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Test Bank Human Anatomy & Physiology, 11th Edition Elaine N. Marieb

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Test Bank Human Anatomy & Physiology, 11th Edition Elaine N. Marieb

Test Bank Human Anatomy & Physiology, 11th Edition Elaine N. Marieb

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

 

1)

Which of these is NOT part of the dorsal cavity?

 

 

1)

 

A) cranial cavity

 

B) vertebral cavity

 

 

 

C) thoracic cavity

 

D) spinal cord

 

 

2)

Which of the following organs or structures would be found in the left iliac region?

2)

 

A) liver

B) stomach

C) intestines

D) appendix

 

3)

You are asked to take a person's heart rate at the popliteal pulse point. You will look for this pulse

3)

 

________.

 

 

 

 

 

A)   on the posterior side of the knee

 

C)   on the palmar side of the hand


 

B)  in the distal end of the lower leg

 

D)  at the posterior side of the wrist

 

 

4)

Generally, what is the result of the negative feedback process?

4)

 

A) to maintain homeostasis

B) to regulate excretion via the kidneys

 

 

C) to control body movement

D) to keep the body's blood sugar level high

 

5)

It is wise to study anatomy alongside with physiology because ________.

5)

 

A)   physiology is only explainable in terms of the underlying anatomy

B)  it makes for more efficient use of students' and teachers' time

C)   anatomy and physiology are practically the same thing

D)   to understand anatomy requires complete understanding of physiology

 

 

6)

The parietal pleura would represent a serous membrane ________.

 

6)

 

A) covering the heart

 

B) covering individual lungs

 

 

C) lining the abdominal cavity

D) lining the thoracic cavity

 

7)

Which of the following describes the operation of the heart and blood vessels?

 

7)

 

A) cardiovascular anatomy

B) systemic anatomy

 

 

 

C) systemic physiology

 

D) cardiovascular physiology

 

8)

The dorsal body cavity is the site of which of the following?

 

8)

 

A) intestines

B) lungs

C) brain

D) liver

 

9)

Prevention of water loss is a necessary function for life that would best fit in the category of

9)

 

________.

 

 

 

 

 

A) excretion

 

B) responsiveness

 

 

 

C) metabolism

 

D) maintaining boundaries

 

10)

The term pollex refers to the ________.

 

 

10)

 

A) calf

B) fingers

C) thumb

D) great toe

 

 

11)

Some of the nerve endings in the skin are sensitive to changes in temperature. They are part of a

11)

 

negative feedback mechanism regulating body temperature. These nerve endings represent a(n)

 

 

________ in the negative feedback mechanism.

 

 

 

 

A) receptor

 

B) homeostatic balance or "ideal" value

 

 

C) control center

 

D) effector

 

 

12)

What is a vertical section through the body, dividing it into anterior and posterior regions called?

12)

 

A) frontal

B) transverse

C) median

D) sagittal

 

13)

Anabolic reactions are chemical reactions of the body that build things, make them bigger or more

13)

 

complex. Catabolic reactions break things down making them smaller or less complex. If the rate

 

 

of anabolic reaction in the body is much faster than the rate of catabolic reactions, which of the

 

 

following necessary life function will be accomplished?

 

 

 

A) responsiveness

B) growth

C) movement

D) digestion

 

14)

The study of anatomy and physiology assumes and describes a healthy body. Select the

14)

 

description below that does NOT explain why this approach is useful.

 

A)   Study of a healthy body is less intimidating and more familiar to new students.

 

B)  A healthy body provides a common standard to compare to.

C)   Study of a healthy body provides a foundation for a more complete understanding of all human bodies.

 

D)   A healthy body establishes what "normal" is.

 

15)

You are asked to draw blood from the median cubital vein. You will search for this vein in the

15)

 

________.

 

 

 

A) proximal arm

B) lateral side of the foot

 

 

C) anterior side of the elbow

D) hand

 

16)

The thoracic cavity contains the ________. It is found ________ to the vertebral cavity.

16)

 

A) digestive viscera; inferior

B) kidneys and spleen; deep

 

 

C) stomach and liver; superficial

D) heart and lungs; anterior

 

17)

Which of the following are survival needs of the body?

