170 Chapter 7 Answers: Introduction to the Human Body

7.2 Organization of the Body

1. How is the human body like a complex machine? Like a complex machine, the human body consists of multiple parts that work together to perform certain functions.
2. Describe the difference between human anatomy and human physiology. Human biology incorporates both human anatomy and human physiology. Human anatomy is the body’s structure, and human physiology is the body’s functioning.
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4. Relate cell structure to cell function, and give examples of specific cell types in the human body. Besides maintaining basic life processes, most human cells carry out special functions, and their structures reflect their functions. Examples may vary. Sample answer: Examples of specific cell types in the human body include blood cells, bone cells, and neurons.
5. Define tissue, and identify the four types of tissues that make up the human body. A tissue is a group of connected cells that have a similar function. The four types of tissues that make up the human body include connective, epithelial, muscle, and nervous tissues.
6. What is an organ? Give three examples of organs in the human body. An organ is a structure that consists of two or more types of tissues that work together to do the same job. Examples may vary. Sample answer: Three examples of organs in the human body are the heart, brain, and lungs.
7. Define organ systems. Name five examples in the human body. An organ system is a group of organs that work together to carry out a complex overall function, with each organ in the system doing part of the larger job. Examples may vary. Sample answer: Five organ systems in the human body are the skeletal, muscular, digestive, respiratory, and nervous systems.
8. How is the human body regulated so all of its organs and organ systems work together? The human body is regulated by the nervous and endocrine systems so all of its organs and organ systems work together. The nervous system controls virtually all body activities, and the endocrine system secretes hormones that help to regulate these activities.
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10. Which organ system’s function is to provide structure to the body and protect internal organs? Skeletal system.
11. Give one example of how the respiratory and circulatory systems work together. Answers may vary. Sample answer: The respiratory system takes in oxygen and the circulatory system transports oxygen throughout the body.

7.3 Cells and Tissues: Review Questions and Answers

1. Give an example of cells that function individually and move freely. Additionally, give an example of cells that act together and are attached to other cells of the same type. Examples may vary. Sample answer: An example of cells that function individually and move freely is red blood cells. An example of cells that act together and are attached to other cells of the same type is epithelial cells.
2. What is an example of cells that can readily divide? What is an example of cells that can divide only under rare circumstances? Examples may vary. Sample answer: An example of cells that can readily divide are skin cells. An example of cells that can divide only under rare circumstances are certain nerve cells.
3. Identify a type of cell that secretes an important substance. Name the substance it secretes. Answers may vary. Sample answer: A type of cell that secretes an important substance is the type of pancreatic cell that secretes insulin, the hormone that regulates the level of glucose in the blood.
4. Explain how different cell types come about when all the cells in an individual human being are genetically identical. The differential regulation of genes explains how different cell types come about when all the cells in an individual human being are genetically identical. Cells with the same genes can be very different because different genes are expressed depending on the cell type.
5. Compare and contrast four sub-types of human bone cells. Four sub-types of human bone cells are osteocytes, osteoblasts, osteogenic cells, and osteoclasts. All four are located in human bones, but each has a different form and function. Osteocytes are star-shaped bone cells that make up most of mature bone. Osteoblasts are immature bone cells that synthesize new bone. Osteogenic cells are undifferentiated stem cells that differentiate to form osteoblasts. Osteoclasts are very large, multinucleated cells that are responsible for the breakdown of bones through resorption.
6. Identify three types of human white blood cells. State their functions. Answers may vary. Sample answer: Three types of human white blood cells are monocytes, which phagocytize pathogens in tissues; eosinophils, which attack larger parasites and set off allergic responses; and neutrophils, which phagocytize single-celled bacteria and fungi in the blood.
7. Why are bone and blood both classified as connective tissues? Connective tissues are made up of living cells that are separated by non-living material, called extracellular matrix, which can be solid or liquid. Bone and blood both have extracellular matrix. In bone, this matrix consists of a rigid mineral framework. In blood, this matrix consists of liquid plasma.
8. Name another type of connective tissue. Describe its role in the human body. Answers may vary. Sample answer: Another type of connective tissues is areolar tissue. It is found in the skin and mucous membranes, where it binds the skin or membrane to underlying tissues such as muscles.
9. Based on the information above about types of epithelial tissues, list four general ways this type of tissue functions in the human body. Answers may vary. Sample answer: Four general functions of epithelial tissues are secreting substances, absorbing substances, protecting other tissues, and allowing organs to expand and stretch.
10. Compare and contrast the three types of muscle tissues. The three types of muscle tissues are skeletal, smooth, and cardiac muscle tissues. Skeletal muscles are striated, attached to bones, and under voluntary control. Smooth muscles are nonstriated, found in the walls of blood vessels and internal organs, and not under voluntary control. Cardiac muscles are striated, found only in the heart, and not under voluntary control.
11. Identify the two main types of cells that make up nervous tissue. Compare their general functions. The two main types of cells that make up nervous tissue are neurons and glial cells. Neurons directly transmit messages, usually through an electrochemical process, while glial cells play more of a supporting role.
12. Of the main types of human tissue, name two that can secrete hormones. Answers may vary. Sample answer: epithelial endocrine glandular tissue, as found in the pancreas, and nervous tissues, which can send out neurotransmitters.
13. Cells in a particular tissue…(C) Work together to carry out a function.
14. Why are mucus membranes often located in regions that interface between the body and the outside world? Answers may vary. Sample answer: Mucus is a slimy substance that traps pathogens, particles, and debris from the outside world to protect the body. Therefore, the mucus membranes that produce it are often located in regions of the body that interface with the outside world.
15. Skin is a type of epithelial tissue.
16. Body fat is a type of connective tissue.

