OAT Biology - Problem Drill 13: The Muscular System Question No. 1 of 10 1. Which statement about muscles is correct? Question #01 (A) Muscles have an origin that is usually attached to a movable bone, thick portion called the belly and they are attached to stationary bones by a tendon such as the Achilles tendon. (B) Muscles have an origin that is usually attached to a stationary bone, thick portion called the belly and they are attached to stationary bones by a tendon such as the Achilles tendon. (C) Muscles provide structural support, are involved in thermoregulation, but have no effect on organ function. (D) Cardiac muscle provides the heart pumping action and support and rigidity throughout the body. (E) All of the above. Muscles are not usually attached to a movable bone. B. Correct! Muscles have an origin that is usually attached to a stationary bone, thick portion called the belly and they are attached to stationary bones by a tendon such as the Achilles tendon. Muscles provide organ function through contraction. Skeletal muscle provides support and rigidity throughout the body. There is only one correct statement above. Muscles have an origin, usually attached to a stationary bone. The thick portion of the muscle between the insertion and origin is called the muscle belly or gaster. Muscles are attached to movable bones by a tendon, such as the Achilles tendon. Muscles are arranged in groups throughout the body. Each group moves and supports the bones and organs in that region, i.e. muscles of the lower extremity move and support the leg. The muscular system is made of muscles, the central nervous system and the peripheral nerves that control them. The muscular system provides structural rigidity and support, and is primarily responsible for heat generated in the body. It is involved in regulating systemic blood pressure by vasoconstriction of smooth muscle in blood vessels. Skeletal muscle provides human motion, cardiac muscle pumps the heart and smooth muscle provides organ function through muscular contraction. The correct answer is (B).
Question No. 2 of 10 2. Which best describes the effect of muscles on peripheral circulation? Question #02 (A) Smooth muscle in the walls of precapillary arterioles modulates peripheral resistance, such as decreasing systemic blood pressure by contracting. (B) Smooth muscle in the walls of precapillary arterioles modulates peripheral resistance, such as increasing systemic blood pressure by contracting. (C) The pressure in veins is high, and this aids the contraction of nearby muscles. (D) The movement of blood through the venous system occurs because of the heart pumping action, the muscles of the legs do not aid in this process. (E) Smooth muscle in the walls of precapillary arterioles does not modulate peripheral resistance. Smooth muscle in the walls of precapillary arterioles modulates peripheral resistance, but it does not decrease systemic blood pressure by contracting. B. Correct! Smooth muscle in the walls of precapillary arterioles modulates peripheral resistance, such as increasing systemic blood pressure by contracting. The pressure in veins is low and the contraction of nearby muscles aid in the movement of blood through the venous system. The contraction of nearby muscles near the veins aids in the movement of blood through the venous system. Smooth muscle in the walls of precapillary arterioles modulates peripheral resistance, such as increasing systemic blood pressure by contracting. Smooth muscle in the walls of precapillary arterioles contract and cause the peripheral vascular resistance to be increased, thereby increasing systemic blood pressure. The pressure in veins is low and the contractions of nearby muscles aid in the movement of blood through the venous system. The correct answer is (B).
Question No. 3 of 10 3. Which of the following statements about the role of muscles in thermoregulation is correct? Question #03 (A) Muscle contraction accounts for most of the heat generated and required by the human body. (B) Muscle contraction accounts for approximately 25% of the heat generated and required by the human body; the rest comes from the external environment. (C) The chemical reactions occurring in muscles during contraction absorb heat and therefore act to lower body temperature. (D) If the normal body temperature drops by at least 8-10 C, shivering results. Shivering is an involuntary, rapid contraction of the muscles, which generates more heat quickly to counter the drop in body temperature. (E) Muscle contraction has nothing to do with the heat generated and required by the human body. A. Correct! Muscle contraction accounts for most of the heat generated and required by the human body. Muscle contraction accounts for most of the heat generated and required by the human body. The chemical reactions occurring in muscles during contraction generate heat. If the normal body temperature drops by even 1-2 C, shivering results. Muscle contraction accounts for most of the heat generated and required by the human body. Muscle contraction accounts for most of the heat generated and required in the human body. The chemical reactions that occur in muscles during contraction generate heat. Specifically, glucose is converted to ATP, which powers the movement of actin against myosin to create muscle contractions. If the normal body temperature drops even 1-2 C, this can result in shivering. Shivering is an involuntary, rapid contraction of the muscles, which will generate more heat quickly to counter the drop in body temperature. The correct answer is (A).
