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USAP science > section 2 > Flashcards

section 2 Flashcards

1
Q

What is the retina?

A

The retina is actually one of the last places where the light shines –the light passes through other parts of the eye first. The conversion of light into electrochemical signals happens here.

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2
Q

What is the cornea?

A

The cornea is the front, transparent layer of the eye. This part is usually shaved down during LASIK SURGERY.

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3
Q

What occurs in the cornea?

A

Refraction (bending/focusing)

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4
Q

What is the iris?

A

The colored part of the eye

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5
Q

What is the pupil?

A

The little hole where the light enters the eye. It can dilate and let in the right amount of light.

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6
Q

What happens in bright lights vs. low and dim lights?

A

Bright lights : the iris becomes the size of the pupil

Dim lights : the iris relaxes and pupil expands

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7
Q

What happens after the light enters the eye?

A

The light passes through the crystalline lens, a structure with many layers behind the cornea. This works to further refract the light to focus the image on the retina.

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8
Q

What is the lens?

A

The lens is dynamic and flexible because it changes shape to focus on different parts of the visual field. There are special muscles that help it be flexible.

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9
Q

What does aging do to the lens?

A

The lens flexibility reduces with age. This causes a form of farsightedness.

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10
Q

How does farsightedness occur?

A

This is caused because the lens isn’t flexible or the eyeball is shaped so that the distance between the cornea and the retina is too short. The image falls behind the retina.

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11
Q

How does myopia (nearsightedness) occur?

A

This is cause because the eyeball is shaped so that the distance between the cornea and the retina is too long. The image falls in front of the retina.

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12
Q

What can fix myopia and/or farsightedness?

A

Glasses, corrective lenses, or LASIK surgery which can change the curve of the cornea to bend the light so the image falls exactly on the retina.

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13
Q

What is the retina?

A

This is a many layered sheet of neurons that converts light in the back of the eye.

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14
Q

Describe the process for the light to get to the back of the retina.

A

The light must first go through this sticky, thick liquid and around the first layers of the retina to get to the photoreceptors.

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15
Q

What are photoreceptors?

A

They recieve and convert light.

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16
Q

What is the one reason that the retina’s layers are seemingly “inside out”?

A

The pigmented epithelium needs to be just outside these cells to help support their function.

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17
Q

What are the pigmented epithelium cells?

A

They absorb excess light so it doesn’t scatter and blur the image. They get rid of old light absorbing segments of the photoreceptors.

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18
Q

What is just outside the pigmented epithelium layer?

A

The choroid, which brings oxygen and nutrients to the photoreceptor cells.

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19
Q

What is in the very center of the retina?

A

The fovea - this is where the vision the sharpest and the best.

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20
Q

What are the two general types of photoreceptors.

A

Rods and cones.

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21
Q

What do both rods and cones have in common?

A

Rods and cones both have disks of membranes where a pigment absorbs light and communicates with the molecular machinery needed to convert the light.

They both convert light in a similar way. They use different pigments.

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22
Q

What is different about rods?

A

Rods have more disks which therefore are more sensitive to low light settings.

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23
Q

What is different about cones?

A

Cones are clustered in the center of the retina, in the fovea. The cornea has a good response to bright light which makes them good for a bright light setting and full color vision.

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24
Q

What’s another word for pigments?

A

Opsins, which each absorb a different wavelength or color of light.

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25
Q

What opsin do rods have?

A

Rods have an opsin called rhodopsin. There are usually three types of cones which each absorb a different wavelength.

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26
Q

What do primates use?

A

Primates use a trichromatic (three-cone) which allows them to see in hundreds of thousands of colors.

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27
Q

What is sound?

A

Sound is a series of pressure change in air that can vary in frequencies and intensities.

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28
Q

What do we experience frequencies and intensities as?

A

Frequencies - pitch or tone
Intensities - loudness or volume

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29
Q

Where do sound waves bounce off of in our ears?

A

They bounce off of the folds of our ears and travel down the auditory canal where they vibrate in the ear drum.

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30
Q

What happens with the vibrations in the ear drum?

A

They are changed from pressure waves to physical movements in the middle ear. These movements are transferred through the middle ear using the tiniest bones (in the human body).

