Unit 1 - Introduction to Physiology Flashcards
1
Q
Physiology is the study of
A) the structure of the body.
B) the tissues and organs of the body at the microscopic level.
C) growth and reproduction.
D) the normal functions of the organ systems.
E) the facial features as an indication of personality.
A
D) the normal functions of the organ systems.
2
Q
The literal meaning of the term physiology is knowledge of A) organs. B) nature. C) science. D) chemistry. E) math.
A
B) nature.
3
Q
Because anatomy and physiology have different definitions, they are usually considered separately in studies of the body.
A) True
B) False
A
B) False
4
Q
The following is a list of several levels of organization that make up the human body. 1. tissue 2. cell 3. organ 4. molecule 5. organism 6. organ system The correct order from the smallest to the largest is A) 2, 4, 1, 3, 6, 5. B) 4, 2, 1, 6, 3, 5. C) 4, 2, 1, 3, 6, 5. D) 4, 2, 3, 1, 6, 5. E) 6, 4, 5, 2, 3, 1.
A
C) 4, 2, 1, 3, 6, 5.
5
Q
Which of the following is a buffer zone between the outside world and most of the cells of the body? A) blood B) lumen C) lymph D) extracellular fluid E) All of the answers are correct.
A
D) extracellular fluid
6
Q
Which of the following is one of Cannon's "internal secretions"? A) hormones B) nutrients C) water D) inorganic ions E) None of the answers are correct.
A
A) hormones
7
Q
The study of body function in a disease state is A) necrology. B) physiology. C) microbiology. D) pathophysiology. E) histology.
A
D) pathophysiology.
8
Q
Homeostasis is the ability of the body to
A) prevent the external environment from changing.
B) prevent the internal environment from changing.
C) quickly restore changed conditions to normal.
D) ignore external stimuli to remain in a state of rest.
E) prevent excessive blood loss.
A
C) quickly restore changed conditions to normal.
9
Q
Oxytocin is a hormone that is released in response to cervical dilation. It in turn causes more uterine contractions that will further dilate the cervix. What type of feedback loop does oxytocin trigger? A) negative feedback B) positive feedback C) local control D) nociceptive feedback
A
B) positive feedback
10
Q
How genetics influences the body's response to drugs is called A) pharmacokinetics. B) pharmacogenetics. C) pharmacogenomics. D) pharmacodynamics. E) pharmageddon.
A
C) pharmacogenomics.
11
Q
a collection of similar cells that carry out similar functions
A
tissue
12
Q
the smallest living unit
A
cell
13
Q
a collection of different tissues that carry out related functions
A
organs
14
Q
groups of organs functioning in a coordinated manner
A
organ systems
15
Q
When cancer develops in one tissue and spreads to another via the blood or the lymph, the cancer is said to have undergone what process? A) differentiation B) metastasis C) cytokinesis D) mutation
A
B) metastasis
16
Q
The space that is surrounded by the tissue wall of hollow organs is known as A) the peritoneal cavity. B) the lumen. C) the extracellular space. D) the epidural space. E) the tract.
A
B) the lumen.
17
Q
The lumen of a hollow organ such as the stomach is considered to be part of the ________ environment.
A) internal
B) external
A
B) external
18
Q
The watery medium that surrounds a cell is known as A) cytosol. B) protoplasm. C) extracellular fluid. D) cytoplasm. E) plasma.
A
C) extracellular fluid.
19
Q
Which of the following terms is NOT used to define the structure that separates the contents of a human cell from its surrounding medium? A) a cell wall B) a cell membrane C) plasma membrane D) plasmalemma E) All of the answers are correct.
A
A) a cell wall
20
Q
Which of the following is NOT a function of membrane proteins?
A) bind to ligands
B) regulate the passage of ions
C) act as transport molecules for various solutes
D) anchor or stabilize the cell membrane
E) produce energy
A
E) produce energy
21
Q
) Cell membranes are said to be A) impermeable. B) freely permeable. C) selectively permeable. D) actively permeable. E) None of the answers are correct.
