Biology Flashcards
1
Q
What is synthesized in the nucleolus?
A
rRNA
2
Q
Which part of the endoplasmic reticulum contains ribosomes?
A
the rough ER (RER)
3
Q
What is the function of the mitochondria?
A
ATP production and apoptosis
4
Q
What is the function of lysosomes?
A
break down cellular waste products and molecules ingested through endocytosis, and can also be involved with apoptosis
5
Q
What is the function of the rough endoplasmic reticulum?
A
synthesize proteins destined for secretion
6
Q
What is the function of the smooth endoplasmic reticulum?
A
involved in lipid synthesis and detoxification
7
Q
What is the function of the Golgi apparatus?
A
package, modify, and distribute cellular products
8
Q
What is the function of peroxisomes?
A
break down long chain fatty acids, synthesize lipids, and contribute to the pentose phosphate pathway
(they are dependent on hydrogen peroxide for their functions)
9
Q
What is the predominant protein in microfilaments?
A
composed of actin
10
Q
What is the predominant protein in microtubules?
A
composed of tubular
11
Q
What is the predominant protein in intermediate filaments?
A
they differ by cell type, but may be composed of keratin, desmin, vimentin, and lamins
12
Q
Describe the mechanism for bacterial genetic recombination of transformation
A
the acquisition of exogenous genetic material that can be integrated into the bacterial genome
13
Q
Describe the mechanism for bacterial genetic recombination of conjugation
A
the transfer of genetic material from one bacterium to another across a conjugation bridge; a plasmid can be transferred from F+ cells to F- cells, or a portion of the genome can be transferred from an Hfr cell to a recipient
14
Q
Describe the mechanism for bacterial genetic recombination of transduction
A
the transfer of genetic material from one bacterium to another by a bacteriophage
15
Q
What are the four phases of the bacterial growth curve?
A
lag phase: bacteria get used to environment; little growth
exponential (log) phase: bacteria use available resources to multiply at an exponential rate
stationary phase: bacterial multiplication slows as resources are used up
death phase: bacteria die as resources become insufficient to support the colony
16
Q
What is determinate cleavage?
A
cell division that results in cells having definitive lineages; that is, at least one daughter cell is programmed to differentiate into a particular cell type
17
Q
What is indeterminate cleavage?
A
cell division that results in cells that can differentiate into any cell type (or a whole organism)
18
Q
From zygote to gastrula, what are the various stages of development?
A
zygote –> 2-,4-,8-, and 16-cell embryo –> morula –> blastula (blastocyst) –> gastrula
19
Q
During which stage of development does implantation occur?
A
implantation occurs during the blastula (blastocyst) stage
20
Q
What are the primary germ layers, and what organs are formed from each?
A
ectoderm: integument (including the epidermis, hair, nails, and epithelia of the nose, mouth, and anal canal), lens of the eye, nervous system (including adrenal medulla), inner ear
mesoderm: musculoskeletal system, circulatory system, excretory system, gonads, muscular and connective tissue layers of the digestive and respiratory systems, adrenal cortex
endoderm: epithelial linings of digestive and respiratory tracts, and parts of the liver, pancreas, thyroid, bladder, and distal urinary and reproductive tracts
21
Q
What is induction and how does it influence development?
A
induction is the process by which nearby cells influence the differentiation of adjacent cells. This ensures proper spatial location and orientation of cells that share a function or have complementary functions
22
Q
What tissues do neural crest cells develop into?
A
neural crest cells become the peripheral nervous system (including the sensory ganglia, autonomic ganglia, adrenal medulla, and Schwann cells) as well as specific cell types in other tissues (such as calcitonin-producing cells of the thyroid, melanocytes in the skin, and others)
23
Q
What is cell differentiation?
A
changing the structure, function, and biochemistry of a cell to match its cell type
24
Q
What is the difference between determination and differentiation?
A
Determination is the commitment of a cell to a particular lineage. Differentiation refers to the actual changes that occur in order for the cell to assume the structure and function of the determined cell type.
25
What are the three types of potency? What lineages can a cell of each type differentiate into?
totipotency: any cell type in the developing embryo (primary germ layers) or in extraembryonic tissues (amnion, chorion, placenta)
pluripotency: any cell type in the developing embryo (primary germ layers)
multipotency: any cell type within a particular lineage (for example, hematopoietic stem cells)
26
What are the four types of cell-cell communication?
Autocrine: the signal acts on the same cell that secreted it
paracrine: the signal acts on local cells
juxtacrine: a cell triggers adjacent cells through direct receptor stimulation
endocrine: the signal travels via the bloodstream to act on cells at distant sites
27
What is the difference between apoptosis and necrosis?
Apoptosis is programmed cell death and results in contained blebs of the dead cell that can be picked up and digested by other cells. Necrosis is cell death due to injury and results in spilling of cytoplasmic contents
28
What is the oxygenation status of the blood in the umbilical arteries?
the umbilical arteries carry deoxygenated blood
29
What is the oxygenation status of the blood in the umbilical vein?
the umbilical vein carries oxygenated blood
30
What are the three fetal shunts? What vessels or heart chambers do they connect? What organ does each shunt bypass?
