A myocardial infarction affects which of the following blood vessels of the heart?

 

Melanin.

Melanin is a pigment produced by cells called melanocytes in the skin.

It protects the skin from ultraviolet (UV) radiation by absorbing and dissipating over 99.9% of absorbed UV radiation.

This helps to prevent DNA damage and other adverse effects of UV radiation on the skin.

Choice B.

Perspiration is not correct because it is a fluid produced by sweat glands in the skin that helps to regulate body temperature, but it does not protect the skin from UV radiation.

Choice C.

Sebum is not correct because it is an oily substance produced by sebaceous glands in the skin that helps to lubricate and protect the skin, but it does not protect the skin from UV radiation.

Choice D.

Keratin is not correct because it is a fibrous protein that provides strength and durability to the skin, hair and nails, but it does not protect the skin from UV radiation.

The two major parts of the nervous system are the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

The CNS is made up of the brain and spinal cord and acts as the integration and command center of the body.

The PNS represents the conduit between the CNS and the body and is further subdivided into the somatic nervous system (SNS) and the autonomic nervous system (ANS).

Choice A is incorrect because it only mentions two subdivisions of the PNS, which are the autonomic nervous system (ANS) and somatic nervous system (SNS).

Choice B is incorrect because it only mentions one major part of the nervous system, which is the PNS, and one subdivision of it, which is the SNS.

Choice D is incorrect because it only mentions one major part of the nervous system, which is the CNS, and one subdivision of the PNS, which is the ANS.

The glomerulus is the main filtering unit of the kidney.

It is formed by a network of small blood vessels (capillaries) enclosed within a sac called the Bowman’s capsule.

The blood supply to the glomerulus is provided via the afferent arteriole.

The blood then flows through the capillary network, where it gets filtered, and then leaves the glomerulus via the efferent arteriole.

Choice B.

Proximal tubule is not correct because it is where the ultrafiltrate collected in the Bowman’s space drains directly into.

Choice C.

Distal tubule is not correct because it is not mentioned in relation to blood exiting the glomerulus.

Choice D.

Afferent arteriole is not correct because it provides blood supply to the glomerulus.

The atomic number of an element represents the number of protons in the nucleus of an atom of that element.

Since lithium has an atomic number of 3, it has 3 protons in its nucleus.

Choice A is not correct because 7 is the mass number of lithium, not the number of protons.

Choice C is not correct because 12 is not the atomic number or mass number of lithium.

Choice D is not correct because 4 is not the atomic number or mass number of lithium.

Control.

A control group is a group in an experiment that does not receive the treatment or manipulation being tested and is used as a benchmark to measure how the other tested subjects do.

The control group is used to minimize the effects of all variables except the independent variable.

This allows researchers to determine if changes in the dependent variable are due to the manipulation of the independent variable or if they are due to some other factor.

Choice A.

Responding is not the correct answer because it refers to the dependent variable, which is the variable that is being measured in an experiment.

Choice B.

Manipulated is not the correct answer because it refers to the independent variable, which is the variable that is being manipulated in an experiment.

Choice D.

Variable is not the correct answer because it refers to any factor that can change in an experiment and can include both independent and dependent variables.

A tsunami is a catastrophic ocean wave that is usually caused by a submarine earthquake.

It can also be caused by an underwater or coastal landslide, the eruption of a volcano, or the impact of a meteor or comet in a body of water.

Choice A is not correct because sunspot activity does not cause tsunamis.

Choice B is not correct because lightning strikes do not cause tsunamis.

Choice D is not correct because flooding does not cause tsunamis.

The approximate threshold value for mammalian neurons is -55 mV.

The threshold potential is the critical level to which a membrane potential must be depolarized to initiate an action potential.

Most often, the threshold potential is a membrane potential value between –50 and –55 mV

The membrane potential of a neuron is determined by the distribution of ions across the cell membrane.

At rest, the inside of a neuron is more negative than the outside due to the presence of negatively charged proteins and other molecules.

The movement of ions across the cell membrane can change the membrane potential.

For example, when sodium ions enter the cell, they make the inside of the cell more positive (less negative), causing depolarization.

Choice B is incorrect because -80 mV is below the typical threshold value for mammalian neurons.

Choice C is incorrect because +35 mV is above the typical threshold value for mammalian neurons.

Choice D is incorrect because 0 mV is above the typical threshold value for mammalian neurons.

A myocardial infarction affects the coronary blood vessels of the heart.

A myocardial infarction, commonly known as a heart attack, occurs when blood flow decreases or stops in the coronary artery of the heart, causing damage to the heart muscle 1.

Choice B is incorrect because the aorta is not a blood vessel of the heart.

The aorta is the main artery that carries oxygenated blood from the heart to the rest of the body.

Choice C is incorrect because the pulmonary blood vessels are not affected by a myocardial infarction.

The pulmonary blood vessels carry deoxygenated blood from the heart to the lungs.

Choice D is incorrect because the vena cava is not a blood vessel of the heart.

The vena cava is a large vein that carries deoxygenated blood from the body to the heart.

Testosterone is classified as an androgen hormone.

Androgens are a type of sex hormone that primarily regulates the development and maintenance of male characteristics, such as body hair growth, muscle mass, and deepening of the voice.

Testosterone is produced primarily in the testes in males and in smaller amounts in the ovaries and adrenal glands in females.

Option A, estrogen, is a female hormone that regulates the development of female sexual characteristics, such as breast growth and menstruation.

While estrogen and testosterone are both steroid hormones and can be converted to one another in the body, testosterone is not categorized as estrogen.

Option B, progestin, is a synthetic form of the hormone progesterone.

Progesterone is a female hormone that plays a role in the menstrual cycle and pregnancy.

Testosterone and progestin are not related, and testosterone is not categorized as progestin.

Option C, aldosterone, is a mineralocorticoid hormone that regulates salt and water balance in the body.

It is produced in the adrenal gland and plays a role in regulating blood pressure.

Testosterone and aldosterone are not related, and testosterone is not categorized as aldosterone.

Plasma B cells.

Antibodies are produced by specialized white blood cells called B lymphocytes (or B cells).

When an antigen binds to the B-cell surface, it stimulates the B cell to divide and mature into a group of identical cells called a clone.

The mature B cells, called plasma cells, secrete millions of antibodies into the bloodstream and lymphatic system.

Choice A, Natural killer cells, is not the correct answer because natural killer cells are a type of white blood cell that play a major role in the host-rejection of both tumors and virally infected cells.

Choice B, Cytotoxic T-cells, is not the correct answer because cytotoxic T-cells are a type of white blood cell that kills cancer cells, cells that are infected (particularly with viruses), or cells that are damaged in other ways.

Choice D, Helper T-cells, is not the correct answer because helper T-cells are a type of white blood cell that play an important role in the immune system by helping other white blood cells fight infections.