A
C) selectively permeable.
22
Q
What is/are the major role(s) of the phospholipid bilayer?
A) the absorption of fats only
B) the formation of a barrier that is selectively permeable to lipid-soluble molecules only
C) to provide a framework for membrane proteins only
D) to carry water-soluble molecules through a hydrophobic environment only
E) the formation of a barrier that is selectively permeable to lipid-soluble molecules and to provide a framework for membrane proteins
A
E) the formation of a barrier that is selectively permeable to lipid-soluble molecules and to provide a framework for membrane proteins
23
Q
Which of the following is NOT a membrane lipid? A) sphingolipids B) cholesterol C) phospholipids D) All are membrane lipids.
A
D) All are membrane lipids.
24
Q
Which cellular organelle is a lipid bilayer that controls which objects can leave or enter the cell? A) endoplasmic reticulum B) Golgi apparatus C) nucleus D) plasma membrane E) ribosome
A
D) plasma membrane
25
A liposome is
A) only an additive to creams and lotions.
B) only a drug-delivery vehicle.
C) only a type of lipid.
D) only a structural component of cell membranes.
E) an additive to creams and lotions and a drug-delivery vehicle.
E) an additive to creams and lotions and a drug-delivery vehicle.
26
```
An immunoliposome is a liposome that
A) suppresses the immune system.
B) stimulates the immune system.
C) can recognize cancer cells.
D) None of the answers are correct.
```
C) can recognize cancer cells.
27
) Intermediate filaments
A) provide the cell with strength.
B) stabilize the position of organelles.
C) transport materials within the cytoplasm.
D) form the neurofilaments in nerve cells.
E) All of the answers are correct.
E) All of the answers are correct.
28
```
The cellular organelle(s) responsible for packaging and transporting proteins is/are the
A) microtubules.
B) mitochondria.
C) rough endoplasmic reticulum.
D) ribosomes.
E) Golgi complex.
```
E) Golgi complex.
29
```
) Each of the following is an example of a nonmembranous organelle except one. Identify the exception.
A) lysosome
B) cilia
C) centriole
D) ribosome
E) cytoskeleton
```
A) lysosome
30
```
The thickest protein fibers from the following group are
A) microtubules.
B) neurofilaments.
C) microfilaments.
D) myosin molecules.
E) keratin filaments.
```
A) microtubules.
31
```
Ribosomal RNA is formed by
A) the endoplasmic reticulum.
B) Golgi complexes.
C) lysosomes.
D) mitochondria.
E) nucleoli.
```
E) nucleoli.
32
Each of the following statements concerning mitochondria is TRUE except one. Identify the exception.
A) The mitochondrial cristae increase the inner surface area of the organelle.
B) The matrix of the mitochondria contains metabolic enzymes involved in energy production.
C) Respiratory enzymes are attached to the surface of the cristae.
D) The mitochondria contain no DNA or RNA.
E) The mitochondria produce most of a cell's ATP.
D) The mitochondria contain no DNA or RNA.
33
```
In humans, only ________ cells have flagella.
A) respiratory tract lining
B) intestine lining
C) stomach lining
D) sperm
E) uterine tube lining
```
D) sperm
34
```
Tay-Sachs is a disease caused by having ineffective
A) mitochondria.
B) Golgi bodies.
C) lysosomes.
D) rough endoplasmic reticulum.
E) smooth endoplasmic reticulum.
```
C) lysosomes.
35
Microvilli are found
A) mostly in muscle cells.
B) on the inside of cell membranes.
C) in large numbers on cells that secrete hormones.
D) in cells that are actively engaged in absorption.
E) only on cells lining the reproductive tract.
D) in cells that are actively engaged in absorption.
36
```
Microtubules
A) are composed of tubulin.
B) are hollow, filamentous structures.
C) form cilia that aid in cell movement.
D) are the largest cytoplasmic fibers.
E) All of the answers are correct.
```
E) All of the answers are correct.
