Physiology of Vomiting - Vomiting reflex (NEW)

Summary

This video delves into the physiology of vomiting, also known as emesis. It explains the involuntary process as the forceful expulsion of stomach contents through the mouth, triggered by the vomiting reflex. The medulla oblongata in the brainstem houses the vomiting center, which initiates the reflex upon stimulation by muscarinic receptors. The chemoreceptor trigger zone (CTZ), located outside the blood-brain barrier, is sensitive to chemicals like those in chemotherapy and motion sickness. It interacts with the vomiting center to induce vomiting. The video also covers the role of the vestibular system in motion sickness and how higher brain centers respond to emotional states and sensory inputs to trigger vomiting. Finally, it outlines the physiological changes during vomiting, including muscle contractions and autonomic responses.

Takeaways

• 🤮 Vomiting, also known as emesis or throwing up, is an involuntary, forceful expulsion of stomach contents through the mouth.
• 🧠 The vomiting reflex is controlled by the vomiting center located in the medulla oblongata of the brainstem, which contains muscarinic receptors.
• 🧪 The chemoreceptor trigger zone (CTZ), situated outside the blood-brain barrier, is sensitive to chemicals and can be stimulated by drugs like those used in chemotherapy.
• 🚫 The blood-brain barrier protects the brain from circulating substances, but the CTZ's location outside this barrier makes it more susceptible to such substances.
• 🌀 Motion sickness, caused by the inner ear's vestibular system, can stimulate the CTZ, leading to the vomiting reflex.
• 🤰 Morning sickness is another condition that can trigger the vomiting reflex, often due to hormonal changes during pregnancy.
• 🤢 The cerebrum can also initiate vomiting through the vomiting center when processing sensory information related to strong smells or sights.
• 🔁 The stomach's enterochromaffin cells release serotonin in response to cytotoxic agents, which can trigger the vomiting reflex via the vagal nerve.
• 🔁 The vomiting reflex involves the relaxation of the lower esophageal sphincter, contraction of the diaphragm and abdominal muscles, and closure of the epiglottis to prevent aspiration.
• 🤧 Autonomic changes during vomiting include increased heart rate, salivation, and peristalsis, which all contribute to the forceful expulsion of stomach contents.

Q & A

What is vomiting also known as?

Vomiting is also known as emesis and throwing up, amongst many other terms.

What is the involuntary forceful expulsion of stomach contents through the mouth called?

The involuntary forceful expulsion of stomach contents through the mouth is called the emetic reflex or the vomiting reflex.

Where is the vomiting center located in the brain?

The vomiting center is located in the medulla oblongata of the brainstem.

What types of receptors are found in the vomiting center?

The vomiting center contains muscarinic receptors.

What is the chemo receptor trigger zone (CTZ) and where is it located?

The chemo receptor trigger zone (CTZ) is an area near the medulla oblongata that gets triggered by chemicals and is located outside the blood-brain barrier.

Which receptors are found in the chemo receptor trigger zone (CTZ)?

The CTZ contains dopamine 2 receptors and 5-HT receptors, which are serotonin receptors.

How does motion sickness relate to the vomiting reflex?

Motion sickness, which originates from the inner ear's Labyrinth, can stimulate the vestibular nuclei, which then sends signals to the CTZ, leading to the vomiting reflex.

What is the role of the higher brain centers in initiating the vomiting reflex?

The higher brain centers can sense emotional overwhelm, severe pain, bad smells, or repulsive sights and send signals to the vomiting center to initiate the vomiting reflex.

How do interoceptive cells in the stomach contribute to the vomiting reflex?

Interoceptive cells in the stomach release serotonin in response to cytotoxic agents, which can stimulate 5-HT3 receptors on sensory nerve fibers, leading to the activation of the vomiting center.

What happens during the vomiting reflex that facilitates the expulsion of stomach contents?

During the vomiting reflex, the lower esophageal sphincter relaxes, the diaphragm and abdominal muscles contract to increase intra-abdominal pressure, and the epiglottis closes to prevent food from entering the lungs.

What autonomic changes occur during the vomiting reflex?

Autonomic changes during the vomiting reflex include an increase in heart rate (tachycardia), increased salivation, and peristalsis.

Outlines

00:00

🤮 Understanding Vomiting Reflex

This paragraph delves into the physiology of vomiting, also known as emesis or throwing up. It explains the involuntary forceful expulsion of stomach contents through the mouth. The emetic reflex, or vomiting reflex, is controlled by the medulla oblongata in the brainstem, which contains the vomiting center with muscarinic receptors. These receptors, when stimulated, trigger the vomiting reflex. The chemoreceptor trigger zone (CTZ), located near the medulla oblongata but outside the blood-brain barrier, is sensitive to chemicals like those found in chemotherapy and motion sickness. The CTZ, when stimulated, activates the muscarinic receptors in the vomiting center. The paragraph also discusses how the vestibular nuclei, which contain histamine and muscarinic receptors, can be stimulated by the inner ear's Labyrinth, leading to motion sickness and vomiting. Lastly, it mentions how higher brain centers can initiate the vomiting reflex in response to emotional, olfactory, or visual stimuli.

