Name: gas exchange in lungs and tissues
Uploaded: 2024-09-12T13:22:46.000Z
Duration: 1 min 24 s
Channel: JoVE

K12 Standards

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

9-12

Human Anatomy and Physiology

Absorption And Excretion

Respiratory System

External and Internal Respiration

体外呼吸は、肺胞と肺の毛細血管との間で酸素と二酸化炭素を交換するものです。
このガス交換は、常に分圧の高い領域から低い領域へ、またはPの高からPの低へ発生します。
酸素は、PO2 が 105 mmHg である肺胞空気から、PO2 が 40 mmHg である肺毛細血管内の血液に拡散します。
同様に、二酸化炭素は、PCO2 が 45 mmHg の血液から PCO2 が 40 mmHg の肺胞空気に駆動されます。
内呼吸では、酸素は全身の毛細血管から全身の組織細胞に移動しますが、CO2は反対方向に移動します。
全身性毛細血管は、細胞内でのATP産生に酸素が消費され、毛細血管から細胞内に酸素が拡散するため、組織細胞よりもPO2が高くなります。
逆に、活発な代謝によるCO2産生は、全身の毛細血管よりも細胞内のPCO2が高くなり、CO2が細胞からこれらの毛細血管に拡散する原因となります。

外呼吸と内呼吸

外呼吸は肺で行われ、酸素が体内に取り込まれる最初のステップです。息を吸うと、酸素は肺に入り、薄い肺胞膜を透過します。肺胞は空気で満たされた小さな袋で、ガス交換のための広い表面積を提供します。肺胞内の酸素は、隣接する肺毛細血管 (40 mmHg) よりも高い分圧 (105 mmHg) を持ち、圧力勾配を形成します。その結果、酸素分子は肺胞から血液に移動し、赤血球内のヘモグロビンと結合します。

同時に、細胞代謝の老廃物として生成された二酸化炭素が血液から肺胞に移動します。血液の PCO_2 は肺胞の空気 (40 mmHg) よりわずかに高く (45 mmHg)、この交換を促進します。交換が完了すると、酸素化された血液は心臓に戻り、全身に送り出され、二酸化炭素は呼気中に排出されます。

内呼吸は全身のガス交換としても知られ、体の組織レベルで起こります。ここでは、左心室から送り出される酸素化された血液が全身動脈を通り、最終的に全身毛細血管に到達します。その目的は、組織細胞に酸素を供給し、老廃物である二酸化炭素を回収することです。全身毛細血管の PO_2 は組織細胞よりも高くなります。これは、酸素が細胞内の ATP 生成に使用され、毛細血管から細胞内に酸素が拡散するためです。逆に、細胞呼吸などの活発な代謝による CO_2 生成により、細胞内の PCO_2 は全身毛細血管よりも高くなり、細胞からこれらの毛細血管への拡散を引き起こします。

内呼吸と外呼吸における拡散速度に影響を与える要因

分圧勾配: 分圧の差が大きいほど、ガス拡散速度が速くなります。肺胞内の O_2 と CO_2 の分圧も肺気流に依存します。モルヒネなどの特定の薬物は呼吸速度を遅くし、O_2 と CO_2 の交換を減らします。高度が高いほど、大気全体の圧力と O2 分圧の両方が低下し、血液への O_2 の拡散が遅くなります。その結果、高山病になり、血中酸素濃度の低下によって、息切れ、頭痛、疲労、不眠、吐き気、めまいなどの症状が現れます。

利用可能な表面積: 肺胞の大きな表面積とそれを囲む豊富な毛細血管により、効率的なガス交換が可能になります。肺気腫など、この表面積を減少させる状態は、ガス交換速度を遅くします。

拡散距離: 薄い呼吸膜と、細い毛細血管を通る赤血球の縦一列の通過により、拡散距離は最小限に抑えられます。肺水腫のように肺胞間で間質液が蓄積すると、拡散距離が伸びるためガス交換が妨げられます。

体外呼吸は、肺胞と肺の毛細血管との間で酸素と二酸化炭素を交換するものです。
このガス交換はいつも...