37
Centrioles
A) function as pipelines to move fluid through the cell.
B) direct the movement of DNA during cell division.
C) hold the cell's ribosomes in place.
D) are white blood cells out of vessels.
E) provide shape and stability to a cell.
B) direct the movement of DNA during cell division.
38
```
Most of the ATP required to power cellular operations is produced in the
A) ribosomes.
B) endoplasmic reticulum.
C) nucleus.
D) mitochondria.
E) Golgi apparatus.
```
D) mitochondria.
39
Which does NOT accurately complete the sentence? One of the major functions of both types of endoplasmic reticulum (ER) is the
A) synthesis of biomolecules.
B) storage of genetic material for the cell.
C) transport of biomolecules.
D) storage of biomolecules.
B) storage of genetic material for the cell.
40
```
All of the following are synthesized along various sites of the endoplasmic reticulum except one. Identify the exception.
A) proteins
B) fatty acids
C) steroids
D) RNA
E) phospholipids
Answer: D
```
D) RNA
41
```
Which of the following is NOT a molecule synthesized in the smooth endoplasmic reticulum (SER)?
A) fatty acids
B) steroids
C) proteins
D) lipids
E) All are synthesized in the SER.
```
C) proteins
42
```
Which of the following consists of a network of intracellular membranes with attached ribosomes?
A) rough endoplasmic reticulum
B) smooth endoplasmic reticulum
C) mitochondria
D) nucleoli
E) Golgi apparatus
```
A) rough endoplasmic reticulum
43
```
All of the structures listed below are involved in storage, EXCEPT
A) lysosomes.
B) peroxisomes.
C) secretory vesicles.
D) storage vesicles.
E) All are involved in cellular storage.
```
E) All are involved in cellular storage.
44
The proteins synthesized in the rough endoplasmic reticulum are then sent to
A) the smooth endoplasmic reticulum for storage.
B) the Golgi complex for packaging.
C) the lysosome for modification.
D) the cell membrane for secretion.
E) the nucleus for cellular use.
B) the Golgi complex for packaging.
45
```
If a cell lacked lysosomes, it would not be able to
A) synthesize lipids.
B) produce enzymes.
C) digest cellular wastes and bacteria.
D) destroy H2O2.
E) transport water-soluble molecules.
```
C) digest cellular wastes and bacteria.
46
```
Which substance is responsible for activating the digestive enzymes inside lysosomes?
A) air
B) water
C) acid
D) enzymes
E) base
```
C) acid
47
Peroxisomes
A) use an enzyme to destroy H2O2 that is toxic to the cell.
B) are a type of lysosome.
C) are responsible for the atrophy of unused muscles.
D) are sites for synthesis of fatty acids, steroids, and phospholipids.
E) All of the answers accurately describe peroxisomes.
A) use an enzyme to destroy H2O2 that is toxic to the cell.
48
The number of mitochondria in skeletal muscle cells is ________ adipose (fat) cells.
A) greater than
B) less than
C) equal to
A) greater than
49
```
The control center for cellular operations is the
A) nucleus.
B) mitochondria.
C) Golgi complex.
D) endoplasmic reticulum.
E) ribosomes.
```
A) nucleus.
50
```
The beta cells of the pancreas produce insulin, a protein-based hormone. Which of the following organelles would be found in higher levels in the beta cells?
A) mitochondria
B) ribosomes
C) microvilli
D) lysosomes
```
B) ribosomes
51
```
If the adrenal cortex produces lipid based hormones such as aldosterone, which organelle would be higher in cells of the adrenal cortex than in the adrenal medulla?
A) Golgi apparatus
B) mitochondria
C) ribosome
D) rough endoplasmic reticulum
E) smooth endoplasmic reticulum
```
E) smooth endoplasmic reticulum
52
```
The nucleus stores all the information needed to synthesize which of the following molecules?
A) carbohydrates
B) lipids
C) proteins
D) phospholipids
E) All of the answers are correct.
```
E) All of the answers are correct.