Foramen ovale: connects the right atrium to the left atrium, bypasses the lungs
Ductus arteriosus: connects the pulmonary artery to the aorta, bypasses the lungs
Ductus venosus: connects the umbilical vein to the inferior vena cava, bypasses the liver
31
What are some of the key developmental features of the first trimester?
organogenesis occurs (development of heart, eyes, gonads, limbs, liver, brain)
32
What are some of the key developmental features of the second trimester?
tremendous growth occurs, movement begins, the face becomes distinctly human, and the digits elongate
33
What are some of the key developmental features of the third trimester?
rapid growth and brain development continue, and there is transfer of antibodies to the fetus
34
What occurs in each of the three phases of birth?
In the first phase of birth, the cervix thins out and the amniotic sac ruptures.
In the second phase, uterine contractions, coordinated by prostaglandins and oxytocin, result in birth of the fetus
In the third phase, the placenta and umbilical cord are expelled
35
What is the axon of a neuron?
transmits an electrical signal (the action potential) from the soma to the synaptic knob
36
What is the axon hillock of a neuron?
integrates excitatory and inhibitory signals from the dendrites and fires an action potential if the excitatory signals are strong enough to reach threshold
37
What is the dendrite of a neuron?
receive incoming signals and carry them to the soma
38
What is the myelin sheath of a neuron?
acts as insulation around the axon and speeds conduction
39
What is the soma of a neuron?
the cell body and contains the nucleus, endoplasmic reticulum, and ribosomes
40
What is the synaptic bouton of a neuron?
lies at the end of the axon and releases neurotransmitters
41
What is a collection of cell bodies called in the CNS?
a nucleus
42
What is a collection of cell bodies called in the PNS?
a ganglion
43
Which two types of glial cells, if not properly functioning, will make an individual most susceptible to a CNS infection?
Astrocytes nourish neurons and form the blood-brain barrier, which helps protect the brain from foreign pathogens gaining entrance.
Microglia ingest and break down waste products and pathogens.
Disruption of either of these mechanisms would increase susceptibility to a CNS infection
44
What neural structure initiates the action potential?
the axon hillock
45
What entity maintains the resting membrane potential? What is the approximate voltage of the resting membrane potential?
the resting membrane potential is maintained by the Na+/K+ ATPase at approximately -70 mV
46
What is the difference between temporal and spatial summation?
Temporal summation is the integration of multiple signals close to each other in time
Spatial summation is the integration of multiple signals close to each other in space
47
During the action potential, which ion channel opens first? How is this ion channel regulated? What effects does the opening of this channel have on the polarization of the cell?
The sodium channel opens first at the threshold (around -50 mV). It is regulated by inactivation, which occurs around +35 mV. Inactivation can only be reversed by repolarizing the cell. The opening of the sodium channel causes depolarization
48
During the action potential, which ion channel opens second? How is this ion channel regulated? What effect does the opening of this channel have on the polarization of the cell?
The potassium channel opens second at approximately +35 mV. It is regulated by closing at low potentials (slightly below -70 mV). The opening of the potassium channel causes repolarization and, eventually, hyperpolarization
49
What is the difference between the absolute and relative refractory period?
During the absolute refractory period, the cell is unable to fire an action potential regardless of the intensity of a stimulus
During the relative refractory period, the cell can fire an action potential only with a stimulus that is stronger than normal
50
What ion is primarily responsible for the fusion of neurotransmitter-containing vesicles with the nerve terminal membrane?
Calcium is responsible for fusion of neurotransmitter vesicles with the nerve terminal membrane
51
What are the three main methods by which a neurotransmitter's action can be stopped?
A neurotransmitter's action can be stopped by enzymatic degradation, reuptake, or diffusion
52
What parts of the nervous system are in the central nervous system (CNS)?
The CNS includes the brain and spinal cord
53
What parts of the nervous system are in the peripheral nervous system (PNS)?
The PNS includes cranial and spinal nerves and sensory nerves
54
What do afferent neurons do?
Afferent (sensory) neurons bring signals from a sensor to the central nervous system
55
What do efferent neurons do?
Efferent (motor) neurons bring signals from the central nervous system to an effector
56
What functions are accomplished by the somatic nervous system?
The somatic nervous system is responsible for voluntary actions - most notable, moving muscles
57
What functions are accomplished by the autonomic nervous system?
The autonomic nervous system is responsible for involuntary processes like heart rate, bronchial dilation, dilation of the pupils, exocrine gland function, and peristalsis
58
What are the effects of the sympathetic nervous system?
The sympathetic nervous system promotes a "fight-or-flight" response, with increased heart rate and bronchial dilation, redistribution of blood to locomotor muscles, dilation of the pupils, and slowing of digestive and urinary function
59
What are the effects of the parasympathetic nervous system?
The parasympathetic nervous system promotes "rest-and-digest" functions, slowing heart rate and constricting the bronchi, redistributing blood to the gut, promoting exocrine secretions, constricting the pupils, and promoting peristalsis and urinary function
60
What is the pathway of neural impulses in a monosynaptic reflex?
a sensory (afferent, presynaptic) neuron fires directly onto a motor (efferent, postsynaptic) neuron
61
What is the pathway of neural impulses in a polysynaptic reflex?
a sensory neuron may fire directly onto a motor neuron, but interneurons are used as well. These interneurons fire onto other motor neurons
62
Compare and contrast peptide and steroid hormones based on the following criteria: chemical precursor, location of receptor, mechanism of action, method of travel in the bloodstream, speed of onset, duration of action
Peptide hormones:
Chemical precursor: amino acids (polypeptides)
Location of receptor: extracellular (cell membrane)
Mechanism of action: stimulates a receptor (usually a G protein-coupled receptor), affecting levels of second messengers (commonly cAMP). Initiates a signal cascade
Method of travel in the bloodstream: dissolves and travels feely
Speed of onset: quick
Duration of action: short-lived
Steroid hormones:
Chemical precursor: cholesterol
Location of receptor: intracellular or intranuclear
Mechanism of action: binds to a receptor, induces conformational change, and regulates transcription at the level of the DNA
Method of travel in the bloodstream: binds to a carrier protein
Speed of onset: slow
Duration of action: long-lived
63
How are amino acid-derivative hormones synthesized?
