Description:Human chorionic gonadotropin (hCG) is a hormone produced by the placenta during pregnancy. It is a glycoprotein hormone that is made up of two subunits, alpha and beta. The alpha subunit is similar to the alpha subunit of luteinizing hormone (LH), while the beta subunit is unique to hCG. hCG is produced by the syncytiotrophoblast, which is the outer layer of the placenta. It is released into the bloodstream and can be detected in urine and blood tests. The levels of hCG in the blood and urine rise rapidly during the first few weeks of pregnancy, and then plateau until about 10 weeks of pregnancy. hCG has a number of functions, including: Maintaining the corpus luteum, which produces progesterone during the first few weeks of pregnancy. Stimulating the ovaries to produce estrogen and progesterone. Preparing the uterus for implantation of the embryo. Supporting the growth of the placenta. hCG levels can be used to diagnose pregnancy and to monitor the progress of a pregnancy. High levels of hCG can be a sign of a molar pregnancy or other complications of pregnancy. The other options are incorrect. The ovary produces estrogen and progesterone, the pituitary produces luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and the gonads produce sex hormones.

Description:The testes are the primary reproductive organs in males. They are responsible for producing sperm cells and secreting hormones such as testosterone. The testes are located in the scrotum, which is a pouch of skin outside the body that helps regulate the temperature of the testes for proper sperm production. The scrotum itself is not considered a gonad. The prostate gland is part of the male reproductive system, but it does not function as a gonad. The glans penis is the sensitive, bulbous structure at the tip of the penis and is not involved in gonadal functions.

Description:Gonads are reproductive organs that produce gametes, which are sex cells involved in sexual reproduction. In males, the gonads are the testes, which produce sperm cells (the male gametes). In females, the gonads are the ovaries, which produce egg cells (the female gametes). Gametes are necessary for fertilization to occur, where a sperm cell fertilizes an egg cell, leading to the formation of a fertilized egg or zygote. The production of semen (c) is not solely the function of the gonads but involves contributions from other accessory reproductive organs. Albicans (d) refers to Candida albicans, which is a type of fungus and is not related to gonadal functions.

Description:Germ cells are the specialized cells involved in the production of gametes (sex cells) in organisms. Gametes are formed through a process called meiosis, which reduces the number of chromosomes in the cell by half. As a result, gametes are haploid, meaning they contain only one set of chromosomes. In humans, for example, normal body cells (somatic cells) are diploid and contain two sets of chromosomes (one from each parent), while gametes (sperm and egg cells) are haploid and contain only one set of chromosomes. Therefore, the type of germ cell seen in the product of gametes is haploid (a). Monoploid (c) and gamaploid (d) are not recognized scientific terms in relation to germ cells or gametes.

Description:In females, the ovaries function as the gonads. The ovaries are the primary reproductive organs responsible for producing and releasing eggs (ova) and secreting female sex hormones such as estrogen and progesterone. The ovaries are located in the pelvic cavity and are involved in the monthly reproductive cycle, where an egg is released during ovulation. The uterus (b) is not considered a gonad. It is a muscular organ where the fertilized egg implants and develops into a fetus during pregnancy. The fallopian tubes (c) are the structures that connect the ovaries to the uterus and provide a pathway for the egg to travel from the ovary to the uterus. The ampulla (d) is a specific part of the fallopian tube, but it is not the reproductive organ functioning as the gonad in females.

Description:Gonadotropin-releasing hormone (GnRH) is a hormone that is produced by neurons in the hypothalamus. It is released into the bloodstream and travels to the anterior pituitary gland, where it stimulates the production of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH and LH then travel to the gonads, where they stimulate the production of sex hormones. The other options are incorrect. The anterior pituitary gland produces FSH and LH, the posterior pituitary gland produces oxytocin and vasopressin, and the medulla oblongata is a part of the brainstem that is involved in a variety of functions, including breathing, heart rate, and blood pressure.

Description:Neurons are the most sensitive cells to hypoxia, which is a condition where there is not enough oxygen in the cells. This is because neurons require a lot of oxygen to function properly. If neurons are not getting enough oxygen, they can die. The other options are incorrect. Liver cells, stem cells, and muscle cells are all less sensitive to hypoxia than neurons. Here are some of the reasons why neurons are so sensitive to hypoxia: Neurons have a high metabolic rate. This means that they use a lot of oxygen to function properly. Neurons have a limited capacity to store oxygen. This means that they can only store a small amount of oxygen, so they are more likely to be affected by a decrease in oxygen supply. Neurons are not very good at repairing themselves. This means that if a neuron dies, it is not likely to be replaced. Hypoxia can lead to a number of problems, including: Brain damage Heart damage Kidney damage Muscle damage In severe cases, hypoxia can be fatal.

