Nervous System Organization and Function

Flashcards covering the structural and functional divisions of the nervous system, homeostasis, feedback loops, receptors, and neurons.

Homeostasis

Equilibrium in the body’s internal environment

Stimuli that disrupt homeostasis

External (e.g., heat, cold, lack of O2) and internal (e.g., psychological stress, exercise)

Body systems responsible for maintaining homeostasis

Endocrine System & Nervous System

Endocrine system signals

Hormones

Nervous system signals

Nerve impulses

System that sends very rapid signals

Nervous System

Components of a feedback loop

Receptor, control center, and effector

Receptor function in the feedback loop

Monitors a controlled condition

Control center function in the feedback loop

Determines next action

Effector function in the feedback loop

Receives directions from the control center and produces a response

Sensory function of the nervous system

Receptors sense changes in internal/external environment; sensory (afferent) neurons conduct sensory impulses

Integrative function of the nervous system

Analyze & store sensory information; make decisions regarding appropriate responses; interneurons serve this function

Motor function of the nervous system

Respond to stimuli by initiating action; motor (efferent) neurons conduct motor impulses to effectors

Central Nervous System (CNS)

Brain and spinal cord.

Peripheral Nervous System (PNS)

Cranial nerves (12 pairs) and spinal nerves (31 pairs)

CNS functions

Analysis and interpretation of neural input (sensory); coordination and execution of neural output (motor); reflexes; logical thought; memory; emotions

PNS functions

Carry sensory nerve impulses to the CNS and carry motor nerve impulses away from the CNS

Somatic Nervous System (SNS)

Carries sensory input about body sensations and special senses to the CNS; allows conscious control of skeletal muscles (voluntary)

Autonomic Nervous System (ANS)

Subconscious control of organs and glands; carries sensory input from visceral receptors to the CNS; carries motor output to smooth muscle, heart muscle, and/or glands (involuntary)

Sympathetic Nervous System

Prepares the body for emergencies or energy expenditure; ‘fight or flight’ response

Parasympathetic Nervous System

‘Restores’ body at rest; energy conservation and restoration; ‘rest & digest’

Enteric Nervous System

Regulates smooth muscle, glands, and endocrine cells of the GI tract and is involuntary.

Nervous System Function - General Model

Receptors -> Sensory Neurons -> CNS (Interneurons) -> Motor Neurons -> Effectors

Receptors Location

External (on body surface) and Internal (within body tissue/organs)

Receptors Function

Detect stimulus and generate nerve impulses in sensory neurons

Mechanoreceptors

Detect deformation, bending, stretching of cells (touch, pressure, vibration, proprioception, hearing)

Thermoreceptors

Detect changes in temperature

Nociceptors

Detect painful stimuli - Physical / chemical damage to tissues

Photoreceptors

Detect light in the retina of the eye

Chemoreceptors

Detect chemicals (taste, smell, body fluids)

Osmoreceptors

Detect osmolarity of body fluids

Sensory (afferent) neurons Location

Part of the PNS

Sensory (afferent) neurons Function

Carry nerve impulses from receptors to the CNS

Interneurons Location

CNS (brain & spinal cord - grey matter)

Interneurons Function

Link sensory, motor and CNS neurons; essential for coordination between various divisions of the nervous system

Motor (efferent) neurons Location

Part of the PNS

Motor (efferent) neurons Function

Carry nerve impulses from the CNS to effectors

Effectors

Muscles (skeletal, cardiac & smooth) and glands that alter their activity in response to motor nerve impulses