relaxation of these muscles causes the pupil to dilate and constrict respectively to regulate the amount of light that can enter the eye.

3. The inner layer of the eye is the retina.

• The retina contains the light receptors.
• At the back of the eye, sensory neurons emerge from the retina as the optic nerve.
• The optic nerve transmits impulses generated in the retina to the brain. The impulses are interpreted as vision in the occipital lobes of the cerebrum.

Question 5

Name the outside layer of the eye and describe it components.

Answer 5

The outside layer is the sclera.

• This is tough and fibrous.
• The sclera is white, except at the front where there is a transparent area called the cornea.
• The cornea allows light into the eye and is covered by the conjunctiva.

Question 6

What is the midddle layer of the eye called & describe it…

Answer 6

The middle layer is the choroid,

• which contains many blood vessels.
• At the front of the eye the choroid forms the iris.
• The iris contains pigment that gives the eye its colour.
• It also contains bands of muscle. The contraction and relaxation of these muscles causes the pupil to dilate and constrict respectively to regulate the amount of light that can enter the eye.

Question 7

What is the Inner layer of the eye called & describe it…

Answer 7

The inner layer of the eye is the retina.

• The retina contains the light receptors.
• At the back of the eye, sensory neurons emerge from the retina as the optic nerve.
• The optic nerve transmits impulses generated in the retina to the brain. The impulses are interpreted as vision in the occipital lobes of the cerebrum.

Question 8

1. What 2 semi fluids fill the eye? What are their consistencies and in what cavity are they found?
2. What do these semi-fluids do?
3. How and where is the lens placed?

Answer 8

1. The eye is filled by aqueous and vitreous humour.

• Aqueous humour is watery and fills the anterior cavity.
• Vitreous humour is jelly-like and fills the posterior cavity.

2. Both of these semi-fluids support the eye and give the eye its shape.
3. The lens, held in place by the suspensory ligaments, is suspended in the aqueous humour at the front of the eye.

Question 9

As light enters the eye, it is ________________ by the ______, the front surface of the lens and the back surface of the lens, before it is _________ on the ______.

If it works correctly what does this mean?

Answer 9

As light enters the eye, it is refracted (bent) by the cornea, the front surface of the lens and the back surface of the lens, before it is converged on the retina.

If this takes place successfully, the light is brought to a point on the retina. This allows the brain to create a focused and clear image from the visual stimulus.

Question 10

Sight Summary

• What is received by the eyes?
• What is the tough outer layer of the eye called?
• What is the middle, vascular layer called?
• What supports the eye internally?
• What governs the amount of light allowed to enter the eye?
• What does the iris control?
• Light entering the eye passes through what two structures?
• What is the path taken by light as it passes through the eye?

Answer 10

Sight Summary

• Visual stimuli are received by the eyes.
• The tough outer layer of the eye is the sclera.
• The middle, vascular layer is the choroid.
• The eye is supported internally by the aqueous and vitreous humour.
• The amount of light allowed to enter the eye is governed by the iris. The iris controls the size of the pupil and gives the eye its colour.
• Light entering the eye passes through the conjunctiva and the cornea.
• Light is refracted (bent) by the cornea and then passed through the lens. It is refracted again by the front and back surfaces of the lens, before it is converged on the retina.

Question 11

The ears are the organs that allow sound to be received. They are capable of hearing even the faintest sounds and can deal with many different stimuli at the same time.

There are three main parts to the ear. Name them and give a brief description….

Answer 11

Only the outer part of the ear can be seen. The other two parts are buried deep within the skull.

• The outer ear is responsible for trapping the sound and passing it to the middle ear.
• The middle ear converts the sound into mechanical vibrations.
• The inner ear, these mechanical vibrations generate nerve impulses that are transmitted to the brain.

Question 12

The outer ear consists of an ______ ____ __ _____ and cartilage called the __a___.

The ___a__ traps and directs the sound into the ________ _______ _______. At the end of this passage is the _________ _______ (ear drum).

Answer 12

The outer ear consists of an external flap of skin and cartilage called the pinna.

The pinna traps and directs the sound into the external auditory meatus. At the end of this passage is the tympanic membrane (ear-drum).