Description:Neuroglia, also known as glial cells, are a type of cell found in the central nervous system (CNS) that play a crucial role in repairing damaged nervous tissue. While neurons are the primary cells responsible for transmitting electrical signals in the nervous system, neuroglia provide support and maintenance functions. Among the various types of neuroglia, microglia (c) specifically play a key role in the immune response of the CNS and are involved in the repair process by removing debris and promoting tissue healing. However, all types of neuroglia contribute to the repair and regeneration of nervous tissue in the CNS. Axons (b) are the long, slender projections of neurons that transmit electrical impulses. While axons can regenerate to some extent under certain conditions, they do not directly repair damaged nervous tissue. Fibroblasts (d) are cells found in connective tissue and are not specific to the repair of nervous tissue in the CNS. Their primary function is to produce the extracellular matrix and aid in wound healing in other parts of the body.

Description:Dendrites are the branched extensions of a neuron that receive information from other neurons. They are covered in tiny protrusions called dendritic spines, which increase the surface area of the dendrites and allow them to receive more information. The other options are incorrect. Axons are the long, thin extensions of a neuron that carry information away from the cell body. Tracts are bundles of axons that travel together in the brain and spinal cord. Projections are any kind of extension of a neuron, including dendrites, axons, and axon terminals.

Description:Nodes of Ranvier are the gaps or spaces that exist between segments of oligodendrocytes in the central nervous system (CNS) or between individual Schwann cells in the peripheral nervous system (PNS). These nodes are crucial for the proper conduction of nerve impulses along myelinated axons. At the nodes of Ranvier, the myelin sheath that surrounds the axon is interrupted, allowing for saltatory conduction. This means that the nerve impulses "jump" from one node to the next, significantly increasing the speed and efficiency of electrical signal transmission along the axon. Synapse (b) refers to the junction between two neurons, where signals are transmitted chemically through neurotransmitters. Synaptic cleft (c) is the small gap between the presynaptic neuron and the postsynaptic neuron at a synapse. Sulci (d) are the grooves or indentations found on the surface of the brain. They are not directly related to the gaps between oligodendrocytes or Schwann cells.

Description:Synaptic vesicles contain neurotransmitters, which are chemicals that allow neurons to communicate with each other. Dendrites typically carry signals toward the cell body. Schwann cells form myelin sheaths, which are insulating layers that surround axons and help to speed up the conduction of nerve impulses. Nodes of Ranvier are gaps in the myelin sheath that allow nerve impulses to jump from one Schwann cell to the next. They are not found in dendrites. Therefore, the correct answer is d. I, II, III only.

Description:Clusters of nerve cell bodies located in the peripheral nervous system (PNS) are called ganglia. Ganglia serve as processing centers and are responsible for coordinating sensory and motor signals in the PNS. Ganglia can be found along nerves or near organs, and they play a role in integrating and transmitting information between different parts of the nervous system. Nuclei (a) are clusters of nerve cell bodies located in the central nervous system (CNS) rather than the PNS. Nerve tracts (c) are bundles of axons in the CNS that carry signals between different regions of the brain and spinal cord. Nerves (d) are bundles of axons in the PNS that transmit signals between the CNS and various parts of the body. Nerves can contain both axons and ganglia, but the specific term for clusters of nerve cell bodies in the PNS is ganglia.

Description:The synaptic cleft is a small gap between the presynaptic terminal of one neuron and the postsynaptic terminal of another neuron. It is filled with extracellular fluid and contains a variety of proteins that help to regulate the release of neurotransmitters. The other options are incorrect. Vesicles are small sacs that contain neurotransmitters. Action potentials are electrical signals that travel along the axon of a neuron. Synaptic terminals are the ends of axons that release neurotransmitters.

Description:An action potential is a rapid and brief change in the membrane potential of a neuron or muscle cell. It occurs when the membrane potential reaches a certain threshold value. When a neuron receives a strong enough stimulus, and the membrane potential reaches the threshold, voltage-gated sodium channels open, allowing an influx of sodium ions into the cell. This causes a rapid depolarization of the membrane potential, leading to the generation of an action potential. Option b, "Negative proteins and ions rapidly enter the cell," is not accurate. During an action potential, ions move across the membrane, but it is primarily the movement of sodium (Na+) and potassium (K+) ions that contributes to the generation and propagation of the action potential. Option c, "The inside of the cell becomes negative compared to the outside," is not correct. During an action potential, the inside of the cell becomes more positive, not negative, compared to the outside. This shift in polarity occurs during the depolarization phase when sodium ions enter the cell. Option d, "Sodium and potassium," is not a complete statement and does not accurately describe the occurrence of an action potential. The movement of sodium and potassium ions across the membrane is involved in generating and propagating the action potential, but it does not fully explain the occurrence of an action potential. The membrane potential reaching the threshold value is the crucial trigger for initiating an action potential.

Description:In a reflex arc, which is the basic functional unit of a reflex, several components are involved to produce a rapid, involuntary response to a stimulus. These components include: a. Afferent neuron: It carries sensory information from the sensory receptor to the central nervous system (CNS). b. Efferent neuron: It carries motor information from the CNS to the target muscle or gland. c. Spinal pathway: It refers to the communication and integration of sensory and motor signals that occur within the spinal cord. d. Effector organ: It is the target tissue that carries out the response generated by the reflex. This can be a muscle that contracts or a gland that secretes a hormone, for example. All of these components are essential for the functioning of a reflex arc except for the effector organ (d). The effector organ is a necessary part of the reflex response, as it carries out the motor output generated by the efferent neuron. Without the effector organ, the reflex response would not be able to manifest.

