A report on Heart and Vagus nerve

Plan of the upper portions of the glossopharyngeal, vagus, and accessory nerves.

H&E stained fibers of the vagus nerve (bottom right) innervate the sinoatrial node tissue (middle left)

Computer-generated animation of a beating human heart

Inferior view of the human brain, with the cranial nerves labeled.

The human heart is in the middle of the thorax, with its apex pointing to the left.

Section of the neck at about the level of the sixth cervical vertebra

Heart being dissected showing right and left ventricles, from above

Transverse section of thorax, showing relations of pulmonary artery

Frontal section showing papillary muscles attached to the tricuspid valve on the right and to the mitral valve on the left via chordae tendineae.

Layers of the heart wall, including visceral and parietal pericardium

Dura mater and its processes exposed by removing part of the right half of the skull, and the brain

The swirling pattern of myocardium helps the heart pump effectively

Arterial supply to the heart (red), with other areas labelled (blue).

Section of the medulla oblongata at about the middle of the olive

Hind- and mid-brains; postero-lateral view

Development of the human heart during the first eight weeks (top) and the formation of the heart chambers (bottom). In this figure, the blue and red colors represent blood inflow and outflow (not venous and arterial blood). Initially, all venous blood flows from the tail/atria to the ventricles/head, a very different pattern from that of an adult.

Upper part of medulla spinalis and hind- and mid-brains; posterior aspect, exposed in situ

The right sympathetic chain and its connections with the thoracic, abdominal, and pelvic plexuses

The cardiac cycle as correlated to the ECG

The celiac ganglia with the sympathetic plexuses of the abdominal viscera radiating from the ganglia

The x-axis reflects time with a recording of the heart sounds. The y-axis represents pressure.

The position and relation of the esophagus in the cervical region and in the posterior mediastinum, seen from behind

Transmission of a cardiac action potential through the heart's conduction system

The thymus of a full-term fetus, exposed in situ

The prepotential is due to a slow influx of sodium ions until the threshold is reached followed by a rapid depolarization and repolarization. The prepotential accounts for the membrane reaching threshold and initiates the spontaneous depolarization and contraction of the cell; there is no resting potential.

3D echocardiogram showing the mitral valve (right), tricuspid and mitral valves (top left) and aortic valve (top right).
The closure of the heart valves causes the heart sounds.

Heart and its blood vessels, by Leonardo da Vinci, 15th century

Elize Ryd making a heart sign at a concert in 2018

The tube-like heart (green) of the mosquito Anopheles gambiae extends horizontally across the body, interlinked with the diamond-shaped wing muscles (also green) and surrounded by pericardial cells (red). Blue depicts cell nuclei.

Basic arthropod body structure – heart shown in red

The human heart viewed from the front and from behind

Heart illustration with circulatory system

Animated Heart 3d Model Rendered in Computer

The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract.

- Vagus nerve

The heart receives nerve signals from the vagus nerve and from nerves arising from the sympathetic trunk.

- Heart

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Autonomic nervous system innervation, showing the parasympathetic (craniosacral) systems in blue.

Parasympathetic nervous system

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One of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system.

Specific nerves include several cranial nerves, specifically the oculomotor nerve, facial nerve, glossopharyngeal nerve, and vagus nerve.

2) The vagus nerve does not participate in these cranial ganglia as most of its parasympathetic fibers are destined for a broad array of ganglia on or near thoracic viscera (esophagus, trachea, heart, lungs) and abdominal viscera (stomach, pancreas, liver, kidneys, small intestine, and about half of the large intestine). The vagus innervation ends at the junction between the midgut and hindgut, just before the splenic flexure of the transverse colon.

Heart rate

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Autonomic Innervation of the Heart – Cardioaccelerator and cardioinhibitory areas are components of the paired cardiac centers located in the medulla oblongata of the brain. They innervate the heart via sympathetic cardiac nerves that increase cardiac activity and vagus (parasympathetic) nerves that slow cardiac activity.

Effects of Parasympathetic and Sympathetic Stimulation on Normal Sinus Rhythm – The wave of depolarization in a normal sinus rhythm shows a stable resting HR. Following parasympathetic stimulation, HR slows. Following sympathetic stimulation, HR increases.

Heart rate (HR) (top trace) and tidal volume (Vt) (lung volume, second trace) plotted on the same chart, showing how heart rate increases with inspiration and decreases with expiration.

The various formulae provide slightly different numbers for the maximum heart rates by age.

