Biology Grade 10 Workbook

Neural Control and Coordination

About the Program

• STEM GENIUS is a foundation program for JEE, NEET, NTSE, NMMSE, OLYMPIAD, etc.
• Designed and executed by IITians, NITians, and Doctors
• The course aims to equip students of 8th, 9th, and 10th grades with a strong foundation in subjects like Science, Mathematics, and Mental ability

Chapter 1: Neural Control and Coordination

• The senses that evoke responses in organisms are called receptors
• Neurons are specialized cells that receive stimuli
• The basic structural unit of the nervous system is the neuron
• Dendrites are branches of a neuron that receive impulses from adjacent neurons
• Axons are long filaments from the cell body of a neuron that transmit impulses
• Myelin sheath is a lipid-containing membrane that surrounds axons and is formed by Schwann cells and oligodendrocytes
• The junction between two neurons or a neuron and a muscle cell or a glandular cell is called a synapse
• Acetylcholine is a neurotransmitter that transmits nerve impulses

Brain Structure

• The brain has three main parts: Forebrain, Midbrain, and Hindbrain
• The Forebrain is the thinking part of the brain and includes the Cerebrum and Cerebellum
• The Cerebrum is divided into two hemispheres: Left hemisphere and Right hemisphere
• The Cerebellum is responsible for maintaining equilibrium and posture
• The Medulla oblongata is the lowest part of the brain and connects to the Spinal cord
• The Spinal cord is a long, thin, tube-like structure that extends from the base of the brain down to the lower back

Reflex Action

• A reflex action is a rapid, automatic response to a stimulus
• The pathway of impulses in a reflex action is called a reflex arc
• Reflex actions do not involve the brain integration
• Cerebral reflexes are reflexes that are under the control of the cerebrum

Nervous System

• The Nervous system is divided into two parts: Central nervous system (CNS) and Peripheral nervous system (PNS)
• The CNS includes the Brain and Spinal cord
• The PNS includes Sensory nerves and Motor nerves
• The Autonomic nervous system is a part of the PNS that controls involuntary actions
• The Autonomic nervous system is divided into two parts: Sympathetic nervous system and Parasympathetic nervous system### Endocrine System
• Definition: The endocrine system is a network of glands that produce and regulate hormones in the body.

Hormones and Their Functions

• Hormones are chemical messengers that help regulate various bodily functions.
• Insulin: produced by the pancreas, regulates blood sugar levels.
• Glucagon: produced by the pancreas, raises blood sugar levels.
• Thyroxine (T4): produced by the thyroid gland, regulates metabolism.
• Parathormone: produced by the parathyroid gland, regulates calcium levels in the blood.
• Adrenaline (Epinephrine): produced by the adrenal gland, stimulates the "fight or flight" response.
• Melatonin: produced by the pineal gland, regulates sleep-wake cycles.

Endocrine Glands

• Pancreas: produces insulin and glucagon.
• Thyroid gland: produces thyroxine (T4).
• Parathyroid gland: produces parathormone.
• Adrenal gland: produces adrenaline (epinephrine).
• Pineal gland: produces melatonin.
• Thymus gland: regulates the development of immune cells.
• Pituitary gland: regulates hormone production in other endocrine glands.

Hormone Regulation

• Feedback mechanisms: hormone levels are regulated through negative feedback loops.
• Hormone receptors: specific receptors on target cells bind to hormones, triggering a response.

Disorders and Conditions

• Diabetes: high blood sugar levels due to insulin deficiency or resistance.
• Hypothyroidism: underactive thyroid gland, leading to low thyroxine levels.
• Hyperthyroidism: overactive thyroid gland, leading to high thyroxine levels.
• Hyperparathyroidism: overactive parathyroid gland, leading to high calcium levels.
• Acromegaly: excessive growth hormone production, leading to abnormal growth.

Pheromones

• Chemical signals: used for communication between organisms, such as attracting mates.

Hormones in Plants

• Ethylene: involved in fruit ripening.
• Auxin: regulates plant growth and development.
• Cytokinin: regulates cell division and growth.
• Abscisic acid: regulates seed dormancy and plant stress responses.

Other Key Concepts

• Homeostasis: the body's ability to maintain a stable internal environment despite changes in external conditions.

• Negative feedback loops: mechanisms that regulate hormone levels and maintain homeostasis.### Endocrine System

• Movement in plants independent of growth: Tropic movements (e.g., phototropism, chemotropism) and nastic movements (e.g., touch, temperature).

Plant Hormones

• Tropisms: Directional growth or movement of plants in response to external stimuli (e.g., light, gravity, chemicals).
• Auxins: Hormones responsible for phototropism, promoting cell elongation and growth.
• Gibberellins: Hormones involved in seed germination, stem elongation, and leaf growth.
• Cytokinins: Hormones that promote cell division, differentiation, and shoot growth.
• Abscisic acid (ABA): Hormone involved in stress responses, seed dormancy, and stomatal closure.

Animal Hormones

• Insulin: Hormone produced by pancreatic beta cells, regulates blood sugar levels.
• Glucagon: Hormone produced by pancreatic alpha cells, raises blood sugar levels.
• Adrenocorticotropic hormone (ACTH): Hormone produced by the pituitary gland, stimulates adrenal cortex to produce glucocorticoids.
• Oxytocin: Hormone produced by the hypothalamus, involved in milk letdown, uterine contractions, and social behavior.

Human Endocrine System

• Pituitary gland: Located at the base of the brain, regulates other endocrine glands through tropic hormones.
• Thyroid gland: Produces thyroxine (T4) and triiodothyronine (T3), regulates metabolism.
• Adrenal glands: Produce glucocorticoids (e.g., cortisol), mineralocorticoids (e.g., aldosterone), and androgens (e.g., testosterone).
• Pancreas: Produces insulin, glucagon, and somatostatin, regulates blood sugar levels.

Hormone Regulation

• Hypothalamus-pituitary axis: The hypothalamus produces releasing hormones, which stimulate the pituitary gland to produce tropic hormones.
• Negative feedback mechanisms: Hormones can inhibit the production of other hormones to maintain homeostasis.

Plant Growth and Development

• Etiolation: Elongation of stems and reduced leaf growth in plants grown in low-light conditions.
• Hydrotropism: Directional growth of plants in response to water.
• Haptotropism: Directional growth of plants in response to physical contact.

Other Concepts

• Pheromones: Chemical substances released by organisms to communicate with others of the same species.
• Nastic movements: Non-directional responses to external stimuli, such as touch, temperature, or light.
• Hydrophily: A type of pollination that occurs in aquatic environments, where water is the medium for transferring pollen.