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31
Q

What are these tiny bones in the middle ear called?

A

The ossicles.

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32
Q

When sick, what can happen to the middle ear?

A

The middle ear is filled with air so when sick, it become congested and the eustachian tube will narrow.

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33
Q

What is the eustachian tube?

A

This tube connects the middle ear to the back of the throat.

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34
Q

What are the three ossicles in the middle ear?

A

The malleus, the incus, and the stapes.

35
Q

What do the three ossicles in the middle ear do?

A

They work together to transfer physical movement of the vibrations of the eardrum through the middle ear to the fluid of the inner ear.

36
Q

How do the three ossicles work in the middle ear?

A

It’s easy to move fluid with air so the ossicle is like a lever which increases the pressure to move the fluid of the inner ear.

37
Q

What are the two sections in the inner ear?

A

The cochlea and the semicircular canals.

38
Q

What does the cochlea do?

A

This is where sound is changed into nerve messages and sends them to your brain.

39
Q

What do the semicircular canals do?

A

This is for converting the movements of the head.

40
Q

How does the cochlea work?

A

This is filled with liquid that ripples with the ossicles beat against it. The stapes beats against the exposed flexible membrane called the oval window. This creates waves. There are nerve endings (hair cells) that transform the vibrations into electrical impulses which go to the brain.

41
Q

What happens in the Organ of Corti and where is it?

A

The Organ Corti is in the Cochlea and this is where the translation of pressure waves through the fluid into an electrochemical signal.

42
Q

What is gustation?

A

Gustation is taste and humans and animals are able to identify things because of the chemicals in them.

43
Q

What are the five tastes?

A

Sweet, sour, bitter, salty, umami.

44
Q

What is umami?

A

Umami, to the human, can also be described as savory and can be tasted as chemical stimuli based on the amino acid L-glutamate.

45
Q

What is the history behind the flavor of umami?

A

Umami means deliciousness and was discovered by the japanese scientist Kikunae Ikeda in 1908.

46
Q

Where are the taste buds found?

A

On the tongue.

47
Q

What are the bumps on the tongue called?

A

Papillae. They are small bumps that contain the taste buds.

48
Q

What are taste buds?

A

Taste buds are in the papillae and they are barrel-shaped structures that consist of many sensory (taste) cells.

49
Q

What does each taste cell have?

A

Each taste cell tends to have one taste receptor for one of the five basic tastes.

50
Q

What is a tastant?

A

A taste particle of the food that binds to the taste receptor. (this will produce the sensation of that taste)

51
Q

What is the olfactory epithelium?

A

The olfactory epithelium is a big cluster of cells the line the top and the back of the nasal cavity.

52
Q

What is the olfactory epithelium composed of?

A

This is composed of basal cells and support cells to provide structure, as well as olfactory receptor neurons (smell receptor neurons)

53
Q

What do the olfactory receptor neurons have?

A

These neurons have specialized dendrites where floating particles may attach to olfactory
receptors to be converted by the olfactory system.

54
Q

How do the receptors work?

A

The molecules are inhaled and they attach to the receptors. The cells convert that event into a series of action potentials.

55
Q

What is population coding?

A

Population coding is when

56
Q

What is somatosensation?

A

Somatosensation is sensory category that includes all sensation received from the skin and mucous membranes.

57
Q

What are the three layers of skin?

A

Epidermis, dermis, and the subcutaneous layer

58
Q

What is the epidermis?

A

The epidermis is the very top layer of skin which is a thin barrier to water and diseases.

59
Q

What is the dermis?

A

Below the epidermis is a thicker layer (the dermis) which contains blood vessels, sweat glands, hair follicles, and other important glands and structures.

60
Q

What is the subcutaneous layer?

A

Below both the epidermis and the dermis is this layer which is fatty that contains the blood vessels, connective tissues, and the axons of the sensory neurons.

61
Q

What do these neurons require?

A

They require many types of receptors to convert many types of sensory input.

62
Q

What are encapsulated mechanoreceptors?

A

They are special sensory receptors that respond to touch, pressure, and vibration. They respond to mechanical stimuli.