7.4 Tissues: Review Questions and Answers

1. Define the term tissue. A cellular organizational level between cells and a complete organ. A tissue is an ensemble of similar cells and their extracellular matrix from the same origin that together carry out a specific function. Organs are then formed by the functional grouping together of multiple tissues.
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3. If a part of the body needed a lining that was both protective, but still able to absorb nutrients, what would be the best type of epithelial tissue to use? Simple cuboidal or simple columnar epithelial tissue.
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5. Where do you find skeletal muscle?  Smooth muscle? Cardiac muscle?  Skeletal muscle is found attached to bones.  Smooth muscle is found in walls of tubes in the body.  Cardiac muscle is found in the heart.
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7. What are some of the functions of neuroglia?  To provide nutrients to neurons, to create the myelin sheath for neural axons, and to remove debris and cellular waste from neurons.
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7.5 Human Organs and Organ Systems: Review Questions and Answers

1. What is the primary tissue in the heart, and what is its role? The main tissue in the heart is cardiac muscle. Its role is to pump blood by making the heart beat.
2. What non-muscle tissues are found in the heart? What are their functions? Non-muscle tissues in the heart include nervous tissues, which control the beating of the heart; and connective tissues, which make up heart valves that keep blood flowing in just one direction through the heart.
3. Identify two vital organs in the human body. Identify their locations and functions. Answers may vary. Sample answer: Two vital organs in the human body are the heart and brain. The heart is located in the centre of the chest, and its function is to keep blood flowing through the body. The brain is located in the head, and it function is to act as the body’s control centre.
4. List three human organ systems. For each organ system, identify some of its organs and functions. Answers may vary. Sample answer: Three human organ systems are the integumentary, skeletal, and muscular systems. Organs of the integumentary system include skin, hair, and nails. Functions of the integumentary system include enclosing internal body structures and providing a site for sensory receptors. Organs of the skeletal system include bones and joints. Functions of the skeletal system include supporting the body and enabling movement. Organs of the muscular system include skeletal muscles and tendons. Functions of the muscular system include enabling movement and helping to regulate body temperature.
5. Compare and contrast the male and female reproductive systems. Both male and female reproductive systems produce sex-specific sex hormones and gametes, but the organs involved in these processes are different. The male reproductive system includes the epididymis, testes, and penis. The female reproductive system includes the uterus, ovaries, and mammary glands. The male and female systems also have different additional roles. For example, the male system delivers gametes to the female reproductive tract, whereas the female system supports an embryo and fetus until birth and also produces milk for the infant after birth.
6. For each of the following pairs of organ systems, describe one way in which they work together and/or overlap:
   1. skeletal system and muscular system The skeletal system and muscular system work together to enable movement of the body.
   2. muscular system and digestive system Smooth muscle tissue in the digestive system allows food to move through it.
   3. endocrine system and reproductive system Some organs in the reproductive system, such as the ovaries and testes, are also in the endocrine system because they produce hormones.
   4. cardiovascular system and urinary system Blood in the cardiovascular system is filtered by the urinary system to remove excess water and the waste product urea.
7. What is the largest organ of the human body? The skin.
8. What are three organ systems involved in regulating human body temperature? The cardiovascular system, the integumentary system, and the muscular system.
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7.6 Human Body Cavities: Review Questions and Answers

