Human Physiology-Neural Control And Coordination Topic
Neural Control and Coordination - Detailed Notes
Reference textbooks: NCERT Biology Class 11 and Class 12
1. The Nervous System:
-
Basic structure and organization:
- Central Nervous System (CNS) - brain and spinal cord.
- Peripheral Nervous System (PNS) - nerves connecting CNS to sensory organs and muscles.
- Neuron: Basic structural and functional unit of the nervous system, responsible for transmitting information/signals.
-
Types of neurons:
- Sensory neurons: Transmit information from sense organs to the CNS.
- Motor neurons: Transmit information from the CNS to muscles and glands.
- Interneurons: Connect sensory neurons and motor neurons within the CNS.
-
Synapse and neuron transmission:
- Electrical transmission - Fast transmission of signals along the neuron’s axon in the form of action potentials (electrical impulses).
- Chemical transmission - Slower transmission of signals across synapses (junctions between neurons) using neurotransmitters (chemical messengers).
2. Central Nervous System (CNS)
-
Structure of the brain:
- Cerebrum: Largest part of the brain involved in higher-level functions such as cognition, reasoning, emotions, and voluntary movements.
- Cerebellum: Controls coordination, balance, and posture.
- Brainstem: Connects the brain to the spinal cord and controls vital functions like breathing, heart rate, and sleep cycles.
-
Functional regions of the brain:
- Motor cortex: Controls voluntary body movements.
- Sensory cortex: Processes sensory information from the body and external environment.
- Association areas: Involved in complex brain functions like memory, learning, and language processing.
-
Reflex arc and its components:
- A rapid, automatic, and involuntary response to stimuli.
- Components:
- Receptor - Detects the stimulus.
- Sensory neuron - Transmits the signal to the spinal cord.
- Motor neuron - Transmits the signal back to the effector muscle.
- Effector (muscle) - Responds to the signal.
-
Role of the spinal cord in reflex actions:
- Conducts sensory information from the body towards the brain and motor commands from the brain towards the body.
- Plays a crucial role in reflex actions that occur at the spinal level.
3. Peripheral Nervous System (PNS):
- Structure and function of the somatic and autonomic nervous systems:
- Somatic Nervous System (SNS): Controls voluntary skeletal muscle movements.
- Autonomic Nervous System (ANS): Controls involuntary functions such as heart rate, digestion, and respiration.
- Sympathetic and parasympathetic divisions of the ANS:
- Sympathetic System - Controls responses for the “Fight-or-flight” response.
- Parasympathetic System - Controls “Rest-and-digest” responses.
- Neurotransmitters involved: Acetylcholine (ACh) is the primary neurotransmitter for most of the PNS, including both SNS and ANS.
4. Sensory Mechanisms:
- General senses and specialized senses:
- General senses: Somatic senses such as touch, pressure, pain, temperature.
- Special senses: Vision, hearing, taste, and smell.
- Structure and function of the sense organs:
- Eye - Detects light and transmits visual information.
- Ear - Detects sound waves and helps in hearing and balance.
- Nose - Detects odors.
- Tongue - Detects taste sensations.
- Skin - Detects sensations of touch, pressure, pain, and temperature.
- Sensory receptors and their role in perception:
- Specialized cells that convert physical stimuli (light, sound, chemicals, etc.) into electrical signals.
- These signals are then transmitted to the CNS for processing and perception.
5. Muscle Physiology:
- Structure and types of muscles:
- Skeletal muscle - Voluntary muscles attached to the skeleton.
- Smooth muscle - Involuntary muscles found in internal organs and blood vessels.
- Cardiac muscle - Involuntary muscle found in the heart.
- Mechanism of muscle contraction:
- Sliding filament theory explains the mechanism of muscle contraction.
- Involves the interaction of actin and myosin filaments in response to nerve signals.
- Role of the neuromuscular junction in muscle contraction:
- The neuromuscular junction is the site of communication between a motor neuron and a muscle fiber.
- When an action potential reaches the neuromuscular junction, it triggers the release of neurotransmitters (e.g., ACh) that initiate muscle contraction.
- Muscle fatigue and relaxation:
- Muscle fatigue: Decreased ability of a muscle to contract, often caused by prolonged use.
- Muscle relaxation: Return of a muscle to its resting state after contraction.
6. Brain Organization:
- Functional areas of the cerebral cortex:
- Motor cortex: Controls voluntary movement.
- Sensory cortex: Processes sensory information.
- Association areas: Involved in higher-level functions such as memory, language, and decision-making.
- Hemispheric specialization and lateralization of functions:
- Left hemisphere: Dominant in language processing and logical thinking.
- Right hemisphere: Dominant in spatial processing, visual perception, and emotions.
7. Hormonal Control:
- Role of hormones in neural coordination:
- Hormones secreted by endocrine glands can affect neural function.
- Examples: Adrenaline (epinephrine) from the adrenal medulla is involved in the fight-or-flight response.
- Pituitary gland and its importance:
- Master gland of the endocrine system, controls other endocrine glands.
- Secretes hormones that regulate growth, reproduction, and metabolism.
- Integration of nervous and hormonal signals:
- The nervous and endocrine systems work together to maintain homeostasis.
- Example: Adrenaline increases heart rate and blood pressure during the fight-or-flight response.
8. Autonomic Nervous System:
- Regulation of heart rate, respiration, and digestion:
- ANS controls heart rate, breathing, and digestive movements.
- Sympathetic division increases these functions during times of stress, while the parasympathetic division decreases them during times of rest and relaxation.
- Fight-or-flight response and its hormonal basis:
- Sudden mobilization of the body’s resources in response to stress or danger.
- Controlled by the sympathetic nervous system and hormones like adrenaline (epinephrine).
9. Neurodegenerative Disorders:
- Basic concepts of neurodegenerative disorders:
- A group of neurological conditions characterized by progressive degeneration and death of neurons.
- Examples: Alzheimer’s disease, Parkinson’s disease, Huntington’s disease.
- Role of neural control and coordination in these disorders:
- Affect motor control, coordination, cognitive functions, and behavior due to the loss of specific types of neurons.