Question 13

The middle ear is connected to the pharynx by the _________ ____. This allows the air pressure on either side of the tympanic membrane to be ________.

The middle ear is bridged by three small bones, the ______, _____ and _______, collectively called ___a_____.

Sound entering the ear causes the tympanic membrane to vibrate. The tympanic membrane then vibrates the ___a____.

The innermost ____a____ is connected to another membrane called the ____ ___b____. The ____ ____b____ transmits the vibrations to the inner ear.

Answer 13

The middle ear is connected to the pharynx by the eustachian tube. This allows the air pressure on either side of the tympanic membrane to be equalised.

The middle ear is bridged by three small bones, the malleus, incus and stapes, collectively called ossicles.

Sound entering the ear causes the tympanic membrane to vibrate. The tympanic membrane then vibrates the ossicles.

The innermost ossicle is connected to another membrane called the oval window. The oval window transmits the vibrations to the inner ear.

Question 14

The inner ear consists of a complicated series of ____ ____ _____. The ___a__ contains the receptors for hearing. Vibrations from the oval window cause pressure waves in the fluid of the ___a____. This causes membranes within the inner ear to vibrate, ultimately resulting in sensory hairs within the ___a___ being moved. This stimulation of the hair cells generates nerve impulses that are transmitted to the brain via the _______ branch of the ________________ (VIII) (auditory) nerve. The brain then interprets these impulses as sound.

Answer 14

The inner ear consists of a complicated series of fluid filled canals. The cochlea contains the receptors for hearing. Vibrations from the oval window cause pressure waves in the fluid of the cochlea. This causes membranes within the inner ear to vibrate, ultimately resulting in sensory hairs within the cochlea being moved. This stimulation of the hair cells generates nerve impulses that are transmitted to the brain via the cochlear branch of the vestibulocochlear (VIII) (auditory) nerve. The brain then interprets these impulses as sound.

Question 15

The inner ear is also responsible for _______. This role belongs to the three _________ ___a_____.

The _________ ___a____ contain ___b__ and __c___ _____. As the head moves, the ___b___ drags the ______ __c___, stimulating sensory neurons. The nerve impulses are then passed to the brain via the ______ ______ of the ________________ (VIII) nerve to give information about the orientation of the head. This information is then used by the brain to co-ordinate movement and posture.

Answer 15

The inner ear is also responsible for balance. This role belongs to the three semicircular canals.

The semicircular canals contain lymph and sensory hairs. As the head moves, the lymph drags the sensory hairs, stimulating sensory neurons. The nerve impulses are then passed to the brain via the vestibular branch of the vestibulocochlear (VIII) nerve to give information about the orientation of the head. This information is then used by the brain to co-ordinate movement and posture.

Question 16

1. Taste is otherwise known as what?
2. This is a _______ sense and so what needs to happen before it can be tasted?

Answer 16

1. Taste is otherwise known as gustatory sensation.
2. Gustatory sensation is a chemical sense and so the substance needs to be dissolved before it can be tasted.

Question 17

1. What is the muscular organ of taste?
2. How many taste zones are there?
3. What are these tastes?

Answer 17

1. The tongue is the muscular organ of taste. It is anchored to the back of the mouth.
2. It contains four taste zones,
3. enabling the detection of sweet, salty, sour and bitter tastes. All other tastes are a combination of these four.

Question 18

1. The tip of the tongue reacts to all four tastes, but is very sensitive to which substances?
2. The posterior part of the tongue is highly sensitive to what substances? and
3. the lateral edges are more sensitive to what substances?

Answer 18

1. The tip of the tongue reacts to all four tastes, but is very sensitive to sweet and salty substances.
2. The posterior part of the tongue is highly sensitive to bitter substances and
3. the lateral edges are more sensitive to sour substances.

Question 19

1. The receptors for taste are located in what? Roughly how many are there?
2. Where are these receptors found?

Answer 19

1. The receptors for taste are located in about 10,000 taste buds.
2. Taste buds are mainly on the tongue, but some are also found on the roof of the back of the mouth, the larynx and pharynx.

Question 20

1. Each taste bud is an ___ structure consisting of __________ cells of which about 50 are ________ ____a____ cells.
2. Each ______ ____a____ cell has a hair-like projection. This ________ hair of each cell projects through an opening in the taste bud called the ______ ______.

