Tissues, Organs, and Organ Systems - High School Biology
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How does the sodium-potassium pump establish a resting potential in neurons?
How does the sodium-potassium pump establish a resting potential in neurons?
The sodium potassium-pump is used in order to establish the negative resting potential in neurons. Since both sodium and potassium ions are positively charged, there needs to be more ions leaving the cell compared to ions entering. The pump accomplishes this by pumping three sodium ions out of the cell, while pumping two potassium ions into the cell. This loss of positive charge inside the cell results in the negative resting potential of neurons.
Thank about the net transfer of ions. Three positive sodium ions out of the cell for every two positive potassium ions into the cell is the same as one positive ion leaving the cell. When positive ions leave, the inside of the cell becomes more negative, helping the cell reach its resting potential of around –70mV.
The sodium potassium-pump is used in order to establish the negative resting potential in neurons. Since both sodium and potassium ions are positively charged, there needs to be more ions leaving the cell compared to ions entering. The pump accomplishes this by pumping three sodium ions out of the cell, while pumping two potassium ions into the cell. This loss of positive charge inside the cell results in the negative resting potential of neurons.
Thank about the net transfer of ions. Three positive sodium ions out of the cell for every two positive potassium ions into the cell is the same as one positive ion leaving the cell. When positive ions leave, the inside of the cell becomes more negative, helping the cell reach its resting potential of around –70mV.
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What is the name of the process that results in a positive voltage inside the neuron?
What is the name of the process that results in a positive voltage inside the neuron?
In the beginning of an action potential voltage-gated sodium channels begin to open, allowing sodium ions to rush into the cell. This influx of positive ions results in a change in the polarity of the cell, making the voltage become positive inside the cell. This process is called depolarization.
Hyperpolarization comes after depolarization, and is caused by potassium ions leaving the cell interior. The removal of these positive ions causes the cell to become more negative than the resting potential.
Repolarization is the final process to return the cell to its resting potential. The sodium-potassium pump brings potassium ions back into the cell and removes the sodium ions, returning the cell to its normal resting state.
In the beginning of an action potential voltage-gated sodium channels begin to open, allowing sodium ions to rush into the cell. This influx of positive ions results in a change in the polarity of the cell, making the voltage become positive inside the cell. This process is called depolarization.
Hyperpolarization comes after depolarization, and is caused by potassium ions leaving the cell interior. The removal of these positive ions causes the cell to become more negative than the resting potential.
Repolarization is the final process to return the cell to its resting potential. The sodium-potassium pump brings potassium ions back into the cell and removes the sodium ions, returning the cell to its normal resting state.
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What are action potentials?
What are action potentials?
Action potentials are electrical signals transmitted by neurons. When a neuron is stimulated, a signal is transmitted down the axon. This signal is the action potential.
An action potential in a neuron can help to stimulate a muscle to contract, but the muscle itself will not conduct an action potential.
Action potentials are electrical signals transmitted by neurons. When a neuron is stimulated, a signal is transmitted down the axon. This signal is the action potential.
An action potential in a neuron can help to stimulate a muscle to contract, but the muscle itself will not conduct an action potential.
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Which structure of the neuron is myelinated to promote propogation of the action potential?
Which structure of the neuron is myelinated to promote propogation of the action potential?
The axon is wrapped in fatty bundles called myelin sheaths that promote fast transmission of an electrical signal. The other structures listed here are not myelinated.
The axon is wrapped in fatty bundles called myelin sheaths that promote fast transmission of an electrical signal. The other structures listed here are not myelinated.
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Consider a neuron with a resting membrane potential of 
.
Which of the following membrane potential values is likely to be the membrane potential of this neuron during its refractory period?
Consider a neuron with a resting membrane potential of
Which of the following membrane potential values is likely to be the membrane potential of this neuron during its refractory period?
The refractory period occurs when the cell repolarizes/hyperpolzarizes beyond the resting potential; that is, the membrane potential drops to a value more negative than when it is at rest. This prevents the firing of another action potential immediately after one has been fired. The other values represent the resting potential (
), the threshold (
), and values that are more positive, and are therefore incorrect.