Question No. 4 of 10 4. Skeletal muscles? Question #04 (A) Are striated, attached to bone and generally under involuntary control. (B) Are made up of 2 fiber types: (a) red (slow-twitch), and (b) those with sarcomeres. (C) Are striated, attached to bone and generally under voluntary control. (D) Are made up of white (fast-twitch) fibers that have more mitochondria and are associated with endurance. (E) Are made up of only the red fiber type. Skeletal muscles are striated, attached to bone and generally under voluntary control. Skeletal muscles are made up of 2 fiber types: (a) red (slow-twitch), and (b) white (fast-twitch). C. Correct! Skeletal muscles are striated, attached to bone and generally under voluntary control. White (fast-twitch) fibers have fewer mitochondria and are explosive. Skeletal muscles are made up of 2 fiber types: (a) red (slow-twitch), and (b) white (fast-twitch). Skeletal muscle is striated and attached to bones. Skeletal muscle facilitates movement by applying forces to bones and joints through its contraction. They are generally under voluntary control. Skeletal muscle has striations due to many sarcomeres (basic unit of contraction). Individual muscle myofibrils make up a muscle fiber. There are 2 types of muscle fibers: (a) red (slow-twitch) have more mitochondria and are associated with endurance, and (b) white (fast-twitch) have fewer mitochondria and are explosive. The correct answer is (C).
Question No. 5 of 10 5. Which of the following statements about sarcomeres is correct? Question #05 (A) Sarcomeres are the basic unit of muscle and are made up of actin and myosin. (B) Sliding filament model: the muscle generates its own signal to contract and then an action potential spreads over the muscle fiber. (C) During muscular contraction, ATP is formed. (D) During muscular contraction zinc is released and binds to tropomyosin, which unblocks actin-binding sites. (E) Sarcomeres are made up of actin only. A. Correct! Sarcomeres are the basic unit of muscle and are made up of actin and myosin. Sliding filament model: after the signal to contract comes from the central nervous system, an action potential spreads over the muscle fiber. During muscular contraction ATP is hydrolyzed. During muscular contraction calcium is released and binds to tropomyosin, which unblocks actin-binding sites. Sarcomeres are made up of actin and myosin. Sarcomeres are the basic unit of muscle, made up of actin and myosin. Skeletal muscles contract according to the sliding filament model. Sliding filament model: after the signal to contract comes from the central nervous system, an action potential spreads over the muscle fiber. Calcium is released and binds to tropomyosin, which unblocks actin binding sites. Myosin (bound with ATP) binds to actin, hydrolyzes ATP and the released energy delivers a power stroke. This hydrolysis also causes the myosin head to turn and ratchet the Z lines closer together. The correct answer is (A).
Question No. 6 of 10 6. Which is true about cardiac muscle? (A) Cardiac muscle is a voluntary striated muscle found exclusively in the heart. (B) Cardiac muscle stimulates its own contraction with the required electrical impulse from the central nervous system (CNS). (C) Special pacemaker cells in the sinoatrial node contract in response to the contraction rate of the adjacent skeletal muscle. Question #06 (D) Cardiac muscle is an involuntary striated muscle found exclusively in the heart. (E) All statements above are true. Cardiac muscle is an involuntary striated muscle found exclusively in the heart. Cardiac muscle stimulates its own contraction without the required electrical impulse from the central nervous system (CNS). Special pacemaker cells in the sinoatrial node spontaneously contract and send electrical impulses throughout the heart. D. Correct! Cardiac muscle is an involuntary striated muscle found exclusively in the heart. There is one true statement above. Cardiac muscle is an involuntary striated muscle found exclusively in the heart. Cardiac muscle has unique properties: (a) Sstimulates its own contraction without the required electrical impulse from the central nervous system (CNS),. (b) Sspecial pacemaker cells in the sinoatrial node (located in the right atrium), spontaneously contract and send electrical impulses throughout the heart., and (c) Nnormally the resting heart rate is between 70 80 bpm, determined by the pacemaker cells. The CNS doesn t does not directly create the impulse to contract, but modulates it through the autonomic nervous system. The correct answer is (D).
Question No. 7 of 10 7. Which of the following statements about smooth muscle is correct? Question #07 (A) Smooth muscle is a voluntary non-striated muscle found in the walls of hollow organs such as the bladder and in blood vessels. (B) Smooth muscle can only be stimulated directly from the central nervous system. (C) Smooth muscle does not require ATP for contraction; instead it contracts passively. (D) Smooth muscle is spindle-shaped and contains actin and myosin, although they are not arranged in a sarcomere. (E) None of the above. Smooth muscle is an involuntary non-striated muscle found in the walls of hollow organs such as the bladder and in blood vessels. Smooth muscle can be directly stimulated by the CNS or can react to hormones secreted locally, such as vasodilators and vasoconstrictors. Smooth muscle hydrolyzes ATP and contracts by myosin and actin fibers sliding over each other. D. Correct! Smooth muscle is spindle-shaped and contains actin and myosin, although they are not arranged in a sarcomere. There is one correct answer above. Smooth muscle is an involuntary non-striated muscle found in the walls of hollow organs such as the bladder, and in blood vessels. Smooth muscle can be directly stimulated by the CNS or can react to hormones secreted locally, such as vasodilators and vasoconstrictors. Smooth muscle is spindle shaped and contains actin and myosin, although they are not arranged in a sarcomere. Smooth muscle hydrolyzes ATP and contracts by myosin and actin fibers sliding over each other. Smooth muscle fibers are arranged in sheets within the walls of organs. The correct answer is (D).
