Essay Questions

Question 1

Distinguish between anatomy and physiology.

Answer 1

Anatomy is the study of the structure and shape of the body and body parts, and their relationships to one another. Physiology is the study of how the body and its parts work or function.

Question 2

List and explain the eight necessary human life functions.

Answer 2

1. Maintenance of boundaries—keeps the internal environment distinct from the external environment; membranes perform this function at the cellular level and skin performs this function for the organism.
2. Movement—includes a change in the position of the body or the propelling of a substance (such as blood, urine, or food) through the body organs; constitutes a major role of the muscular system.
3. Responsiveness (irritability)—the ability to react to stimuli; constitutes a major role of the nervous system.
4. Metabolism—includes all the chemical reactions that occur within the body’s cells.
5. Excretion—elimination of carbon dioxide by the lungs and nitrogenous wastes by the kidneys.
6. Digestion—the process of breaking down ingested foodstuffs into simpler molecules that can then be absorbed into the blood for delivery to the body’s cells.
7. Growth—an increase in size, which is usually accompanied by an increase in the number of cells.
8. Reproduction—the production of new cells for growth and repair, and also the production of offspring.

Question 3

List and explain the three major body planes and sections.

Answer 3

1. Sagittal—cut is made along the longitudinal (lengthwise) plane of the body (or an organ), dividing it into right and left parts.
2. Frontal (coronal)—cut is made along the longitudinal (lengthwise) plane of the body (or an organ), dividing it into anterior and posterior parts.
3. Transverse (cross-section)—cut is made along the transverse (horizontal) plane, dividing the body into superior and inferior parts.

Question 4

Explain how scratching an itch is an example of the negative feedback mechanism.

Answer 4

1. Stimulus or input is the itch.
2. A receptor carries the information about the stimulus (itch) to the brain via an afferent pathway.
3. Control center (brain) analyzes this information an turns on an effector which will cancel the stimulus.
4. Information reaches the effector via the efferent pathway from the brain. Muscles move the hand to scratch the itch.
5. Scratching continues until the itch goes away. The brain shuts off the effector once homeostatis is restored.

Question 5

Explain the difference between homeostatis and metabolism.

Answer 5

Homeostasis is the body’s attempt to maintain balance during which time internal conditions may vary. Metabolism is all chemical reactions that occur in the body.

Question 6

Describe anatomical position. Explain why anatomical position is used.

Answer 6

Anatomical position is defined as standing erect, feet parallel to the arms, palms facing forward. Anatomical position is used because it is a standard position; it also helps us to avoid confusion. Additionally, anatomical position is a reference point that helps us accurately describe body parts and position.

Question 7

List and explain the three general functions of the nervous system

Answer 7

1. Sensory (input) function?the nervous system uses millions of sensory receptors to monitor changes (stimuli) inside and outside the body; the gathered information is called the sensory function.
2. Integrative function?the nervous system processes and interprets sensory input and makes decisions about what should be done and the magnitude to which it should be done at each moment.
3. Motor (output) function?the process of reaction to stimuli; the body responds by activating muscles that can produce motion or glands that can produce and secrete hormones.

Question 8

List and explain the four major events that take place during the conduction of a nerve impulse beginning with the resting membrane.

Answer 8

1. Electrical condition of a resting (polarized) membrane in a resting membrane, the external face of the membrane is slightly positive; its internal face is slightly negative. The chief extracellular ion is sodium, whereas the chief intracellular ion is potassium. A polarized membrane is relatively impermeable to both ions.
2. Depolarization and generation of an action potential a stimulus changes the permeability of a “patch” of the membrane, and sodium ions diffuse rapidly into the cell. This changes the polarity of the membrane (the outside becomes more negative). If the stimulus is strong enough, an action potential is initiated.
3. Propagation of an action potential depolarization of the first membrane patch causes permeability changes in the adjacent membrane and the events described in “2” (above) are repeated. Thus the action potential propagates rapidly along the entire length of the membrane.
4. Repolarization potassium ions diffuse out of the cell as membrane permeability changes again, restoring the negative charge on the inside of the membrane and the positive charge on the outside surface. Repolarization occurs in the same direction as depolarization. The ionic conditions of the resting state are later restored by the activity of the sodium-potassium pump.

Question 9

List the four events that lead to transmission of an impulse across a synapse.