Education

JoVE Core

Anatomy and Physiology

解剖生理学

Unit 1

ユニット1

The Respiratory System

呼吸器系

KEY TERMS AND CONCEPTS

主要用語と概念

gas exchange in lungs and tissues

Gas exchange in the lungs and body tissues moves oxygen into the blood and removes carbon dioxide. External respiration happens in the lungs, where inhaled oxygen enters the alveoli, the tiny air sacs that provide a large surface area for diffusion. Oxygen moves across the thin alveolar membrane into the pulmonary capillaries because its partial pressure is higher in the alveoli than in the blood. At the same time, carbon dioxide moves in the opposite direction and is later breathed out during exhalation.

After gas exchange in the lungs, oxygen binds to hemoglobin in red blood cells and oxygenated blood returns to the heart. The heart then pumps this blood through the body. Internal respiration, also called systemic gas exchange, happens at the tissues. Here, oxygen leaves the systemic capillaries and enters the cells, where it is used for ATP production. Carbon dioxide made during cellular metabolism moves from the cells into the capillaries because its partial pressure is higher in the tissues than in the blood.

The rate of diffusion depends on several factors. A larger partial pressure gradient increases gas movement, and lung airflow helps maintain the oxygen and carbon dioxide levels in alveolar air. Drugs such as morphine can slow breathing and reduce gas exchange. High altitude also lowers atmospheric pressure and oxygen partial pressure, which slows oxygen diffusion into the blood and can cause high-altitude sickness with breathlessness, headache, fatigue, insomnia, nausea, and dizziness.

Surface area and diffusion distance also affect how well respiration works. The many alveoli and surrounding capillaries create a large exchange surface, while emphysema can reduce that surface area and slow gas transfer. The thin respiratory membrane and narrow capillaries keep diffusion distance short. In pulmonary edema, extra interstitial fluid builds up around the alveoli and makes the diffusion path longer, which hinders gas exchange.

Gas Exchange in Lungs and Tissues

overview of respiratory system

How Breathing Moves Air and Gases

The respiratory system moves air in and out of the body and exchanges oxygen and carbon dioxide with the environment. This gas exchange is part of respiration, which is essential for life. The system supplies the blood with oxygen so it can carry that oxygen to the rest of the body. Breathing starts when air enters through the nose or mouth. The nose and nasal cavity form the main external opening and the first part of the airway. Air then passes through the pharynx, or throat, which is shared...

nose and nasal cavity

How the Nose Filters and Senses Air

The nose filters, warms, moistens, and senses the air that enters the body. It also helps shape speech as sound vibrations pass through its large air spaces. The nose has an external part that is visible on the face and an internal part called the nasal cavity. The external nose is built from bone and hyaline cartilage, which gives it flexibility. It is covered by skin and muscle and lined with a mucous membrane. The frontal bone, nasal bones, and maxillary bone support this structure. The...

pharynx

Pharynx Pathways for Air and Food

The pharynx is a muscular tube lined with mucous membrane that connects the nasal cavities to the throat. It is divided into three parts: the nasopharynx, oropharynx, and laryngopharynx. Each part has a different role in moving air and food through the upper throat. The nasopharynx sits behind the nasal cavity and serves only as an air passage. Its upper region contains the pharyngeal tonsils, also called adenoids. These are clusters of lymphoid reticular tissue, similar to a lymph node, and...

larynx

Voice Box Anatomy and Function

The larynx is the voice box in the neck. It carries air into the lungs and helps produce voice. Its structure is complex because it must support both breathing and sound production. The larynx contains cartilage, muscles, and the vocal cords, also called vocal folds. It includes three large unpaired cartilages: the thyroid, cricoid, and epiglottis. It also includes three paired cartilages: the arytenoids, corniculates, and cuneiforms. Ligaments and membranes hold these parts together. The...

