from nerves cells 2 Flashcards
What are the main functions of the nervous system?
Communication, coordination, and control: sensing the environment, processing information, and responding.
How did nervous systems evolve in simple organisms like Amoeba and Hydra?
Amoeba: Uses the nucleus for basic communication.
Hydra: Has a nerve net for intercellular communication and specialized functions like secretion and movement.
What is cephalization, and which organism demonstrates it?
Cephalization is the clustering of sensory receptors at the front end of an organism, forming a primitive brain. Example: Planaria (flatworms).
How is the nervous system of an earthworm specialized?
It is segmented, with ganglia in each segment to coordinate regional functions and decentralized brain activity.
What are the three types of neurons based on function?
Afferent neurons: Carry information to the CNS.
Efferent neurons: Carry information away from the CNS.
Interneurons: Connect neurons within the CNS.
What are the three types of neurons based on morphology?
Unipolar: Branched axon, no dendrites (e.g., sensory neurons).
Bipolar: One axon, one dendrite (e.g., retina).
Multipolar: One axon, several dendrites (e.g., motor neurons).
What are the two anatomical divisions of the nervous system?
Central Nervous System (CNS): Brain and spinal cord.
Peripheral Nervous System (PNS): Sensory (afferent) and motor (efferent) neurons.
What are the two functional divisions of the Peripheral Nervous System (PNS)?
Somatic Nervous System: Controls voluntary movements (skeletal muscles).
Autonomic Nervous System (ANS): Regulates involuntary functions (internal organs, smooth muscle, glands).
What are the two subdivisions of the Autonomic Nervous System (ANS)?
Sympathetic: “Fight or flight” response (e.g., increases heart rate, dilates pupils).
Parasympathetic: “Rest and digest” response (e.g., reduces heart rate, stimulates digestion).
What neurotransmitters are used by the nervous system?
Preganglionic neurons: Acetylcholine (ACh).
Sympathetic postganglionic neurons: Noradrenaline.
Parasympathetic postganglionic neurons: Acetylcholine (ACh).
What are the main sensory receptors, and what do they detect?
External: Touch, temperature, pain, light, sound, taste, smell.
Internal: Blood pressure, blood volume, temperature, pain, blood gases.
What are the main features of the sympathetic and parasympathetic nervous systems?
Sympathetic: Short preganglionic, long postganglionic neurons; “Fight or flight.”
Parasympathetic: Long preganglionic, short postganglionic neurons; “Rest and digest.”
