Sensory Pathways and Reflexes

Vocabulary flashcards covering sensory pathways, reflexes, pain, and the autonomic nervous system.

Sensory Receptor/Primary Neuron

Detects sensation from different sources and sends it to the CNS, converting stimuli into electrical signals.

Secondary Neuron

Occurs in the CNS, carries sensory information to the brain (thalamus).

Tertiary Neuron

Delivers sensory signals to the cerebral cortex for processing.

Somatic Reflex

A reflex where the response is carried out by skeletal muscle.

Visceral Reflex

A reflex where the response is carried out by smooth or cardiac muscle or a gland.

Ipsilateral Reflex

A reflex that begins and ends on the same side of the body.

Contralateral Reflex

A reflex that begins and ends on opposite sides of the body.

Withdrawal Reflex

A reflex where painful stimuli directly cause contraction of skeletal muscle.

Stretch Reflex

Rapid, involuntary contraction of a muscle in response to being stretched.

Tendon Reflex

Inhibits muscle contraction to prevent overstretching of tendons.

Crossed-Extensor Reflex

Activates the opposite side of the body, usually in response to painful stimuli.

Sensory Receptors

Receptors that receive sensory information (like touch, temperature, or pain).

Transducers

Another name for sensory receptors because they transduce information into electrical signals.

Adaptation (Sensory)

The process by which receptors become less sensitive to stimuli over time.

Phasic Receptors

Receptors that respond to a stimulus initially and then adapt quickly.

Tonic Receptors

Receptors that provide a constant response to a stimulus, adapting slowly or not at all.

Chemoreceptors

Receptors that detect changes in the concentration of specific chemical stimuli.

Osmoreceptors

A type of chemoreceptor that responds to solute concentrations of body fluids.

Thermoreceptors

Receptors that detect temperature changes.

Mechanoreceptors

Receptors that detect physical stimuli like pressure and vibration.

Baroreceptors

Receptors that detect blood pressure changes.

Nociceptors

Receptors that detect pain.

Photoreceptors

Receptors in the eye that detect light.

Nociceptors

Receptors that detect pain.

Somatic Pain

Pain that originates from skin, muscles, bones, and joints.

Visceral Pain

Pain that originates from internal organs, blood vessels, or the lining of a body cavity.

Referred Pain

Pain that occurs when the brain becomes confused as to the origin of the pain.

Phantom Pain

Pain that occurs when a limb is lost but the sensory nerves and pathways remain intact.

Substance P

A chemical released by nociceptors that sends a pain signal to the brain.

Endorphins

Natural painkillers released by the body to block the release of substance P.

Opioid Receptors

Receptors on the nociceptor that bind with endorphins.

Opsins

Pigments contained in cones that detect color.

Cones

Photoreceptors that work in bright light.

Light Adaptation

The process of adjusting from dark to bright light.

Sympathetic Division

The division of the autonomic nervous system that responds to threats and enables survival.

Preganglionic Neuron

The first neuron in the sympathetic pathway, with its cell body in the thoracolumbar region.

Ganglion

A cluster of nerve cells where the signal is passed to the postganglionic neuron.

Postganglionic Neuron

The second neuron in the sympathetic pathway, with its cell body in the ganglion.

Sympathetic Chain Ganglia

23 ganglia located next to the vertebral column.

Cholinergic Synapses

Synapses that use acetylcholine (ACh) as the neurotransmitter.

Adrenergic Synapses

Synapses that use norepinephrine as the neurotransmitter.

Acetylcholine (ACh)

A neurotransmitter released at cholinergic synapses.

Norepinephrine

A neurotransmitter released at adrenergic synapses.

Nicotinic Receptors

A type of receptor that binds acetylcholine in cholinergic systems.

Muscarinic Receptors

A type of receptor that binds acetylcholine in cholinergic systems.

Endogenous Ligand

A ligand produced by the body, such as acetylcholine.

Exogenous Ligand

A ligand not made by the body, such as nicotine or muscarine.

Ligand

A substance that binds to a receptor.

Parasympathetic Division

The division of the autonomic nervous system active when the body is not stressed.

Parasympathetic Ganglia

Ganglia that recieve signals from cranial nerves, which then passes the message to the organs

Nerve Plexus

Structure that spinal parasympathetic nerves travel through to pass messages.

Autonomic Reflexes

Pathways the body uses to respond to changes and maintain internal homeostasis.

Autonomic Effectors

Smooth muscle, cardiac muscle, and glands, which are the targets of autonomic reflexes.

Autonomic Plexuses

Nerve networks where sympathetic and parasympathetic axons mix.

Cardiac Plexus

An autonomic plexus that controls heart rate and contraction strength.

Pulmonary Plexus

An autonomic plexus that controls airway size in the lungs.

Esophageal Plexus

An autonomic plexus that controls swallowing and food movement.

Abdominal Aortic Plexus

An autonomic plexus that controls the functions of abdominal and pelvic organs.

Autonomic Tone

The balance of control exerted by the sympathetic and parasympathetic systems on an organ.

Celiac Plexus

Sub-plexus of the abdominal aortic plexus; controls the Liver, stomach, and pancreas

Superior Mesenteric Plexus

Sub-plexus of the abdominal aortic plexus; controls the small intestine and the first part of the large intestine

Inferior Mesenteric Plexus

Sub-plexus of the abdominal aortic plexus;control the later parts of the large intestine.

Hypogastric Plexus

Sub-plexus of the abdominal aortic plexus; controls the pelvic organs like bladder, uterus, and rectum.

Autonomic Tone= Balance control

Each organ is constantly influenced by either the sympathetic or

parasympathetic system — even at rest — but one usually dominates

depending on the organ

Which system would keep the heart rate, slow and steady

Parasympathetic system