17)

 

A)   water, atmospheric pressure, growth, and movement

B)  nutrients, water, movement, and reproduction

C)   nutrients, water, atmospheric pressure, and oxygen

D)   nutrients, water, growth, and reproduction

 

 

18) Anatomical position is important because ________.

18)

A)   it provides the greatest circulation to the extremities

B)  it allows diagrams within textbooks to display a greater surface area of the body with one simple diagram

 

C)   it allows a common point of reference for body position to help communicate anatomical relationships

 

D)   it is the position most comfortable to hospital patients


19)

Which of the following statements is the most correct regarding homeostatic imbalance?

19)

 

A) The internal environment is becoming more stable.

 

 

B) Negative feedback mechanisms are functioning normally.

 

 

C) It is considered the cause of most diseases.

 

 

D) Positive feedback mechanisms are overwhelmed.

 

20)

Select the most correct statement.

20)

 

A)   Organ systems can be composed of cells or tissues, but not both.

B)  The endocrine system is not a true structural organ system.

C)   Organ systems operate independently of each other to maintain life.

D)   The immune system is closely associated with the lymphatic system.

 

 

21)

A good example of a positive feedback mechanism would be ________.

21)

 

A) blood calcium level regulation

B) regulating glucose levels in the blood

 

 

C) body temperature regulation

D) enhancement of labor contractions

 

22)

Choose the following statement that is NOT completely correct regarding serous membranes.

22)

 

A)   Serous membranes secrete a watery lubricating fluid.

B)  Serous membranes are divided into parietal and visceral membranes with a virtual space between the two.

 

C)   Visceral pericardium covers the outer surface of the heart, and parietal pericardium lines the internal walls of the heart.

 

D)   Serosa are very thin, double-layered structures.

 

 

23) One of the descriptions below is from the perspective of physiological study, the rest are from an

23)

anatomical perspective. Select the description below that comes from physiological perspective.

 

 

A)   The pancreas lies deep to the stomach within the abdominal cavity.

 

B)  The skull is formed by 22 facial and cranial bones.

C)   The chambers of the heart and blood vessels leading to and from the heart are separated by valves composed of fibrous connective tissue.

 

D)   The contraction of smooth muscle in blood vessels (vasoconstriction) can reduce the flow of blood through the vessel.

 

24) Which of the following describes a parasagittal plane?

24)

A)   any sagittal plane except in the midline

B)  a transverse cut just above the knees

C)   any cut dividing the body into anterior and posterior portions

D)   two cuts dividing the body into left and right halves

 

 

25)

Histology would be best defined as a study of ________.

 

25)

 

A) the gross structures of the body

B) cell chemistry

 

 

 

C) cells

 

D) tissues

 

 

26)

What is a vertical section through the body, dividing it into left and right, called?

26)

 

A) frontal

B) sagittal

C) transverse

D) regional

 

 

27) Which of the following is the best explanation for why cells are considered the smallest units of

27)

living things.

 

 

A)   Cells cannot be seen with the naked eye and are considered microscopic.

 

B)  Cells have the ability to reproduce identical copies of themselves in a process called mitosis.

C)   Cells are the simplest structure to fit all of the characteristics necessary to be considered alive.

D)   Cells are highly ordered and complex.

 

28)

In which quadrant of the abdominopelvic cavity is the stomach located?

28)

 

A) right upper quadrant

B) left upper quadrant

 

 

C) right lower quadrant

D) left lower quadrant

 

29)

You are told to take an axillary temperature on a small child. You will place the thermometer

29)

 

________.

 

 

 

A) in the rectum

B) under the tongue

 

 

C) on the forehead

D) in the armpit

 

30)

One of the functional characteristics of life is excitability or responsiveness. This refers to ________.

30)

 

A)   the necessity for all organisms to reproduce

B)  sensing changes in the environment and then reacting or responding to them

C)   indigestible food residues stimulating the excretory system

D)   the nervous system causing all living things to sometimes experience anger

 

 

31)

Which one of the following systems responds fastest to environmental stimuli?

 

31)

 

A) lymphatic

B) nervous

C) immune

D) muscular

 

32)

Which of the following imaging devices would best localize a tumor in a person's brain?

32)

 

A) PET

B) X-ray

C) DSA

 

D) MRI

 

33)

In which body cavities are the lungs located?

