Biology Notes – Grade 10
National Curriculum Pakistan - NCP
Chapter 5: Nervous System
Internal SLO Based Questions-An in-depth look at the urinary system, its components, and key historical contributions to our understanding of urinary system.
1. What is the overall function of the nervous system?
The overall function of the nervous system is to coordinate and control the activities of the body. It receives information from the environment and within the body, interprets this information, and initiates responses to maintain homeostasis and allow for behavior.
2. How does the nervous system enable rapid responses?
The nervous system enables rapid responses through the transmission of electrical and chemical signals along specialized cells called neurons. These signals travel quickly throughout the body, allowing for swift reactions to stimuli.
3. What are the three main interconnected functions of the nervous system?
The three main interconnected functions of the nervous system are sensory input (receiving information), integration (processing and interpreting information), and motor output (initiating responses through effectors like muscles and glands).
4. What are the two main divisions of the human nervous system?
The human nervous system is divided into two main divisions: the central nervous system (CNS), which consists of the brain and spinal cord, and the peripheral nervous system (PNS), which includes all the nerves that extend from the CNS to the rest of the body.
5. What does the central nervous system (CNS) consist of?
The central nervous system (CNS) consists of the brain, which is the control center of the body, and the spinal cord, which extends from the brainstem down through the vertebral column and serves as a major communication pathway between the brain and the peripheral nervous system.
6. What does the peripheral nervous system (PNS) comprise?
The peripheral nervous system (PNS) comprises all the nerves that branch out from the brain and spinal cord to all other parts of the body, including sensory receptors, muscles, and glands. It acts as the communication network between the CNS and the rest of the body.
7. Where is the brain enclosed and protected?
The brain is enclosed and protected within the cranium (skull), a bony structure that provides physical protection. It is also surrounded by membranes called meninges and cushioned by cerebrospinal fluid, which helps to absorb shocks and provide nutrients.
8. What are the three main parts of the brain?
The brain is divided into three main parts: the forebrain (cerebrum, thalamus, and hypothalamus), the midbrain, and the hindbrain (cerebellum, pons, and medulla oblongata). Each part has specialized functions.
9. What are the main components of the forebrain?
The forebrain is the largest part of the brain and consists of the cerebrum, which is responsible for higher-level functions like thinking and memory; the thalamus, which relays sensory information; and the hypothalamus, which controls vital functions like body temperature and hunger.
10. What is the cerebrum and what are its hemispheres?
The cerebrum is the largest part of the human brain, responsible for higher-level functions. It is divided into two halves, the left and right cerebral hemispheres, connected by the corpus callosum.
11. What are the four lobes of each cerebral hemisphere and their general functions?
Each cerebral hemisphere has four lobes: frontal (thinking, movement), parietal (touch, spatial awareness), temporal (hearing, memory), and occipital (vision).
12. What is the function of the corpus callosum?
The corpus callosum is a large bundle of nerve fibers that connects the left and right cerebral hemispheres. It allows for communication and coordination of functions between the two sides of the cerebrum.
13. What is the thalamus and its main role?
The thalamus is located below the cerebrum and acts as a major relay center for sensory information. It receives sensory input from various parts of the body and relays it to the appropriate areas of the cerebral cortex for processing.
14. What are some important functions controlled by the hypothalamus?
The hypothalamus is a small but vital region located below the thalamus. It regulates various homeostatic functions, including body temperature, hunger, thirst, sleep-wake cycles, and the release of hormones from the pituitary gland.
15. What is the pituitary gland and its relationship with the hypothalamus?
The pituitary gland is an endocrine gland located below the hypothalamus. It is controlled by the hypothalamus, which secretes hormones that either stimulate or inhibit the release of pituitary hormones, regulating various bodily functions.
16. What is the midbrain and where is it located?
The midbrain is a relatively small part of the brainstem located just below the forebrain and above the hindbrain. It serves as a connection point between these regions and plays a role in sensory and motor functions.