Answer 9

1. The impulse arrives at the synaptic knob of the presynaptic neuron.
2. The synaptic vesicle fuses with the presynaptic neuron membrane and the chemical neurotransmitter is released via exocytosis.
3. The neurotransmitter is released, travels across the synaptic cleft, and binds to receptor sites on the postsynaptic neuron. If sufficient neurotransmitter is released, the entire series of events involved in the conduction of a nerve impulse will occur in the postsynaptic neuron.
4. The electrical changes prompted by neurotransmitter binding are very brief because the neurotransmitter is quickly removed from the synapse either by re-uptake into the axonal terminal or by enzymatic breakdown.

Question 10

Explain how multiple sclerosis affects nerve functioning.

Answer 10

People with multiple sclerosis (MS) experience destruction of their myelin sheaths. As destruction progresses, the electrical current is short-circuited. The person affected with MS may experience visual and speech disturbances and lose muscle control.

Question 11

List and describe the protective structures found in the CNS.

Answer 11

1. The brain and spinal cord are protected by a bony skull and a bony vertebral column.
2. There are three layers of membranes (meninges) covering the structures in the CNS.
   a. The outermost dura mater surround the brain. This double-layered membrane is a leathery covering.
   b. The middle membrane layer is the arachnoid mater, which has a cobweb appearance.
   c. The pia mater is the innermost layer, which clings to the surface of the brain and spinal cord.
3. Cerebrospinal fluid forms a water cushion that circulates in and around the brain and spinal cord. The CSF protects the CNS from blows and other trauma. Also, remember from a previous chapter that water has a high heat capacity that prevents changes in temperature.

Question 12

Describe the pathway of light through the eyeball and the process of light refraction.

Answer 12

Light travels through the cornea, aqueous humor, lens, and vitreous humor before being focused on the retina during normal vision. Refraction by the cornea and humors is constant, whereas the lens changes its shape to be either more or less convex as needed. The greater the convexity, the more light is bent.

Question 13

Explain the mechanism of hearing.

Answer 13

Sound waves enter the pinna and are transmitted down the external auditory canal until they hit the tympanic membrane and cause it to vibrate. Vibration of the tympanic membrane then causes the ossicles of the middle ear to vibrate, which in turn presses on the oval window of the inner ear. Vibration of the oval window sets the fluids of the inner ear in motion. Movement of the cochlear fluids then stimulate the hair cells of the organ of Corti, which in turn transmit impulses along the cochlear nerve to the auditory cortex in the temporal lobe, where interpretation of sound occurs.

Question 14

Explain the relationship between taste and smell

Answer 14

They are both chemoreceptors and work similar to each other. Taste is greatly influenced by smell and because they share a pathway to the brain are usually interpreted simultaneously in the olfactory and gustatory cortex in the temporal lobe.

Question 15

List and describe the functions of the four major lobes of the brain.

Answer 15

frontal- reasoning, problem solving, personality, speaking, spatial relationships
parietal- sensory interpretation and motor output as well as procedural memory and coordination
occipital- all visual interpretation and processing
temporal- memory, hearing, taste and emotional response

Question 16

Explain the two major chemical classifications of hormones.

Answer 16

The amino acid-based molecules include proteins, peptides, and amines. The steroid hormones include the sex hormones made by the gonads and the hormones produced by the adrenal cortex.

Question 17

Describe the three types of stimuli that activate the endocrine organs.

Answer 17

The most common stimulus is hormonal. In hormonal stimulus, endocrine organs are prodded into action by other hormones, known as tropic hormones. Another type of stimulus is humoral, in which changing blood levels of certain ions and nutrients stimulate hormone release. The third type of stimulus is neural, in which nerve fibers stimulate hormone release.

Question 18

Compare the effects of hypersecretion and hyposecretion of growth hormone on a child.

Answer 18

Hyposecretion of growth hormone in a child leads to pituitary dwarfism. Body proportions are normal, but the person does not exceed 4 feet in height.
Hypersecretion of growth hormone in a child leads to gigantism. Although body proportions are normal, the person can reach 8 to 9 feet in height.

Question 19

Filtration is a nonselective, passive process with the glomerulus acting as the filter. The filtrate formed is essentially blood plasma without blood proteins, which are too large to pass through the filtration membrane into the renal tubule. Reabsorption is the process by which the body reclaims substances within the filtrate that it wants to keep. Most reabsorption is an active process using membrane carriers. Substances that are typically reabsorbed include amino acids, glucose, and ions. Most reabsorption occurs in the proximal convoluted tubules. Secretion is the opposite process. With secretion, substances such as hydrogen ions, potassium ions, and creatinine are removed from the peritubular capillaries into the tubules to be eliminated in urine.