The refractory period occurs when the cell repolarizes/hyperpolzarizes beyond the resting potential; that is, the membrane potential drops to a value more negative than when it is at rest. This prevents the firing of another action potential immediately after one has been fired. The other values represent the resting potential (
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What causes the hyperpolarization during an action potential?
What causes the hyperpolarization during an action potential?
As an action potential begins, there's a rapid influx of sodium in to cell, causing the cell's membrane potential to rapidly increase, depolarizing the cell. Once the cell has reached its action potential peak, the sodium channels begin to close. This closing activates the potassium channels. These channels allow potassium to leave the cell. Since potassium is a positive ion, as it leaves, the cell's membrane potential becomes more negative, repolarizing. The slight dip in the action potential curve, labeled as hyperpolarization, is result of the potassium channels lagging to close, and potassium loss is "overshot". As a result, too much potassium lost from the cell will cause the cell's potential to become more negative relative to its normal potential.
As an action potential begins, there's a rapid influx of sodium in to cell, causing the cell's membrane potential to rapidly increase, depolarizing the cell. Once the cell has reached its action potential peak, the sodium channels begin to close. This closing activates the potassium channels. These channels allow potassium to leave the cell. Since potassium is a positive ion, as it leaves, the cell's membrane potential becomes more negative, repolarizing. The slight dip in the action potential curve, labeled as hyperpolarization, is result of the potassium channels lagging to close, and potassium loss is "overshot". As a result, too much potassium lost from the cell will cause the cell's potential to become more negative relative to its normal potential.
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An action potential is generally driven by the movement of which two ions?
An action potential is generally driven by the movement of which two ions?
Action potentials are largely due to the movements of potassium 
and sodium 
across a membrane. While other ions and neurotransmitters can affect action potential firing, the movements of these two ions have the greatest effect on a neuron firing.
Action potentials are largely due to the movements of potassium
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Once an action potential arrives at the synaptic bud, what kind of ion channels open?
Once an action potential arrives at the synaptic bud, what kind of ion channels open?
As an action potential is essentially an electrical current, it makes sense for it to open voltage-gated channels. Specifically, voltage-gated calcium channels are opened to allow calcium ions to flow into the cell and bind to synaptic vesicles.
As an action potential is essentially an electrical current, it makes sense for it to open voltage-gated channels. Specifically, voltage-gated calcium channels are opened to allow calcium ions to flow into the cell and bind to synaptic vesicles.
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The spleen is an intra-abdominal organ whose function is __________.
The spleen is an intra-abdominal organ whose function is __________.
The spleen is like a giant lymph node, and it is organized in a somewhat similar manner. Although it can be surgically removed if it is damaged, such patients are at life-long risk of death from fairly ordinary infectious processes. The spleen is a reservoir of immune competence. Blood passes through the spleen for exposure to white blood cells. When the white blood cells detect antigens or foreign particles in the blood, they initiate the immune response. The spleen is essentially a screening center to check the blood for contaminants.
The spleen is like a giant lymph node, and it is organized in a somewhat similar manner. Although it can be surgically removed if it is damaged, such patients are at life-long risk of death from fairly ordinary infectious processes. The spleen is a reservoir of immune competence. Blood passes through the spleen for exposure to white blood cells. When the white blood cells detect antigens or foreign particles in the blood, they initiate the immune response. The spleen is essentially a screening center to check the blood for contaminants.
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When a person is exposed to an organism and produces specific antibodies against it, this type of immunity is referred to as __________.
When a person is exposed to an organism and produces specific antibodies against it, this type of immunity is referred to as __________.
Adaptive immunity occurs when antibodies are produced as a result of exposure to a pathogen or immunization. These antibodies are specific for the particular microorganism and memory cells are produced. Cell-mediated immunity is a direct form of defense based on the action of lymphocytes to attack foreign cells and destroy them. Congenital immunity is immunity one is born with. This may result from antibodies received from the mother's blood. Innate immunity is not pathogen-specific and includes the secretion of proteins and the activities of natural killer cells. Passive immunity involves the introduction of preformed antibodies into an unprotected individual. This may occur through infusion of immune globulin or antibodies that pass from the mother to the fetus through the placenta.