17. What are some functions of the midbrain?
The midbrain is involved in controlling auditory and visual reflexes, as well as eye movement and posture. It also relays sensory information and contributes to motor control.
18. What are the main parts of the hindbrain?
The hindbrain consists of the cerebellum, pons, and medulla oblongata. These structures are located in the lower part of the brainstem and play crucial roles in motor control, coordination, and vital functions.
19. What is the cerebellum and its primary function?
The cerebellum is located behind the brainstem and is responsible for coordinating voluntary movements, posture, balance, and fine motor skills. It receives input from the sensory systems and motor cortex and integrates this information to produce smooth, coordinated movements.
20. What is the pons and what are some of its functions?
The pons is located above the medulla oblongata and below the midbrain. It acts as a relay center between the cerebrum and cerebellum. It also plays a role in regulating breathing, sleep cycles, and sensory information.
21. What is the medulla oblongata and what vital functions does it control?
The medulla oblongata is the lowest part of the brainstem, connecting to the spinal cord. It controls several vital involuntary functions essential for survival, including breathing rate, heart rate, blood pressure, and reflexes like swallowing and vomiting.
22. Describe the shape and location of the spinal cord.
The spinal cord is a long, cylindrical structure that extends downwards from the base of the brain (medulla oblongata) through the vertebral canal formed by the vertebrae of the spinal column.
23. What is the spinal cord's primary function?
The spinal cord serves as the main communication pathway between the brain and the peripheral nervous system. It transmits sensory information from the body to the brain and motor commands from the brain to the muscles and glands. It also controls reflexes.
24. What protects the spinal cord?
The spinal cord is protected by the bony vertebral column, which surrounds it. It is also covered by the meninges (membranes) and cushioned by cerebrospinal fluid, similar to the brain.
25. What is the basic structure of a cross-section of the spinal cord?
A cross-section of the spinal cord shows a central region of gray matter, which is butterfly-shaped and contains neuron cell bodies, surrounded by white matter, which consists of myelinated nerve fibers (axons) arranged in tracts.
26. What are the dorsal and ventral roots of a spinal nerve?
Each spinal nerve is formed by the union of a dorsal root, which carries sensory information from the body to the spinal cord, and a ventral root, which carries motor commands from the spinal cord to the muscles and glands.
27. What does the peripheral nervous system link the CNS to?
The peripheral nervous system (PNS) links the central nervous system (CNS), which includes the brain and spinal cord, to all other parts of the body, including sensory receptors, muscles, and glands.
28. How many pairs of cranial and spinal nerves are there in the PNS?
The peripheral nervous system consists of 12 pairs of cranial nerves that originate from the brain and 31 pairs of spinal nerves that originate from the spinal cord.
29. What are the two main functional divisions of the PNS?
The peripheral nervous system has two main functional divisions: the somatic nervous system, which controls voluntary movements of skeletal muscles, and the autonomic nervous system, which controls involuntary functions.
30. What does the somatic nervous system control?
The somatic nervous system controls voluntary movements of the skeletal muscles. It receives sensory information from the skin, skeletal muscles, and joints and sends motor commands to these muscles to produce conscious movements.
31. What does the autonomic nervous system regulate?
The autonomic nervous system regulates involuntary functions of the body, such as heart rate, blood pressure, digestion, and gland secretion. It operates largely unconsciously to maintain homeostasis.
32. What is the neuron and what are its main parts?
A neuron is the basic structural and functional unit of the nervous system, specialized for transmitting information. Its main parts include the cell body (soma), dendrites (receiving signals), and an axon (transmitting signals).
33. What is the function of dendrites and axons?
Dendrites are branched extensions of a neuron that receive signals from other neurons. The axon is a long projection of a neuron that transmits signals away from the cell body to other neurons, muscles, or glands.
34. What are the two main divisions of the autonomic nervous system?
The autonomic nervous system is divided into two main divisions: the sympathetic nervous system and the parasympathetic nervous system. These systems often have opposing effects on various organs.