Answer 20

1. Each taste bud is an oval structure consisting of epithelial cells of which about 50 are gustatory receptor cells.
2. Each gustatory receptor cell has a hair-like projection. The gustatory hair of each cell projects through an opening in the taste bud called the taste pore.

Question 21

The gustatory hairs make contact with the food and initiate the nerve impulses that will ultimately be perceived as taste.

1. Taste impulses are conducted from the taste buds along 3 ______ nerves (__ __ & ___) to the _____a___ _________.
2. From the ____a____, some taste fibres go via the ________ to the primary gustatory area in the _______ ____ of the ________, where the information is perceived as taste.

Answer 21

The gustatory hairs make contact with the food and initiate the nerve impulses that will ultimately be perceived as taste.

1. Taste impulses are conducted from the taste buds along 3 cranial nerves (VII, IX and X - see Cranial Nerves) to the medulla oblongata.
2. From the medulla, some taste fibres go via the thalamus to the primary gustatory area in the parietal lobe of the cerebrum, where the information is perceived as taste.

Question 22

1. Which is the stronger stimulant taste or smell?

Answer 22

Much of what we think we taste we actually smell. Food odours pass into the nasal cavity and stimulate the olfactory receptors (see ‘Smell’). Substances stimulate the sense of smell thousands of times more strongly than the sense of taste.

Sufferers of colds or allergies sometimes complain that they cannot taste their food. In these circumstances it is common that the sense of taste is functioning normally but the olfactory system (responsible for the sense of smell) is not.

Question 23

The sense of smell is the most immediate of the senses and the least understood but it does tire…

On first exposure to an aroma the perception of it is quick and sharp. After a fairly short period of time the ability to perceive it fades. This is called?

Answer 23

The sense of smell is the most immediate of the senses and the least understood but it does tire…

On first exposure to an aroma the perception of it is quick and sharp. After a fairly short period of time the ability to perceive it fades. This is called anosmia.

Question 24

1. Smell, like taste, is a chemical sense. It is detected by the __________ system.
2. What is smell often linked to?

Answer 24

1. Smell, like taste, is a chemical sense. It is detected by the olfactory system.
2. The olfactory system is capable of building a library of more than 10,000 odours, many of which may be linked to a memory of a person, place or event.

Question 25

There are tens of millions of olfactory receptors. They are positioned in the ______ ___________ at the back of the nasal cavity.

Olfactory receptors are ___a____. Each _____a___ has several cilia, called _____b____ ______, protruding from the dendrites. These __b___ are positioned in the _______ _________ covering the nasal epithelium. The olfactory hairs respond to chemical stimuli.

Answer 25

There are tens of millions of olfactory receptors. They are positioned in the nasal epithelium at the back of the nasal cavity.

Olfactory receptors are neurons. Each neuron has several cilia, called olfactory hairs, protruding from the dendrites. These hairs are positioned in the mucous membrane covering the nasal epithelium. The olfactory hairs respond to chemical stimuli.

Question 26

The nasal cavity is divided into left and right cavities by the _____ ______, and it receives a rich blood supply. As the air is inhaled into the nasal cavities, it is warmed and moistened by _____, and dust particles are trapped by the _____ and so filtered out.

The air passes to the back of the nasal cavities where the odorant molecules pass over the ________ ________.

Answer 26

The nasal cavity is divided into left and right cavities by the nasal septum, and it receives a rich blood supply. As the air is inhaled into the nasal cavities, it is warmed and moistened by mucus, and dust particles are trapped by the cilia and so filtered out.

The air passes to the back of the nasal cavities where the odorant molecules pass over the olfactory receptors.

Question 27

When stimulated, the olfactory receptors transmit the impulse along the ____.

These unite to form the _______ ______.

Which then run to a pair of _________ ____.

Which in turn are are composed of _____ ______ and are positioned beneath the _____ _____ of the _________.

Answer 27

When stimulated, the olfactory receptors transmit the impulse along the axon.

These axons of the olfactory receptors unite to form the olfactory nerves.

The olfactory nerves run to a pair of olfactory bulbs.

