Anatomy and Physiology II (M8) Comprehensive Lecture Exam

Correct Answer: B. Have receptors to which hormones bind

Explanation of the Correct Answer:

Target cells are specific cells in the body that respond to hormones. What makes them "targets" is that they have specific receptor proteins either on their surface or inside the cell that can recognize and bind to a particular hormone. When the hormone binds to its receptor, it triggers a biological response such as altering gene expression, activating enzymes, or changing cell metabolism. Without the appropriate receptor, a hormone has no effect on a cell. For example, insulin receptors on liver, muscle, and fat cells allow those cells to take in glucose in response to insulin. Cells that lack insulin receptors do not respond to insulin.

Why the Other Options Are Incorrect:

A. Are found in the blood

This is incorrect. Target cells are not found in the blood; they are found in tissues and organs throughout the body. While hormones travel through the blood, they leave the bloodstream and act on specific cells in organs like the liver, kidney, pancreas, or brain. Blood may carry hormones, but the target cells themselves are located in specific body tissues, not circulating in blood.

C. Secrete hormones

This is incorrect. Target cells do not secrete hormones; they respond to them. Hormone secretion is the role of endocrine glands such as the pituitary, thyroid, adrenal glands, pancreas, and gonads. Once secreted, hormones travel through the bloodstream to find their target cells.

D. Produce their own hormones

This is also incorrect. While endocrine cells produce hormones, target cells are distinct from hormone-producing cells. Target cells are designed to receive and react to hormones, not make them. For example, muscle cells are target cells for insulin, but they do not produce insulin themselves.

Correct Answer: D. Produce sounds

Explanation of the Correct Answer:

D. Produce sounds

The larynx, commonly known as the voice box, houses the vocal cords, which are essential for sound production. When air passes through the vocal cords, they vibrate and create sound, which is then shaped by the mouth, tongue, and lips into speech. If the larynx is surgically removed (a procedure known as a laryngectomy), the vocal cords are also removed, making normal voice production impossible. People who undergo this procedure may need alternative ways to speak, such as using an electrolarynx or esophageal speech.

Why the Other Options Are Incorrect:

A. Cough

Coughing is primarily a reflex involving the trachea, bronchi, and lungs. While the larynx does help close the glottis to build up pressure before a cough, other mechanisms can still produce a cough reflex even after the larynx is removed, though it may be less effective.

B. Sneeze

Sneezing is a reflex initiated by irritation in the nasal cavity, and it involves the soft palate, pharynx, and muscles of the face and chest. It is not dependent on the larynx, so a person can still sneeze after larynx removal.

C. Swallow

Swallowing primarily involves the pharynx, esophagus, and muscles of the tongue and throat. While the larynx normally elevates and closes the airway during swallowing to prevent aspiration, people without a larynx can still swallow, though they may be at higher risk for aspiration and may need assistance from speech or swallowing therapists.

Correct Answer: B. Duodenum

Explanation of the Correct Answer:

B. Duodenum

The main pancreatic duct carries pancreatic juices (which include digestive enzymes like amylase, lipase, and proteases and bicarbonate) from the pancreas into the duodenum. The duodenum is the first part of the small intestine, where pancreatic juices mix with chyme (partially digested food) from the stomach. These juices help neutralize the acidic chyme from the stomach and assist in further digestion by breaking down proteins, fats, and carbohydrates.

Why the Other Options Are Incorrect:

A. Stomach

The stomach is not the destination for pancreatic juices. The stomach produces gastric acid and digestive enzymes to break down food. Pancreatic juices are not secreted into the stomach, but into the duodenum.

C. Gallbladder

The gallbladder stores bile, which is released into the duodenum to aid in fat digestion. It does not receive pancreatic juices, which are transported to the duodenum via the main pancreatic duct.

D. Liver

The liver produces bile (which aids in fat digestion) and releases it into the duodenum via the bile ducts, but it does not receive pancreatic juices. The pancreatic juices are directed to the duodenum, not the liver.

Correct Answer: D. Metabolism

Explanation of the Correct Answer:

D. Metabolism

Metabolism refers to the sum of all chemical reactions that occur within the body to maintain life. These reactions are involved in processes like energy production, growth, repair, and maintenance. Metabolism can be divided into two categories: catabolism, which breaks down molecules to release energy, and anabolism, which uses energy to build molecules.

Why the Other Options Are Incorrect:

A. Phosphorylation

Phosphorylation is a specific chemical process where a phosphate group is added to a molecule, typically a protein, to alter its activity. While important in regulating many metabolic pathways, it is just one of the many reactions that occur during metabolism, not the entire sum of reactions.

B. Oxidation

Oxidation is a chemical reaction where a molecule loses electrons, often associated with the release of energy. It is a part of many metabolic pathways, particularly in the production of ATP in the mitochondria, but it does not describe the entirety of the body's chemical processes.

C. Homeostasis

Homeostasis refers to the body’s ability to maintain a stable internal environment (e.g., temperature, pH, and electrolyte balance). It is a regulatory process that involves various physiological mechanisms but does not refer to the totality of chemical reactions occurring in the body.