35. When is the sympathetic nervous system primarily active?
The sympathetic nervous system is primarily active during emergency or stressful situations, preparing the body for "fight or flight" responses. It increases heart rate, blood pressure, and alertness.
36. What are some effects of sympathetic nervous system activation?
Activation of the sympathetic nervous system leads to increased heart rate, dilation of pupils, release of adrenaline, increased blood glucose levels, and diversion of blood flow to skeletal muscles.
37. When is the parasympathetic nervous system most active?
The parasympathetic nervous system is most active during resting and digesting conditions, promoting relaxation and conserving energy. It slows heart rate and stimulates digestion.
38. What are some effects of parasympathetic nervous system activation?
Activation of the parasympathetic nervous system leads to a decreased heart rate, constriction of pupils, stimulation of digestion and salivation, and relaxation of sphincter muscles.
39. What are nerves composed of?
Nerves are bundles of nerve fibers (axons) enclosed by connective tissue. These bundles transmit signals throughout the body.
40. What are the main parts of the nervous system?
The nervous system consists of the central nervous system (brain and spinal cord) and the peripheral nervous system. They work together to process information and control body responses.
41. What is the myelin sheath and its function?
The myelin sheath is a fatty insulating layer that surrounds the axons of many neurons. It speeds up the transmission of nerve impulses.
42. What are the Nodes of Ranvier?
The Nodes of Ranvier are gaps in the myelin sheath along the axon. Nerve impulses jump from one node to the next, increasing the speed of transmission (saltatory conduction).
43. What are the three main types of neurons based on function?
Based on their function, there are three main types of neurons: sensory neurons, motor neurons, and interneurons.
44. What is the function of sensory neurons?
Sensory neurons carry impulses from sensory receptors throughout the body towards the central nervous system (brain and spinal cord).
45. What is the function of motor neurons?
Motor neurons carry impulses from the central nervous system to effectors, such as muscles and glands, causing them to respond.
46. What is the function of interneurons?
Interneurons are located within the central nervous system and connect sensory and motor neurons. They are involved in processing information and complex reflexes.
47. What is a stimulus?
A stimulus is any change or signal in the internal or external environment that can be detected by a receptor and elicit a response in the nervous system.
48. Give examples of external stimuli.
Examples of external stimuli include light, sound, smell, taste, touch, pressure, temperature, and pain originating from outside the body.
49. Give examples of internal stimuli.
Examples of internal stimuli include changes in blood pressure, blood glucose levels, body temperature, and the sensation of pain originating from within the body.
50. What is the role of receptors in detecting stimuli?
Receptors are specialized structures or nerve endings that are sensitive to specific types of stimuli. When a stimulus is detected, receptors convert it into an electrical signal that can be transmitted by the nervous system.
51. What is a nerve impulse?
A nerve impulse, or action potential, is a rapid, self-propagating electrical signal that travels along the axon of a neuron. It is the fundamental way neurons communicate.
52. What is the resting potential of a neuron?
The resting potential is the electrical potential difference across the membrane of a neuron when it is not transmitting an impulse. The inside of the neuron is typically negatively charged compared to the outside.
53. What ions are primarily involved in establishing the resting potential?
The resting potential is primarily established and maintained by the unequal distribution of sodium ions (Na+) and potassium ions (K+) across the neuron's membrane, along with the action of the sodium-potassium pump.
54. Briefly describe the sodium-potassium pump.
The sodium-potassium pump is an active transport protein in the neuron's membrane that uses ATP to pump sodium ions (Na+) out of the cell and potassium ions (K+) into the cell, maintaining the concentration gradients essential for the resting potential.
55. What happens during an action potential (depolarization)?
During an action potential, there is a rapid reversal of the electrical charge across the neuron's membrane. Sodium channels open, allowing a large influx of positive sodium ions into the cell, making the inside temporarily positive relative to the outside.
