Nervous System Physiology

The brain is divided into four main regions: the cerebrum, diencephalon, brainstem, and cerebellum.

The cerebrum and diencephalon make up the forebrain, responsible for higher-level functions.

The brainstem connects the brain to the spinal cord, controlling vital functions like breathing and heart rate.

The cerebellum is involved in coordination, balance, and movement.

The brain has four interconnected cavities called ventricles, filled with cerebrospinal fluid (CSF) that protects and cushions the CNS.

The meninges are three membranes that surround the brain and spinal cord: the dura mater, arachnoid, and pia mater.

The blood-brain barrier (BBB) is a selectively permeable barrier that prevents harmful substances from entering the brain while allowing essential nutrients to pass through.

The cerebrum is the largest part of the brain, responsible for sensory perception, emotions, consciousness, memory, and voluntary movements.

The cerebrum is divided into two hemispheres: left and right, each controlling different functions.

The surface of the cerebrum is folded into gyri (bumps) and sulci (grooves), increasing its surface area and processing power.

The cerebellum is the second largest part of the brain and is key in coordinating movements. It receives information from sensory receptors and processes it to initiate and fine-tune movements. Its main function is to ensure smooth and coordinated movements by adjusting muscle activity.

The diencephalon houses the thalamus and hypothalamus, which are responsible for important functions within the brain.

The thalamus is the relay center for all sensory information going to the cerebral cortex except smell. It plays a crucial role in processing and filtering sensory input. The thalamus acts like a gatekeeper for the senses, regulating what information reaches the cortex for conscious awareness.

The hypothalamus has a wide range of functions related to maintaining homeostasis, regulating behaviors, and controlling hormonal secretions. It is a vital control center for many bodily functions.

The brainstem consists of three structures: the midbrain, the pons, and the medulla oblongata. It is a vital relay center for signals between the brain and the spinal cord. It also controls many crucial functions such as breathing, heart rate, and sleeping.

The midbrain is involved in controlling visual and auditory reflexes, playing a role in eye movements, and regulating alertness. Its functions are key in our responses to visual and auditory stimuli as well as in maintaining our level of consciousness.

The pons is involved in regulating breathing and sleep, and it plays a role in facial expressions and taste. It also aids in coordinating movement and posture.

The medulla oblongata controls vital functions such as breathing, heart rate, swallowing, coughing, sneezing, and vomiting. It is the most inferior part of the brainstem and plays a crucial role in keeping us alive.

The spinal cord is a long, slender column of nerve tissue that extends from the brainstem down to the lower back. It carries information between the brain and the rest of the body.

The gray matter of the spinal cord, shaped like a butterfly, contains interneurons, the cell bodies and dendrites of motor neurons, and the axons of sensory neurons. This area processes information and integrates it into a response.

The left hemisphere of the brain interprets sensory information from the right side of the body, and vice versa. This means damage to one side of the brain can cause symptoms on the opposite side of the body.

The Peripheral Nervous System (PNS) transmits signals between the Central Nervous System (CNS) and the rest of the body.

The PNS includes 43 pairs of nerves: 12 cranial nerves and 31 spinal nerves.

Cranial nerves connect and transmit signals directly to the brain, affecting sensation and muscle activity in and around the head and neck.

Spinal nerves connect and transmit messages directly to the spinal cord.

Cervical nerves innervate the neck, shoulders, arms, and hands.

Thoracic nerves are associated with the chest and upper abdomen.

Lumbar nerves are associated with the lower abdomen, hips, and legs.

Sacral nerves are associated with the genitals and lower digestive tract.

All spinal nerves contain both afferent (sensory) and efferent (motor) fibers, but some cranial nerves are only afferent (carrying sensory signals) or only efferent (carrying motor signals).

The part of the peripheral nervous system responsible for controlling involuntary bodily functions like sweating, digestion, and heart rate.

The division of the ANS that triggers the 'fight or flight' response, increasing heart rate, respiration, and alertness.

The division of the ANS that counteracts the sympathetic response, promoting calmness and restoring bodily functions to a resting state.

The group of neurons in the wall of the intestinal tract that governs gut motility and digestion.

The neuron that connects the central nervous system (CNS) to a ganglion in the autonomic nervous system.

The neuron that connects a ganglion in the autonomic nervous system to the target tissue.

A cluster of nerve cell bodies outside the CNS, where the preganglionic and postganglionic neurons of the autonomic nervous system synapse.

The efferent fibers of the PNS that directly innervate skeletal muscles, responsible for voluntary movement.

The neurotransmitter released by somatic motor neurons at the neuromuscular junction, causing muscle contraction.

A motor neuron in the somatic nervous system that directly controls muscle contraction.