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Biology > 14 The Senses > Flashcards

14 The Senses Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

THE SENSES

What is sensation?

A

The concious perception of stimuli

Sensation does not occur until nerve signals arrive at the cerebral cortex of the brain

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2
Q

THE SENSES

How does sensation occur?

A
  1. sensory receptors respond to environmental stimuli
  2. nerve impulses travel to the cerebral cortex
  3. sensation!
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3
Q

THE SENSES

What is sensory adaptation?

A

Sensory adaptation is the decrease in stimulus perception which can occur with repetative stimuli (i.e. odor or vision)

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4
Q

THE SENSES

What are sensory receptors?

A

Dendrites of neurons specialized to detect certain types of stimuli:

  1. Exteroceptors: detect stimuli from outside the body (taste, hearing, vision)
  2. interoceptors: receive stimuli from inside the body (change in blood pressure, pH, osmolarity (salt), gastrointestinal or urinary tract distention)
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5
Q

THE SENSES

Types of sensory receptors

A
  1. chemoreceptors: respond to nearby chemicals - taste, smell, pH, etc.
  2. pain receptors: type of chemoreceptor that responds to chemical released by damaged tissues
  3. photo receptors: responds to light energy
  4. mechanoreceptors: responds to forces such as pressure - sound, position, touch
  5. thermoreceptors: stimulated by temperature change
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6
Q

THE SENSES

The Knee-Jerk Reflex

A

Proprioceptors called spindle cells inside muscle monitor muscle length to maintain posture.

When suddenly stretched, the spindle cells fire action potentials to spinal cord interneurons, causing them to send action potentials back down motor neurons.

This causes contraction of mucle fibers to decrease muscle length, and return to its original length.

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7
Q

THE SENSES

What mechanoreceptors are involved in reflex actions?

A

Proprioceptors

They are in skin, muscles, joints, tendons, organs

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8
Q

THE SENSES

Cuteneous Receptors

A

In the dermis, they make the skin sensitive to touch, pressure, pain and temperature.

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9
Q

THE SENSES

Taste Receptors

A

Sensitive to sweet, sour, salty and bitter tastes in food

3,000 taste buds, mostly on the tongue

80-90% of what we perceive is taste is actually due to the sense of smell

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10
Q

THE SENSES

Smell Receptors

A

10-20 million olfactory cells (modified neurons) in the nasal cavity

Olfactory cells are in the roof of nasal cavity. Each has only one of several thousand types of receptor proteins - each smell stimulates certain combinations of receptors.

Direct connection to the Limbic System of the brain, generates emotion and memory.

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11
Q

THE SENSES

Vision: Anatomy of the Eye

What are the 2 compartments of the eye?

A
  1. Anterior Chamber: between the cornea and lens filled with a clear fluid called aqueous humor
  2. Posterior Chamber: most of the eye, behind the lens, contains a clear gelatinous material called vitreous humor.
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12
Q

THE SENSES

The Eye’s 3 layers

A
  1. Sclera: outer, mostly white and fibrous except the cornea (clear)
  2. Choroid: middle, darkly pigmented vascular layer
  3. Retina: inner layer containing photoreceptors
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13
Q

THE SENSES

Front of the Eye: Cornea

A

Cornea

Transparent portion of the sclera that (along with the lens) transmits and refracts (bends) light

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14
Q

THE SENSES

Front of the Eye: Iris

A

Iris

colored portion of the eye, controls how much light enters the eye by opening and closing pupil, the dark hole in the center is the iris

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15
Q

THE SENSES

Front of the Eye: Ciliary Body

A

Ciliary Body

Muscular structure behind the iris that controls the shape of the lens and iris

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16
Q

THE SENSES

Front of the Eye: Lens

A

Lens

refracts and focuses light rays on the retina

(you strain more when you look at things close up)

17
Q

THE SENSES

Retina

A

Contains photoreceptors called rods and cones

The fovea centralis is a central area of the retina densely packed with cones, where images are focused

Rods and cones synapse with neurons in the retina that form the optic nerve, which takes nerve impuses generated by light striking the retina to the brain

18
Q

THE SENSES

Rods

A

Located mostly in the periphery of retina

important for peripheral and night vision - extremely sensitive to low light, but not sensitive to color

19
Q

THE SENSES

Cones

A

Located mostly in the fovea centralis (central retina)

Important for detection of central fine detail and color but not sensitive to dim light

20
Q

THE SENSES

Photoreceptors of the retina

A

Rods, contain visual pigment Rhodopsin, made of opsin and retinal (made from Vit A)

Cones, also contain Rhodopsin, but 3 different kinds of cones contain red, green and blue pigments, each sensitive to different wavelength (colors) of light

Light energy causes rhodopsin to split into retinal and opsin. This causes a cascade of chemical reactions that eventually result the rod or cone sending neural impulses to the brain.

21
Q

THE SENSES

Blind Spots

A

where the optic nerve leaves the eye.

Having no cones and rods, the spot on the retina with no vision.

22
Q

THE SENSES

How the eyes are connected to the brain?

A

We have stereo vision since our eye is divided.

Both eyes contain:

right visual cortex

left visual cortex

thalamic nucleus

optic tract

optic charisma

optic nerve

23
Q

THE SENSES

Abnormalities of the Eye

A

Color Blindness: genetic disability most common in males in which they usually cannot correctly see shades of red and green.

Cataracts: lens of the eye become cloudy

Glaucoma: fluid pressure builds up in the eye

Astigmatism: the cornea or lens is uneven, leading to a fuzzy image on the retina

Nearsightedness: eyeball is too long making it hard to see far away objects

Farsightedness: eyeball is too short making it hard to see near objects

24
Q

THE SENSES

Anatomy of the Ear

A

3 Divisions:

Outer Ear - for hearing, air filled, pinna to ear drum

Middle Ear - for hearing, air filled, ear drum to oval window

Inner Ear - for hearing and balance, cochlea and semicirular canals, filled with fluid (no air)

25
Q

THE SENSES

Outer Ear

A

Pinna: external ear flap that catches and amplifies sound waves

Auditory Canal: direct sound waves to the typanic membrane, lined with fine hairs and modified sweat glands that secrete ear wax - a natural insect repellant

26
Q

THE SENSES

Middle Ear

A

Tympanic Membrane (ear drum): converts sound waves to mechanical vibrations and transmits them to three tiny bones called ossicles

Ossicles (malleus, incus, stapes) tiny bones that amplify and transmit vibrations made by sound from eardrum to inner ear

Eustachian Tube: connects the pharynx to the middle ear, equalizes pressure on either side of the eardrum so it does not burse with varying ambient (external) pressure

27
Q

THE SENSES

Inner Ear

A

Important for both hearing and balance

3 areas: cochlea, semicircular canals, vestibule

Stapes (last of the three ossicles) vibrates and strikes the membrane of the oval window, causing fluid waves in the cochlea

Vestibule: gravitational equilibrium

Semicircular canals: rotation equilibrium

28
Q

THE SENSES

Cochlea

A

Contains the organ of Corti (spiral organ) -sense organ with hair cells that covert vibration into neural impulses

Hair cells (cilia) move by tectorial membrane, sits on basilar membrane. Cilia moving is the action potential

29
Q

THE SENSES

Inner Ear Balance

A

Vestibule detects vertical and horizontal movement of the head (gravitational equilibrium). Depends on hair cells in the the utricle and saccule

Semiciruclar Canals detect rotational equilibrium, spinning (angular movement) - depends on hair cells at the base of each semiciruclar canal (ampulla)

Biology (10 decks)

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