63
Q

What are the four major types of encapsulated mechanoreceptors?

A

Meissner’s corpuscles, Ruffini’s corpuscles, Pacinian corpuscles, and Merkel’s disks.

64
Q

What do all four types of mechanoreceptors have?

A

They all have long thickly myelinated axons that help information get to the brain quickly. However, some temperature and pain information doesn’t have this as it is not as critical for survival.

65
Q

What are pacinian corpuscles?

A

Located in the subcutaneous layer of the skin, they detect deep vibrations and pressure.

When the stimulus is applied, the corpuscle deforms and the fluid is smooshed. Once the stimulus is gone, the corpuscles fluid redistributes–reshaping it.

66
Q

What are Meissner’s corpuscles?

A

Located in the dermis, these corpuscles are smaller than the pacinian and can be found in hairless places.

They convert low frequency vibrations or little flutters.

67
Q

What are Ruffini’s corpuscles (endings)?

A

Located in the dermis, they can be found on both hairy and hairless skin and they detect skin stretch and tangential force.

68
Q

What are Merkel’s disks?

A

Located in the dermis, they can be found on hairy and hairless skin and convert light touch. They perceive light touch, shape, and texture.

69
Q

What is the difference between Pacinian and Meissner’s corpuscles vs. Ruffini’s endings and Merkel’s disks?

A

Pacinian and Meissner’s corpuscles both have a rapid adapting property while Ruffini’s endings and Merkel’s disks don’t adapt rapidly. They fire action potentials for the entire duration of the touch stimulus.

70
Q

What are touch receptive fields?

A

Each mechanoreceptor responds to a touch stimulus in a specific area of the skin, a region called the receptive field of the receptor. When the receptive field is touched, the mechanoreceptor will be activated.

71
Q

What is two-point discrimination?

A

This is a measure of how close two nearby objects that are both touching the skin can be to one another before your skin cannot tell that they are truly two distinct points.

72
Q

What are dermatomes?

A

A dermatome is all the skin innervated by one level or segment of spinal cord.

73
Q

What must all receptors do?

A

They all have to send their axons with info to the brain except for the ones in the face and neck which use cranial nerves.

74
Q

How are the thirty spinal segments divided up?

A

There are thirty spinal segments which are divided into four major groups named based on that specific part of the vertebrae. There are eight cervical spine segments, twelve thoracic spine segments, five lumbar and five sacral.

75
Q

Why are dermatomes useful?

A

They can help point out places where a certain condition is, diagnosing and assessing these conditions.

76
Q

What are temperature receptors called?

A

Thermoreceptors - they don’t have any specializations and are therefore free nerve endings.

77
Q

What are thermoreceptors?

A

These receptors react to temperature. They are divided into high and low thresholds.

Low-threshold receptors - react to 15 degrees C - 45 degrees C

High threshold receptors - react to below 15 degrees C and higher than 45 degrees C

The information has a slow transmission to the brain because it is not as critical.

78
Q

What are nociceptors?

A

Nociceptors are specialized nerve endings that detect and transmit pain signals. They are found throughout the body and are sensitive to stimuli like extreme temperatures, pressure, and chemicals released during tissue damage or inflammation. When activated, nociceptors send signals to the brain, helping us perceive and respond to pain.

79
Q

What is hyperalgesia?

A

Hyperalgesia is when the threshold is reduced for an inflamed area so that you’re more gentle towards that area and so it heals faster. The area becomes red, warm, and swollen.

80
Q

What is Congenital analgesia?

A

Congenital analgesia is a hereditary insensitivity to pain and is rare because is so dangerous to one’s health. This can be caused by defects in the free nerve endings.

81
Q

Why is pain so important?

A

Pain is important it is one of the most crucial signs for survival. Without it, a child doesn’t learn to avoid dangerous things like fire and sharp objects.

82
Q

Where are pain receptors located?

A

They are located in the epidermis and are free nerve endings.

83
Q

What do all three of the sensory neurons discussed have in common?

A

They all have nerve endings or dendrites in the skin and synapse on to the next neuron somewhere in the spinal cord or brainstem. This means those neurons are really long!

84
Q
A

USAP science (18 decks)

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