Systems Biology and Tissue Types - MCAT Biology
Card 0 of 7392
Which hormone is most responsible for decreased levels of blood calcium?
Which hormone is most responsible for decreased levels of blood calcium?
Calcitonin lowers plasma calcium, while parathyroid hormone (PTH) increases it. Insulin and glucagon are responsible for blood glucose, not calcium.
Calcitonin lowers plasma calcium, while parathyroid hormone (PTH) increases it. Insulin and glucagon are responsible for blood glucose, not calcium.
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Which important structure(s) line the small intestine and are key for maximizing nutrient absorption?
Which important structure(s) line the small intestine and are key for maximizing nutrient absorption?
Microvilli surround villa which line the small intestine. These structures greatly increase the surface area (and therefore nutrient absorption capability) of the small intestine.
Microvilli surround villa which line the small intestine. These structures greatly increase the surface area (and therefore nutrient absorption capability) of the small intestine.
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What is the means by which organisms maintain a constant internal environment in spite of fluctuations in the external environment?
What is the means by which organisms maintain a constant internal environment in spite of fluctuations in the external environment?
Homeostasis, or "steady-state" physiology, is the system of feedback loops that enables an organism to create a stable, adaptive environment. For example, the pancreas and the brain together work to regulate the blood sugar levels via the hormones insulin and glucagon.
Homeostasis, or "steady-state" physiology, is the system of feedback loops that enables an organism to create a stable, adaptive environment. For example, the pancreas and the brain together work to regulate the blood sugar levels via the hormones insulin and glucagon.
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Haversian systems are found in which of the following?
Haversian systems are found in which of the following?
Compact and spongy bone have similar chemical and structural compositions and are both hard and resistant to compression; however, due to the fact that compact bone is denser, nutrients are delievered through canals called Haversian systems in compact bone; spongy bone is less dense and lacks these specialized canals.
Compact and spongy bone have similar chemical and structural compositions and are both hard and resistant to compression; however, due to the fact that compact bone is denser, nutrients are delievered through canals called Haversian systems in compact bone; spongy bone is less dense and lacks these specialized canals.
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Where is blood pressure the greatest?
Where is blood pressure the greatest?
Blood pressure tends to be the greatest near the heart, and decreases as blood flows to the capillaries. The pressure is greatest at the aorta and gradually decreases as blood moves from the aorta to large arteries, smaller arteries, and capillaries. The pressure is lowest in the venous system, which is why blood can pool in the veins and act as a "blood reservoir". Veins contain valves that allow them to pump blood back to the heart.
Blood pressure tends to be the greatest near the heart, and decreases as blood flows to the capillaries. The pressure is greatest at the aorta and gradually decreases as blood moves from the aorta to large arteries, smaller arteries, and capillaries. The pressure is lowest in the venous system, which is why blood can pool in the veins and act as a "blood reservoir". Veins contain valves that allow them to pump blood back to the heart.
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In what form is carbon dioxide usually circulated in human blood?
In what form is carbon dioxide usually circulated in human blood?
Carbon dioxide is usually circulated in human blood in the form of 
, or bicarbonate. This is an important part of the blood buffering system, as the bicarbonate ion is the conjugate base of carbonic acid.
Carbon dioxide is usually circulated in human blood in the form of
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Heart burn is experienced when stomach acid and contents enter the esophagus through which sphincter?
Heart burn is experienced when stomach acid and contents enter the esophagus through which sphincter?
The lower esophageal sphincter separates the esophagus from the stomach. When stomach acid and contents leak through the lower esophageal sphincter, the acid irritates the esophagus and can lead to pain around the area of the heart. The heart is not actually affected.
The lower esophageal sphincter separates the esophagus from the stomach. When stomach acid and contents leak through the lower esophageal sphincter, the acid irritates the esophagus and can lead to pain around the area of the heart. The heart is not actually affected.
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In mammals, what muscles are involved in inhalation?
In mammals, what muscles are involved in inhalation?
During inhalation, the external intercostal muscles and diaphragm both contract to help expand the thoracic cavity and draw in air. The internal intercostal muscles are involved in exhalation, and compress the thoracic cavity during contraction.
During inhalation, the external intercostal muscles and diaphragm both contract to help expand the thoracic cavity and draw in air. The internal intercostal muscles are involved in exhalation, and compress the thoracic cavity during contraction.