53
The term secretion refers to
A) the process by which a cell releases a substance into the extracellular space for a particular use.
B) synthesis of a protein for export from the cell.
C) the manufacture and assembly of a material.
D) storage of a material, until it is time for it to leave the cell.
E) None of the answers describe secretion.
A) the process by which a cell releases a substance into the extracellular space for a particular use.
54
```
Which cellular organelle is considered the powerhouse of the cell?
A) endoplasmic reticulum
B) Golgi apparatus
C) mitochondria
D) nucleus
E) ribosome
```
C) mitochondria
55
Arrange the following events in protein secretion in the proper sequence.
1. The polypeptide chain enters the lumen of the endoplasmic reticulum.
2. A secretory vesicle is formed.
3. A transport vesicle is formed.
4. The polypeptide chain enters the lumen of the Golgi complex.
A) 1, 2, 3, 4
B) 1, 3, 2, 4
C) 1, 3, 4, 2
D) 4, 3, 1, 2
E) 3, 1, 4, 2
A) 1, 2, 3, 4
56
```
Movement of material between cells is known as the ________ pathway.
A) transcellular
B) paracellular
C) metacellular
D) transendothelial
E) cisendothelial
```
B) paracellular
57
```
All but one of the structures listed below are a type of cell junction. Identify the exception.
A) desmosomes
B) tight junctions
C) gap junctions
D) loose junctions
E) adherens junctions
```
D) loose junctions
58
```
The esophagus is a tube that carries food from the mouth to the stomach. It does not secrete any enzymes or absorb any nutrients, but it does need to stand up to significant friction and stress. The type of epithelium most likely lining the esophagus would be:
A) cuboidal epithelium.
B) simple squamous epithelium.
C) simple columnar epithelium.
D) stratified squamous epithelium.
E) transitional epithelium.
```
D) stratified squamous epithelium.
59
```
The type of protein found in gap junctions is the
A) claudin.
B) occludin.
C) cadherin.
D) connexin.
E) integrin.
```
D) connexin.
60
Disappearance of which type of junction most likely contributes to the metastasis of cancer cells throughout the body?
A) gap
B) tight
C) anchoring
C) anchoring
61
```
The types of junction proteins important in growth and development are
A) claudins.
B) occludins.
C) CAMs.
D) connexins.
E) integrins.
```
C) CAMs.
62
```
Each of the following is a primary tissue type except one. Identify the exception.
A) muscle tissue
B) neural tissue
C) osseous tissue
D) connective tissue
E) epithelial tissue
```
C) osseous tissue
63
```
Functions of epithelia include all of the following EXCEPT
A) providing physical protection.
B) controlling permeability.
C) producing specialized secretions.
D) storing energy reserves.
E) movement.
```
D) storing energy reserves.
64
```
Epithelial cells that are adapted for membrane transport of materials, such as ions and nutrients, usually have ________ on their apical surface.
A) mitochondria
B) cilia or flagella
C) microvilli
D) junctional complexes
E) vesicles
```
C) microvilli
65
Epithelia are connected to underlying connective tissues by
A) a basement membrane only.
B) protein filaments embedded in glycoprotein only.
C) a basal lamina only.
D) a basement membrane and protein filaments embedded in glycoprotein only.
E) a basement membrane, protein filaments embedded in glycoprotein, and a basal lamina.
E) a basement membrane, protein filaments embedded in glycoprotein, and a basal lamina.
66
```
Glands that secrete hormones into the blood via tissue fluids are
A) endocrine glands.
B) mixed glands.
C) exocrine glands.
D) unicellular glands.
E) None of the answers are correct.
```
A) endocrine glands.
67
Exocrine glands
A) may make either mucous or serous secretions.
B) release their secretions into the external environment.
C) release their secretions through open tubes, called ducts.
D) may work as single cells or as a multicellular organ.
E) All of the statements are true.
E) All of the statements are true.
68
Every substance that enters or leaves the internal environment of the body must cross an epithelium.
