Class 10 Science Chapter 6 Notes

Control And Coordination Class 10 Science Chapter 6 Notes are available here. Developed by subject experts from CBSE Wale. These notes offer a reliable and trustworthy resource for students to enhance their understanding and support their studies.

Control And Coordination Class 10 Science Chapter 6 Notes

Introduction

• Life processes involved in maintenance functions in living organisms were discussed in the previous chapter.
• Initial notion: moving entities are considered alive.
• Some movements are due to growth, as seen in plants.
• Example: a germinating seed moves by pushing soil aside as it grows.
• Movement stops if growth is halted.
• Certain movements in animals and some plants are unrelated to growth.
• Examples: a running cat, children playing on swings, and buffaloes chewing cud.
• Visible movements are associated with life because they are responses to environmental changes.
• Movements are attempts by organisms to use environmental changes to their advantage.
• Examples: plants growing towards sunlight, children swinging for fun, buffaloes chewing cud for better digestion.
• Movement as a response to protect from changes like bright light or touching a hot object.
• Movement in response to the environment is carefully controlled.
• Appropriate movements are triggered by specific environmental changes.
• Example: whispering in class instead of shouting.
• Controlled movement depends on recognizing environmental events and responding correctly.
• Living organisms use systems for control and coordination.
• In multicellular organisms, specialized tissues provide control and coordination activities.

Animals – Nervous System

• Control and coordination in animals are provided by nervous and muscular tissues.
• Touching a hot object is an urgent and dangerous situation requiring detection and response.
• Detection of environmental information is done by specialized tips of nerve cells located in sense organs (inner ear, nose, tongue, etc.).
• Gustatory receptors detect taste; olfactory receptors detect smell.
• Information acquired at the dendritic tip of a nerve cell sets off a chemical reaction that creates an electrical impulse.
• The electrical impulse travels from the dendrite to the cell body, then along the axon to its end.
• At the axon end, the electrical impulse triggers the release of chemicals.
• These chemicals cross the synapse and start a similar electrical impulse in the dendrite of the next neuron.
• Nervous impulses travel in the body through this mechanism.
• Synapses allow the delivery of impulses from neurons to other cells (muscle cells or glands).
• Nervous tissue consists of an organized network of neurons, specialized for conducting information via electrical impulses.
• Identify parts of a neuron: (i) where information is acquired, (ii) through which information travels as an electrical impulse, (iii) where the impulse is converted into a chemical signal for onward transmission.
• Question to consider: Does food taste different if your nose is blocked? Why might this happen? Discuss possible explanations, especially in the context of having a cold.

What happens in Reflex Actions?

• “Reflex” refers to sudden actions in response to environmental stimuli, such as jumping away from danger or pulling back from heat.
• These actions occur without conscious thought or deliberate control.
• Despite the lack of conscious control, these actions are responses to changes in the environment.
• Control and coordination in reflex actions involve rapid and automatic responses to ensure safety or immediate adjustment to stimuli.
• Touching a flame is perceived as urgent and dangerous.
• The response involves consciously thinking about the pain and potential harm.
• The speed of response depends on the time it takes to process these thoughts and impulses.
• Thinking involves a complex interaction of nerve impulses from multiple neurons.
• Nerve impulses play a crucial role in the transmission of sensory information and decision-making processes.
• The brain, which processes thoughts and responses, is densely networked with neurons.
• It is located at the forward end of the skull and integrates signals from across the body.
• Signals from various parts of the body are received and processed before a response is generated.
• Nerves connect the brain to different parts of the body for signal transmission.
• Delays in processing these signals could result in potential harm, such as getting burnt when touching a hot object.
• The body’s design solves the problem of delayed responses by using reflex arcs.
• Reflex arcs connect sensory nerves detecting stimuli (like heat) directly to motor nerves that control muscles.
• This direct connection allows for quick detection of stimuli and immediate motor response.
• Reflex arcs are commonly formed in the spinal cord, where sensory and motor nerves first meet.
• The spinal cord serves as a central point for reflex arc connections, though sensory information also continues to the brain for further processing.
• Reflex arcs have evolved in animals because the brain’s thinking process is not fast enough for immediate responses.
• Many animals lack the complex neuron networks required for higher-level thinking.
• Reflex arcs are efficient mechanisms for quick responses to stimuli.
• Even with the evolution of complex neuron networks, reflex arcs remain effective for rapid reactions.