 

 

33)

 

A) pleural, ventral, and thoracic

B) mediastinal, thoracic, and ventral

 

 

C) pericardial, ventral, and thoracic

D) pleural, dorsal, and abdominal

 

34)

The body cavities that protect the nervous system are located in the ________ cavity.

34)

 

A) ventral

B) cranial

C) thoracic

D) vertebral

E) dorsal

 

35)

Homeostasis is the condition in which the body maintains ________.

 

35)

 

A)   a relatively stable internal environment, within limits

B)  a dynamic state within an unlimited range, depending on circumstances

C)   the lowest possible energy usage

D)   a static state with no deviation from preset points

 

 

36) The study of large body structures, visible to the naked eye, such as the heart is called ________

36)

anatomy.

 

 

 

 

A) systemic

B) gross

C) developmental

D) microscopic

 

 

37) Place the following in correct sequence from simplest to most complex:

37)

 

 

1. molecules

 

 

 

2. atoms

 

 

 

3. tissues

 

 

 

4. cells

 

 

 

5. organs

 

 

 

A) 1-2-4-3-5

B) 1-2-3-4-5

C) 2-1-4-3-5

D) 2-1-3-4-5

38) Choose the anatomical topic and definition that is NOT correctly matched.

38)

A)   Cytology: study of the structures in a particular region.

B)  Microscopic anatomy: study of structures too small to be seen by the naked eye.

C)   Gross anatomy: study of structures visible to the eye.

D)   Embryology: study of the changes in an individual from conception to birth.

 

 

39)

Expiration (breathing out) is how the body removes excessive carbon dioxide from the blood. This

39)

 

is an example of ________.

 

 

 

 

 

A) excretion of metabolic waste

B) metabolism

 

 

 

C) responsiveness

 

D) maintaining boundaries

 

40)

When a baby suckles at its mother's breast the stimulus at the breast is sent to the mother's brain (a

40)

 

region called the hypothalamus). The brain responds by releasing hormones to stimulate the

 

 

production and the ejection of milk from the breast. This helps the newborn to receive

 

 

nourishment and encourages more suckling. This example is best described as a ________.

 

 

A) loss of homeostasis

 

B) positive feedback

 

 

 

C) negative feedback

 

D) necessary life function

 

41)

A structure that is composed of two or more tissue types that work together to perform specific

41)

 

functions for the body is a(n) ________.

 

 

 

 

A) complex tissue

B) complex cell

C) organ system

D) organ

 

42)

One of the descriptions below is from the perspective of anatomical study, the rest are from a

42)

 

physiological perspective. Select the description below that comes from an anatomical perspective.

 

 

A)   The cell-to-cell connections between heart (cardiac) muscle cells are strong. They hold the tissue together for a life time of forceful contractions.

 

B)  The direction of blood flow through the heart is directed by one way valves.

 

C)   The innermost lining of the lungs is composed primarily of a thin tissue called simple squamous epithelium.

 

D)   The extremely thin tissue (simple squamous epithelium) of the lungs allows for the quick diffusion of respiratory gases into and out of the body.

 

43)

The coxal joint is most likely found in the ________ region of the body.

 

43)

 

A) foot

B) hip

C) groin

D) hand

 

44)

The anatomical position is characterized by all of the following EXCEPT ________.

44)

 

A) arms at sides

 

B) thumbs pointed laterally

 

 

C) palms turned posteriorly

D) body erect

 

 

 

45) Positive feedback differs from negative feedback because ________.

45)

A)   positive feedback is critical to health while negative feedback serves only to alert us to potential health threats

 

B)  positive feedback provides moment-to-moment wellbeing while negative feedback causes a cascade effect

 

C)   positive feedback tends to enhance the triggering stimulus while negative feedback tends to return the body to a homeostatic balance or "ideal" level

 

D)   positive feedback is generally beneficial while negative feedback is typically harmful

 

 

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

 

Figure 1.1

 

Using Figure 1.1, match the following cavities:

 

46)

Vertebral cavity.

46)

47)

Describe the opposing ways that the muscular system and integumentary system act as

47)

 

effectors in the regulation of body temperature.

 

 

 

Figure 1.2

 

Using Figure 1.2, match the following descriptions to the most appropriate letter on the diagram:

 

48)

Sweat glands are stimulated as well as blood being distributed to the skin to allow cooling

48)

 

of the body to return the body's temperature to a physiological level.