Answer 19

Identify and describe the three major processes involved in urine formation.

Question 20

Describe the normal characteristics of freshly-voided urine in a healthy adult.

Answer 20

Urine is a pale, straw-colored liquid that progressively becomes a darker yellow color as it becomes more concentrated. The yellow color is a result of the presence of urochrome pigment, a by-product of hemoglobin breakdown. Urine is more dense than water with a specific gravity of 1.001 to l.035. Urine is sterile and slightly aromatic and has an acidic pH of around 6. Urine normally contains sodium and potassium ions, urea, uric acid, creatinine, ammonia, and bicarbonate ions, as well as other ions the body needs to dispose of.

Question 21

Describe and explain urethral control and concepts related to incontinence.

Answer 21

The urethra contains two sphincters. The internal urethral sphincter is involuntary and is formed from a thickening of smooth muscle at the bladder-urethra junction. The second sphincter is the external urethral sphincter, made from skeletal muscle and under voluntary control. Control of the external urethral sphincter often develops at around 2 years of age. Prior to that time, the child is simply not able to control urination and is incontinent. Other causes for incontinence include emotional problems, pressure on the bladder, such as with pregnancy, stroke, spinal cord injury, and the aging process.

Question 22

List the three male accessory glands and describe their contributions to the formation of semen.

Answer 22

1. The seminal vesicles produce fluid that contributes about 60% of the fluid volume of semen. The secretion is thick, yellowish, and is rich in sugar, vitamin C, prostaglandins, and other substances that nourish and activate the sperm passing through the male’s reproductive tract.
2. The prostate produces a milky secretion that also activiates the sperm.
3. The bulbourethral glands produce a thick, clear mucus that drains into the penile urethra to cleanse it of acidic urine. This secretion is the first to be released during sexual excitement and serves as a lubricant during sexual intercourse.

Question 23

List and describe the three major stages of the menstrual cycle.

Answer 23

Menses occurs during days 1 through 5 of the menstrual cycle. During this stage, the endometrial lining detaches from the uterine wall and sloughs off. Days 6 through 14 are the proliferative stage wherein rising estrogen levels cause the endometrial lining to regenerate. It becomes thick and velvety again and is highly vascularized. Ovulation occurs on approximately the last day of this stage in response to an LH surge. The secretory stage is from days 15 through 28. During this stage, the corpus luteum produces progesterone, which increases the endometrial blood supply and causes the endometrial glands to increase in size and begin secreting nutrients into the uterine cavity. If fertilization occurs, these nutrients will help sustain the embryo until implantation. If fertilization does not occur, the hormone levels decline and the endometrium spasms, setting the stage for menses to begin again on day 28.

Question 24

Describe the events of embryonic development from conception until the fetal stage, including development of the primary germ layers.

Answer 24

A fertilized egg (zygote) undergoes rapid mitotic cell division in a stage called cleavage. Cleavage provides the building blocks for constructing the embryo, which develops until it has about 100 cells and then hollows out to form a blastocyst. The blastocyst has two areas: the trophoblast and the inner cell mass. The inner cell mass forms the primary germ layers, which are the ectoderm, the endoderm, and the mesoderm. The ectoderm gives rise to the nervous system, the epidermis, and the skin. The endoderm forms the mucosae and associated glands. The mesoderm gives rise to everything else. The trophoblast develops projections called chorionic villi which form the placenta along with tissues from the mother’s uterus. By the eighth week, all the organ systems have been laid down and the embryo looks distinctly human. Beginning in the ninth week, the embryo is referred to as a fetus.

Question 25

List and describe the three stages of labor.

Answer 25

Stage 1 is the dilation stage, which extends from the appearance of true contractions until full dilation of the cervix (dilation to about 10 cm in diameter). Usually the amnion ruptures during this stage, which is the longest part of labor and lasts for 6 to 12 hours. Stage 2 is the expulsion stage. It extends from full dilation to delivery of the infant. In this stage, the infant passes through the cervix and vagina to the outside of the body. This stage takes 20 minutes to 2 hours. Stage 3 is the placental stage, which usually lasts about 15 minutes, culminating in delivery of the placenta.