trachea

Trachea: Layers, Rings, and Airflow

The trachea is the windpipe, and it is a key airway in the human respiratory system. It carries air between the larynx and the bronchi so oxygen can reach the lungs. About half of the trachea lies in the neck, and it sits in front of the esophagus. In an average adult, the trachea is about 10 to 12 cm long. It extends from the larynx at the level of the sixth cervical vertebra to the level of the fifth thoracic vertebra. Its wall is supported by C-shaped cartilaginous rings. The back side is...

the bronchial tree

Bronchial Branching and Airflow Control

The bronchial tree carries air from the trachea into the lungs and helps control breathing. The trachea, or windpipe, connects the larynx to the bronchi. At the carina, the trachea splits into two primary bronchi. The right primary bronchus is wider, shorter, and more vertical than the left. Because of that shape, foreign objects and infections are more likely to enter the right lung. The carina is a cartilaginous ridge at the split in the airway. It helps keep the airway open. It also has...

alveoli and alveolar ducts

How Alveoli Enable Gas Exchange

The respiratory zone of the human body is where gas exchange happens. It begins when the terminal bronchioles branch into respiratory bronchioles, the smallest bronchiole type. These then lead into alveolar ducts and finally into clusters of alveoli. Alveoli are tiny air sacs that look like bunches of grapes. They connect to alveolar ducts, and a group of alveoli forms an alveolar sac. A single alveolus is about 200 μm wide, and its elastic shape lets it expand during inhalation. Nearby...

gross anatomy of the lungs

Lung Lobes, Airways, and Blood Flow

The lungs are paired organs that connect to the trachea through the left and right bronchi. Their base rests against the diaphragm, the dome-shaped muscle below the lungs. The lungs are covered by the pleurae and sit next to the mediastinum, the central space in the chest. The right lung is shorter and wider than the left lung, and it has a larger volume. The left lung has a cardiac notch, which is an indentation for the heart. The top of each lung is the apex, and the lower part is the base.

pleura of the lungs

Pleura Layers and Lung Protection

The pleura are membranes that protect the lungs inside the chest cavity. They are a type of serous membrane and wrap around each lung. The pleura have two layers: the visceral pleura and the parietal pleura. The visceral pleura covers the surface of the lung. The parietal pleura is the outer layer. It lines the thoracic wall, the mediastinum, and the diaphragm. The hilum is the point where the visceral and parietal layers connect. The space between these layers is called the pleural cavity. <br...

pressure relationships in thoracic cavity

pressure-relationships-in-thoracic-cavity

How Pressure Drives Breathing in the Lungs

Breathing depends on pressure changes in the lungs, chest, and airways. Pulmonary ventilation is the movement of air into and out of the lungs. It is driven by atmospheric pressure, intra-alveolar pressure inside the alveoli, and intrapleural pressure in the pleural cavity. Inhalation and exhalation rely on pressure differences between the atmosphere and the lungs. Gas pressure comes from the movement of confined molecules. Boyle’s law explains that pressure and volume are inversely...

pulmonary ventilation: inhalation

Pulmonary Ventilation and Breathing Pressures

Pulmonary ventilation depends on breathing movements and the pressure changes that move air into and out of the lungs. It supports the exchange of oxygen and carbon dioxide by letting the body take in oxygen and remove waste carbon dioxide. Boyle's law is important here because changes in volume and pressure affect how air moves in the respiratory system. Several respiratory volumes help describe how much air the lungs move. Tidal volume is the air inspired or expired during normal, quiet...

pulmonary cycle: exhalation

Exhalation and Lung Pressure Changes

Exhalation is the process of expelling air from the lungs. It depends on pressure differences between the lungs and the atmosphere. During normal quiet breathing, exhalation is passive and does not require muscle contraction. The elastic recoil of the lungs and chest wall helps both structures return to their resting positions after inhalation. When the muscles used for inhalation stop working, the diaphragm and external intercostal muscles relax. The diaphragm moves upward, and the ribs move...

factors affecting pulmonary ventilation

What Changes Breathing Ease in the Lungs

Breathing ease in the lungs depends on alveolar surface tension, lung compliance, and airway resistance. These factors affect how hard it is to move air during pulmonary ventilation, along with the pressure difference between the outside environment and the lungs. Alveolar surface tension comes from the fluid lining the inside of the alveoli. Water molecules in this fluid attract each other more strongly than they attract the air, so the liquid tends to pull the alveoli inward. That force must...