56. What happens during repolarization?
Following depolarization, potassium channels open, allowing positive potassium ions to flow out of the cell. This outflow of positive charge restores the negative charge inside the neuron, returning the membrane potential towards the resting state.
57. Why is the action potential described as "all-or-none"?
The action potential is described as "all-or-none" because if a stimulus is strong enough to reach the threshold potential, a full action potential will be generated. If the stimulus is subthreshold, no action potential will occur.
58. How does the action potential propagate along the axon?
The action potential propagates along the axon as the depolarization of one region of the membrane triggers the depolarization of the adjacent region. This wave of depolarization travels down the length of the axon.
59. How does myelination affect the speed of action potential propagation?
Myelination significantly increases the speed of action potential propagation through saltatory conduction. The impulse jumps from one Node of Ranvier to the next, rather than traveling continuously along the entire axon membrane.
60. What is a synapse?
A synapse is the junction between two neurons, or between a neuron and an effector cell (like a muscle or gland). It is the site where communication occurs between these cells.
61. What are the main components of a synapse?
A synapse typically consists of the presynaptic neuron (the neuron sending the signal), the synaptic cleft (a small gap between the cells), and the postsynaptic neuron or effector cell (the cell receiving the signal).
62. How does communication occur across the synaptic cleft?
Communication across the synaptic cleft is primarily chemical. The presynaptic neuron releases chemical messengers called neurotransmitters that diffuse across the cleft and bind to receptors on the postsynaptic cell.
63. What is synaptic transmission?
Synaptic transmission is the process by which a nerve impulse is transmitted from a presynaptic neuron to a postsynaptic neuron or effector cell across a synapse.
64. Can action potentials directly cross the synaptic cleft?
No, action potentials cannot directly cross the synaptic cleft. The electrical signal is converted into a chemical signal (neurotransmitter release) to bridge the gap.
65. In which direction does synaptic transmission typically occur?
Synaptic transmission is typically unidirectional, from the presynaptic neuron to the postsynaptic neuron or effector cell. This ensures a directed flow of information in the nervous system.
66. What are neurotransmitters?
Neurotransmitters are chemical messengers released by the presynaptic neuron at a synapse. They transmit signals across the synaptic cleft to the postsynaptic neuron or effector cell.
67. Where are neurotransmitters stored in the presynaptic neuron?
Neurotransmitters are stored in small, membrane-bound sacs called synaptic vesicles located in the axon terminal of the presynaptic neuron.
68. What triggers the release of neurotransmitters into the synaptic cleft?
The arrival of an action potential at the axon terminal of the presynaptic neuron triggers the influx of calcium ions (Ca²⁺) into the terminal, which in turn stimulates the synaptic vesicles to fuse with the presynaptic membrane and release neurotransmitters into the synaptic cleft.
69. How do neurotransmitters affect the postsynaptic cell?
Neurotransmitters diffuse across the synaptic cleft and bind to specific receptors on the membrane of the postsynaptic neuron or effector cell. This binding can cause a change in the postsynaptic cell's membrane potential, either excitatory or inhibitory.
70. Give examples of neurotransmitters mentioned in the text.
Examples of neurotransmitters mentioned in the text include acetylcholine, dopamine, serotonin, norepinephrine (noradrenaline), and epinephrine (adrenaline).
71. What happens to neurotransmitters after they bind to postsynaptic receptors?
After binding to postsynaptic receptors, neurotransmitters are typically removed from the synaptic cleft. This can occur through enzymatic degradation, reuptake into the presynaptic neuron, or diffusion away from the synapse.
72. What is reuptake of neurotransmitters?
Reuptake is a process where neurotransmitters are transported back into the presynaptic neuron from the synaptic cleft. This allows the neurotransmitter to be recycled and also terminates its signal on the postsynaptic cell.
73. What is a reflex action?
A reflex action is a rapid, automatic, and involuntary response to a stimulus. It occurs without conscious thought or involvement of the brain in the initial response.