As for tracing the sequence of events when a bright light is focused on your eyes, it typically involves:

• The light stimulus is detected by photoreceptors in the retina of the eye.
• Nerve impulses are generated in the retina and transmitted via the optic nerve.
• These impulses travel to the brain, specifically to the visual cortex for processing.
• Simultaneously, a reflex arc may cause the pupils to constrict to protect the retina from excessive light (the pupillary light reflex).

Human Brain

• The spinal cord is not solely responsible for reflex actions; it also serves to transmit information for thinking.
• Thinking involves complex mechanisms and neural connections.
• The brain is the main coordinating center of the body.
• The brain and spinal cord together form the central nervous system (CNS).
• The CNS receives and integrates information from all parts of the body.
• The brain controls voluntary actions such as writing, talking, and moving objects.
• Messages from the brain are sent to muscles for voluntary actions.
• The peripheral nervous system includes cranial nerves from the brain and spinal nerves from the spinal cord, facilitating communication with the rest of the body.
• The brain enables thinking and actions based on decisions.
• Different parts of the brain integrate various inputs and outputs.
• The brain is divided into three major regions: forebrain, midbrain, and hindbrain.
• The fore-brain is responsible for processing sensory impulses from various receptors.
• Different regions of the fore-brain specialize in processing sensory information related to hearing, smell, sight, etc.
• There are areas of association within the fore-brain where sensory information is interpreted and integrated with stored information.
• Decisions on responses are made based on integrated sensory information.
• Motor areas in the fore-brain control voluntary muscle movements, such as those in the legs.
• The fore-brain includes centers that handle sensations like hunger and feeling full, which are distinct from sensory perceptions like sight or hearing.
• The human brain has specific functions associated with its different parts.
• Reflex actions include involuntary responses like salivation, heartbeat, and digestion, which occur without conscious control.
• Involuntary actions, such as those controlled by the mid-brain and hind-brain, include functions like blood pressure regulation and vomiting.
• The medulla in the hind-brain controls many involuntary actions.
• The cerebellum, located in the hind-brain, is responsible for coordinating voluntary actions like walking, cycling, and fine motor movements.
• The cerebellum also maintains posture and balance in the body.
• These involuntary and voluntary actions are crucial for everyday activities, even when not consciously thought about.

How are these Tissues protected?

• The brain is a delicate and crucial organ.
• The brain needs careful protection due to its importance for various activities.
• The body is designed to protect the brain by encasing it in a bony box (the skull).
• Inside the skull, the brain is contained in a fluid-filled balloon for shock absorption.
• The vertebral column (backbone) protects the spinal cord.
• The vertebral column can be felt as a hard, bumpy structure down the middle of the back.

How does the Nervous Tissue cause Action?

• Nervous tissue collects, sends, and processes information in the body.
• Nervous tissue makes decisions based on information and conveys them to muscles for action.
• Muscle tissue performs the final job of movement.
• When a nerve impulse reaches a muscle, muscle fibers shorten.
• Muscle cells change shape by altering the arrangement of special proteins in response to nervous impulses.
• Different types of muscles include voluntary and involuntary muscles.
• Voluntary muscles are likely under conscious control, while involuntary muscles operate without conscious effort.

Coordination In Plants

• Animals have a nervous system and muscles for controlling and coordinating body activities.
• Plants lack a nervous system and muscles.
• Plants respond to stimuli differently than animals.
• Example: Chhui-mui (touch-me-not) plants fold up and droop when touched.
• Another example: Germinating seeds show directional movement—roots grow down, stems grow up.
• Movement in sensitive plants like chhui-mui is rapid and not linked to growth.
• Movement in seedlings is directional and caused by growth.
• If growth is hindered, seedlings do not exhibit movement.
• Plants exhibit two types of movement: growth-dependent and growth-independent.

Immediate Response to Stimulus

• Sensitive plants like the chhui-mui respond to touch without involving growth.
• Plants lack nervous tissue and muscle tissue.
• The plant detects touch and moves its leaves in response using electrical-chemical means.
• Movement occurs at a point different from where the plant is touched.
• Information about touch is communicated through electrical-chemical signals between cells.
• Unlike animals, plants lack specialized tissue for conducting information.
• Cells in plants change shape by adjusting water content, causing swelling or shrinking.
• This change in cell shape allows for movement in response to stimuli.