respiratory volumes and capacities

Lung Volume Measurements in Breathing

Lung volume measurements show how air moves in and out of the respiratory system during breathing. They help explain how the body takes in oxygen and removes carbon dioxide. Respiratory volumes and capacities also give useful information about lung function. Tidal volume is the air breathed in and out during normal, quiet breathing. Inspiratory reserve volume is the extra air that can be forcefully inhaled beyond tidal volume. Expiratory reserve volume is the extra air that can be forcefully...

physical principles governing gas exchange

physical-principles-governing-gas-exchange

Gas Laws in Lung Gas Exchange

Gas laws explain how oxygen and carbon dioxide move during respiration. External respiration is the exchange of gases in the lungs. Oxygen diffuses into the blood, and carbon dioxide diffuses out. Internal respiration happens in body tissues, where the gases move in the opposite directions. Two gas laws guide this process: Dalton's law of partial pressures and Henry's law. Dalton's law says the total pressure of a gas mixture equals the sum of the pressures of each gas acting alone. The...

external and internal respiration

Gas exchange in the lungs and body tissues moves oxygen into the blood and removes carbon dioxide. External respiration happens in the lungs, where inhaled oxygen enters the alveoli, the tiny air sacs that provide a large surface area for diffusion. Oxygen moves across the thin alveolar membrane into the pulmonary capillaries because its partial pressure is higher in the alveoli than in the blood. At the same time, carbon dioxide moves in the opposite direction and is later breathed out during...

oxygen transport in the blood

How Hemoglobin Loads and Releases Oxygen

Hemoglobin is the main molecule that carries oxygen in blood. It is found in red blood cells and has four polypeptide chains, each attached to an iron-containing heme group. This structure lets one hemoglobin molecule bind up to four oxygen molecules quickly and reversibly. When hemoglobin is fully loaded with oxygen, it is called oxyhemoglobin. When it has released oxygen, it is called reduced hemoglobin, or deoxyhemoglobin. As hemoglobin binds oxygen, its shape changes, which helps it pick...

carbon dioxide transport in the blood

How Blood Carries Carbon Dioxide

Carbon dioxide is carried in the blood from body tissues to the lungs. Cells make about 200 mL of CO2 each minute, and the lungs remove about the same amount. The blood moves this waste gas in three main forms. A small amount, about 7-10%, stays dissolved in the plasma. Just over 20% binds to hemoglobin and forms carbaminohemoglobin. In this case, CO2 attaches to the amino acids of globin, not to the heme part of hemoglobin. The rest, about 70%, is carried as bicarbonate ions, or HCO3-. CO2...

hypoxia

Hypoxia: Types and Carbon Monoxide Poisoning

Hypoxia is a medical condition in which body tissues do not get enough oxygen. It can cause a bluish color in the skin and mucosae, especially in fair-skinned people. This sign is often seen when hemoglobin (Hb) saturation drops below 75%. Hypoxia can happen for several different reasons. Anemic hypoxia occurs when there are too few red blood cells (RBCs) or when RBCs have abnormal or too little Hb. Ischemic hypoxia comes from poor blood circulation or blocked blood flow, so blood becomes...

neural control of respiration

Brainstem Centers That Control Breathing

Breathing is controlled by nerve centers in the brainstem. These respiratory centers send nerve signals to the muscles that move the lungs. The main centers are in the medulla oblongata and the pons.

chemical factors affecting respiration centers

chemical-factors-affecting-respiration-centers

How Blood Gases Control Breathing Rate

Blood gases and blood pH help control breathing rate and depth. Changes in carbon dioxide, oxygen, and hydrogen ion levels in arterial blood are detected by chemoreceptors, which are special sensors in the body. Central chemoreceptors are found throughout the brain stem, including the ventrolateral medulla. Peripheral chemoreceptors are located in the aortic arch and carotid arteries. Together, these sensors help the respiratory system respond to chemical changes in the blood. Carbon dioxide...