 

49)

Which body system would be most affected by a lower than normal atmospheric

49)

 

pressure?

 

50)

What is the serous membrane that covers the intestines called?

50)

51)

The integumentary system helps to maintain a boundary between the internal and

51)

 

external environment. Give an example of something that is prevented entry to the body

 

 

and an example of something prevented from escaping the body by the integumentary

 

 

system.

 

52)

What is a dynamic equilibrium of your internal environment termed?

52)

53)

Similar cells that have a common function are called ________.

53)

 

 

Figure 1.2

 

Using Figure 1.2, match the following descriptions to the most appropriate letter on the diagram:

 

54)

A change in the temperature of the external environment (getting warmer).

54)

55)

Can lungs carry out excretory functions? Explain your answer.

55)

56)

What is the action of all of the negative feedback mechanisms of the body?

56)

57)

What is the single most abundant chemical substance in the body?

57)

 

 

Figure 1.1

 

Using Figure 1.1, match the following cavities:

 

58)

Cranial cavity.

58)

59)

Thoracic cavity.

59)

 

 

Figure 1.2

 

Using Figure 1.2, match the following descriptions to the most appropriate letter on the diagram:

 

60)

Appropriate response information is sent through efferent pathways.

60)

61)

Information about body temperature is sent through afferent pathways to the brain.

61)

62)

Free nerve endings in the skin detect changes in skin temperature (getting warmer).

62)

63)

Which feedback mechanism causes the variable to deviate further and further from its

63)

 

original value or range?

 

64)

Why must a normal body temperature be maintained in order for chemical reactions to be

64)

 

continued at life-sustaining rates?

 

65)

Describe the overlap in function between the muscular system and skeletal system. In

65)

 

other words, describe how they work together.

 

66)

Why are the abdominopelvic cavity organs the most vulnerable to blunt deceleration in an

66)

 

automobile accident with seat belts?

 

 

 

Figure 1.1

 

Using Figure 1.1, match the following cavities:

 

67)

Abdominal cavity.

67)

68)

Describe the overlap in function between the cardiovascular system and respiratory

68)

 

system. In other words, describe how they work together.

 

69)

Why is anatomical terminology necessary?

69)

70)

The ability to sense changes in the environment and respond to them is called ________.

70)

71)

What is the pathway between the receptor and the control center in the reflex pathway

71)

 

called?

 

72)

The term that describes the neck region is ________.

72)

73)

What broad term covers all chemical reactions that occur within the body cells?

73)

74)

What does the "principle of complementarity of structures and function" mean?

74)

 

11

 

 


75)

What can happen when the usual negative feedback mechanisms are overwhelmed and

75)

 

destructive positive feedback mechanisms take over?

 

76)

What type of homeostatic feedback reflex is the withdrawal reflex?

76)

77)

What is the function of the serous membranes?

77)

78)

Which cavity contains the bladder, some reproductive organs, and the rectum?

78)

79)

________ is explained by chemical and physical principles and is concerned with the

79)

 

function of specific organs or organic systems.

 

80)

The term that describes the back of the elbow is ________.

80)

81)

The heart is ________ to the lungs.

81)

 

 

TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false.

 

82)

A major function of serous membranes is to decrease friction.

82)

83)

It is important for any organism to maintain its boundaries, so that its internal environment

83)

 

remains distinct from the external environment surrounding it.

 

84)

The part of the serous membrane that lines the peritoneal cavity wall is called visceral peritoneum.

84)

85)

Positive feedback mechanisms tend to enhance the original stimulus so that the response is

85)

 

accelerated.

 

86)

The epigastric region is superior to the umbilical region.

86)

87)

Embryology concerns the structural changes that occur in an individual from conception through

87)

 

old age.

 

88)

Digital Subtraction Angiography (DSA) imaging is most useful in discovering obstructed blood

88)

 

supplies in organs and tissues.

 

89)

Lungs carry out an excretory function.

89)

90)

Without some sort of negative feedback mechanism, it would be impossible to keep our body

90)

 

chemistry in balance.

 

91)

Responsiveness or irritability is the ability to sense changes in the environment and then respond

91)

 

to them.

 

92)

The right hypochondriac region contains the majority of the stomach.

92)

93)

The elbow is proximal to the shoulder.