Adaptive immunity occurs when antibodies are produced as a result of exposure to a pathogen or immunization. These antibodies are specific for the particular microorganism and memory cells are produced. Cell-mediated immunity is a direct form of defense based on the action of lymphocytes to attack foreign cells and destroy them. Congenital immunity is immunity one is born with. This may result from antibodies received from the mother's blood. Innate immunity is not pathogen-specific and includes the secretion of proteins and the activities of natural killer cells. Passive immunity involves the introduction of preformed antibodies into an unprotected individual. This may occur through infusion of immune globulin or antibodies that pass from the mother to the fetus through the placenta.
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How is VDJ recombination indispensible for adaptive immunity?
How is VDJ recombination indispensible for adaptive immunity?
VDJ recombination occurs during early B- and T-cell maturation, resulting in diverse antibodies and T-cells. This DNA recombination occurs between the V, D, and J segments of the antibody or T-cell before transcription occurs. As a result, a unique sequence is generated, transcribed, and then translated to a functional protein. This recombination is responsible for creating the unique series of antibodies that the body is capable of producing in order to detect the various antigens represented by foreign pathogens.
VDJ recombination occurs during early B- and T-cell maturation, resulting in diverse antibodies and T-cells. This DNA recombination occurs between the V, D, and J segments of the antibody or T-cell before transcription occurs. As a result, a unique sequence is generated, transcribed, and then translated to a functional protein. This recombination is responsible for creating the unique series of antibodies that the body is capable of producing in order to detect the various antigens represented by foreign pathogens.
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Which of the following is true regarding B cell and T cell interactions?
Which of the following is true regarding B cell and T cell interactions?
B cells and T cells are both part of the adaptive immunity. B cells secrete antibodies that bind to foreign antigens. Upon binding to a specific antigen, B cells can be activated by T cells, which facilitate the synthesis of specific antibodies for the antigen. This enhances the antibody-antigen binding and allows for a better immune response. T cells have receptors on their surface that detect antigens. Once they detect the antigen, T cells can activate B cells and other immune system cells (such as macrophages and neutrophils) to eliminate the foreign antigen. B cells do not play a role in the activation of T cells.
B cells and T cells are both part of the adaptive immunity. B cells secrete antibodies that bind to foreign antigens. Upon binding to a specific antigen, B cells can be activated by T cells, which facilitate the synthesis of specific antibodies for the antigen. This enhances the antibody-antigen binding and allows for a better immune response. T cells have receptors on their surface that detect antigens. Once they detect the antigen, T cells can activate B cells and other immune system cells (such as macrophages and neutrophils) to eliminate the foreign antigen. B cells do not play a role in the activation of T cells.
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A researcher is analyzing a specific immune complex that is made up of an antibody-antigen complex. What can the researcher conclude about this immune response?
A researcher is analyzing a specific immune complex that is made up of an antibody-antigen complex. What can the researcher conclude about this immune response?
The question states that the immune complex has antibodies bound to antigens. Recall that B cells eliminate pathogens by secreting antibodies. These antibodies bind to antigens and release factors called cytokines. Cytokines recruit phagocytic cells like macrophages and neutrophils that kill the infected cell. They also activate a part of the innate immune system called the complement, which aids in the elimination of the pathogen. This type of immune response is called a humoral immune response. Elimination of the pathogen using T cells is called a cell-mediated immune response.
Note that both the humoral and the cell-mediated immune responses are very specific responses that are part of the adaptive immunity. Innate immunity involves non-specific immune responses via macrophages, granulocytes (neutrophils, eosinophils, and basophils), complement system, and NK cells.
The question states that the immune complex has antibodies bound to antigens. Recall that B cells eliminate pathogens by secreting antibodies. These antibodies bind to antigens and release factors called cytokines. Cytokines recruit phagocytic cells like macrophages and neutrophils that kill the infected cell. They also activate a part of the innate immune system called the complement, which aids in the elimination of the pathogen. This type of immune response is called a humoral immune response. Elimination of the pathogen using T cells is called a cell-mediated immune response.
Note that both the humoral and the cell-mediated immune responses are very specific responses that are part of the adaptive immunity. Innate immunity involves non-specific immune responses via macrophages, granulocytes (neutrophils, eosinophils, and basophils), complement system, and NK cells.
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Which of the following is/are characteristic(s) of T cells?