74. Are reflex actions voluntary or involuntary?
Reflex actions are involuntary, meaning they occur automatically without conscious control.
75. What is a reflex arc?
A reflex arc is the neural pathway that mediates a reflex action. It typically includes a sensory receptor, sensory neuron, integration center (in the spinal cord or brainstem), motor neuron, and effector.
76. Describe the sequence of events in a simple reflex arc, like touching a hot object.
When touching a hot object, sensory receptors in the skin detect the heat. Sensory neurons transmit this impulse to the spinal cord. In the spinal cord, the impulse is relayed to a motor neuron, which then sends a signal to a muscle (effector) to withdraw the hand.
77. What is the role of the spinal cord in many reflex actions?
In many reflex actions, the spinal cord acts as the integration center, processing the sensory information and generating the motor response without direct involvement of the brain. This allows for a very rapid response.
78. Give an example of the effector in a reflex action.
An example of an effector in a reflex action is a muscle that contracts to produce a movement, such as the arm muscles contracting to withdraw the hand from a hot object.
79. Why are reflex actions important?
Reflex actions are important for providing rapid protection against harmful stimuli and for maintaining basic bodily functions without requiring conscious attention.
80. What are the components of a reflex arc in the example of the hand withdrawing from a hot object?
In this reflex arc, the components are: sensory receptors in the skin (detecting heat), sensory neuron (transmitting the signal), spinal cord (integration center), motor neuron (sending the signal to the muscle), and arm muscle (effector, causing withdrawal).
81. Why is the sudden blinking of the eye when a hand is waved in front of it considered a reflex action?
The blinking of the eye in response to a hand waved in front of it is a reflex action because it is a rapid, automatic, and involuntary response to a potential threat to the eye. It occurs without conscious thought.
82. What are hormones and how are they transported in the body?
Hormones are chemical messengers produced by endocrine glands. They are secreted directly into the bloodstream and transported throughout the body to target organs or cells where they exert their specific effects.
83. How does the endocrine system compare to the nervous system in terms of speed and duration of response?
The endocrine system generally has slower and longer-lasting responses compared to the rapid and short-lived responses of the nervous system. Hormones travel through the bloodstream, taking longer to reach their targets, but their effects can persist for minutes, hours, or even longer.
84. What are endocrine glands?
Endocrine glands are ductless glands that secrete hormones directly into the surrounding tissue fluid, from where they diffuse into the bloodstream to reach their target cells.
85. Name some major endocrine glands shown in the diagram.
Major endocrine glands shown include the hypothalamus, pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, ovaries (in females), and testes (in males).
86. Where is the pituitary gland located and what controls it?
The pituitary gland is a small gland located at the base of the brain, below the hypothalamus. It is often called the "master gland" because it controls the activity of other endocrine glands and is itself controlled by the hypothalamus.
87. Name the two main lobes of the pituitary gland.
The pituitary gland has two main lobes: the anterior pituitary and the posterior pituitary. These lobes secrete different sets of hormones with diverse functions.
88. What are some hormones secreted by the anterior pituitary and their general functions?
The anterior pituitary secretes several hormones, including growth hormone (regulates growth), thyroid-stimulating hormone (stimulates the thyroid), and follicle-stimulating hormone (involved in reproduction).
89. What hormones are released by the posterior pituitary and where are they produced?
The posterior pituitary releases oxytocin (involved in uterine contractions and milk ejection) and antidiuretic hormone (ADH, regulates water reabsorption). These hormones are produced in the hypothalamus and stored in the posterior pituitary.
90. Where is the thyroid gland located and what hormones does it produce?
The thyroid gland is located in the neck, just below the larynx (voice box). It produces thyroid hormones (thyroxine and triiodothyronine), which regulate metabolism, and calcitonin, which plays a role in calcium regulation.
91. What is the importance of iodine for the thyroid gland?
Iodine is essential for the synthesis of thyroid hormones. A deficiency in iodine can lead to thyroid disorders like goiter.
