Deck 28: Sensory Input and Motor Output

Question 1

The thick filaments in a sarcomere are composed mainly of

A) calcium.
B) actin.
C) myosin.
D) rhodopsin.
E) Both b and c are correct.

Answer 1

A muscle fiber has many myofibrils. A myofibril has many sarcomeres. Sarcomeres are considered the contractile units. A sarcomere contains proteins. There are two types of proteins. The two proteins are myosin and actin. The thick filament is made up of myosin. The thin filament is made up of actin. Contraction occurs when the thin filament slides over the thick filament.
Hence, the correct answer is (c) myosin.
Calcium ions (Ca 2+ ) are necessary for muscle contraction. Ca 2+ attaches to actin. This attachment triggers the binding of actin onto the myosin. The hydrolysis of ATP (adenosine triphosphate) moves actin over the myosin. This sliding motion creates muscle contraction. Thus, the thick filament is not composed of calcium. Hence, the option (a) calcium is incorrect.
Actin is a type of protein in muscle. The thin filament is composed of actin. During contraction, the thin filament slide over the thick filament. Thus, the thick filament is not composed of actin. Hence, the option (b) actin is incorrect.
Rhodopsin is a pigment in rods. Rods are photoreceptors. Rhodopsin is a visual pigment. Rhodopsin is made up of opsin and retinal. Opsin is a protein. Retinal is a light-absorbing molecule. Thus, rhodopsin is an important component of rods. The thick filament is not made up of rhodopsin. Hence, the option (d) rhodopsin is incorrect.
Both actin and myosin are muscle proteins. Actin and myosin are present in sarcomeres. However, the thin filament is composed of actin. The thick filament is composed of myosin. Hence, the option (e) both b and c are correct is incorrect.

Question 2

A freely movable, fluid-filled joint is a(n) _____ joint.

A) synovial
B) proprioceptive
C) Golgi
D) otolithic
E) hydrostatic

Answer 2

A synovial joint consists of two bones. The two bones are held together by two ligaments. Synovial fluid is filled between the two bones. The synovial fluid lubricates the bones and prevents friction. There are two types of synovial joints. The two types of synovial joints are ball-and-socket joint and hinge joint. Synovial joints are freely movable.
Hence, the correct answer is (a) synovial.
Proprioceptive is associated with receptors. Proprioceptive is not a joint. Hence, the option (b) proprioceptive is incorrect.
Golgi is not a joint. Hence, the option (c) Golgi is incorrect.
Otolithic is associated with stones. Otolithic is not a joint. Hence, the option (d) otolithic is incorrect.
Hydrostatic is associated with water. It may involve movement in water. Hydrostatic is not a joint. Hence, the option (e) hydrostatic is incorrect.

Question 3

The contractile portion of a skeletal muscle fiber is the

A) myofibril.
B) thin filament.
C) thick filament.
D) sarcoplasmic reticulum.

Answer 3

A muscle fiber is composed of many myofibrils. Each myofibril is composed of many sarcomeres. Sarcomeres are the contractile units of a muscle. The sarcomeres contract and relax. Thus, a myofibril is the contractile portion of a muscle fiber.
Hence, the correct answer is (a) myofibril.
The thin filament is part of a sarcomere. A sarcomere has many thin filaments. However, the thin filament is not a contractile unit. Hence, the option (b) thin filament is incorrect.
The thick filament is part of a sarcomere. A sarcomere has many thick filaments. However, the thick filament is not considered a contractile unit. Hence, the option (c) thick filament is incorrect.
Sarcoplasmic reticulum encloses a muscle fiber. Sarcoplasmic reticulum stores calcium ions (Ca 2+ ). Sarcoplasmic reticulum releases Ca 2+ to the myofibrils. Calcium is necessary for muscle contraction. However, sarcoplasmic reticulum is not a contractile portion of a muscle fiber. Hence, the option (d) sarcoplasmic reticulum is incorrect.

Question 4

Which cell type deposits bone tissue?

A) osteocyte
B) osteoclast
C) osteoblast
D) None of these are correct.

Question 5

The basic unit of a skeletal muscle contraction is called the

A) osteoclast.
B) myosin filament.
C) sarcomere.
D) ligament.

Question 6

Which type of skeleton is found in humans?

A) endoskeleton
B) exoskeleton
C) hydrostatic skeleton

Question 7

The human eye focuses by

A) changing the thickness of the lens.
B) changing the shape of the lens.
C) opening and closing the pupil.
D) rotating the lens.

Question 8

The _____ is the region of the eye that controls the amount of light that enters.

A) cornea
B) pupil
C) lens
D) fovea
E) retina

Question 9

For question identify the type of sensory receptor that matches the description. Some answers may be used more than once. Key:

A) propioreceptor
B) chemoreceptor
C) mechanoreceptor
D) nociceptor
E) photoreceptor
Detects pain

Question 10

For question identify the type of sensory receptor that matches the description. Some answers may be used more than once. Key:

A) propioreceptor
B) chemoreceptor
C) mechanoreceptor
D) nociceptor
E) photoreceptor
Responds to wavelengths of light

Question 11

For question identify the type of sensory receptor that matches the description. Some answers may be used more than once. Key:

A) propioreceptor
B) chemoreceptor
C) mechanoreceptor
D) nociceptor
E) photoreceptor
Involved in the sense of hearing

Question 12

For question identify the type of sensory receptor that matches the description. Some answers may be used more than once. Key:

A) propioreceptor
B) chemoreceptor
C) mechanoreceptor
D) nociceptor
E) photoreceptor
Involved in the senses of taste and smell

Question 13

For question identify the type of sensory receptor that matches the description. Some answers may be used more than once. Key:

A) propioreceptor
B) chemoreceptor
C) mechanoreceptor
D) nociceptor
E) photoreceptor
Helps the body maintain posture

Question 14

Label the parts of the ear in the following illustration.

Question 15

Label the parts of the eye in the following illustration.