Amino acid-derivative hormones are made by modifying amino acids, such as the addition of iodine to tyrosine (in thyroid hormone production)
64
What is the difference between a direct and a tropic hormone?
Direct hormones are secreted into the bloodstream and travel to a target tissue, where they have direct effects. Tropic hormones cause secretion of another hormone that then travels to the target tissue to cause an effect.
65
For the hypothalamic releasing hormone gonadotropin-releasing hormone (GnRH), what hormone(s) does it affect in the anterior pituitary? On which organ does each pituitary hormone act? What hormones(s) are released by the target organ?
Hormone(s) from anterior pituitary: follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
Target organ: gonads (testes or ovaries)
Hormone(s) released by target organ: testosterone (testes) or estrogen and progesterone (ovaries)
66
For the hypothalamic releasing hormone corticotropin-releasing factor (CRF), what hormone(s) does it affect in the anterior pituitary? On which organ does each pituitary hormone act? What hormones(s) are released by the target organ?
Hormone(s) from anterior pituitary: adrenocorticotropic hormone (ACTH)
Target organ: adrenal cortex
Hormone(s) released by target organ: glucocorticoids (cortisol and cortisone)
67
For the hypothalamic releasing hormone thyroid-releasing hormone (TRH), what hormone(s) does it affect in the anterior pituitary? On which organ does each pituitary hormone act? What hormones(s) are released by the target organ?
Hormone(s) from anterior pituitary: thyroid-stimulating hormone (TSH)
Target organ: thyroid
Hormone(s) released by target organ: triiodothyronine (T3), thyroxine (T4)
68
For the hypothalamic releasing hormone dopamine, what hormone(s) does it affect in the anterior pituitary? On which organ does each pituitary hormone act? What hormones(s) are released by the target organ?
Hormone(s) from anterior pituitary: prolactin
Target organ: breast tissue
Hormone(s) released by target organ: N/A
69
For the hypothalamic releasing hormone growth hormone-releasing hormone (GHRH), what hormone(s) does it affect in the anterior pituitary? On which organ does each pituitary hormone act? What hormones(s) are released by the target organ?
Hormone(s) from anterior pituitary: growth hormone
Target organ: bone, muscle
Hormone(s) released by target organ: N/A
70
Which two hormones are primarily involved in calcium homeostasis? Where does each come from, and what effect does each have on blood calcium concentrations?
- Calcitonin from the parafollicular (C-) cells of the thyroid decreases blood calcium concentration.
- Parathyroid hormone from the parathyroid glands increases blood calcium concentration.
71
Which endocrine tissue synthesizes catecholamines? What are the two main catecholamines it produces?
The adrenal medulla synthesizes catecholamines, including epinephrine and norepinephrine
72
Which two pancreatic hormones are the major drivers of glucose homeostasis? Where does each come from, and what effects does each have on blood glucose concentrations?
- Glucagon from the alpha-cells of the pancreas increases blood glucose concentration.
- Insulin from the beta-cells of the pancreas decreases blood glucose concentration.
73
Which three hormones are primarily involved in water homeostasis? Where does each come from, and what effect does each have on blood volume and osmolarity?
- Antidiuretic hormone (ADH or vasopressin) from the hypothalamus (released by the posterior pituitary) increases blood volume and decreases blood osmolarity.
- Aldosterone from the adrenal cortex increases blood volume with no effect on blood osmolarity.
- Atrial natriuretic peptide (ANP) from the heart decreases blood volume with no effect on blood osmolarity.
74
List the structures in the respiratory pathway, from where air enters the nares to the alveoli.
Nares --> nasal cavity --> pharynx --> larynx --> trachea --> bronchi --> bronchioles --> alveoli
75
Which muscle(s) are involved in inhalation? Exhalation?
Inhalation uses the diaphragm and external intercostal muscles; in labored breathing, muscles of the neck and back may also be involved. Passive exhalation uses the recoil of these same muscles; active exhalation also uses the internal intercostal muscles and abdominal muscles.
76
What is the purpose of surfactant?
Surfactant reduces surface tension at the air-liquid interface in the alveoli. This prevents their collapse.
77
What is the mathematical relationship between vital capacity (VC), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), and tidal volume (TV)?
Vital capacity is the sum of the inspiratory reserve volume, expiratory reserve volume, and tidal volume: VC = IRV + ERV + TV
78
If blood levels of CO2 become too low, how does the brain alter the respiratory rate to maintain homeostasis?
When CO2 levels become too low, the brain can decrease the respiratory rate in order to raise CO2 levels.
79
What are some of the mechanisms used in the respiratory system to prevent infection?
Immune mechanisms in the respiratory system include vibrissae in the nares, lysozyme in the mucous membranes, the mucociliary escalator, macrophages in the lungs, mucosal IgA antibodies, and mast cells.
80
What is the chemical equation for the bicarbonate buffer system?