I. T cells can differentiate into plasma cells.
II. T cells can differentiate into cells that inhibit activity of other T cells.
III. HIV attacks helper T cells.
Which of the following is/are characteristic(s) of T cells?
I. T cells can differentiate into plasma cells.
II. T cells can differentiate into cells that inhibit activity of other T cells.
III. HIV attacks helper T cells.
Plasma cells are circulating cells that form part of adaptive immunity that secrete antibodies to specific antigens. These cells arise from naïve B cells. Broadly specific naïve B cells have the ability to bind to several antigens. Once bound, these naïve B cells differentiate into plasma cells that secrete antibodies that are very specific to the antigen. T cells facilitate this differentiation, but only B cells give rise to plasma cells.
A naïve T cell has the ability to differentiate into three kinds of cells. First, it can differentiate into a helper T cell. These cells facilitate the activation of other immune cells such as B cells, macrophages, and granulocytes. Second, a naïve T cell can differentiate into a cytotoxic T cell. These cells bind to infected cells and induce their death. Third, a naïve T cell can differentiate into a regulatory T cell. These T cells bind to the same antigens as the first two cells; however, instead of initiating an immune response, they regulate it by suppressing the activity of T cells.
HIV is a virus that likes to reside inside helper T cells. A person infected with HIV will have a decreased helper T cell count, which makes the person more susceptible to other opportunistic infections (infections that only occur in immune-compromised individuals). A patient with very low helper T cell count develops AIDS and often passes away due to these opportunistic infections.
Plasma cells are circulating cells that form part of adaptive immunity that secrete antibodies to specific antigens. These cells arise from naïve B cells. Broadly specific naïve B cells have the ability to bind to several antigens. Once bound, these naïve B cells differentiate into plasma cells that secrete antibodies that are very specific to the antigen. T cells facilitate this differentiation, but only B cells give rise to plasma cells.
A naïve T cell has the ability to differentiate into three kinds of cells. First, it can differentiate into a helper T cell. These cells facilitate the activation of other immune cells such as B cells, macrophages, and granulocytes. Second, a naïve T cell can differentiate into a cytotoxic T cell. These cells bind to infected cells and induce their death. Third, a naïve T cell can differentiate into a regulatory T cell. These T cells bind to the same antigens as the first two cells; however, instead of initiating an immune response, they regulate it by suppressing the activity of T cells.
HIV is a virus that likes to reside inside helper T cells. A person infected with HIV will have a decreased helper T cell count, which makes the person more susceptible to other opportunistic infections (infections that only occur in immune-compromised individuals). A patient with very low helper T cell count develops AIDS and often passes away due to these opportunistic infections.
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CD8 is a surface glycoprotein found in many T cells. Which of the following T cells will NOT have a CD8?
CD8 is a surface glycoprotein found in many T cells. Which of the following T cells will NOT have a CD8?
There are three kinds of T cells: helper T cells, cytotoxic T cells, and regulatory T cells. All T cells have glycoproteins on their surfaces that act as receptors. CD4 and CD8 are two glycoproteins that can be found on T cells. Helper T cells and regulatory T cells have CD4 glycoproteins, whereas cytotoxic T cells have CD8. These glycoproteins serve as markers to distinguish between T cell types.
The question is asking about CD8, or cytotoxic, T cells. Recall that cytotoxic T cells bind to infected cells and induce their death. Typically, cytotoxic T cells bind to infected cells that have the pathogen inside them (meaning intracellular pathogens). Intracellular pathogens include viruses and intracellular bacteria; therefore, T cells that attack these cells will be CD8 cells. In addition, cytotoxic T cells also attack cancer cells; therefore, these T cells will also be CD8 cells.
Extracellular bacterial cells do not infect host cells; therefore, these bacteria are eliminated via the helper T cells. These T cells bind to the bacteria and activate other immune cells such as B cells, macrophages, and granulocytes that eliminate the bacteria.
There are three kinds of T cells: helper T cells, cytotoxic T cells, and regulatory T cells. All T cells have glycoproteins on their surfaces that act as receptors. CD4 and CD8 are two glycoproteins that can be found on T cells. Helper T cells and regulatory T cells have CD4 glycoproteins, whereas cytotoxic T cells have CD8. These glycoproteins serve as markers to distinguish between T cell types.
