BIOL-203-604 2025 FA Anatomy and Physiology I at Howard Community College

Explanation
In a spinal reflex arc, the sequence of events begins with the receptor, which detects the stimulus (such as pain or heat). The sensory neuron then carries the signal to the spinal cord, where it is processed by the interneurons. A response is sent through the motor neuron to the effector, such as a muscle or gland, which carries out the reflex action (like pulling away from a hot surface). Importantly, the reflex arc does not typically involve the brain, allowing for a rapid, involuntary response.

Explanation

At the neuromuscular junction, acetylcholine (ACh) is the neurotransmitter that is released from motor neurons. It binds to receptors on the skeletal muscle cell membrane (sarcolemma), leading to muscle contraction. Dopamine, glutamate, and norepinephrine are neurotransmitters involved in other parts of the nervous system, but they are not used at the neuromuscular junction for skeletal muscle activity.

Correct Answer Is:

A. acetylcholine

Explanation
Sympathetic stimulation prepares the body for "fight or flight" responses. One of its key effects is to increase heart rate (tachycardia) to pump more blood and oxygen to muscles and vital organs in preparation for physical exertion or stress. Sympathetic activation also typically raises blood pressure and inhibits non-essential functions such as digestion.

Explanation
The correct sequence for information flow through a neuron is:
1.​Dendrites receive incoming signals from other neurons or sensory receptors.
2.​The signals travel to the soma (cell body) for processing.
3.​If the signal is strong enough, it triggers an action potential at the axon hillock.
4.​The action potential then travels down the axon.
5.​Finally, the signal reaches the axon terminal, where it is transmitted to the next neuron or target cell.

Explanation

Parathyroid hormone (PTH) is produced by the parathyroid glands and plays a key role in regulating blood calcium levels. When blood calcium levels are low, PTH is released to increase calcium levels by stimulating osteoclasts to break down bone and release calcium, increasing calcium reabsorption by the kidneys, and activating vitamin D to enhance calcium absorption from the intestines. It does not affect blood glucose levels or stimulate growth directly.

Correct Answer Is:

A. increase blood calcium levels

Explanation

Shivering is a process that generates heat through muscle contractions, helping the body increase its core temperature in response to cold. Decreased metabolism would actually reduce heat production, not increase it. Sweating, on the other hand, helps cool the body down, not gain heat. Therefore, the correct answer is shivering, which is a way to generate heat in the body.

Correct Answer Is:

C. shivering

Explanation

Luteinizing hormone (LH) plays a crucial role in the female reproductive system. It triggers ovulation, which is the release of an egg from the ovary, and also stimulates the production of gonadal steroids, such as estrogen and progesterone. These hormones are essential for regulating the menstrual cycle and supporting pregnancy if fertilization occurs.

Correct Answer Is:

C. Trigger ovulation and gonadal steroid production

Explanation

The parasympathetic nervous system is responsible for the rest and digest functions. It promotes activities that occur when the body is at rest, such as increased digestive activity (stimulating the digestive organs to process food and absorb nutrients). It also helps to slow the heart rate and reduce sweating, as well as constrict blood vessels in the skin. In contrast, the sympathetic nervous system prepares the body for fight or flight, increasing heart rate, blood flow to muscles, and sweating.

Correct Answer Is:

A. increased digestive activity

Explanation

Growth hormone (GH) is a peptide hormone, which is a type of amino acid-based hormone. These hormones are made up of chains of amino acids and are water-soluble, meaning they bind to receptors on the surface of target cells.

Correct Answer Is:

D. Growth hormone