other factors affecting respiration centers

other-factors-affecting-respiration-centers

Respiratory Reflexes That Change Breathing

Breathing is controlled by the brainstem, but it can also be changed by the nervous system and by body signals. The cerebral motor cortex can override the medullary respiratory centers and send signals directly to the breathing muscles. This makes voluntary actions like holding your breath or taking deeper breaths possible. That control is limited. When carbon dioxide, or CO2, builds up in the blood to a critical level, the brainstem respiratory centers start breathing again. This is why a...

hyperpnea and hyperventilation

Breathing Changes in Exercise and Anxiety

Breathing changes in exercise and anxiety can look similar, but they do not have the same cause. Hyperventilation is a higher-than-normal rate and depth of breathing. It often happens during anxiety attacks and can push out more carbon dioxide than the body needs to remove. When too much carbon dioxide is lost, the blood develops hypocapnia, which means an unusually low level of carbon dioxide. Hypocapnia can narrow cerebral blood vessels and reduce blood flow to the brain. This may cause...

chronic obstructive pulmonary disease

COPD Signs, Causes, and Lung Damage

COPD is a lung condition that causes ongoing breathing problems. It leads to shortness of breath, cough, and sputum production because the airways become blocked and airflow is reduced. Smoking is the main risk factor for COPD, and more than 80% of patients have a history of it. People with COPD often develop worsening dyspnea, or labored breathing. They may also cough often and get repeated lung infections. Many patients with COPD can develop respiratory failure. This happens when...

other pulmonary disorders

Asthma, TB, Lung Cancer, and Sleep Apnea

Asthma, lung cancer, tuberculosis, and sleep apnea are major pulmonary disorders. They affect breathing in different ways. Some are chronic, some are infectious, and some can become life-threatening if not found and treated early. Asthma is marked by chronic airway inflammation and hypersensitivity. It can cause airway obstruction from bronchial spasms, mucosal edema, increased mucus secretion, or epithelial damage. Triggers vary and can include allergens or emotional upset. Treatment often...

key terms and concepts

Learn how oxygen and carbon dioxide move in external and internal respiration, plus how pressure, surface area, and diffusion distance affect exchange.

Gas Exchange in Lungs and Tissues | JoVE K12

anatomy and physiology

JoVE Core 解剖学と生理学では、人体の解剖学的および生理学的な詳細を、包括的で明確で魅力的なビデオ アニメーションで紹介します。このレッスン集は、人体の構造、コンポーネント、機能、要件に焦点を当てています。この知識を実際の医療および研究現場で応用することを実証する科学者による実際のビデオによって補完されています。

Florida Department of Education

High School

Life Science

SC.912.L.14

SC.912.L.14.44

Major Organs of the Digestive System

The human digestive system consists of two major parts: the gastrointestinal &#8212; GI &#8212; tract and the accessory organs.
The GI tract begins with ...

Peritoneum

The peritoneum is the body&#39;s largest serous membrane enveloping the abdominal cavity.
It has two portions &#8212; the parietal and visceral peritoneum ...

histology-of-the-gastrointestinal-gi-tract

Histology of the Gastrointestinal (GI) Tract

The gastrointestinal tract has four tissue layers.
The innermost layer, mucosa, is characterized as a mucous membrane. It consists of an epithelium, ...

Nerve Supply of the GI Tract

The gastrointestinal tract has its own intrinsic set of nerves forming the enteric nervous system or ENS,&#160; which is partly controlled by the ...

Regulation of the Digestive System

Along with the enteric nervous system, digestive activity is regulated by mechanical and chemical stimuli and hormones.
Various receptors located within ...

Blood Supply to the Digestive System

Splanchnic circulation refers to the network of blood vessels that supply and drain blood from the abdominal organs involved in digestion, including the ...

Oral Cavity

The oral cavity, or mouth, comprises the lips, cheeks, palate, and tongue.
The walls of the mouth are lined with thick, stratified squamous epithelium, ...

Tongue

The tongue, an accessory digestive organ, forms the floor of the oral cavity and extends into the oropharynx.
It is composed of two types of skeletal ...