CO2(g) + H2O(l) ↔ H2CO3(aq) ↔ HCO3–(aq) + H+(aq)
81
Respiratory failure refers to inadequate ventilation to provide oxygen to the tissues. How would the pH change in respiratory failure?
In respiratory failure, ventilation slows, and less carbon dioxide is blown off. As this occurs, the buffer equation shifts to the right, and more hydrogen ions are generated. This results in a lower pH of the blood.
82
Starting from entering the heart from the venue cave, what are the four chambers through which blood passes in the heart? Which valve prevents back flow into each chamber?
Right atrium: tricuspid valve
Right ventricle: pulmonary valve
Left atrium: mitral (bicuspid) valve
Left ventricle: aortic valve
83
Starting with the site of impulse initiation, what are the structures in the conduction system of the heart?
sinoatrial (SA) node --> atrioventricular (AV) node --> bundle of His (AV bundle) and its branches --> Purkinje fibers
84
Compare and contrast arteries, capillaries, and veins.
Artery: carries blood away from the heart, walls are thick, a lot of smooth muscle is present, and does not contain valves
Capillary: carries blood from arterioles to venules, walls are very thin (one cell layer), no smooth muscle present, and does not contain valves
Vein: carries blood towards the heart, walls are thin, a little smooth muscle is present, and they do contain valves
85
Why does the right side of the heart contain less cardiac muscle than the left side?
The right side of the heart pumps blood into a lower-resistance circuit and must do so at lower pressures; therefore, it requires less muscle. The left side of the heart pumps blood into a higher-resistance circuit at higher pressures; therefore, it requires more muscle.
86
If all autonomic input to the heart were cut, what would happen?
If all autonomic innervation to the heart were lost, the heart would continue beating at the intrinsic rate of the pacemaker (SA node). The individual would be unable to change his or her heart rate via the sympathetic or parasympathetic nervous system, but the heart would not stop beating.
87
What are the components of plasma?
Plasma is an aqueous mixture of nutrients, salts, respiratory gases, hormones, and blood proteins (clotting proteins, immunoglobulins, and so on)
88
An individual with B+ blood is in an automobile accident and requires a blood transfusion. What blood types can he receive? The same individual is so thankful that, after recovery, he decides to donate blood. To which blood types could he donate?
The B+ person could receive blood from a B+, B-, O+, or O- person. The B+ person could donate blood to a B+ or AB+ person.
89
What does a hematocrit measure? What are the units for hematocrit?
Hematocrit measures the percentage of a blood sample occupied by red blood cells. It is measured in percentage points.
90
Which types of leukocytes are involved in the specific immune response?
Lymphocytes are involved in specific immune defense
91
Where do platelets come from?
Platelets are cellular fragments or shards that are given off by megakaryocytes in the bone marrow
92
Which cell type(s) in blood contain nuclei? Which do not?
Only leukocytes (including neutrophils, eosinophils, basophils, monocytes/macrophages, and lymphocytes) contain nuclei. Erythrocytes and platelets do not
93
In bacterial sepsis (overwhelming bloodstream infection), a number of capillary beds throughout the body open simultaneously. What effect would this have on the blood pressure? Besides the risk of infection, why might sepsis be dangerous for the heart?
Opening up more capillary beds (which are in parallel) will decrease the overall resistance of the circuit. The cardiac output will therefore increase in an attempt to maintain constant blood pressure. This is a risk to the heart because the increased demand on the heart can eventually tire it, leading to a heart attack or a precipitous drop in blood pressure.
94
What is the chemical equation for the bicarbonate buffer system? What enzyme catalyzes this reaction?
The bicarbonate buffer system equation is
CO2(g) + H2O(l) --> H2CO3(aq) --> H+(aq) + HCO3-(aq)
The combining of carbon dioxide and water is catalyzed by carbonic anhydrase
95
Where should you look on the oxyhemoglobin dissociation curve to determine the amount of oxygen that has been delivered to tissues?
The amount of oxygen delivery can be seen as a drop in the y-value (percent hemoglobin saturation) on an oxyhemoglobin dissociation curve. For example, if the blood is 100% saturated while in the lungs (at 100 mmHg O2) and only 80% saturated while in tissues (at 40 mmHg O2), then 20% of the oxygen has been released to tissues
96
What direction does the oxyhemoglobin dissociation curve shift as a result of exercise? What physiological changes cause this shift and why?
The oxyhemoglobin dissociation curve shifts to the right during exercise in response to increased arterial CO2, increased [H+], decreased pH, and increased temperature. This right shift represents hemoglobin's decreased affinity for oxygen, which allows more oxygen to be unloaded at the tissues.
97
Exposure to which sub endothelial compounds start the coagulation cascade? What protein helps stabilize the clot?
The coagulation cascade can be started by the exposure of collagen and tissue factor to platelets and coagulation factors. The clot is stabilized by fibrin.
98
What are the differences between innate and adaptive immunity?
Innate immunity consists of defenses that are always active against pathogens, but that are not capable of targeting specific invaders. It takes longer to mount a response with adaptive immunity, but the response targets a specific pathogen and maintains immunologic memory of the infection to mount a faster response during subsequent infections.
99
Discuss the properties of B-cells
Site of development: bone marrow
Site of maturation: bone marrow (but are activated in spleen or lymph nodes)
Major functions: produce antibodies
Specific or nonspecific? specific
Humoral or cell-mediated? humoral
100
Discuss the properties of T-cells
Site of development: bone marrow
Site of maturation: thymus
Major functions: coordinate immune system and directly kill infected cells
Specific or nonspecific? specific
Humoral or cell-mediated? cell-mediated
101
Which cells are considered granulocytes? Which are considered agranulocytes?