1. What is a body cavity? A body cavity is a fluid-filled space inside the body that holds and protects internal organs.
2. Compare and contrast the ventral and dorsal body cavities. The ventral and dorsal body cavities are the two major human body cavities. Each is subdivided into smaller body cavities. The ventral cavity is at the front of the body, whereas the dorsal cavity is at the back of the body. The ventral cavity includes just the trunk; the dorsal cavity includes the head as well as the trunk.
3. Identify the subdivisions of the ventral cavity, and the organs each contains. The ventral cavity is subdivided into the thoracic cavity, which contains the lungs and heart, and the abdominopelvic cavity, which contains the kidneys digestive and reproductive organs.
4. Describe the subdivisions of the dorsal cavity and their contents. The dorsal cavity is subdivided into the cranial cavity and the spinal cavity. The cranial cavity fills most of the upper part of the skull and contains the brain. The spinal cavity is long and narrow and runs throughout the vertebral column. It contains the spinal cord.
5. Identify and describe all the tissues that protect the brain and spinal cord. The brain and spinal cord are protected by the bones of the skull and the vertebrae of the vertebral column. Within the bones, the brain and spinal cord are protected by the meninges, which is a three-layer membrane that encloses the brain and spinal cord. In addition, between two of the layers of the meninges, the brain and spinal cord are protected and cushioned by a thin layer of cerebrospinal fluid.
6. What do you think might happen if fluid were to build up excessively in one of the body cavities? Answers may vary. Sample answer: I think that if fluid were to build up excessively in one of the body cavities, it could put pressure on the organs inside of it, which might cause problems with their functioning.
7. Explain why a woman’s body can accommodate a full-term fetus during pregnancy without damaging her internal organs. Answers may vary. Sample answer: There is room within the ventral body cavity for organs to expand — such as the uterus that holds the fetus — without interfering with other internal organs.
8. Which body cavity does the needle enter in a lumbar puncture? The spinal cavity
9. What are the names given to the three body cavity divisions where the heart is located?What are the names given to the three body cavity divisions where the kidneys are located? Ventral, thoracic, and pericardial.  Ventral, abdominopelvic, and abdominal.
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7.7 Interactions of Organ Systems: Review Questions and Answers