Description:Dopamine, norepinephrine, and acetylcholine are all examples of neurotransmitters. Neurotransmitters are chemicals that allow neurons to communicate with each other. They are released from the presynaptic terminal of one neuron and bind to receptors on the postsynaptic terminal of another neuron. This binding of neurotransmitters to receptors causes changes in the postsynaptic neuron, which can lead to either an excitatory or inhibitory response. Other examples of neurotransmitters include: Glutamate GABA Serotonin Endorphins Enkephalins Neurotransmitters play a role in a variety of functions, including: Movement Learning Memory Emotion Pain perception

Description:The axolemma is the cell membrane surrounding an axon. Sodium channels open when the threshold potential is reached, facilitating a rapid influx of sodium into the axolemma interior and producing depolarization. Option c refers to sodium influx (move inside)

Description:Dopamine, GABA (Gamma Amino Benzol Acid), Serotonin (5-HT) are neurotransmitters. Troponins are specific proteins found in heart muscles. It is considered as a biomarker in diagnosis of myocardial infarction (MI)

Description:Cortisone is a steroid (glucocorticoid) while other function as a neurotransmitters.

Description:The middle layer of the meninges, which are the protective membranes that surround the brain and spinal cord, is called the arachnoid mater. It is located between the outer dura mater and the innermost pia mater. The meninges consist of three layers: a. Dura mater: It is the tough, outermost layer that lines the inside of the skull and vertebral canal. b. Arachnoid mater: It is the middle layer that lies beneath the dura mater. The arachnoid mater is a thin, web-like membrane that covers the brain and spinal cord. It forms a space called the subarachnoid space, which contains cerebrospinal fluid. c. Pia mater: It is the innermost layer that directly covers the brain and spinal cord. The pia mater is a delicate membrane that follows the contours of the brain and spinal cord, providing nourishment and protection. d. Choroid plexuses: These are specialized structures within the ventricles of the brain that produce cerebrospinal fluid. They are not part of the meninges and are not the middle layer.

Description:The outermost layer of the meninges, which are the protective membranes that surround the brain and spinal cord, is called the dura mater. It is a tough, fibrous membrane that provides structural support and protection to the central nervous system. The meninges consist of three layers: a. Dura mater: It is the tough, outermost layer that lines the inside of the skull and vertebral canal. b. Arachnoid mater: It is the middle layer, located between the dura mater and the pia mater. The arachnoid mater is a thin, web-like membrane that forms a space called the subarachnoid space, which contains cerebrospinal fluid. c. Pia mater: It is the innermost layer that directly covers the brain and spinal cord. The pia mater is a delicate membrane that follows the contours of the brain and spinal cord, providing nourishment and protection. d. Choroid plexuses: These are specialized structures within the ventricles of the brain that produce cerebrospinal fluid. They are not part of the meninges and are not the outermost layer.

Description:• Hearing is not a function of cerebellum. The auditory cortex located at the temporal lobe of the brain is responsible for hearing. • Cerebellum also called “Little brain” is located at the back of the brain, under the occipital and temporal lobes of the cerebral cortex. The following are the functions of Cerebellum: • Coordinates voluntary movements • Controls tone, posture and equilibrium • Plays a role in cognition • Helps in learning of special motor skills • Maintenance of muscle tone and posture

Description:White matter is the tissue in the central nervous system (CNS) that is made up of bundles of axons. These axons are covered in a fatty sheath called myelin, which gives white matter its white color. Myelin helps to speed up the conduction of nerve impulses. The other options are incorrect. Nerve cell bodies and their dendrites make up gray matter, nuclei are clusters of nerve cell bodies, and sulci are grooves in the surface of the brain.

Description:Brainstem is the area at the base of the brain that connects the cerebrum with the spinal cord. It includes mid brain (mesencephalon), pons (part of metencephalon) and medulla oblongata (myelencephalon). The brainstem regulates vital cardiac and respiratory function and acts as a vehicle for sensory information.

Description:The generation and propagation of an action potential rely on the movement of sodium (Na+) and potassium (K+) ions across the cell membrane. During an action potential, the membrane potential of a neuron rapidly changes. It begins with a brief depolarization phase, where voltage-gated sodium channels open, allowing an influx of sodium ions into the cell. This causes the inside of the cell to become more positive compared to the outside. Following the depolarization phase, voltage-gated potassium channels open, allowing an efflux of potassium ions out of the cell. This leads to repolarization, where the inside of the cell becomes more negative again, returning to the resting membrane potential. The movement of sodium and potassium ions across the cell membrane creates the electrical signals that propagate along the neuron, allowing for the transmission of information. Calcium (Ca2+), magnesium (Mg2+), iron (Fe2+), and iodide (I-) are not directly involved in the generation and propagation of action potentials.