The question is asking about CD8, or cytotoxic, T cells. Recall that cytotoxic T cells bind to infected cells and induce their death. Typically, cytotoxic T cells bind to infected cells that have the pathogen inside them (meaning intracellular pathogens). Intracellular pathogens include viruses and intracellular bacteria; therefore, T cells that attack these cells will be CD8 cells. In addition, cytotoxic T cells also attack cancer cells; therefore, these T cells will also be CD8 cells.
Extracellular bacterial cells do not infect host cells; therefore, these bacteria are eliminated via the helper T cells. These T cells bind to the bacteria and activate other immune cells such as B cells, macrophages, and granulocytes that eliminate the bacteria.
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Which bone cell is responsible for resorbing bone matrix and releasing calcium into the blood?
Which bone cell is responsible for resorbing bone matrix and releasing calcium into the blood?
Osteogenic cells are a type of stem cell that differentiate into osteoblasts, which allow bone to form. Eventually, osteoblasts will become enveloped into the bone matrix and differentiate into osteocytes. Osteoclasts have the opposite function of osteoblasts, and are responsible for the resorption of bone matrix. This releases calcium into the bloodstream by breaking down bone.
Osteogenic cells are a type of stem cell that differentiate into osteoblasts, which allow bone to form. Eventually, osteoblasts will become enveloped into the bone matrix and differentiate into osteocytes. Osteoclasts have the opposite function of osteoblasts, and are responsible for the resorption of bone matrix. This releases calcium into the bloodstream by breaking down bone.
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Red blood cell development takes place in what structure in bones?
Red blood cell development takes place in what structure in bones?
Red bone marrow is found in the epiphyses, or ends of long bones. It is the site of hematopoiesis, or red blood cell development.
Yellow bone marrow is primarily composed of fat. Osteons are the functional units of bone, and house the cells that build and break down the bony matrix. Cartilage is found on the articular surfaces of bone, and helps provide support for joints.
Red bone marrow is found in the epiphyses, or ends of long bones. It is the site of hematopoiesis, or red blood cell development.
Yellow bone marrow is primarily composed of fat. Osteons are the functional units of bone, and house the cells that build and break down the bony matrix. Cartilage is found on the articular surfaces of bone, and helps provide support for joints.
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Which of the following is NOT a function of the skeletal system?
Which of the following is NOT a function of the skeletal system?
The skeletal system has a variety of functions, including protecting internal organs, storing minerals and energy molecules, and assisting in movement.
The production of heat, however, is a function of the muscular system.
The skeletal system has a variety of functions, including protecting internal organs, storing minerals and energy molecules, and assisting in movement.
The production of heat, however, is a function of the muscular system.
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Which of the following is a primary function of bone marrow?
Which of the following is a primary function of bone marrow?
Bone marrow is the major producer of blood cells, including most of those in the immune system.
The other answer options listed are functions of the bones in the skeletal system, but are not directly linked to the bone marrow. The skeletal system stores calcium and phosphorus, which in turn make the bones strong. Bones can complement to liver to detoxify blood by removing metals such as lead and radium. Muscles attach to bones and generate movement. The skull protects the brain. The rib cage protects the heart and lungs.
Bone marrow is the major producer of blood cells, including most of those in the immune system.
The other answer options listed are functions of the bones in the skeletal system, but are not directly linked to the bone marrow. The skeletal system stores calcium and phosphorus, which in turn make the bones strong. Bones can complement to liver to detoxify blood by removing metals such as lead and radium. Muscles attach to bones and generate movement. The skull protects the brain. The rib cage protects the heart and lungs.
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Ligaments connect __________.
Ligaments connect __________.
Ligaments are made of dense connective tissue and connect bone to bone. Have you ever sprained your ankle? Chances are you partially or fully tore some ligaments in your ankle. Unfortunately, ligaments do not heal very well since there is almost no blood supply to them, and instead lay down scar tissue. Tendons connect bone to muscle. Muscles are already attached to tendons.
Ligaments are made of dense connective tissue and connect bone to bone. Have you ever sprained your ankle? Chances are you partially or fully tore some ligaments in your ankle. Unfortunately, ligaments do not heal very well since there is almost no blood supply to them, and instead lay down scar tissue. Tendons connect bone to muscle. Muscles are already attached to tendons.
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