05:01

🔍 Anatomy and Physiology of Vomiting

The second paragraph recaps the anatomy involved in vomiting, starting from the mouth down to the stomach and small intestine. It highlights the role of Intero chromin cells in the stomach, which release serotonin in response to cytotoxic agents, potentially stimulating 5-HT3 receptors on sensory nerve fibers. This stimulation, via the vagal nerve, communicates with the vomiting center to trigger the vomiting reflex. The paragraph summarizes that all causes of vomiting stimulate the vomiting center, leading to the emetic reflex. It then describes the process of vomiting, which includes the relaxation of the lower esophageal sphincter, contraction of the diaphragm and abdominal muscles to increase intra-abdominal pressure, and autonomic changes like increased heart rate and salivation. The vomiting reflex also causes the epiglottis to close to prevent food from entering the lungs, culminating in the expulsion of food.

Keywords

💡Vomiting

Vomiting, also known as emesis or throwing up, is an involuntary forceful expulsion of the contents of the stomach through the mouth. It is a key concept in the video as it sets the stage for discussing the physiological mechanisms behind this reflex. The video explains that vomiting is triggered by various stimuli and is controlled by specific areas in the brain.

💡Emetic Reflex

The emetic reflex, synonymous with the vomiting reflex, is the body's response to certain stimuli that result in vomiting. The video delves into the reflex's physiological process, highlighting how it is initiated and executed by the body to expel stomach contents. This reflex is central to understanding the video's theme of the physiology of vomiting.

💡Medulla Oblongata

The medulla oblongata is a part of the brainstem that houses the vomiting center. The video explains that this area contains muscarinic receptors, which, when stimulated, can trigger the vomiting reflex. It is crucial in the process of vomiting as it is the location where the reflex is initiated.

💡Chemoreceptor Trigger Zone (CTZ)

The chemoreceptor trigger zone, or CTZ, is another area near the medulla oblongata that plays a significant role in vomiting. It is sensitive to chemicals and contains dopamine 2 and 5-HT (serotonin) receptors. The video mentions that the CTZ, being outside the blood-brain barrier, can be stimulated by circulating substances, leading to the vomiting reflex.

💡Blood-Brain Barrier

The blood-brain barrier is a protective layer that prevents substances in the bloodstream from entering the brain. The video explains that the CTZ's location outside this barrier makes it more susceptible to external stimuli, such as those from chemotherapy, which can cause vomiting.

💡Labyrinth

The labyrinth is a bony structure in the inner ear that contributes to balance. The video describes how motion sickness, a common cause of vomiting, originates from the labyrinth. It sends signals to the brain stem when there are spatial orientation issues, which can lead to the activation of the vomiting reflex.

💡Vestibular Nuclei

The vestibular nuclei are located in the brainstem and are involved in balance and spatial orientation. The video mentions that when the vestibular nuclei are stimulated, such as during motion sickness, it can send signals to the CTZ, which then triggers the vomiting reflex.

💡Cerebrum

The cerebrum is the largest part of the brain, responsible for higher cognitive functions. The video explains that sensory information processed by the cerebrum, such as emotional stress or repulsive sights and smells, can lead to the activation of the vomiting center and initiate the vomiting reflex.

💡Interoceptive Cells

Interoceptive cells, found in the stomach, release serotonin in response to cytotoxic agents. The video describes how these cells are involved in the vomiting process, as their release of serotonin can stimulate the 5-HT3 receptors on sensory nerve fibers, leading to the activation of the vomiting center.

💡Vagal Nerve

The vagal nerve is a cranial nerve that plays a role in the vomiting reflex. The video explains that stimulation of the sensory nerve fibers, which include the vagal nerve, can bring information to the vomiting center, thus triggering the reflex. This nerve is crucial in the communication between the stomach and the vomiting center.

Highlights

Vomiting, also known as emesis, is an involuntary forceful expulsion of stomach contents through the mouth.

The emetic reflex, or vomiting reflex, is a key mechanism in understanding vomiting.

The medulla oblongata in the brainstem houses the vomiting center, which initiates the vomiting reflex.

The vomiting center contains muscarinic receptors that, when stimulated, trigger vomiting.

The chemo receptor trigger zone (CTZ) is located near the medulla oblongata and is sensitive to chemicals.

The CTZ contains dopamine 2 and 5-HT (serotonin) receptors, which can be stimulated by various substances.

Chemotherapy, which stimulates the CTZ, is a common cause of vomiting due to its chemical nature.

Motion sickness, caused by the inner ear's Labyrinth, can trigger the vomiting reflex via the vestibular nuclei.

The vestibular nuclei, containing histamine and muscarinic receptors, play a role in balance and vomiting.

Emotional states, severe pain, and repulsive sights or smells can cause vomiting by stimulating the higher brain centers.

The stomach's Intero chromin cells release serotonin in response to cytotoxic agents, potentially triggering vomiting.

The vomiting reflex involves the relaxation of the lower esophageal sphincter to allow food to move upwards.

Contraction of the diaphragm and abdominal muscles increases intra-abdominal pressure, aiding in vomiting.

