Biology Neural System Chapter Quiz

Study Notes

Composed of specialized cells called neurons for detecting, receiving, and transmitting stimuli.
Simplest neural organization in lower invertebrates, like Hydra, which has a network of neurons.
Insects possess a more advanced structure with a brain, ganglia, and neural tissues.
Vertebrates, including humans, have a highly developed neural system.

Divided into two main parts:
- Central Nervous System (CNS): Includes the brain and spinal cord; processes and controls information.
- Peripheral Nervous System (PNS): Comprises all nerves linked to the CNS.
PNS consists of two types of nerve fibres:
- Afferent fibres: Transmit impulses from organs to CNS.
- Efferent fibres: Carry regulatory impulses from CNS to peripheral tissues.
Further divided into:
- Somatic Nervous System: Relays impulses to skeletal muscles.
- Autonomic Nervous System: Relays impulses to involuntary organs and smooth muscles.

Neurons are excitable cells with polarized membranes.
At rest, axonal membranes are more permeable to potassium ions (K+) than to sodium ions (Na+).
Sodium-potassium pump maintains ionic concentration gradients, critical for impulse generation.
Action potential is the electrical potential difference across the membrane when depolarization occurs.
Impulse conduction involves sequential depolarization along the axon, creating a wave of action potentials.

Occurs at synapses, the junctions between neurons.
Signals are transmitted chemically using neurotransmitters.
Each presynaptic neuron connects with a postsynaptic neuron, often separated by a synaptic cleft.

Sensory organs detect changes in the environment and send signals to the CNS for processing.
The nose detects smell through olfactory receptors located in the olfactory epithelium, sending signals to the olfactory bulb in the limbic system.
The tongue perceives taste via taste buds, integrating signals for complex flavor interpretations.

Human eyes are located in orbits and serve as sensory organs for vision.
Information regarding environmental changes is relayed through sensory organs to the CNS for further processing.

The brain is divided into three major parts:
- Forebrain: Includes the cerebrum (longitudinally divided, connected by corpus callosum), thalamus, and hypothalamus, which regulates body temperature, thirst, and hunger.
- Midbrain: Integrates visual, tactile, and auditory inputs.
- Hindbrain: Comprises pons, cerebellum, and medulla; regulates respiration, cardiovascular reflexes, and muscle coordination.

Reflex actions are involuntary responses to stimuli, processed by the CNS after sensory input.
Crucial for rapid responses to environmental changes, reinforcing the importance of the neural system in coordinating bodily functions.

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