Granulocytes include neutrophils, eosinophils, and basophils. Agranulocytes include B- and T-cells (lymphocytes) and monocytes (macrophages)
102
Provide a brief description for the noncellular nonspecific immune defense of the skin
Skin provides a physical barrier and secretes antimicrobial enzymes
103
Provide a brief description for the noncellular nonspecific immune defense of defensins
Defensins are examples of antibacterial enzymes on the skin
104
Provide a brief description for the noncellular nonspecific immune defense of lysozymes
Lysozyme is antimicrobial and is present in tears and saliva
105
Provide a brief description for the noncellular nonspecific immune defense of mucus
Mucus is present on mucous membranes and traps incoming pathogens; in the respiratory system, cilia propel the mucus upward so it can be swallowed or expelled.
106
Provide a brief description for the noncellular nonspecific immune defense of stomach acid
Stomach acid is an antimicrobial substance in the digestive system
107
Provide a brief description for the noncellular nonspecific immune defense of normal gastrointestinal flora
The normal gastrointestinal flora provides competition, making it hard for pathogenic bacteria to grow in the gut
108
Provide a brief description for the noncellular nonspecific immune defense of complement
Complement is a set of proteins in the blood that can create holes in bacteria
109
Which cells are professional antigen-presenting cells?
Professional antigen-presenting cells include macrophages, dendritic cells in the skin, some B-cells, and certain activated epithelial cells
110
What are the differences between MHC-I and MHC-II?
MHC-I is found in all nucleated cells and presents pieces of proteins (peptides) created within the cell (endogenous antigens); this can allow for detection of cells infected with intracellular pathogens (especially viruses).
MHC-II is only found in antigen-presenting cells and presents proteins that result from the digestion of extracellular pathogens that have been brought in by endocytosis (exogenous antigens)
111
What stimulus activates natural killer cells?
Natural killer cells are activated by cells that do not present MHC (such as virally infected cells and cancer cells)
112
What stimulus activates neutrophils?
Neutrophils are activated by bacteria, especially those that have been opsonized (tagged with an antibody on their surface)
113
What stimulus activates eosinophils?
Eosinophils are activated by invasive parasites and allergens
114
What stimulus activates basophils and mast cells?
Basophils and mast cells are activated by allergens
115
What is the main function of the lymphocyte: plasma cell?
Plasma cells form from B-cells exposed to antigens and produce antibodies
116
What is the main function of the lymphocyte: memory B-cell?
Memory B-cells also form from B-cells exposed to antigen and lie in wait for a second exposure to a given antigen to mount a rapid, robust response.
117
What is the main function of the lymphocyte: helper T-cell?
Helper T-cells coordinate the immune system through lymphokines and respond to antigen bound to MHC-II
118
What is the main function of the lymphocyte: cytotoxic T-cell?
Cytotoxic T-cells directly kill virally infected cells and respond to antigens bound to MHC-I
119
What is the main function of the lymphocyte: suppressor (regulatory) T-cell?
Suppressor (regulatory) T-cells quell the immune response after a pathogen has been cleared and promote self-tolerance
120
What is the main function of the lymphocyte: memory T-cell?
Memory T-cells, like memory B-cells, lie in wait until a second exposure to a pathogen to mount a rapid, robust response
121
What are the three main effects circulating antibodies can have on a pathogen?
Circulating antibodies can mark a pathogen for destruction by phagocytic cells (opsonization), cause agglutination of the pathogen into insoluble complexes that can be taken up by phagocytic cells, or neutralize the pathogen by preventing it from invading tissues
122
How do antibodies become specific for a given antigen?
B-cells originally mature in the bone marrow and have some specificity at that point; however, antibodies that can respond to a given antigen undergo hypermutation, or rapid mutation of their antigen-binding sites. Only those B-cells that have the highest affinity for the antigen survive and proliferate, increasing the specificity for the antigen over time
123
A T-cell appropriately passes through positive selection, but then inappropriately passes through negative selection. What will this T-cell be reactive towards?
Positive selection occurs when T-cells in the thymus that are able to respond to antigen presented on MHC are allowed to survive (those that do not respond undergo apoptosis). Negative selection occurs when T-cells that respond to self-antigens undergo apoptosis before leaving the thymus. A T-cell that appropriately passes through positive selection, but then inappropriately passes through negative selection will be reactive to self-antigens
124
Which cells account for the fact that secondary response to a pathogen is much more rapid and robust than the primary response?
Memory cells allow the immune system to carry out a much more rapid and robust secondary response
125
What is the difference between active and passive immunity?
Active immunity refers to the stimulation of the immune system to produce antibodies against a pathogen. Passive immunity refers to the transfer of antibodies to prevent infection, without stimulation of the plasma cells that produce these antibodies
126
Filariasis is the name for an infection with a member of a certain group of parasites, most notably Wuchereria bancrofti. This parasite resides in lymph nodes and causes blockage of flow. If an individual had a W. bancrofti infection in the lymph nodes of his or her thigh, what would likely happen?
Fluid would be unable to return from the lower leg, and edema would result. This infection leads to elephantiasis, severe swelling of the limb with thickening of the skin
127
What structure is primarily responsible for returning materials from lymphatic circulation to the cardiovascular system?
