The Nervous System and Sense Organs Flashcards
Coordination is the way in which [__] receive a stimulus and communicate with an [__]. The two systems involved include the [__] system and the [__] system.
receptors - effector - nervous - endocrine
❥ A [__] is any change in the internal or external organism’s environment that can cause a response or reaction in the organism.
❥ The specialized cell that detects a stimulus is called a [___].
❥ The body part that responds to a stimulus is called an [___].
❥ stimulus
❥ receptor
❥ effector
❥[___] neurons connect a [___] to the [__] so they convey sensory impulses to the brain and spinal cord.
❥ [__] neurons connect the [__] to an [__] so they transmit motor impulses from the brain or spinal cord to the muscle or gland.
❥ [__] neuron or interneuron carries impulses from the [__] neuron to the [__] neuron and are located in the CNS. Therefore, they conduct impulses between different parts of the CNS.
❥ Sensory - receptor - CNS
❥ Motor - CNS - effector
❥ Relay - sensory - motor
Describe saltatory conduction.
❥ [__ __] is a fatty insulating sheath (layer) that surrounds the axon.
❥ Myelin sheath is made by the [__] cells present at the axons.
❥ Mylein sheath is interrupted at the nodes of [__].
❥ The electrical impulse, traveling down a [__ __], cannot move through the axon in the insulated regions and, thus, skips over these insulated regions, jumping from one node to the next in a process called [__ __].
❥ The [__ __] is conducted very rapidly by saltatory conduction.
❥ Mylein sheath ❥ Schwann ❥ Ranvier ❥ myelinated axon - saltatory conduction ❥ nerve impulse
A [__] is the junction between two adjacent neurons, including the [__] cleft together with the ends of the presynaptic and the [__] neurons on either sides of the cleft.
synapse - synaptic - postsynaptic
In a [__ __], which is a very rapid response to a particular stimulus, the pathway taken by the nerve impulse from the receptor to the effector is called a [__ __].
reflex action - reflex arc
The components of the reflex arc in sequential order are the receptor, [__ __], relay neuron in CNS, [__ __], and the [__].
sensory neuron - motor neuron - effector
Where is the cell body of a motor neuron located in a hand withdrawal reflex
action?
The cell body of a motor neuron is located in the grey matter of the spinal cord.
Which neuron has its cell body entirely inside the central nervous system?
The relay neuron is entirely inside the central nervous system.
The cell body of the sensory neuron is located in the [__], which is a collection of cell bodies outside the [__].
ganglion - CNS
When light stimulates the rods and cones in the retina, a [__] nerve, called the optic nerve, carries nerve impulses generated by these receptors to the brain.
cranial -
❥ The choroid is [__] the retina.
❥ The choroid is [__] in humans, it absorbs [__] light scattered from the retina, thus preventing blurring of vision.
❥ It also contains many [__ __] to [__] the eye.
❥ behind
❥ black - excess
❥ blood vessels - nourish
The fovea is the part of the retina where cone cells are most [__ __]. The sharpest and most detailed color image is produced when light falls on the [__].
densely packed - fovea
The white, tough, opaque outer layer of the eye is called the [__]. The sclera is an [__] layer and thus it does not allow light into the eye.
sclera - opaque
The opaque, colored, circular part of the eye, which can be seen through the transparent cornea, is called the [__]. A gap, which looks like a black circle, at the center of the iris is called the [__]. It allows light to enter the eyes.
iris - pupil
Describe the muscles of the iris.
❥ The muscles of the iris are responsible for the changes in [__ __] observed in a pupil reflex. They control the amount of [__] entering the eye by [__] the diameter of the pupil.
❥ The iris consists of [__ __] sets of muscles that regulate the size of the [__]. The [__] muscles and the [__] muscles.
❥ The circular muscles [__] the pupil. The radial muscles [__] out from the edge of the pupil.
❥ pupil diameter - light - regulating
❥ 2 antagonistic - pupil - circular - radial
❥ encircle - radiate
What does the suspensory ligaments do?
The suspensory ligaments hold the lens in place and attach it to the ciliary muscle
The diameter of the pupil can be regulated by a cranial reflex action called the [__ __].
pupil reflex
The pupil reflex protects the [__] from damage due to excess light and allows more light to reach the retina in dim light for better vision.
retina
When walking into a brightly lit room: ❥ Radial muscles of the iris [\_\_]. ❥ Circular muscles of the iris [\_\_]. ❥ Pupil becomes [\_\_]. ❥ [\_\_] light is allowed into the eye preventing damage of the [\_\_].
❥ relax
❥ contract
❥ smaller
❥ Less - retina
When walking into a dim room or dark room: ❥ Radial muscles of the iris [\_\_]. ❥ Circular muscles of the iris [\_\_]. ❥ Pupil becomes [\_\_]. ❥ [\_\_] light is allowed into the eye.
❥ contract
❥ relax
❥ larger
❥ More
Accommodation is the ability to focus on objects at [__ __]. The ciliary muscle is responsible for the [__ __].
varying distances - accommodation reflex
Explain how the eye accommodates for a distant object?
❥ To accommodate the eye for a distant object, the [__] muscles [__].
❥ The suspensory ligaments are pulled [__]
❥ which then pulls the lens so that it becomes [__], [__] and [__].
❥ The parallel rays of light from the distant object are bent [__] and focused on the [__] of the [__].
❥ ciliary - relax
❥ tight
❥ thin - longer - less convex
❥ less - fovea - retina
Describe how the eye accommodates for a near object.
❥ To accommodate the eye for a near object, the [__] muscles [__].
❥ This causes the suspensory ligaments to become [__]
❥ releasing tension on the lens, which then becomes [__], [__] and [__ __].
❥ The light bends [__] and the divergent rays of light from the near object are bent strongly to focus them on the [__] of the [__].
❥ ciliary - contract
❥ slack
❥ thicker - shorter - more convex
❥ more - fovea - retina