A) True
B) False
A) True
69
Due to the fact that they divide frequently, epithelia are prone to the genetic mutations associated with cancer.
A) True
B) False
A) True
70
The function of microvilli, often seen on the apical membrane of transporting epithelia, is to
A) increase the movement of extracellular fluid.
B) increase the resistance of the cell to viruses.
C) increase the cell's surface area.
D) increase the toughness of the cell.
E) allow the cell to move through a fluid medium.
C) increase the cell's surface area.
71
```
The simple squamous epithelial lining of blood vessels is called
A) basolateral epithelium.
B) endothelium.
C) luteal cells.
D) the vasa recta.
E) None of the answers are correct.
```
B) endothelium.
72
```
Which type of tissue below has minimal extracellular matrix?
A) epithelial only
B) connective only
C) neural only
D) muscle only
E) epithelial, neural, and muscle
```
E) epithelial, neural, and muscle
73
) Functions of connective tissue include
A) establishing a structural framework for the body.
B) transporting fluids and dissolved materials.
C) providing protection for delicate organs.
D) storing energy reserves.
E) All of the answers are correct.
E) All of the answers are correct.
74
```
Cells that store fat are called
A) fibroblasts.
B) liposomes.
C) adipocytes.
D) mast cells.
E) melanocytes.
```
C) adipocytes.
75
```
Loose connective tissue functions in
A) supporting small glands.
B) supporting epithelia.
C) anchoring blood vessels and nerves.
D) All of the answers are correct.
```
D) All of the answers are correct.
76
```
Plasma is
A) found within the circulatory system.
B) the fluid portion of blood.
C) a subdivision of the ECF.
D) sometimes donated instead of blood.
E) All of the answers are correct.
```
E) All of the answers are correct.
77
```
The term meaning programmed cell death is
A) necrosis.
B) apoptosis.
C) oncogenesis.
D) diuresis.
E) cytocide.
```
B) apoptosis.
78
```
The term meaning a mitotic population of cells that persists into adulthood applies to
A) stem cells.
B) totipotent cells.
C) apoptosis.
D) nurse cells.
E) gametocytes.
```
A) stem cells.
79
Groups of tissues that carry out related functions may form structures known as
A) cells.
B) organs.
C) organelles.
D) organisms.
E) impossible to tell from the information given
B) organs.
80
```
The heaviest organ in the body is the
A) liver.
B) brain.
C) skin.
D) stomach.
E) urinary bladder.
```
C) skin.
81
The "powerhouse" of the cell, ATP is produced here.
mitochondria
82
These degrade long chain fatty acids and toxic foreign molecules.
peroxisomes
83
It is the digestive system of a cell, degrading and/or recycling bacterial or organic components.
lysosomes
84
It modifies proteins and packages them into secretory vesicles for export from the cell.
Golgi apparatus
85
simplest cell-cell junction
gap junction
86
contributes to the blood-brain barrier
tight junction
87
can be cell-matrix junctions
anchoring junction
88
their loss is characteristic of cancer
anchoring junction
89
adipocyte
fat
90
fibroblast
loose connective tissue
91
chondrocyte
cartilage
92
osteocyte
maintains bone matrix
93
osteoclast
destroys bone matrix
94
```
If an animal cell lacked centrioles, it would not be able to
A) maintain its balance.
B) synthesize proteins.
C) produce DNA.
D) metabolize sugars.
E) undergo nuclear division.
```
E) undergo nuclear division.
95
```
Which of the following cytoskeleton components are responsible for the movement of chromosomes during cell division?
A) microfilaments
B) intermediate filaments
C) thick filaments
D) microtubules
E) All of the answers are correct.
```
D) microtubules
96
```
A flagellum moves a cell through a fluid medium. What moves the fluid medium across the surface of cells that are not free to move?
A) centrioles
B) thick filaments
C) cilia
D) ribosomes
E) endoplasmic reticulum
```
C) cilia
97
Which of the following statements is NOT true regarding mitochondria?