Correct Answer:

Cell membrane

Explanation:

The cell membrane, also known as the plasma membrane, is a selectively permeable barrier that surrounds the cell. It regulates the entry and exit of substances such as nutrients, waste, and ions. The membrane is made up of a lipid bilayer with embedded proteins that allow for transport, signaling, and structural support.

Why Other Options are Wrong:

Nuclear membrane

The nuclear membrane encloses the nucleus and regulates transport between the nucleus and the cytoplasm, not between the cell and its external environment.

Cell’s cytoplasm

The cytoplasm is the internal fluid of the cell where organelles are suspended. It does not regulate movement into or out of the cell.

Cell wall

The cell wall provides structural support and protection (mainly in plants, fungi, and some bacteria), but it is not responsible for the selective transport of materials in and out of the cell.

Correct Answer: C. 3.6.1.4.2.5

Explanation of the Correct Answer:

C. 3.6.1.4.2.5

This is the correct physiological order in which the action potential travels through the heart's conduction system.

3. sinoatrial (SA) node

This is the pacemaker of the heart. It initiates the electrical impulse that sets the rhythm of the heartbeat.

4. atrioventricular (AV) node

The impulse reaches the AV node next, where it is briefly delayed. This allows the atria to contract and push blood into the ventricles before they contract.

5. atrioventricular (AV) bundle

The impulse then travels from the AV node into the AV bundle, also called the bundle of His.

6. right and left bundle branches

From the AV bundle, the signal travels down the right and left bundle branches located in the interventricular septum.

7. Purkinje fibers

The impulse spreads through the Purkinje fibers, which rapidly conduct the signal throughout the ventricular walls.

8. contractile cells of cardiac muscle tissue

Finally, the signal reaches the contractile cells of the ventricles, causing them to contract and pump blood.

Why the Other Options Are Incorrect:

A. 3.1.6.4.5.2 places the AV bundle before the AV node and ends prematurely.

B. 3.1.6.4.2.5 has incorrect placement of AV bundle before the AV node.

D. 3.6.4.1.7.5 includes "7," which is not a valid part of the list and places steps out of order.

Correct Answer: C. Thyroid gland

Explanation of the Correct Answer:

C. Thyroid gland

The thyroid gland is anatomically located in the anterior neck, just inferior (below) to the larynx (voice box) and anterior (in front of) the trachea. It is a butterfly-shaped endocrine gland composed of two lobes connected by a central isthmus. The thyroid produces essential hormones such as thyroxine (T4) and triiodothyronine (T3), which regulate the body’s metabolism, growth, and development. Because of its location and critical endocrine function, it is the gland most associated with the anterior neck region.

Why the Other Options Are Incorrect:

A. Pancreas

The pancreas is located in the abdominal cavity, specifically in the upper abdomen behind the stomach. It functions as both an endocrine gland (producing insulin and glucagon) and an exocrine gland (producing digestive enzymes), but it is not in the neck region.

B. Pituitary gland

The pituitary gland is located at the base of the brain, seated in the sella turcica of the sphenoid bone, directly beneath the hypothalamus. Though it is a crucial endocrine gland often called the "master gland," it is not located in the neck.

D. Thymus

The thymus is located in the upper anterior part of the chest (mediastinum), just behind the sternum and in front of the heart. It plays a major role in the development of the immune system, particularly in children, but it is not situated in the neck, and it lies inferior to the thyroid.

Correct Answer:

Small intestine

Explanation:

The small intestine is the main site for nutrient absorption. Specifically, the jejunum and ileum absorb carbohydrates, proteins, fats, vitamins, and minerals into the bloodstream through structures called villi and microvilli.

Why Other Options are Wrong:

Lungs

These are part of the respiratory system and are involved in gas exchange (oxygen and carbon dioxide), not nutrient absorption.

Kidney

The kidneys filter blood and maintain fluid/electrolyte balance. They excrete waste, not absorb nutrients.

Large intestine

This mainly absorbs water and electrolytes. Very few nutrients are absorbed here.

Correct Answer: C. 23 chromosomes

Explanation of the Correct Answer:

Meiosis is the process by which gametes (sperm and eggs) are produced. It involves two rounds of division (meiosis I and meiosis II) and results in the halving of the chromosome number.

In humans, the parent cell has 46 chromosomes (23 pairs). After meiosis, the resultant gametes (sperm or eggs) will have half of the chromosome number, which is 23 chromosomes.

This halving of chromosomes is critical because when a sperm and an egg combine during fertilization, the 46 chromosomes (23 from the sperm and 23 from the egg) combine to form a zygote with the full set of chromosomes (46 total).

Why the Other Options Are Incorrect:

A. 46 chromosomes:

This is the chromosome number in a somatic (body) cell, not a gamete. The parent cell starts with 46 chromosomes, but meiosis reduces this number by half.

B. 14 chromosomes:

This is not the correct number of chromosomes for human gametes. Humans have 46 chromosomes, and after meiosis, each gamete will have 23 chromosomes, not 14.

D. 92 chromosomes:

This is the chromosome number after the DNA has been replicated before meiosis, but 92 chromosomes are not present in the final gametes. Meiosis reduces the chromosome number to 23 in gametes, not 92.