1. What is the autonomic nervous system? The autonomic nervous system is the part of the nervous system that controls involuntary functions, such as heart rate, blood flow, and digestion.
2. How do the autonomic nervous system and endocrine system communicate with other organ systems so the systems can interact? The autonomic nervous system sends out messages via chemical messengers called neurotransmitters that communicate with other parts of the nervous system or with other organ systems. The endocrine system consists of glands that secrete hormones directly into the bloodstream. These hormones can affect cells anywhere in the body.
3. Explain how the brain communicates with the endocrine system. The brain communicates with the endocrine system via a part of the brain called the hypothalamus. The hypothalamus secretes hormones that travel directly to cells of an endocrine gland called the pituitary, which is located beneath the hypothalamus. The pituitary gland controls the rest of the endocrine system.
4. What is the role of the pituitary gland in the endocrine system? The pituitary gland is the master gland of the pituitary system. Most of its hormones either turn on or turn off other endocrine glands.
5. Identify the organ systems that play a role in cellular respiration. Organ systems that play a role in cellular respiration include the digestive, cardiovascular, and respiratory systems.
6. How does the hormone adrenaline prepare the body to fight or flee? What specific physiological changes does it bring about? Adrenaline floods the circulation and affects other organ systems throughout the body, including the cardiovascular, respiratory, and digestive systems. Specific responses include increased heart rate, more rapid breathing, and a shunting of blood away from the digestive system and toward the muscles, brain, and other vital organs needed for fight or flight.
7. Explain the role of the muscular system in digesting food. Food passes through the organs of the digestive tract by rhythmic contractions of muscles in the walls of the organs.
8. Describe how three different organ systems are involved when a player makes a particular play in hockey, such as catching a fly ball. Answers may vary. Sample answer: Three organ systems that are involved when a player catches a fly ball include the nervous system, muscular system, and skeletal system. The player sees the ball and decides to go for it (nervous system). The player runs toward the ball and reaches out to catch it (muscular and skeletal systems).
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10. What are two types of molecules that the body uses to communicate between organ systems? Neurotransmitters and hormones.
11. Explain why hormones can have such a wide variety of effects on the body. Answers may vary. Sample answer: Hormones can have a wide variety of effects on the body because they travel throughout the body via the bloodstream, so they can affect many different organ systems.

7.8 Homeostasis and Feedback: Review Questions and Answers

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3. Compare and contrast negative and positive feedback loops. Both negative and positive feedback loops are cycles that control a variable by feeding back to change its value. In a negative feedback loop, feedback serves to reduce an excessive response and keep a variable within the normal range. In a positive feedback loop, feedback serves to intensity a response until an end point is reached.
4. Explain how negative feedback controls body temperature. The human body’s temperature regulatory centre is the hypothalamus in the brain. When the hypothalamus receives data from sensors in the skin and brain that body temperature is higher or lower than the set point, it sets into motion responses that bring the temperature back to the set point. For example, if body temperature is higher than the set point, the hypothalamus sets into motion the following responses: blood vessels in the skin dilate to allow more heat to come to the body surface where it can be radiated into the environment; sweat glands in the skin are activated to increase their output of sweat so there can be more evaporative cooling; and breathing becomes deeper to increase heat loss from the lungs.
5. Give two examples of physiological processes controlled by positive feedback loops. Two examples of physiological processes that are controlled by positive feedback loops are blood clotting and childbirth.
6. During breastfeeding, the stimulus of the baby sucking on the nipple increases the amount of milk produced by the mother. The more sucking, the more milk is usually produced. Is this an example of negative or positive feedback? Explain your answer. What do you think might be the evolutionary benefit of the milk production regulation mechanism you described? Answers may vary. Sample answer: Having a positive feedback loop for milk production helps the mother’s body produce enough milk for the baby, but not too much, because the amount of milk is matched to the amount that the baby nurses. That way the baby can be sufficiently fed without the mother’s body dedicating extra energy to making more milk than is needed. I think this would be beneficial evolutionarily by increasing the chance of survival for both the mother and the baby.
7. Explain why homeostasis is regulated by negative feedback loops, rather than positive feedback loops. Answers may vary. Sample answer: Homeostasis is regulated by negative feedback loops, rather than positive feedback loops, because negative feedback loops serve to keep a variable within a normal range by preventing an excessive response. Homeostasis is a steady state where the body functions optimally, or at least normally. In positive feedback loops, a response is intensified instead of remaining steady.
8. The level of a sex hormone, testosterone (T), is controlled by negative feedback. Another hormone, gonadotropin-releasing hormone (GnRH), is released by the hypothalamus of the brain, which triggers the pituitary gland to release luteinizing hormone (LH). LH stimulates the gonads to produce T. When there is too much T in the bloodstream, it feeds back on the hypothalamus, causing it to produce less GnRH. While this does not describe all the feedback loops involved in regulating T, answer the following questions about this particular feedback loop.
   1. What is the stimulus in this system? Explain your answer. Testosterone (T) is the stimulus, because it is the variable being regulated.
   2. What is the control centre in this system? Explain your answer. The cells in the hypothalamus that produce GnRH are the control centre, because this is the region that matches T levels with normal levels and then adjusts output of GnRH accordingly.
   3. In this system, is the pituitary considered the stimulus, sensor, control centre, or effector? Explain your answer. The pituitary is an effector in this system because it acts on a signal from the control centre (the hypothalamus) to move the variable (T) back to its set point by releasing more or less LH.