A) The outer mitochondrial membrane is responsible for its shape.
B) The intermembrane space is used in the production of ATP.
C) Mitochondria contain their own DNA and RNA.
D) Mitochondria can replicate themselves only when directed by the cell's nuclear DNA.
E) Mitochondria are responsible for providing energy to the cell.
Mitochondria can replicate themselves only when directed by the cell's nuclear DNA.
98
```
Plasma is to blood as ________ is to cytoplasm.
A) inclusion
B) organelle
C) protein
D) cytosol
E) serum
```
D) cytosol
99
```
Examination of a sample of glandular cells reveals an extensive network of smooth endoplasmic reticulum. Which of the following would be a likely product of these cells?
A) digestive enzymes
B) steroid hormones
C) protein (peptide) hormones
D) transport proteins
E) antibodies
```
B) steroid hormones
100
In a pancreatic cell producing digestive enzyme, you would expect to find an elaborate
A) rough endoplasmic reticulum.
B) smooth endoplasmic reticulum.
A) rough endoplasmic reticulum.
101
```
Chondrocytes are to cartilage as osteocytes are to
A) blood.
B) epithelium.
C) fat.
D) bone.
E) neural tissue.
```
D) bone.
102
The tissue(s) that is/are considered excitable because of the ability to generate electrical signals is/are called
A) muscle tissue.
B) neural tissue.
C) epithelial tissue.
D) muscle tissue and neural tissue.
E) muscle tissue, neural tissue, and epithelial tissue.
D) muscle tissue and neural tissue.
103
You are looking at a slide of an unknown organ that has an empty lumen with stratified squamous epithelium contacting the lumen. Deep to the epithelium is a basement membrane and then two layers of smooth muscle. Which of the following organs would this most likely belong to and why?
A) The intestines because they need to move food along and absorb digested products.
B) The liver because it secretes enzymes and bile and needs to move them to the gallbladder.
C) The esophagus because it is a passageway that needs to move but not absorb food products.
D) The urinary bladder because it needs to stretch and constrict to store and eliminate urine.
C) The esophagus because it is a passageway that needs to move but not absorb food products.
104
```
A layer of glycoproteins and a network of fine protein filaments that prevents the movement of proteins and other large molecules from the connective tissue to epithelium describes
A) interfacial canals.
B) the basal lamina.
C) the reticular lamina.
D) areolar tissue.
E) endothelium.
```
B) the basal lamina.
105
The distinguishing characteristic of connective tissue is
A) that it is arranged in sheets of tissue that lie on body surfaces.
B) always dividing, constantly being replaced throughout the body.
C) the presence of extensive extracellular matrix containing widely scattered cells.
D) the collagen fibers that offer support.
E) All of these characteristics help make connective tissue unique.
C) the presence of extensive extracellular matrix containing widely scattered cells.
106
```
Which type of connective tissue does NOT fit with the typical characteristic regarding relative cell density?
A) cartilage
B) bone
C) adipose
D) blood
E) dense
```
C) adipose
107
```
Close examination of an organ reveals a lining of several layers of cells. The layers do not contain any blood vessels, and one surface of the cells faces the internal cavity of the organ. This tissue is probably
A) epithelium.
B) muscle tissue.
C) connective tissue.
D) neural tissue.
E) fat tissue.
```
A) epithelium.
108
Increasing muscle mass and decreasing fat content in your body can increase resting metabolism. Why is this?
A) because doing so requires exercise and exercising burns calories
B) because muscle cells have more mitochondria than fat cells, allowing for more energy to be made from sugar
C) because adipocytes contain more cytoplasmic inclusions which slow down metabolism
D) because fat cells have no blood supply and cannot carry nutrients to be metabolized
B) because muscle cells have more mitochondria than fat cells, allowing for more energy to be made from sugar
109
Microscopic examination of a tissue reveals an open framework of fibers with a large volume of fluid ground substance and elastic fibers. This tissue would most likely have come from the
A) inner wall of a blood vessel.
B) lungs.