Movement Due to Growth

• Plants like the pea plant use tendrils to climb by wrapping around supports upon contact.
• Tendrils circle objects because the part in contact grows slower than the unattached part.
• Plants commonly respond to stimuli through directional growth, which gives the appearance of movement.
• Environmental triggers like light or gravity influence the direction of plant growth.
• Tropic movements, such as phototropism and gravitropism, involve bending towards or away from stimuli.
• Shoots exhibit positive phototropism (bending towards light), while roots show negative phototropism (bending away from light).
• These tropic movements help plants optimize their growth towards light for photosynthesis or anchor themselves more effectively in soil.
• Roots of plants exhibit positive geotropism (growing downwards) while shoots show negative geotropism (growing upwards).
• Geotropism is the response to gravity’s pull on the Earth.
• ‘Hydrotropism’ refers to directional growth in response to water, and ‘chemotropism’ refers to directional growth in response to chemicals.
• An example of chemotropism is the growth of pollen tubes towards ovules during the reproductive process of plants.
• Information communication in multicellular organisms involves different speeds of response.
• The sensitive plant shows very quick movement in response to touch.
• Sunflowers exhibit slower movement in response to day or night.
• Growth-related movements in plants are even slower.
• In animal bodies, growth occurs in carefully controlled directions, not randomly.
• Controlled movements in animals can vary in speed.
• Fast responses to stimuli require rapid information transfer.
• Rapid transmission mediums are necessary for quick responses to stimuli.
• Electrical impulses are effective for communication.
• Limitations of electrical impulses include reaching only cells connected by nervous tissue.
• Cells require time to reset mechanisms between generating impulses.
• Continuous creation and transmission of electrical impulses by cells are not possible.
• Multicellular organisms use chemical communication as an alternative means of cell communication.
• Stimulated cells release chemical compounds instead of electrical impulses.
• These compounds diffuse around the original cell.
• Cells with specific molecules on their surfaces can detect and transmit this information.
• Chemical communication is slower but can potentially reach all cells of the body.
• Hormones used by multicellular organisms are diverse and aid in control and coordination.
• Plant hormones coordinate growth, development, and responses to the environment.
• Hormones are synthesized at one location and diffuse to their target areas of action.
• Auxin, synthesized at the shoot tip, helps plants grow longer in response to light.
• Auxin diffuses towards the shaded side of the shoot, causing cells to elongate on the opposite side, bending the plant towards light.
• Gibberellins aid in stem growth similar to auxins.
• Cytokinins promote cell division and are found in high concentrations in areas like fruits and seeds.
• Abscisic acid inhibits growth and causes leaf wilting.

Hormones In Animals

• Animals, including humans, use hormonal means for information transmission and coordination.
• In scary situations, animals like squirrels prepare for fight or flight responses.
• These activities require energy and coordination across various tissue types.
• Adrenaline, secreted from the adrenal glands, is a key hormone involved.
• Adrenaline is released into the bloodstream, affecting target organs like the heart.
• Effects of adrenaline include increased heart rate to supply more oxygen to muscles.
• Adrenaline also reduces blood flow to the digestive system and skin, diverting it to skeletal muscles.
• Breathing rate increases due to muscle contractions, preparing the body for action.
• Animal hormones, such as adrenaline, are part of the endocrine system for control and coordination.
• Hormonal signals reach all cells of the body, ensuring widespread physiological changes in preparation for action.
• Animal hormones serve different functions compared to plant hormones.
• Unlike plants, animal hormones do not regulate directional growth.
• Animal growth occurs in specific, controlled areas of the body.
• The body’s design ensures precise growth patterns, such as not growing fingers on faces.
• Growth in animals is carefully maintained during development, including in children.
• Iodine is crucial for the synthesis of thyroxin hormone by the thyroid gland.
• Thyroxin regulates carbohydrate, protein, and fat metabolism for balanced growth.
• Iodine deficiency can lead to conditions like goitre, characterized by a swollen neck.
• Growth hormone, secreted by the pituitary gland, regulates overall growth and development.
• Deficiency of growth hormone in childhood can result in dwarfism or excessive growth (gigantism).
• Puberty brings dramatic changes due to the secretion of testosterone in males and estrogen in females.
• Diabetes patients may need to reduce sugar intake and use insulin injections to regulate blood sugar levels.
• Insulin, produced by the pancreas, plays a crucial role in maintaining proper blood sugar levels.
• Hormone secretion is regulated by feedback mechanisms to ensure precise timing and amounts.
• When blood sugar levels rise, pancreas cells increase insulin production; when levels fall, insulin secretion decreases.