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Which two muscles do humans use primarily for inhalation?
Which two muscles do humans use primarily for inhalation?
The two muscles that help with breathing are the diaphragm and the external intercostal muscles. The diaphragm pulls the thoracic cavity downward and the external intercostal muscles expand the cavity outward. This expansion of the thoracic cavity leads to a decrease in pressure and allows air to be drawn into the lungs.
The two muscles that help with breathing are the diaphragm and the external intercostal muscles. The diaphragm pulls the thoracic cavity downward and the external intercostal muscles expand the cavity outward. This expansion of the thoracic cavity leads to a decrease in pressure and allows air to be drawn into the lungs.
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A new species found by scientists exhibits indeterminate cleavage up to the third cleavage. If all of the cells in the embryo are separated and incubated in healthy conditions on their own after the third cleavage, how many organisms will develop?
A new species found by scientists exhibits indeterminate cleavage up to the third cleavage. If all of the cells in the embryo are separated and incubated in healthy conditions on their own after the third cleavage, how many organisms will develop?
After the third cleavage, the embryo would be composed of 8 cells. If every cleavage step up up to this point was indeterminate, then each cell still has the necessary components to develop into a complete organism. The result would be 8 genetical identical organisms.
After the third cleavage, the embryo would be composed of 8 cells. If every cleavage step up up to this point was indeterminate, then each cell still has the necessary components to develop into a complete organism. The result would be 8 genetical identical organisms.
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Which structures contain deoxygenated blood?
Which structures contain deoxygenated blood?
When blood returns to the heart via the superior and inferior vena cavae, it is deoxygenated. It remains this way as it passes through the right atrium, the right ventricle, and the pulmonary arteries, through which it travels to the lungs to conduct gas exchange with the alveoli. Both the right ventricle and the pulmonary artery contain deoxygenated blood.
All of the other answer choices contain at least one component that carries oxygenated blood.
When blood returns to the heart via the superior and inferior vena cavae, it is deoxygenated. It remains this way as it passes through the right atrium, the right ventricle, and the pulmonary arteries, through which it travels to the lungs to conduct gas exchange with the alveoli. Both the right ventricle and the pulmonary artery contain deoxygenated blood.
All of the other answer choices contain at least one component that carries oxygenated blood.
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What is embryonic cleavage?
What is embryonic cleavage?
Embryonic cleavage is the division of cells without cell growth. Once an ovum is fertilized by a sperm cell, it is called a zygote. The zygote undergoes multiple rapid cell cycles (rounds of mitosis) without significant growth, producing a dense cluster of cells that is the same size as the original zygote. This process is called cleavage.
Embryonic cleavage is the division of cells without cell growth. Once an ovum is fertilized by a sperm cell, it is called a zygote. The zygote undergoes multiple rapid cell cycles (rounds of mitosis) without significant growth, producing a dense cluster of cells that is the same size as the original zygote. This process is called cleavage.
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Which of the following structures does not arise from the mesoderm?
Which of the following structures does not arise from the mesoderm?
The mesoderm gives rise to muscles, bones, the circulatory system, the gonads, and the kidneys. Think of the mesoderm as the means by which your body gets around on a daily basis: muscles and bones, heart to pump blood, and kidneys to excrete waste.
The respiratory system arises from the endoderm.
The mesoderm gives rise to muscles, bones, the circulatory system, the gonads, and the kidneys. Think of the mesoderm as the means by which your body gets around on a daily basis: muscles and bones, heart to pump blood, and kidneys to excrete waste.
The respiratory system arises from the endoderm.
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During an action potential, depolarization is associated with which of the following?
During an action potential, depolarization is associated with which of the following?
During depolarization, voltage-gated sodium channels open and allow a rapid influx of sodium ions. The membrane voltage rises from its resting potential of -70 mV to 35 mV. Depolarization is not associated with endocytosis of neurotransmitters.
During depolarization, voltage-gated sodium channels open and allow a rapid influx of sodium ions. The membrane voltage rises from its resting potential of -70 mV to 35 mV. Depolarization is not associated with endocytosis of neurotransmitters.
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When blood moves from the right atrium to the right ventricle, it must pass through which heart valve?