93)

 


 

 

12


94) A tissue consists of groups of similar cells that have a common function.

 

MATCHING. Choose the item in column 2 that best matches each item in column 1.

 

Match the following examples of feedback mechanisms:

 

95) Used for childbirth.                                                         A) Positive feedback

 

Match the following systems and organs:

 

96) Trachea, bronchi, alveoli.                                              A) Respiratory

 

Match the following cavities and organs:

 

97)

Stomach.

A) Abdominal

Match the following systems to their functions:

 

98)

Provides a ridged framework to

A) Skeletal

 

support the body and stores minerals.

 

 

Match the regional/directional terms and examples:

 

99) The fingers are ________ to the wrist.                      A) Distal

 

Match the following examples of feedback mechanisms:

 

100) Used for changes in blood pressure.                         A) Negative feedback

 

Match the following systems and organs:

 

101)

Kidneys, bladder, ureters.

A) Cardiovascular

102)

Arteries, veins, heart.

B) Urinary

Match the regional/directional terms and examples:

 

103)

The upper arm is ________ to the

A) Proximal

 

forearm.

 

 

Match the following systems to their functions:

 

104) Responds to environmental changesA) Nervous by transmitting appropriate electrical

 

impulses.

 

Match the following cavities and organs:

 

105) Uterus.                                                                                A) Pelvic

 


106) Lungs.

 

Match the following systems to their functions:

 

107)  A functional organ system which provides a means of protecting us from foreign invaders.

 

Match the following regional terms and common terms:

 

108) Arm.

 

Match the following systems to their functions:

 

109)  Delivers oxygen and nutrients to the tissues.

 

Match the regional/directional terms and examples:

 

110)  The lungs are ________ to the heart.

 

111)  The stomach is ________ to the spine.

 

Match the following regional terms and common terms:

 

112)  Chest.

 

113)  Head.

 

Match the following systems to their functions:

 

114)  Provides the force to move bones about their joints.

 

Match the following systems to their functions:

 

115)  Controls the body with chemical molecules called hormones.

 

Match the following regional terms and common terms:

 

116) Knee (anterior aspect).

 

Match the following systems to their functions:

 

 

Match the following examples of feedback mechanisms:

 

118) Used for blood clotting.

A) Positive feedback

118)

 

 

 

 

 

 

Match the following systems to their functions:

 

119) Prevents water loss, entry of germs                           A) Integumentary

119)

into the body and synthesizes vitamin

 

D.

 

Match the following cavities and organs:

 

120) Heart.

A) Thoracic

120)

 

 

 

 

 

 

Match the following examples of feedback mechanisms:

 

121)

Used for changes in blood glucose

A) Negative feedback

121)

 

 

levels.

 

 

 

 

 

 

Match the following cavities and organs:

 

 

 

122)

Brain.

A) Cranial

122)

 

 

 

 

 

 

 

Match the following regional terms and common terms:

 

123) Buttock.

A) Gluteal

123)

 

 

 

 

 

 

Match the following systems and organs:

 

124)

Esophagus, large intestine, rectum.

A) Digestive

124)

 

 

 

 

 

Match the regional/directional terms and examples:

 

 

 

125)

The bridge of the nose is ________ to

A) Medial

125)

 

 

 

 

 

 

the left eye.

 

 

Match the following systems and organs:

 

126) Adrenal glands, pancreas, pituitary.

A) Endocrine

126)

 

 

 

 

 

 

ESSAY. Write your answer in the space provided or on a separate sheet of paper.

 

127)  A small family was traveling in its van and had a minor accident. The children in the back seats were wearing lap belts, but still sustained numerous bruises about the abdomen, and had some internal organ injuries. Why is this area more vulnerable to damage than others?

 

128)  The nurse charted: "Patient has an open wound located on lateral aspect of leg." Describe where the wound is located.


129)  Steve was injured in a football accident. X-ray examination showed a fracture underlying his left brachial deformity. What part of his body was injured?

 

130)  Judy is 16 years old and collapses on the gym floor with severe pain in her chest wall every time she takes a deep breath. She is rushed by ambulance to the emergency room. Judy is diagnosed with pleurisy and is given an anti-inflammatory drug through the intravenous route. Explain why an anti-inflammatory drug would be prescribed for someone with pleurisy.