Salivary Glands and Saliva

Saliva is composed of 97 to 99.5% water. The remaining proportion includes enzymes such as lipases and amylases, electrolytes, dissolved gasses, IgA, ...

Teeth

Teeth are accessory digestive organs that aid in physically breaking down food.
&#160;The gums, or gingivae, of both the mandible and maxilla hold the ...

Tooth Anatomy

The tooth has a crown and a root connected via a constricted area known as the neck.
The crown is visible above the gingivae and is protected by enamel.
...

Esophagus

The esophagus is a muscular conduit approximately 25 cm long that helps transport food from the mouth to the stomach.
It courses through the mediastinum ...

Deglutition

Deglutition, or swallowing, is a mechanism that transports food from the mouth to the stomach.
This process has three stages &#8212; the buccal, ...

Gross Anatomy of the Stomach

The stomach is a J-shaped organ connecting the esophagus to the duodenal end of the small intestine in the abdominal cavity.
The size and shape of the ...

Stomach Histology

The stomach wall consists of several layers, including the serosa, muscularis externa, submucosa, and mucosa.
The outermost layer, the serosa, is composed ...

Hormones Secreted by the Stomach

The specialized enteroendocrine cells of the gastric glands secrete most of the digestive hormones.
These cells, such as the G, D, and ...

Cephalic Phase of Digestion

Digestion has three overlapping phases &#8212; cephalic, gastric, and intestinal &#8212; based on the location of their control center.
The cephalic phase ...

Gastric Phase of Digestion

Local, neural and hormonal mechanisms trigger the gastric phase after food enters the stomach, lasting approximately 3-4 hours.
The incoming food bolus ...

Diseases of the Liver and Gallbladder

Prominent liver and gallbladder diseases include cirrhosis, hepatitis, non-alcoholic fatty liver disease or NAFLD, and gallstones.
Cirrhosis is a liver ...

Intestinal Phase of Digestion

After the gastric phase, the chyme from the stomach moves into the small intestine, gradually decreasing the stomach distention.
In contrast, the arrival ...

Pancreas

The pancreas is a pinkish-gray organ located behind the stomach. It extends from the duodenum to the spleen.
It can be divided into a broad head located ...

Mucosal Barrier of the Stomach

In the gastric glands, the parietal cells are involved in hydrochloric acid or HCl formation.
These cells first synthesize carbonic acid, which ...

Pancreatic Juice and Secretion

Pancreatic juice is a colorless liquid composed of water, salts, sodium bicarbonate, and enzymes secreted by the exocrine cells.
During digestion, chyme ...

Gastric Motility

Gastric motility is the coordinated movement of stomach muscles and secretions, which propels food and liquids through the stomach.
As the swallowed food ...

Small Intestine

The small intestine is a tubular structure extending from the pyloric sphincter of the stomach to the ileocecal valve of the large intestine.
This long, ...

Gastric Emptying

Gastric emptying is the gradual release of chyme from the stomach into the duodenum.
Stomach distention triggers the gastroenteric reflex, releasing ...

Histology of the Small Intestine

The histology of each part of the small intestine varies. The jejunum has the most prominent folds and villi, while the distal ileum has fewer folds but ...

Gross Anatomy of the Liver

The liver is the largest gland in the body, weighing approximately 1.4 kg in adults.
It is wedge-shaped and located more in the right hypochondriac and ...

mechanical-and-chemical-digestion-in-the-small-intestine

Mechanical and Chemical Digestion in the Small Intestine

The small intestine plays a crucial role in our digestive system, performing both mechanical and chemical digestion.
Mechanical digestion in the small ...

Liver Histology

The liver comprises several histological components, such as hepatocytes, bile canaliculi, and sinusoids.
Hepatocytes are specialized epithelial cells ...

Large Intestine

The large intestine is divided into three main regions: the cecum, colon, and rectum. Extending from the ileocecal valve to the anus, it frames the small ...

Bile

Bile is a yellow-green alkaline liquid secreted by the liver into the right and left hepatic ducts and then into the common hepatic duct. From here, it ...