7.9 Case Study Conclusion: Review Questions and Answers

1. Compare and contrast tissues and organs. Answers may vary. Sample answer: Tissues and organs are both units within the body that carry out a particular function, and are composed of cells. Tissues, however, consist of cells that have similar properties, while organs are made up of two or more types of tissue. Organs are generally more structurally complex than tissues.
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4. Which type of tissue lines the inner and outer surfaces of the body? Epithelial.
5. What is a vital organ? What happens if a vital organ stops working? A vital organ is an organ that is necessary for survival. If a vital organ stops working, death will occur unless there is medical intervention to keep the person alive.
6. Name three organ systems that transport or remove wastes from the body. Answers will vary but may include: the digestive system, integumentary system, cardiovascular system, urinary system, and respiratory system.
7. Name two types of tissue in the digestive system. Answers may vary. Sample answer: Epithelial tissue (such as mucous membranes) and muscle tissue.
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9. Describe one way in which the integumentary and cardiovascular systems work together to regulate homeostasis in the human body. Answers may vary. Sample answer: The skin in the integumentary system and blood and blood vessels are in the cardiovascular system. One way in which the body regulates body temperature is to dilate or constrict the blood vessels at the skin’s surface to either dissipate or conserve heat at the skin. In this way, the integumentary and cardiovascular systems work together to regulate homeostasis of body temperature.
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11. True or False: Body cavities are filled with air. False.
12. In which organ system is the pituitary gland? Describe how the pituitary gland increases metabolism.  The pituitary gland secretes thyroid stimulating hormone, which travels through the circulation to the thyroid gland, which is then stimulated to secrete thyroid hormone. Thyroid hormone then travels to cells throughout the body, where it increases their metabolism.
13. When the level of thyroid hormone in the body gets too high, it acts on other cells to reduce production of more thyroid hormone. What type of feedback loop does this represent?  Positive feedback.
14. Hypothetical organ A is the control centre in a feedback loop that helps maintain homeostasis. It secretes molecule A1 which reaches organ B, causing organ B to secrete molecule B1. B1 negatively feeds back onto organ A, reducing the production of A1 when the level of B1 gets too high. Answers may vary. Sample answer: A1 will likely increase because the level of B1 has dropped below the normal range and the system is trying to maintain homeostasis. A1 increases in order to increase the level of B1.
    1. What is the stimulus in this feedback loop? The level of molecule B1.
    2. If the level of B1 falls significantly below the set point, what do you think happens to the production of A1? Why? Answers may vary. Sample answer: A1 will likely increase because the level of B1 has dropped below the normal range and the system is trying to maintain homeostasis. A1 increases in order to increase the level of B1.
    3. What is the effector in this feedback loop? Organ B.
    4. If organs A and B are part of the endocrine system, what type of molecules do you think A1 and B1 are likely to be? Answers may vary. Sample answer: I think A1 and B1 are most likely hormones because the endocrine system secretes hormones. Also, hormones are messenger molecules that are often involved in regulation of homeostasis.
15. What are the two main systems that allow various organ systems to communicate with each other? The autonomic nervous system and endocrine system.
16. What are two functions of the hypothalamus? Answers will vary but may include: controlling the endocrine system, regulating body temperature, and controlling the process of childbirth.