The thoracic duct carries lymphatic fluid to the left subclavian vein.
128
What is the difference between mechanical and chemical digestion?
Mechanical digestion, such as chewing, physically breaks down food into smaller pieces. Chemical digestion involves hydrolysis of bonds and breakdown of food into smaller biomolecules.
129
Trace the path of food through the body, starting with ingestion and ending with excretion of feces
oral cavity (mouth) --> pharynx --> esophagus --> stomach --> small intestine --> large intestine --> rectum --> anus
130
What effect does the parasympathetic nervous system have on the digestive system?
The parasympathetic nervous system increases secretions from all of the glands of the digestive system and promotes peristalsis.
131
What effect does the sympathetic nervous system have on the digestive system?
The sympathetic nervous system slows peristalsis.
132
What two main enzymes are found in saliva? What do these enzymes do?
Saliva contains salivary amylase (ptyalin), which digests starch into smaller sugars (maltose and dextrin); and lipase, which digests fats
133
What are the major secretions and functions of these secretions in mucous cells?
Mucous cells secrete mucus. Mucus functions are to protect the lining of the stomach and increase pH (bicarbonate)
134
What are the major secretions and functions of these secretions in chief cells?
Chief cells secrete pepsinogen. Pepsinogens functions are to digest proteins and are activated by H+
135
What are the major secretions and functions of these secretions in parietal cells?
Parietal cells secrete HCl and intrinsic factor. HCl decreases pH, kills microbes, denatures proteins, and carries out some chemical digestion. Intrinsic factor absorbs vitamin B12
136
What are the major secretions and functions of these secretions in G-cells?
G-cells secrete gastrin. Gastrin increases HCl production and increases gastric motility
137
Is sucrase a digestion enzyme or hormone? What is its function?
Sucrase is a digestive enzyme. It is a brush-border enzyme; breaks down sucrose into monosaccharides
138
Is secretin a digestion enzyme or hormone? What is its function?
Secretin is a digestive hormone. It increases pancreatic secretions, especially bicarbonate; reduces HCl secretions; decreases motility
139
Is dipeptidase a digestion enzyme or hormone? What is its function?
Dipeptidase is a digestive enzyme. It is a brush-border enzyme; breaks down dipeptides into free amino acids
140
Is cholecystokinin a digestion enzyme or hormone? What is its function?
Cholecystokinin is a digestive hormone. It recruits secretions from the gallbladder and pancreas; promotes satiety
141
Is enteropeptidase a digestion enzyme or hormone? What is its function?
Enteropeptidase is a digestive enzyme. It activates trypsinogen, which initiates an activation cascade
142
How do bile and pancreatic lipase work together to digest fats?
Bile accomplishes mechanical digestion of fats, emulsifying them and increasing their surface area. Pancreatic lipase accomplishes chemical digestion of fats, breaking their ester bonds
143
What pancreatic enzymes digest carbohydrates?
pancreatic amylase
144
What pancreatic enzymes digest proteins?
trypsin, chymotrypsin, carboxypeptidases A and B
145
What pancreatic enzymes digest fats?
pancreatic lipase
146
What are the main components of bile?
Bile is composed of bile salts (amphipathic molecules derived from cholesterol that emulsify fats), pigments (especially bilirubin from the breakdown of hemoglobin), and cholesterol.
147
Where is bile synthesized? Where is bile stored? Where does bile carry out its digestive function?
Bile is synthesized in the liver, stored in the gallbladder, and serves its function in the duodenum
148
List at least four functions of the liver
The liver processes nutrients (through glycogenesis and glycogenolysis, storage and mobilization of fats, and gluconeogenesis), produces urea, detoxifies chemicals, activates or inactivates medications, produces bile, and synthesizes albumin and clotting factors.
149
The accessory organs of digestion originate from which primary germ layer?
As outgrowths of the gut tube, the accessory organs of digestion arise from embryonic endoderm
150
What are the two circulatory vessels in a villus? What biomolecules are absorbed into each?
The two circulatory vessels are capillaries and lacteals. The capillary absorbs water-soluble nutrients like monosaccharides, amino acids, short-chain fatty acids, water-soluble vitamins, and water itself. The lacteal absorbs fat-soluble nutrients, like fats, cholesterol, and fat-soluble vitamins.
151
What are the four fat-soluble vitamins?
The fat-soluble vitamins are A, D, E, and K
152
What are the three sections of the small intestine, in order?
The small intestine consists of the duodenum, jejunum, and ileum.
153
What are the three sections of the large intestine, in order?
The large intestine consists of the cecum, colon, and rectum
154
Vibrio cholera causes a severe infection in the intestines, leading to massive volumes of water diarrhea - up to 20 liters per day. Given these symptoms, does cholera likely impact the small intestine or the large intestine?
While the large intestine's main function is to absorb water, the small intestine actually absorbs a much larger volume of water. Thus, massive volumes of watery diarrhea are more likely to arise from infections in the small intestine than in the large intestine.
155
What is the mnemonic for the major waste products excreted in the urine?
Dump the HUNK
H+
Urea
NH3
K+
156
List the structures in the excretory pathway, from where filtrate enters the nephron to the excretion of urine from the body.