Histology of the Large Intestine

The large intestine, a vital component of the gastrointestinal tract, is structured with four main layers: the mucosa, submucosa, muscularis, and serosa. ...

Gallbladder

The gallbladder is a muscular sac located in a shallow fossa on the inferior surface of the liver. It measures about 10 cm in length and is roughly the ...

Bacterial Flora of the Large

Intestine

The vast and varied community of bacteria colonizing the large intestine forms the gut microbiome.
Bacteria start residing in the gut at birth and ...

Liver Physiology

Liver functions primarily include bile production, metabolic regulation, and hematological functions.
During carbohydrate metabolism, the liver regulates ...

digestive-functions-of-the-large-intestine

Digestive Functions of the Large Intestine

The final stages of digestion occur in the large intestine when the cecum receives chyme, which has little nutritional value except for the indigestible ...

Absorption of Nutrients

During digestion in the small intestine, macromolecules&#8212; carbohydrates, proteins, and fats &#8212; are broken down into their simplest forms.
These ...

Feces Formation and Defecation

After spending 3 to 10 hours in the large intestine, chyme loses a lot of water and becomes feces, the final product of digestion. Feces consist of ...

Other Disorders of Digestive System

The gastrointestinal tract of the digestive system is susceptible to various disorders.
The incompetence of the lower esophageal sphincter results in the ...

Digestive System

Content elaboration: The digestive system consists of the gastrointestinal tract (alimentary canal) as well as various accessory organs including the teeth, tongue, salivary glands, liver, gallbladder and pancreas. The digestive system processes and supplies the molecules needed to sustain the living tissues within the body through the absorption of nutrients. Six major functions of the digestive system include secretion, ingestion, mechanical processing, enzymatic digestion, absorption and excretion. The lining of the digestive system protects surrounding tissues from the mechanical and enzymatic stresses of the digestive process. Processes of the digestive system include the mechanical and chemical breakdown of food into small molecules which are then absorbed by the digestive tract. Specific actions within the digestive system include mastication, peristalsis, segmentation and the release of hormones and enzymes necessary for digestion. The metabolic functions of the accessory organs play strategic roles in the breakdown of food products, the maintenance of glucose levels within the blood and the regulation of homeostasis in the body. Indigestible material is excreted as waste. Homeostatic imbalances are explored. These include, but are not limited to, conditions such as gallstones, heartburn, ulcers, dehydration, diarrhea, cirrhosis and cancers of the digestive system. Investigations are used to understand and explain the digestive system in a variety of inquiry and design scenarios that can incorporate evolutionary concepts, scientific reasoning, comparative analysis, communication skills and real-world applications.

Digestive System

Overview of Respiratory System

The respiratory system includes both upper and lower respiratory organs.
The upper respiratory organs consist of the nose and nasal cavity, paranasal ...

Nose and Nasal Cavity

The nose is composed of an observable exterior segment (external nose) and an internal segment within the skull known as the nasal cavity (internal nose). ...

Respiratory System

Content elaboration: The respiratory system is comprised of the airways, lungs and diaphragm. The airways include the nasal and oral cavities, pharynx, larynx, trachea, bronchi, bronchioles and alveoli. The respiratory system transports and exchanges gases including oxygen and carbon dioxide. Processes involved in the respiratory system include respiration mechanics and gas exchange. Respiration mechanics is the process by which humans breathe and includes the movement of the diaphragm and pressure-volume relationships. Gas exchange refers to the diffusion of gas across the alveolar epithelium in the respiratory system and capillary endothelium of the cardiovascular system. Lung volumes and capacities can be measured using spirometry. Homeostatic imbalances are explored. These include, but are not limited to, asthma, chronic obstructive pulmonary disease (COPD), tuberculosis, cystic fibrosis and the effects of smoking and pollution. Investigations are used to understand and explain the respiratory system in a variety of inquiry and design scenarios that can incorporate evolutionary concepts, scientific reasoning, comparative analysis, communication skills and real-world applications.

Gas Exchange in Lungs and Tissues

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