92. Where are the parathyroid glands located and what hormone do they secrete?
The parathyroid glands are small glands located on the posterior surface of the thyroid gland. They secrete parathyroid hormone (PTH), which plays a crucial role in regulating calcium levels in the blood.
93. Where is the pancreas located and what are its endocrine functions?
The pancreas is located in the abdominal cavity, behind the stomach. Its endocrine functions involve secreting hormones that regulate blood glucose levels, primarily insulin and glucagon.
94. What cells in the pancreas produce insulin and what is insulin's main effect?
Beta cells in the pancreas produce insulin. Insulin's main effect is to lower blood glucose levels by promoting the uptake of glucose by cells and its conversion to glycogen for storage in the liver and muscles.
95. What cells in the pancreas produce glucagon and what is glucagon's main effect?
Alpha cells in the pancreas produce glucagon. Glucagon's main effect is to raise blood glucose levels by stimulating the breakdown of glycogen into glucose in the liver and the synthesis of glucose from non-carbohydrate sources.
96. What happens if there is a deficiency in insulin production?
A deficiency in insulin production leads to diabetes mellitus, a condition characterized by high blood glucose levels because glucose cannot be effectively taken up by cells or stored.
97. What hormone is secreted by the pituitary gland and what is its general function listed in the table?
Growth hormone (GH) is secreted by the pituitary gland, and its general function listed is regulating growth and development.
98. What hormone is secreted by the thyroid gland and what is its general function listed?
Thyroxine is secreted by the thyroid gland, and its general function listed is controlling metabolism.
99. What hormone is secreted by the pancreas and what is its general function listed?
Insulin is secreted by the pancreas, and its general function listed is lowering blood sugar.
100. What hormone is secreted by the adrenal gland (medulla) and what is its function?
Adrenaline (epinephrine) is secreted by the adrenal medulla, and its function is to increase blood pressure, heart rate, and prepare the body for "fight or flight" responses.
101. What hormone is secreted by the adrenal gland (cortex) and what is one of its functions?
Aldosterone is secreted by the adrenal cortex, and one of its functions is to control the body's salt and water balance.
102. What hormone is secreted by the ovary and what is its function?
Estrogen is secreted by the ovary, and one of its functions is to promote the development of female secondary sexual characteristics.
103. What hormone is secreted by the testis and what is its function?
Testosterone is secreted by the testis, and its function is to promote the development of male secondary sexual characteristics and sperm production.
104. What hormone is secreted by the pancreas and what is its function (opposite to insulin)?
Glucagon is secreted by the pancreas, and its function is to increase blood glucose levels.
105. What hormone is secreted by the pituitary gland and what is its role in water balance?
Antidiuretic hormone (ADH) is secreted by the pituitary gland, and its role is to aid in the reabsorption of water by the kidneys.
106. Where are the adrenal glands located and what are their two main parts?
The adrenal glands are located on top of each kidney. They have two main parts: the outer adrenal cortex and the inner adrenal medulla, each producing different hormones.
107. What type of hormones does the adrenal cortex secrete?
The adrenal cortex secretes a group of hormones called corticosteroids, including mineralocorticoids (like aldosterone), glucocorticoids (like cortisol), and small amounts of sex hormones.
108. What type of hormones does the adrenal medulla secrete?
The adrenal medulla secretes catecholamines, primarily adrenaline (epinephrine) and noradrenaline (norepinephrine), in response to stress.
109. What are the gonads and what are their primary endocrine functions?
The gonads are the testes in males and the ovaries in females. Their primary endocrine functions are to produce sex hormones (testosterone in males, estrogen and progesterone in females) and gametes (sperm and eggs).
110. What are some secondary sexual characteristics influenced by hormones from the gonads?
Hormones from the gonads influence the development of secondary sexual characteristics such as facial hair and voice deepening in males (testosterone), and breast development and widening of hips in females (estrogen).