 

131)  Sara is giving birth to her first child. She is concerned that her labor is taking longer than she thought it would. Why does giving birth usually take time for the contractions to proceed to the point when the child is born?

 

Answer Key

Testname: CHAPTER 1

 

 

1)  C

 

2)  C

3)  A

4)  A

5)  A

6)  D

7)  D

8)  C

9)  D

10)  C

11)  A

12)  A

13)  B

14)  A

15)  C

16)  D

17)  C

18)  C

19)  C

20)  D

21)  D

22)  C

23)  D

24)  A

25)  D

26)  B

27)  C

28)  B

29)  D

30)  B

31)  B

32)  D

33)  A

34)  E

35)  A

36)  B

37)  C

38)  A

39)  A

40)  B

41)  D

42)  C

43)  B

44)  C

45)  C

46)  B

47)  The integument cools the body through sweat while the muscular system warms the body by shivering.

48)  E

49)  respiratory system

50)  visceral peritoneum


Answer Key

Testname: CHAPTER 1

 

 

51)  The integument prevents entry of pathogens (germs, viruses, bacteria) OR harmful chemicals. The integumentary system prevents water (body fluid) loss.

 

52)  homeostasis

 

53)  tissues

54)  A

55)  Yes, carbon dioxide is a metabolic waste the lungs excrete.

56)  They provide a mechanism to maintain levels of substances within physiological limits.

57)  water

58)  A

59)  C

60)  D

61)  C

62)  B

63)  positive feedback

64)  If body temperature is too low, chemical reactions slow and eventually stop. If body temperature is too high, chemical reactions speed up and body proteins lose their normal shape, resulting in loss of function.

 

65)  The skeleton provides the ridged frame work (levers) for muscles to attach to. Muscles provide the force to move the bones about the joints.

 

66)  The walls of the abdominal cavity are formed only by trunk muscles and are not reinforced by bone. The pelvic organs receive a somewhat greater degree of protection from the bony pelvis.

 

67)  D

 

68)  The blood is provided a consistent supply of oxygen from the lungs while the circulatory system delivers carbon dioxide which will be removed from the body by the respiratory system.

 

69)  Anatomical terms are precise words that have limited usage, which prevents confusion when describing the location of body parts.

 

70)  responsiveness or excitability

 

71)  afferent pathway

72)  cervical

73)  metabolism

74)  Structure is specific to meet the needs of it's function.

75)  Homeostatic imbalances increase our risk for disease processes and produce the changes we associate with aging.

76)  negative

77)  They act to reduce friction and allow the organs to slide across cavity walls.

78)  pelvic

79)  Physiology

80)  olecranal

81)  medial

82)  TRUE

83)  TRUE

84)  FALSE

85)  TRUE

86)  TRUE

87)  FALSE

88)  TRUE

89)  TRUE

90)  TRUE

91)  TRUE

92)  FALSE

93)  FALSE

94)  TRUE

 

Answer Key

Testname: CHAPTER 1

 

 

95)  A

 

96)  A

97)  A

98)  A

99)  A

100)  A

101)  B

102)  A

103)  A

104)  A

105)  A

106)  A

107)  A

108)  A

109)  A

110)  A

111)  B

112)  A

113)  B

114)  A

115)  A

116)  A

117)  A

118)  A

119)  A

120)  A

121)  A

122)  A

123)  A

124)  A

125)  A

126)  A

127)  The abdominal organs are the least protected in the body because they are not surrounded by a bony covering such as the ribs, pelvis, or cranium.

 

128)  The wound is located on the outer side of the leg, the peroneal or fibular area.

 

129)  His left upper arm

130)  The pleural space contains a small amount of fluid that acts as a lubricant, allowing the pleurae to slide smoothly over each other as the lungs expand and contract. Pleurisy is an inflammation of the pleura around the lungs. When inflammation occurs in the pleural space, the pleurae do not slide smoothly and this causes severe pain that is more directly transmitted by the parietal than the visceral pleura.

 

131)  Childbirth is based on the increasing levels of oxytocin that cause the uterine contractions. Under positive feedback, oxytocin levels increase which results in increasing strong contractions by the upper uterus that will ultimately result in the birth of the child. But this positive feedback needs numerous contraction cycles to overcome the muscular resistance to stretching in the lower uterus in order for the head to pass.