Reflex actions are involuntary, rapid responses to stimuli, crucial for human survival. The nervous system, divided into the CNS and PNS, coordinates these reflexes through neural circuits known as reflex arcs. Reflexes like the knee-jerk and pupillary light reflex are vital for immediate protection and are categorized into types such as stretch, withdrawal, and crossed-extensor reflexes.
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Reflex actions are rapid, involuntary responses to specific stimuli that do not require the involvement of consciousness
Stretch Reflex
The stretch reflex results in muscle contraction in response to muscle stretching
Flexor or Withdrawal Reflex
The flexor or withdrawal reflex prompts a quick withdrawal from painful stimuli
Crossed-Extensor Reflex
The crossed-extensor reflex provides balance by coordinating the extension of limbs opposite to the one withdrawn
Golgi Tendon Reflex
The Golgi tendon reflex protects muscles from excessive tension by causing relaxation when the tension is too high
Reflex actions are characterized by their speed, brevity, specificity, and involuntary nature
The nervous system is a complex network of nerves and cells that transmit signals between different parts of the body
Central Nervous System (CNS)
The CNS consists of the brain and spinal cord, serving as the control center for processing information
Peripheral Nervous System (PNS)
The PNS extends from the CNS and is composed of nerves that connect the CNS to the rest of the body
Motor Nervous System
The motor nervous system is divided into the somatic nervous system and the autonomic nervous system
Somatic Nervous System
The somatic nervous system enables conscious control over skeletal muscles
Autonomic Nervous System
The autonomic nervous system regulates the activity of internal organs, blood vessels, and glands without conscious effort
Sensory Neurons
Sensory neurons carry signals from sensory receptors to the CNS
Motor Neurons
Motor neurons transmit commands from the CNS to muscles and glands
Reflex Arcs
Reflex arcs are the neural circuits responsible for reflex actions
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Nature of Reflex Actions
Rapid, involuntary responses to stimuli, bypassing conscious thought.
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Example of Reflex Action
Hand withdrawal from heat to prevent burn injuries.
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The human nervous system is divided into the ______ and the ______ nervous system.
central
peripheral
