Question

1) What is the best definition of the "receptive field" of an afferent neuron?

A) The area of the cerebral cortex in which information from that afferent neuron is initially received.

B) All of the interneuron cell bodies and dendrites onto which the afferent neuron synapses.

C) The number of interneurons with which the central process of the afferent neuron makes synaptic contact via divergence.

D) The type of stimulus energy to which the afferent neuron is most sensitive.

E) The area of the body that, when stimulated, leads to activity in that particular afferent neuron.

2) Which of the following statements regarding the precision of locating a somatic stimulus is FALSE?

A) Lateral inhibition of parallel afferent pathways increases the precision of locating a stimulus.

B) The precision is greater in areas of the body that have small, overlapping receptive fields than in areas with large, nonoverlapping receptive fields.

C) The precision is greater for the skin than for the internal organs.

D) Convergence of afferent neurons onto common ascending pathways increases acuity.

E) The precision is greater in the lips and fingers than on the back.

3) During normal viewing of a distant object, the:

A) light rays striking the eyes are diverged by the cornea.

B) ciliary muscles are contracted.

C) zonular fibers are slackened.

D) firing of parasympathetic nerves to ciliary muscles increases.

E) lens flattens.

4) Which of the following statements about rods and cones in the retina is TRUE?

A) Rods and cones all have the same kind of opsin.

B) Cones enable us to see in dim light; rods provide color vision.

C) Rods provide higher visual acuity than do cones.

D) Rods require brighter light to activate them than do cones.

E) Cones are found in highest density in the fovea; rods are more prevalent near the edges of the retina.

5) The membrane potential of rod and cone cells is around:

A) -70 mV in the dark, and the cells depolarize in the light.

B) -35 mV in the dark, and the cells depolarize in the light.

C) -35 mV in the dark, and the cells hyperpolarize in the light.

D) -70 mV in the dark, and the cells hyperpolarize in the light.

These questions were pulled from Biology/Physiology exam.
PLEASE: Could you put an explanation for each answer why it is a correct answer?!
I would really appreciate that.

Answer 1

Answer:

1). E. The area of the body that, when stimulated, leads to activity in that particular afferent neuron.

Explanation:

The receptive field of an individual sensory neuron is the particular region of the sensory space (e.g., the body surface, or the visual field) in which a stimulus will modify the firing of that neuron. This region can be a hair in the cochlea or a piece of skin, retina, tongue or other part of an animal's body.

2). D) Convergence of afferent neurons onto common ascending pathways increases acuity.

3). E) lens flattens.

Explanation:

During accomidation , the lens becomes rounder to focus the image of a nearby object on the retina; the lens flattens when we focus on a distant object

4). E) Cones are found in highest density in the fovea; rods are more prevalent near the edges of the retina.

Explanation:

In the fovea, cone density increases almost 200-fold, reaching, at its center, the highest receptor packing density anywhere in the retina. This high density is achieved by decreasing the diameter of the cone outer segments such that foveal cones resemble rods in their appearance. The increased density of cones in the fovea is accompanied by a sharp decline in the density of rods. In fact, the central 300 µm of the fovea, called the foveola, is totally rod-free.

Rodsare responsible for vision at low light levels whereas cones are responsible for color vision.