C) spleen.
D) tissue that separates skin from underlying muscle.
E) bony socket of the eye.
D) tissue that separates skin from underlying muscle.
110
```
Mature nerve and muscle cells are expected to lack which organelle(s)?
A) nucleus
B) endoplasmic reticulum
C) centrioles
D) ribosomes
E) Golgi bodies
```
C) centrioles
111
```
Neurons in the CNS of the adult don't contain centrioles. What does that tell you about CNS neurons?
A) They don't produce any products.
B) It doesn't tell you much of anything.
C) They don't replicate themselves.
D) They don't carry nerve impulses.
```
C) They don't replicate themselves.
112
Only totipotent stem cells are capable of producing new cells in an adult.
A) True
B) False
B) False
113
Found in the epidermis, esophagus, and mouth, these stacked layers of cells prevent exchange, while they resist chemicals, bacteria, and other destructive forces.
protective
114
This tissue actively and selectively regulates the exchange of nongaseous material, such as ions and nutrients, and can be regulated in response to various stimuli.
transport
115
These thin, flattened cells allow the rapid passage of O2 and CO2 through the cells of the lungs and of certain blood vessels.
exchange
116
These cells produce a substance and release it, either onto a surface or directly into the blood.
secretory
117
This tissue is composed of cells with membrane extensions that beat in a coordinated fashion to move fluid and particles across the tissue.
ciliated
118
Cancer is abnormal, uncontrolled cell division. What property of epithelial tissues makes them more prone to develop this condition?
Epithelial tissues contain a population of dividing cells, which divide at a moderate rate.
119
Describe the anatomical and fluid compartments of the body. How do the lumens of hollow organs fit into these classifications? Which fluid-containing cavities are considered to be internal and which are external? Of those that are external, why are they external (give examples)?
The anatomical compartments are the cranial cavity, containing the brain; the thoracic cavity, containing the heart and lungs; and the abdominopelvic cavity, containing organs of the digestive, urinary, and reproductive systems. The fluid compartments are the intracellular fluid (inside the cells) and the extracellular fluid (outside the cells). The extracellular fluids are found in the interstitial fluid between cells and the plasma of the blood, which is in the lumen of the circulatory system. Lumens of hollow organs such as the digestive and urinary tracts are part of the external environment, whereas the intracellular and interstitial fluids are internal. The lumen of the circulatory system is also internal. External lumens are those that open to the outside environment. These openings include the mouth, nostrils, anus, urethral and vaginal orifices.
120
Give three examples of structures whose formation involves molecular interactions that either increase or decrease contact with water molecules, explaining how they are similar and how they differ from each other.
Phospholipids have a polar portion that is attracted to water and a nonpolar portion that repels water.
Micelles, in which a single layer of phospholipids forms a sphere with the hydrophobic tails in the middle
Liposomes, which are hollow spheres made from phospholipid bilayers that can be filled with water-soluble molecules.
121
Define and distinguish between necrosis and apoptosis, and give specific examples of each.
Necrosis is cell death as a result of damage from toxins, physical trauma, or lack of oxygen; damaged cells release chemicals that may damage neighboring cells. An example is death of skin cells as a result of sunburn. Apoptosis is programmed cell death, which is an internally regulated process and does not involve neighboring cells unless they too are so programmed. An example is the loss of skin webbing between fingers and toes in a fetus.
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During a lab practical, Kevin examines a tissue that is composed of densely packed protein fibers that are running parallel and form a cord. There are few nuclei and no striations, and there is no evidence of other cellular structures. Kevin identifies the tissue as skeletal muscle. Why is Kevin's choice wrong, and what tissue is he probably observing?
Skeletal muscle tissue is made up of densely packed fibers running in the same direction, but since muscle fibers are composed of cells, they would have many nuclei and mitochondria. Skeletal muscle also has an obvious banding pattern or striations due to the arrangement of the actin and myosin filaments within the cell. Kevin is probably looking at a slide of tendon (dense connective tissue).