Olfactory bulbs are composed of grey matter and are positioned beneath the frontal lobes of the cerebrum.

Question 28

Nerve impulses leave the olfactory bulbs by way of the ______ _____.

This splits into ___ pathways.

One pathway goes to the ______ _______ of the _______ ______ where the nerve impulse is perceived as smell.

The other pathway goes to the inferior surface of the brain and extends to the ______ __________. This connection may account for the ability of the perception of smell to induce memories and emotional responses.

Answer 28

Nerve impulses leave the olfactory bulbs by way of the olfactory tract.

The olfactory tract splits into two pathways.

One pathway goes to the olfactory portion of the cerebral cortex where the nerve impulse is perceived as smell.

The other olfactory tract pathway goes to the inferior surface of the brain and extends to the limbic system. This connection with the limbic system may account for the ability of the perception of smell to induce memories and emotional responses.

Question 29

The sense of touch is provided by the _______ ______ and allows a variety of different sensations to be perceived. The sense of touch plays a __________ role in maintaining awareness of the perimeters of the body and allows the early detection of invasion.

The sense of touch becomes of particular importance in providing information about the environment when other senses fail. However, over recent years, the realization of the importance of touch in maintaining health has grown. Research has shown that the sense of touch plays a significant role in promoting healing, good health and recovery from illness.

Answer 29

The sense of touch is provided by the nervous system and allows a variety of different sensations to be perceived. The sense of touch plays a protective role in maintaining awareness of the perimeters of the body and allows the early detection of invasion.

The sense of touch becomes of particular importance in providing information about the environment when other senses fail. However, over recent years, the realization of the importance of touch in maintaining health has grown. Research has shown that the sense of touch plays a significant role in promoting healing, good health and recovery from illness.

Question 30

The sensory receptors of touch are in the ____. They are called ________ __________.

These allow ______ sensations, thermal sensations and pain to be detected.

Answer 30

The sensory receptors of touch are in the skin. They are called cutaneous receptors.

Cutaneous receptors allow tactile sensations (touch, pressure, vibration), thermal sensations (hot and cold) and pain to be detected. The more receptors present in an area of skin, the more sensitive that area of skin will be.

Question 31

Cutaneous receptors consist of the ___________ of sensory neurons.

In their simplest form, these structures are unspecialized and are called ____ ______ _______.

Other receptors are more __________.

On stimulation, cutaneous receptors generate _____ _________.

These are transmitted along _______ (afferent) neurons in the _______ and ______ nerves, through the _________, to the _________ lobes of the cerebrum where they are interpreted as touch.

Answer 31

Cutaneous receptors consist of the dendrites of sensory neurons.

In their simplest form, these structures are unspecialized and are called free nerve endings. Pain and temperature are detected by free nerve endings.

Other receptors are more specialized.

On stimulation, cutaneous receptors generate nerve impulses.

These nerve impulses are transmitted along sensory (afferent) neurons in the spinal and cranial nerves, through the thalamus, to the parietal lobes of the cerebrum where they are interpreted as touch.

Question 32

What are the major tactile sensations the cutaneous receptors allow?

Answer 32

• Touch
• Pressure
• Vibration
• Temperature
• Pain

Question 33

There are 2 types of touch. What are they?

Answer 33

There are 2 types of touch:

1. Discriminative touch is when the exact point of contact is known.
2. Crude touch is when there is an awareness that the body has been touched, but the exact location of the contact is unknown.

Question 34

Touch is detected by tactile receptors in the skin or in the tissues immediately below the skin. Tactile receptors include:

Answer 34

Touch is detected by tactile receptors in the skin or in the tissues immediately below the skin. Tactile receptors include:

• Corpuscles of touch - Egg-shaped receptors for discriminative touch. The dendrites are encapsulated by connective tissues and are located in the dermal papillae. They transmit impulses rapidly and are most abundant in the fingertips, palms of the hands and soles of the feet.
• Root hair plexuses - Dendrites arranged in networks around the hair follicles. The movement of the hair stimulates the dendrites. This allows the detection of movement on the surface of the skin when the hair is disturbed.
• Merkel discs - Flattened portions of dendrites that make contact with Merkel cells in the deepest layer of the epidermis. They function in discriminative touch.
• End organs of Ruffini - Dendrites located deep in the dermis and in deeper tissues of the body. They detect heavy and continuous touch sensations.