At 21 days after conception, the human heart begins beating at 70 to 80 beats per minute and accelerates linearly for the first month of beating.

Heart rate monitor with a wrist receiver

In obstetrics, heart rate can be measured by ultrasonography, such as in this embryo (at bottom left in the sac) of 6 weeks with a heart rate of approximately 90 per minute.

Pulsatile retinal blood flow in the optic nerve head region revealed by laser Doppler imaging

Heart rate (or pulse rate) is the speed of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm).

The accelerans nerve provides sympathetic input to the heart by releasing norepinephrine onto the cells of the sinoatrial node (SA node), and the vagus nerve provides parasympathetic input to the heart by releasing acetylcholine onto sinoatrial node cells.

Sinoatrial node

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Figure 2: Low magnification stained image of the SA node (center-right on image) and its surrounding tissue. The SA node surrounds the sinoatrial nodal artery, seen as the open lumen. Cardiac muscle cells of the right atrium can be seen to the left of the node, and fat tissue to the right.

Figure 3: Sinoatrial node action potential waveform, outlining major ion currents involved (downward deflection indicates ions moving into the cell, upwards deflection indicates ions flowing out of the cell).

Schematic representation of the atrioventricular bundle

The sinoatrial node (also known as the sinuatrial node, SA node or sinus node) is a group of cells known as pacemaker cells, located in the wall of the right atrium of the heart.

The parasympathetic nerves supplying the SA node (in particular the Vagus nerves) originate in the brain.

Lung

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The lungs are the primary organs of the respiratory system in humans and most animals, some fish and some snails.

Thick elastic fibres from the visceral pleura (outer lining) of lung

TEM image of collagen fibres in a cross sectional slice of mammalian lung tissue.

A lobule of the lung enclosed in septa and supplied by a terminal bronchiole that branches into the respiratory bronchioles. Each respiratory bronchiole supplies the alveoli held in each acinus accompanied by a pulmonary artery branch.

3D Medical illustration showing different terminating ends of bronchioles.

The lungs as main part of respiratory tract

3D rendering of a high-resolution CT scan of the thorax. The anterior thoracic wall, the airways and the pulmonary vessels anterior to the root of the lung have been digitally removed in order to visualize the different levels of the pulmonary circulation.

Lungs during development, showing the early branching of the primitive bronchial buds

The effect of the respiratory muscles in expanding the rib cage.

Tissue death of the lung due to a pulmonary embolism

3D still image of constricted airways as in bronchial asthma.

Lung tissue affected by emphysema using H&E stain.

On inhalation, air travels to air sacs near the back of a bird. The air then passes through the lungs to air sacs near the front of the bird, from where the air is exhaled.

The cross-current respiratory gas exchanger in the lungs of birds. Air is forced from the air sacs unidirectionally (from left to right in the diagram) through the parabronchi. The pulmonary capillaries surround the parabronchi in the manner shown (blood flowing from below the parabronchus to above it in the diagram). Blood or air with a high oxygen content is shown in red; oxygen-poor air or blood is shown in various shades of purple-blue.

The axolotl (Ambystoma mexicanum) retains its larval form with gills into adulthood

In mammals and most other vertebrates, two lungs are located near the backbone on either side of the heart.

Input from the parasympathetic nervous system occurs via the vagus nerve.

Esophagus

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Organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the stomach.

The esophagus is constricted in three places.

A mass seen during an endoscopy and an ultrasound of the mass conducted during the endoscopy session.

The esophagus is a fibromuscular tube, about 25 cm long in adults, that travels behind the trachea and heart, passes through the diaphragm, and empties into the uppermost region of the stomach.

Its smooth muscle is innervated by involuntary nerves (sympathetic nerves via the sympathetic trunk and parasympathetic nerves via the vagus nerve) and in addition voluntary nerves (lower motor neurons) which are carried in the vagus nerve to innervate its striated muscle.

Cardiac plexus

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The cardiac plexus is a plexus of nerves situated at the base of the heart that innervates the heart.

It is formed by the superior cervical cardiac branch of the left sympathetic trunk and the inferior cardiac branch of the left vagus nerve.

Atropine

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Tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery.

In cardiac uses, it works as a nonselective muscarinic acetylcholinergic antagonist, increasing firing of the sinoatrial node (SA) and conduction through the atrioventricular node (AV) of the heart, opposes the actions of the vagus nerve, blocks acetylcholine receptor sites, and decreases bronchial secretions.