Human Physiology: Sensory Receptors Quiz

Nervous System Overview

• The nervous system is divided into two main parts: the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).
• The CNS includes the brain and spinal cord.
• The brain receives and processes sensory information, initiates responses, stores memories, generates thoughts, and emotions.
• The spinal cord conducts signals to and from the brain, and controls reflex activities.
• The PNS transmits signals between the CNS and the rest of the body.
• The PNS is further divided into the Somatic Nervous System and the Autonomic Nervous System.
• The Somatic Nervous System controls voluntary movements.
• The Autonomic Nervous System controls involuntary responses, such as heart rate and digestion.
• The Autonomic Nervous System has two divisions: the sympathetic and parasympathetic divisions.
• The sympathetic division is associated with "fight or flight" responses.
• The parasympathetic division is associated with "rest or digest" responses.

Nervous Tissue

• Nervous tissue is composed of two main types of cells: nerve cells (neurons) and neuroglia.
• Neurons are specialized cells designed to transmit electrical signals.
• Neuroglia are supporting cells that provide support and protection for neurons.

Nerve Cells (Neurons)

• Neurons have three main parts: a cell body, dendrites, and an axon.
• The cell body contains the nucleus and other organelles.
• Dendrites receive incoming signals from other neurons.
• The axon transmits signals away from the cell body to other neurons or target organs.
• Neurons come in different types, including multipolar, bipolar, and unipolar neurons.
• The structure of neurons is optimized for transmission of electrical signals.

Neuroglia

• Neuroglia in the CNS include astrocytes, oligodendrocytes, microglia, and ependymal cells.
• Neuroglia in the PNS include Schwann cells and satellite cells.
• Astrocytes provide metabolic and mechanical support for neurons.
• Oligodendrocytes produce an insulating barrier called the myelin sheath in the CNS.
• Microglia act as immune defense cells against invading microorganisms and pathogens.
• Ependymal cells create, secrete, and circulate cerebrospinal fluid.
• Schwann cells produce an insulating barrier called the myelin sheath in the PNS.
• Satellite cells support neuron cell bodies in ganglia.

Synapses

• A synapse is the meeting point between two neurons, where signals are transmitted from one neuron to another.
• Synapses have a structure designed for signal transmission.
• Synapses are essential for communication in the nervous system.

Ganglia

• Sensory ganglia are collections of neuron cell bodies outside the CNS, that receive and transmit sensory impulses.
• Autonomic ganglia are associated with the autonomic nervous system and are located within or near certain organs.
• Ganglia are critical for integrating and relaying nerve signals.

Nerve Endings

• Nerve endings include receptors and effectors.
• Receptors receive stimuli or impulses from outside the body or from tissues and transmit these signals to the CNS.
• Effectors transmit impulses from the CNS to skeletal or smooth muscles and glands (such as secretory endings), causing actions.
• Receptors and effectors are essential for the overall function of the nervous system.

Receptors

• Receptors are classified according to the site of stimulation, type of stimulation, and histological structure.
• Receptors include exteroceptors, proprioceptors, and visceroceptors.
• Receptors also include mechanoreceptors, thermoreceptors, nociceptors (pain receptors) and those for special senses (such as sight, hearing, taste, touch, smell).
• Different types of receptors detect and respond to different stimuli.

Effectors

• Effectors transmit impulses from the CNS to perform specific responses.
• The two types are somatic effectors, which stimulate skeletal muscle, and autonomic effectors, which stimulate smooth muscle, cardiac muscle, and glands.
• Autonomic effectors use different neurotransmitters than somatic effectors.

Autonomic Nervous System Pathway

• Autonomic pathways consist of two neurons that synapse in an autonomic ganglion.
• Preganglionic fibers originate in the CNS, and postganglionic fibers connect to effectors.

Types of Ganglia

• Ganglia are collections of nerve cell bodies outside the CNS. Some types of Ganglia are sensory ganglia and autonomic ganglia, and the sympathetic and parasympathetic divisions.