Question No. 8 of 10 8. Which of the following statements about the nervous control of muscle is correct? Question #08 (A) Sensory (afferent) information travels to the CNS, providing information about temperature, pressure and pain. (B) Peripheral nerves transmit afferent information only. (C) Sensory (afferent) information travels from the CNS, providing muscles information about temperature, pressure and pain. (D) Motor (efferent) impulses travel from the muscle to the CNS along the peripheral nerves. (E) None of the above. A. Correct! Sensory (afferent) information travels to the CNS, providing information about temperature, pressure and pain. Peripheral nerves transmit both sensory and motor impulses. Sensory (afferent) information travels to the CNS, providing information about temperature, pressure and pain. Motor (efferent) impulses travel from the CNS along the peripheral nerves, to the target muscles. There is one correct answer above. The CNS (brain and spinal cord) is connected to muscles by peripheral nerves. These nerves transmit both sensory and motor impulses. Sensory (afferent) information travels to the CNS, providing information about temperature, pressure and pain. Motor (efferent) impulses travel from the CNS along the peripheral nerves to the target, i.e. foot, and initiate movement. The correct answer is (A).
Question No. 9 of 10 9. Motor neurons. Question #09 (A) Originate in the spinal cord and transmit afferent (sensory) impulses to the target muscle. (B) Originate in the spinal cord and transmit motor (effector) impulses to the target muscle. (C) Are divided into two branches: (a) autonomic, and (b) lower motor neurons. (D) Connect the brain to the spinal cord (Lower motor neurons). (E) Motor neurons typically locate in the peripheral nervous system. Originate in the spinal cord and transmit motor impulses to the target muscle. B. Correct! Originate in the spinal cord and transmit motor (effector) impulses to the target muscle. Are divided into two branches: (a) upper motor neurons, and (b) lower motor neurons. Lower motor neurons connect the spinal cord to the muscles. Motor neuron classically applies to neurons located in the central nervous system that project their axons outside the CNS and directly or indirectly control muscles. The motor neuron and the muscle fibers it innervates are called the motor unit. Groups of motor units work together to contract a muscle. Motor neurons originate in the spinal cord and transmit motor (effector) impulses to the target muscle. Motor neurons are divided into 2 branches: (a) upper motor neurons that connect the brain and spinal cord, and (b) lower motor neurons that connect the spinal cord to the muscles. The correct answer is (B).
Question No. 10 of 10 10. Which of the following statements about the autonomic nervous system is correct? Question #10 (A) Parasympathetic nervous system: (a) slows the heart rate, which conserves energy and (b) uses acetylcholine to induce the release of adrenaline. (B) The parasympathetic branch of the autonomic nervous system has been called fight or flight because it stimulates the heart and prepares the skeletal muscles for increased work. (C) The autonomic nervous system is divided into two components, the parasympathetic branch and the sympathetic branch. (D) The sympathetic branch of the autonomic nervous system has been called rest and digest, because it slows down the body and increases digestive activity. (E) Autonomic nervous system is part of the central nervous system. Parasympathetic nervous system: (a) slows the heart rate, which conserves energy, and (b) increases intestinal blood flow and activity for digestion and absorption. The sympathetic branch of the autonomic nervous system has been called fight or flight because it stimulates the heart and prepares the skeletal muscles for increased work. C. Correct! The autonomic nervous system is divided into two components, the parasympathetic branch and the sympathetic branch. The parasympathetic branch of the autonomic nervous system has been called rest and digest, because it slows down the body and increases digestive activity. The autonomic nervous system is a division of the peripheral nervous system, which is responsible for coordinating involuntary functions, such as breathing and digestion. The autonomic nervous system is divided into two components: the parasympathetic branch and the sympathetic branch. The parasympathetic nervous system: (a) slows the heart rate, which conserves energy, and (b) increases intestinal blood flow and activity for digestion and absorption. The sympathetic branch of the autonomic nervous system has been called fight or flight because it stimulates the heart and prepares the skeletal muscles for increased work. The parasympathetic branch of the autonomic nervous system has been called rest and digest, because it slows down the body and increases digestive activity. The correct answer is (C).