Bowman's space --> proximal convoluted tubule --> descending limb of the loop of Henle --> ascending limb of the loop of Henle --> distal convoluted tubule --> collecting duct --> renal pelvis --> ureter --> bladder --> urethra
157
List the vessels in the renal vascular pathway, starting from the renal artery and ending at the renal vein
Renal artery --> afferent arteriole --> glomerulus --> efferent arteriole --> vasa recta --> renal vein
158
What arm of the nervous system is responsible for contraction of the detrusor muscle?
The parasympathetic nervous system causes contraction of the detrusor muscle
159
What are the three processes by which solutes are exchanged between the filtrate and the blood? What happens in each process?
Filtration is the movement of solutes from blood into filtrate at Bowman's capsule.
Secretion is the movement of solutes from blood into filtrate anywhere besides Bowman's capsule
Reabsorption is the movement of solutes from filtrate into blood
160
What is the major function of the segment of the nephron known as the Bowman's capsule?
Bowman's capsule is the site of filtration, through which water, ions, amino acids, vitamins, and glucose pass (essentially everything besides cells and proteins)
161
What is the major function of the segment of the nephron known as the proximal convoluted tubule?
The proximal convoluted tubule controls solute identity, reabsorbing vitamins, amino acids, and glucose, while secreting potassium and hydrogen ions, ammonia, and urea
162
What is the major function of the segment of the nephron known as the descending limb of the loop of Henle?
The descending limb of the loop of Henle is important for water reabsorption, and uses the medullary concentration gradient
163
What is the major function of the segment of the nephron known as the ascending limb of the loop of Henle?
The ascending limb of the loop of Henle is important for salt reabsorption and dilution of the urine in the diluting segment
164
What is the major function of the segment of the nephron known as the distal convoluted tubule?
The distal convoluted tubule, like the PCT, is important for solute identity by reabsorbing salts while secreting potassium and hydrogen ions, ammonia, and urea
165
What is the major function of the segment of the nephron known as the collecting duct?
The collecting duct is important for urine concentration; its variable permeability allows water to be reabsorbed based on the needs of the body
166
What is the predominant cell type in the epidermis?
Keratinocytes are the primary cells of the epidermis
167
What are the layers of the epidermis, from superficial to deep?
```
stratum corneum
stratum lucidum
stratum granulosum
stratum spinosum
stratum basale
```
168
What are the layers of the dermis, from superficial to deep?
the papillary layer
| the reticular layer
169
What are some mechanisms the body uses to cool itself?
The body can cool itself through sweating and vasodilation
170
What are some mechanisms the body uses to retain heat?
The body can warm itself through vasoconstriction, piloerection, and shivering
171
What type(s) of muscle (skeletal, smooth, or cardiac) does this describe: striated
skeletal and cardiac muscle
172
What type(s) of muscle (skeletal, smooth, or cardiac) does this describe: always uninucleated
smooth muscle
173
What type(s) of muscle (skeletal, smooth, or cardiac) does this describe: always polynucleated
skeletal muscle
174
What type(s) of muscle (skeletal, smooth, or cardiac) does this describe: voluntary
skeletal muscle
175
What type(s) of muscle (skeletal, smooth, or cardiac) does this describe: innervated by the autonomic nervous system
smooth and cardiac muscle
176
What type(s) of muscle (skeletal, smooth, or cardiac) does this describe: exhibits myogenic activity
smooth and cardiac muscle
177
Which zone or band in the sarcomere does NOT change its length during muscle contraction? Why?
The A-band does not change length during muscle contraction because it is the entire length of the myosin filament. The filaments do not change length, but rather slide over each other; thus, the A-band should remain a constant length during contraction
178
What are the events that initiate muscle contraction, in order? Start with neurotransmitter release and trace the pathway to the point where myosin binds with actin.
Release of acetylcholine from motor neuron --> activation of acetylcholine receptors in sarcolemma --> depolarization of sarcolemma --> spreading of signal using T-tubules --> release of calcium from sarcoplasmic reticulum (SR) --> binding of calcium to troponin --> conformational shift in tropomyosin --> exposure of myosin-binding sites --> myosin binds to actin
179
What role does the binding of ATP to the myosin head play in the cross-bridge cycle? What about the dissociation of ADP and inorganic phosphate from the myosin head?
ATP binding allows the myosin filament to disconnect from actin.
Dissociation of ADP and inorganic phosphate from myosin causes the powerstroke
180
What is tetanus (the physiological phenomenon, not the disease)?
Tetanus is the summation of multiple simple twitches that occur too quickly for the muscle to relax. This leads to a stronger and more prolonged contraction of the muscle
181
What is the difference between compact and spongy bone?
Compact bone is dense and is used for its strength; it form most of the outer layers of a bone.
Spongy (cancellous) bone has many spaces between bony spicules called trabeculae and is the site of marrow production. It is found in the interior core of the bone and also helps distribute forces or pressures on the bone
182
What are the three structural parts of a bone? Which part contributes most to linear growth?
The three parts of a bone are the diaphysis, metaphysis, and epiphysis. Growth plates are found in epiphysis and contribute to linear growth
183
What chemical forms most of the inorganic component of bone?
Most inorganic bone is composed of hydroxyapatite crystals
184
What are the functions of osteoblasts?
Osteoblasts build bone
185
What are the functions of osteoclasts?
Osteoclasts "chew" bone (break it down)
186
What are the functions of chondrocytes?
Chondrocytes form cartilage
187
What liquid provides the lubrication for movable joints? What tissue produces it?
Synovial fluid, produced by the synovium, lubricates movable joints
188
What does it mean for an allele to be dominant? Recessive?
