Nokea
From which type of tissue is the myelin sheath derived, a fatty substance that insulates nerve fibers?
- A. Epithelial tissue
- B. Muscle tissue
- C. Nervous tissue (glial cells)
- D. Connective tissue
Correct Answer: C
Rationale: The myelin sheath, a fatty substance that insulates nerve fibers, is derived from nervous tissue, specifically glial cells. Glial cells, including oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system, are responsible for producing the myelin sheath that surrounds and insulates nerve fibers, aiding in the conduction of nerve impulses. Epithelial tissue (Choice A), Muscle tissue (Choice B), and Connective tissue (Choice D) are not responsible for producing the myelin sheath; instead, nervous tissue (glial cells) plays this crucial role.
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Which of the following structures is responsible for filtering blood in the kidneys?
- A. Ureter
- B. Glomerulus
- C. Nephron
- D. Renal artery
Correct Answer: B
Rationale: The correct answer is B: Glomerulus. The glomerulus, located in the nephron of the kidney, is a network of tiny blood vessels responsible for filtering blood. It removes waste products and excess substances to form urine. The ureter carries urine from the kidneys to the bladder and is not involved in blood filtration. The nephron is the functional unit of the kidney where blood is filtered and urine is produced. The renal artery supplies blood to the kidneys but is not directly involved in the filtration process.
Which of the following neurotransmitters slows down the activity of neurons to prevent overexcitation?
- A. Acetylcholine
- B. Dopamine
- C. GABA
- D. Serotonin
Correct Answer: C
Rationale: The correct answer is C: GABA (gamma-aminobutyric acid). GABA is an inhibitory neurotransmitter that slows down neuronal activity, helping to prevent overexcitation in the brain. It counterbalances the effects of excitatory neurotransmitters like glutamate, playing a crucial role in maintaining the balance of neuronal activity in the brain. Acetylcholine (Choice A) is primarily an excitatory neurotransmitter involved in muscle movement and cognitive functions. Dopamine (Choice B) plays a role in reward-motivated behavior and motor control. Serotonin (Choice D) is involved in regulating mood, appetite, and sleep but is not primarily responsible for slowing down neuronal activity to prevent overexcitation.
Skeletal muscles are attached to bones by tough connective tissues called
- A. Ligaments
- B. Tendons
- C. Cartilage
- D. Fascia
Correct Answer: B
Rationale: Skeletal muscles are attached to bones by tough connective tissues called tendons. Tendons are strong, fibrous cords that connect muscles to bones, allowing for movement and stability in the body. Ligaments (option A) connect bones to other bones, not muscles to bones. Cartilage (option C) is firm and flexible connective tissue found in various parts of the body, but it does not attach muscles to bones. Fascia (option D) is a connective tissue that surrounds muscles, providing support and protection, but it does not directly attach muscles to bones.
Which part of the nervous system is responsible for transmitting signals from the sensory organs to the central nervous system?
- A. Autonomic nervous system
- B. Somatic nervous system
- C. Peripheral nervous system
- D. Central nervous system
Correct Answer: C
Rationale: The correct answer is C, the peripheral nervous system. The peripheral nervous system is responsible for transmitting signals from the sensory organs to the central nervous system. It consists of nerves that connect the central nervous system to the rest of the body, including sensory nerves that carry information from the sensory organs to the brain and spinal cord. Choices A, B, and D are incorrect. The autonomic nervous system is responsible for involuntary functions like heart rate and digestion, the somatic nervous system controls voluntary movements, and the central nervous system consists of the brain and spinal cord.
Which type of joint allows for the greatest range of motion?
- A. Hinge joint
- B. Ball-and-socket joint
- C. Pivot joint
- D. Saddle joint
Correct Answer: B
Rationale: The correct answer is B: Ball-and-socket joint. The ball-and-socket joint, like the shoulder joint, allows for the greatest range of motion due to its structure, enabling movement in multiple directions. In contrast, hinge joints, pivot joints, and saddle joints have more restricted ranges of motion compared to ball-and-socket joints. Hinge joints primarily allow movement in one plane, pivot joints allow rotation around a central axis, and saddle joints have limited movement compared to ball-and-socket joints.