Question 35

Corpuscles of touch -

• ____ _______ receptors for ____________ touch.
• The dendrites are encapsulated by _______ _______ and are located in the _____ __________.
• They transmit impulses _______ and are most abundant in the ________, _____ and _______.
• Detect ____ __________ vibrations.

Answer 35

Corpuscles of touch - Touch & Vibration

• Egg-shaped receptors for discriminative touch.
• The dendrites are encapsulated by connective tissues and are located in the dermal papillae.
• They transmit impulses rapidly and are most abundant in the fingertips, palms of the hands and soles of the feet.
• Detect low-frequency vibrations

Question 36

Root hair plexuses -

• Dendrites arranged in _______ around the ____ _________.
• The __________ of the hair stimulates the dendrites.

Answer 36

Root hair plexuses -

• Dendrites arranged in networks around the hair follicles.
• The movement of the hair stimulates the dendrites. This allows the detection of movement on the surface of the skin when the hair is disturbed.

Question 37

Merkel discs -

• __________ portions of dendrites that make contact with _______ ______ in the ____________ layer of the epidermis.
• They function in _____________ touch.

Answer 37

Merkel discs -

• Flattened portions of dendrites that make contact with Merkel cells in the deepest layer of the epidermis.
• They function in discriminative touch.

Question 38

End organs of Ruffini -

• Dendrites located _____ in the _______ and in _______ ______ of the body.
• They detect _______ and ___________ touch sensations.

Answer 38

End organs of Ruffini - Touch & Pressure

• Dendrites located deep in the dermis and in deeper tissues of the body.
• They detect heavy and continuous touch sensations.

Question 39

Pressure is a _________ sensation, felt over a _____ area than touch.

Pressure sensations are generally created by the stimulation of receptors in the _______ tissues.

What are the pressure receptors?

Answer 39

Pressure is a sustained sensation, felt over a larger area than touch.

Pressure sensations are generally created by the stimulation of receptors in the deeper tissues.

The pressure receptors are:

• End organs of Ruffini - Dendrites located deep in the dermis and in the deeper tissues of the body.
• Lamellated corpuscles - Dendrites enclosed in an oval, layered capsule composed of connective tissue. They are located in the subcutaneous layer of the skin, under mucous membranes, around joints, tendons and muscles, in the mammary glands and in certain organs.

Question 40

Lamellated corpuscles -

• Dendrites enclosed in an ____, layered capsule composed of ___________ tissue.
• They are located in the ___________ layer of the skin, under _______ membranes, around _____, _______ and _______, in the _______ glands and in certain organs.
• Detect ____ ___________ vibrations.

Answer 40

Lamellated corpuscles - Pressure & Vibration

• Dendrites enclosed in an oval, layered capsule composed of connective tissue.
• They are located in the subcutaneous layer of the skin, under mucous membranes, around joints, tendons and muscles, in the mammary glands and in certain organs.
• Detect high-frequency vibrations.

Question 41

The sensation of vibration arises from _____, __________, sensory impulses from the receptors.

What are the receptors for vibration are?

Answer 41

The sensation of vibration arises from rapid, repetitive, sensory impulses from the receptors.

The receptors for vibration are:

• Corpuscles of touch - detect low-frequency vibrations.
• Lamellated corpuscles - detect high-frequency vibrations.

Question 42

1. The thermal sensations are what?
2. What are the receptors of temperature called?
3. and what are they?
4. Thermoreceptors are ?

Answer 42

1. The thermal sensations are hot and cold.
2. The receptors of temperature are called thermoreceptors
3. and are simply free nerve endings.
4. Thermoreceptors are selective - some respond to hot and some respond to cold.

Question 43

1. What are the receptors for pain are called?
2. What are the receptors for pain?
3. and wher are they found?
4. What will they respond to?

Answer 43

1. The receptors for pain are called nociceptors.
2. As for temperature, the receptors for pain are simply free nerve endings and
3. are found in almost every tissue of the body.
4. Nociceptors will respond to any stimulus if it is causing tissue damage.

Answer 44

Answer 45

Answer 46