A dominant allele is one that requires only one copy for expression
A recessive allele requires two copies for expression
189
What does it mean for a genotype to be homozygous? Heterozygous? Hemizygous?
A homozygous genotype is one in which the two alleles are the same.
A heterozygous genotype is one in which the two alleles are different.
A hemizygous genotype is one in which only one allele is present for a given gene (such as parts of the X chromosome in males).
190
What is the difference between complete dominance, codominance, and incomplete dominance?
Complete dominance occurs when one allele (the dominant one) completely masks the expression of the other (the recessive one).
Codominance occurs when a gene has more than one dominant allele, and two different dominant alleles can be expressed simultaneously.
Incomplete dominance occurs when a gene has no dominant alleles, and heterozygotes have phenotypes that are intermediate between homozygotes.
191
What is the difference between penetrance and expressivity?
Penetrance describes the proportion of the population that expresses a phenotype, given a particular genotype.
Expressivity describes the differences in expression (severity, location, and so on) of a phenotype in individuals
192
With which phase of meiosis does each of Mendel's laws most closely correlate?
Mendel's first law (of segregation) most aligns with anaphase I of meiosis.
Mendel's second law (of independent assortment) most aligns with prophase I of meiosis.
193
What are the three main types of point mutations? What change occurs in each?
Silent point mutations occur when one nucleotide is changed for another, but there is no change in the protein coded for by this DNA sequence (due to redundancy in the genetic code).
Missense mutations occur when one nucleotide is changed for another, and one amino acid is substituted for another in the final protein.
Nonsense mutations occur when one nucleotide is changed for another, and a stop codon substitutes for an amino acid in the final protein.
194
What are the two main types of frameshift mutations?
The two types of frameshift mutations are insertion and deletion mutations
195
What are the three main types of chromosomal mutations that do NOT share their name with a type of frameshift mutation? What change occurs in each?
Duplication mutations occur when a segment of DNA is copied multiple times in the genome.
Inversion mutations occur when a segment of DNA is reversed in the genome
Translocation mutations occur when a segment of DNA from one chromosome is swapped with a segment of DNA from another chromosome
196
Why would genetic leakage in animals be rare prior to the last century?
Genetic leakage requires the formation of a hybrid organism that can then mate with members of one or the other parent species. While hybrids existed historically (especially mules), fertile hybrids were certainty rare before a more modern understanding of genetics (and before a commercial, financial, or academic impetus existed to create these organisms)
197
Why is genetic drift more common in small populations? What relationship does this have to the founder effect?
Genetic drift occurs due to chance, so its effects will be more pronounced with a smaller sample size (in smaller populations). The founder effect occurs when a small group is reproductively isolated from the larger population, allowing certain alleles to take on a higher prevalence in the group than in the rest of the population.
198
What is the phenotypic ratio for a cross between Bb x Bb
3 dominant: 1 recessive
199
What is the phenotypic ratio for a cross between Aa x aa
1 dominant: 1 recessive
200
What is the phenotypic ratio for a cross between DdEe x ddEE
1 dominant (for D)/dominant (for E): 1 recessive (for D)/dominant (for E)
201
What is the phenotypic ratio for a cross between XqX x XY
Female: all unaffected
Male: 1 unaffected: 1 affected
202
What is the phenotypic ratio for a cross between XrX x XrY
Both male and female: 1 unaffected: 1 affected
203
If genes Q and R have a recombination frequency of 2%, genes R and S have a recombination frequency of 6%, genes S and T have a recombination frequency of 23%, and genes Q and T have a recombination frequency of 19%, then what is the order of these four genes in the chromosome?
S Q R T
204
All five criteria of the Hardy-Weinberg principle are required to imply what characteristic of the study population?
The criteria for the Hardy-Weinberg principle all imply that the study population is not undergoing evolution; thus, the allele frequencies will remain stable over time
205
What are the key tenets of the theory of evolution known as natural selection?
Natural selection states that certain traits that arise from chance are more favorable for reproductive success in a given environment, and that those traits will be passed on to future generations.
206
What are the key tenets of the theory of evolution known as the modern synthesis model?
The modern synthesis model takes natural selection and explains that selection is for specific alleles, which are passed on to future generations through formation of gametes; the alleles for these favorable traits arise from mutations.
207
What are the key tenets of the theory of evolution known as inclusive fitness?
Inclusive fitness explains that the reproductive success of an organism is not only due to the number of offspring it creates, but also the ability to care for young (that can then care for others); it explains changes not only at the individual level, but changes based on the survival of the species (and that individual's alleles within the species, including in other related individuals).
208
What are the key tenets of the theory of evolution known as punctuated equilibrium?
Punctuated equilibrium states that for some species, little evolution occurs for a long period, which is interrupted by rapid bursts of evolutionary change.
209
What are the three patterns of selection? What changes would each create to the population phenotype?
Stabilizing: loss of extremes, maintenance of phenotype in a small window
Directional: movement toward one extreme or the other
Disruptive: movement toward both extremes with loss of the norm; speciation may occur
210
What are the three patterns of evolution between species? What is the outcome of each one?
Divergent: two species with a common ancestor become less similar because of different evolutionary pressures
Parallel: two species with a common ancestor remain similar because of similar evolutionary pressures
Convergent: two species with no recent common ancestor become more similar because of similar evolutionary pressures
211
What is the biological definition of a species?
A species is defined as the largest group of organisms capable of breeding to form fertile offspring