Autonomic changes such as tachycardia, increased salivation, and peristalsis occur during vomiting.

The epiglottis closes during vomiting to prevent food from entering the lungs.

All causes of vomiting essentially stimulate the vomiting center, initiating the emetic reflex.

The process of vomiting involves a complex interplay of physiological mechanisms to expel stomach contents.

Transcripts

hello in this video we're going to talk

about the physiology of vomiting now

vomiting is also known as emesis and

throwing up amongst many other terms and

it is a involuntary forceful expulsion

of the contents of one's stomach

essentially through the mouth we will

look at the so-called emetic reflex

which is the vomiting reflex and in

order to understand the vomiting reflex

we need to talk about the brain so here

is the brain and the brain stem there's

an area of the brain stem called the

medulla oblongata where we find What's

called the vomiting

Center the vomiting Center contains

essentially muscarinic receptors types

of receptors and when these receptors

are stimulated within the vomiting

Center this will trigger the vomiting

reflex so the process of vomiting

close to the vomiting Center also near

the mola oblongata of the brain stem is

another area called the chemo receptor

trigger zone or ctz for

short now the ctz as the name suggests

gets triggered by

chemicals and the ctz contains a few

types of receptors and these are the

dopamine 2 receptors and the 5 HT

receptors 5ht essentially is serotonin

so these are serotonin

receptors it's easy to remember ctz

because we know that

chemotherapy stimulates this chemo

receptor trigger zone so when the chemo

receptor triggers Z the ctz is

stimulated it will then stimulate the

muscarinic receptors of the vomiting

Center and when the muscarinic receptors

of the vomiting Center are stimulated

this this will cause the vomiting reflex

the Ematic

reflex though the chema receptor trigger

zone is located in the medulla like the

vomiting Center the chemo receptor

trigger zone is located conveniently

outside the blood brain barrier now the

blood brain barrier is a barrier

preventing circulating substances in the

blood from making contact with the brain

um and areas of the brain stem because

the chemo receptor trigger zone is

situated outside the blood brain barrier

it is thus more permeable to circulating

substances such as cytotoxic agents

chemotherapy motion sickness is a very

common thing people experience and the

cause of motion sickness actually comes

from the inner ear a bony structure

called The

Labyrinth the Labyrinth is made up of

many areas one of which is called the

the Tibu a structure important for

balance in

space problems here will send electrical

signals to the brain stem via the

vestibular ccka nerve and the signals

will get sent to an area specifically in

the brain stem called the vestibular

nuclei which is located in the ponds of

the brain

stem the vestibular nuclei contain

histamine one receptors

and also muscarinic

receptors so when the vestibular nuclei

is stimulated during let's just say

motion

sickness or during also morning

sickness these signals will then be

passed on to the chemo receptor trigger

Zone and from here the chemo receptor

trigger Zone will then send signals to

the vomiting Center in the mola

oblongata to trigger the vomiting reflex

another cause of vomiting are things

that occur from the cerebrum or the

brain after it has processed all this

sensory information so what I mean is

that for example when people are

emotionally

overwhelmed or when people are in severe

pain or when they smell something really

bad or they see something repulsive

something really bad essentially all

this stuff will get sensed by the brain

by the higher centers of the brain and

from the higher brain centers this will

then this this signal then travel down

to the vomiting Center to stimulate the

vomiting Center to initiate the vomiting

reflex this makes sense because some

people get really nauseous when they see

blood or guts or they smell something

like a type of food that just smells

horrible again the higher brain centers

stimulate the vomiting Center through

muscarinic

receptors other causes of vomiting occur

in the stomach so let's just recap some

Anatomy here so we have the mouth which

connects to the esophagus which will

travel down through the diaphragm which

is the muscle muscular structure the

esophagus will then join onto the

stomach and then the stomach joins onto

the small

intestin if we were to zoom into the

stomach we can see they form deep pits

deep pits and glands and these are lined

up by many different types of cells one

of which are called Intero chromin

cells the Intero chromin cells release

serotonin in response to cytotoxic

agents which is ALS which is thought to

stimulate then um five ht3 receptors on

sensory nerve fibers around the area

and stimulation of this sensory nerve

fiber which is actually the vagal nerve

will bring this information to the

vomiting Center to trigger the vomiting

reflex in summary all the causes of

vomiting we talked about essentially

will stimulate the vomiting Center which

is the output from which the vomiting

reflex or the emetic reflex is

initiated let's focus on what the

vomiting reflex is and actually what

happens during the

process first it actually causes the

lower esophagal sphincter to relax which

makes sense because we need food to come

up towards the mouth when we

vomit we also need the diaphragm to

contract and also the abdominal muscles

to contract so that it will help push

the food back up and this happens

because we are increasing intraabdominal

pressure when we contct our

muscles there are also autonomic changes

such as tadia which is increase in heart

rate and we also increase salvation as

well as

peristalsis the vomiting reflex also

causes the epiglottis to close on um at

the top part because we don't want food

to travel down to the

lungs and once the vomiting reflex does

all these things then the vomit or the

food exposion of food can

happen so that was the physiology of

vomiting The emetic Reflex the vomiting

reflex