When blood moves from the right atrium to the right ventricle, it must pass through which heart valve?
When blood passes from the right atrium into the right ventricle, it must pass through the tricuspid valve.
The mitral, or bicuspid, valve separates the left atrium and ventricle. The semilunar valves are the aortic and pulmonary valves. The aortic valve separates the left ventricle and aorta, while the pulmonary valve separates the right ventricle and pulmonary arteries.
When blood passes from the right atrium into the right ventricle, it must pass through the tricuspid valve.
The mitral, or bicuspid, valve separates the left atrium and ventricle. The semilunar valves are the aortic and pulmonary valves. The aortic valve separates the left ventricle and aorta, while the pulmonary valve separates the right ventricle and pulmonary arteries.
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What are the four types of tissue?
What are the four types of tissue?
The four types of tissue are muscular, connective, nervous, and epithelial.
Muscular tissue encompasses skeletal, cardiac, and smooth muscle. Nervous tissue creates the central and peripheral nervous systems (CNS, PNS) and consists of all neurons and glial cells. Epithelial tissue makes up "borders" and lines most organs. Connective tissue generally fills spaces and provides the suspensory matrices for the body, such as bone, fat, blood, and cartilage.
The four types of tissue are muscular, connective, nervous, and epithelial.
Muscular tissue encompasses skeletal, cardiac, and smooth muscle. Nervous tissue creates the central and peripheral nervous systems (CNS, PNS) and consists of all neurons and glial cells. Epithelial tissue makes up "borders" and lines most organs. Connective tissue generally fills spaces and provides the suspensory matrices for the body, such as bone, fat, blood, and cartilage.
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Which is the only valve in the heart to have two operational flaps?
Which is the only valve in the heart to have two operational flaps?
The semilunar valves refer to the aortic valve and pulmonary valve, both of which have three flaps. The atrioventricular valves separate the atria from the ventricles. The right side of the heart is separated by the tricuspid valve, while the left is separated by the bicuspid, or mitral, valve. The mitral valve is the only heart valve with two flaps.
The semilunar valves refer to the aortic valve and pulmonary valve, both of which have three flaps. The atrioventricular valves separate the atria from the ventricles. The right side of the heart is separated by the tricuspid valve, while the left is separated by the bicuspid, or mitral, valve. The mitral valve is the only heart valve with two flaps.
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Albumin is created in the liver and is an important protein found in the blood. If a vial of blood is centrifuged, in which of the following layers would albumin be found?
Albumin is created in the liver and is an important protein found in the blood. If a vial of blood is centrifuged, in which of the following layers would albumin be found?
When centrifuged, blood will divide into three parts: the plasma layer, the buffy coat layer, and the red blood cell layer. The plasma layer contains albumin, immunoglobulins, and blood clotting factors. The buffy coat is composed of leukocytes, and the red blood cell layer is composed of erythrocytes.
When centrifuged, blood will divide into three parts: the plasma layer, the buffy coat layer, and the red blood cell layer. The plasma layer contains albumin, immunoglobulins, and blood clotting factors. The buffy coat is composed of leukocytes, and the red blood cell layer is composed of erythrocytes.
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Which of the following is an example of an immovable joint?
Which of the following is an example of an immovable joint?
Immovable joints are fused shortly after birth, so that they are no longer functional for articulation. The bones of the skull remain open, joined with strips of cartilage, until an infant has passed through the birth canal. They stay open for a short period, giving the baby's brain room to grow. After the brain has finished its major growth stages, the bones of the skull knit together, forming a protective barrier.
Immovable joints are fused shortly after birth, so that they are no longer functional for articulation. The bones of the skull remain open, joined with strips of cartilage, until an infant has passed through the birth canal. They stay open for a short period, giving the baby's brain room to grow. After the brain has finished its major growth stages, the bones of the skull knit together, forming a protective barrier.
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Tendons connect which two structures?
Tendons connect which two structures?
Tendons connect muscles to bones, allowing for the muscle contraction to affect the bone and result in articulation. Tendons are essential to provide articulation and leverage points to for motion and locomotion.
Tendons connect muscles to bones, allowing for the muscle contraction to affect the bone and result in articulation. Tendons are essential to provide articulation and leverage points to for motion and locomotion.
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