Temat: Układ oddechowy i jego funkcje

Autor: Zyta Sendecka

Adresat

Uczeń klasy VII szkoły podstawowej.

Podstawa programowa

III. Organizm człowieka.

7. Układ oddechowy. Uczeń:

1) rozpoznaje elementy budowy układu oddechowego (na schemacie, modelu, rysunku, według opisu itd.) i przedstawia ich funkcje oraz określa związek budowy tych elementów z pełnioną funkcją;

4) analizuje przebieg wymiany gazowej w tkankach i w płucach; planuje i przeprowadza doświadczenie wykrywające obecność dwutlenku węgla oraz pary wodnej w powietrzu wydychanym.

Cel lekcji

Uczniowie opisują przystosowania w budowie płuc do sprawnej wymiany gazowej i jej mechanizm.

Kryteria sukcesu

• wskażesz położenie narządów układu oddechowego;

• przeprowadzisz obserwację pęcherzyków płucnych;

• opiszesz mechanizm wymiany gazowej w pęcherzykach płucnych i komórkach ciała.

Kompetencje kluczowe

• porozumiewanie się w języku ojczystym; 

• porozumiewanie się w języku obcym;

• kompetencje matematyczne i podstawowe kompetencje naukowo‑techniczne; 

• kompetencje informatyczne; 

• umiejętność uczenia się; 

Metody/formy pracy

Pogadanka, praca z tekstem i obserwacja zastępcza.

Praca indywidualna.

Środki dydaktyczne

• abstrakt;

• tablica interaktywna lub tradycyjna;

• tablety/komputery;

Fazy lekcji

Wstępna

1. Nauczyciel podaje temat i cele lekcji.

2. Nauczyciel pyta uczniów:

• Dlaczego organizmy muszą dostarczać tlen do organizmu?

• Który składnik krwi jest odpowiedzialny za transport gazów oddechowych?

• Na czym polega dyfuzja?

• Jakie narządy budują układ oddechowy i jakie pełnią funkcje?

Realizacyjna

1. Nauczyciel prosi uczniów, aby korzystając z abstraktu zapoznali się z budową i rolą poszczególnych odcinków układu oddechowego.

2. Nauczyciel prosi uczniów, aby samodzielnie wykonali zadanie interaktywne.

3. Uczniowie zostają zapoznani z filmem: “Budowa płuc kręgowców”.

4. Nauczyciel zatrzymuje film na kadrze z obrazem mikroskopowym pęcherzyków płucnych. Uczniowie wykonują rysunek biologiczny pęcherzyków płucnych zgodnie z poznanymi wcześniej zasadami (film “Jak wykonuje się rysunek obrazu mikroskopowego”). Nauczyciel ocenia rysunki uczniów.

5. Nauczyciel prosi uczniów, aby podczas emisji filmu zaobserwowali:

• właściwości fizyczne płuc,

• zmianę barwę cieczy, w której zanurzone są płuca.

6. Nauczyciel prosi uczniów o sformułowanie wniosków na podstawie obserwacji.

7. Uczniowie zapoznają się z informacjami zamieszczonymi w abstrakcie dotyczącymi wymiany gazowej.

Podsumowująca

• Nauczyciel prosi uczniów o samodzielne wykonanie ćwiczenie 4.

• Prosi uczniów o dokończenie zdań:

Na dzisiejszej lekcji nauczyłem/am się…

Na dzisiejszej lekcji zainteresowało mnie…

W tej lekcji zostaną użyte m.in. następujące pojęcia oraz nagrania

Pojęcia

Teksty i nagrania

The respiratory system and its functions

The respiratory system provides for an efficient collection and transport of respiratory gases – oxygen and carbon dioxide, as well as gas exchange. It consists of the upper and lower airways and gas‑exchange organs – lungs. The upper airways include the nasal cavity and the pharynx. The lower airways consist of the larynx, the trachea and the bronchi.

The air introduced into the body must first be heated and moisturized, as well as purified of dust. Airways have numerous adaptations to perform these functions:

• air purification – the airways are lined with an epithelium provided with cilia and mucous glands; dust particles adhere to the mucus covering the epithelium and they are stuck together; the movement of the cilia moves them to the pharynx from where the contaminants are expectorated or when swallowed they end up in the gastrointestinal tract; what is more, the inside of the nasal cavity is overgrown with hairs that are a barrier to dust; cough and sneezing are ways to get rid of excess mucus and impurities; irritants are removed by the air that comes out of the lungs under high pressure at a speed of up to 160 km/h;

• air moisturizing – water contained in the mucus evaporates and moisturizes the air, thanks to which it facilitates the penetration of oxygen into the blood in the final part of the airways;

• air heating – the inside of the nose and the airways are well supplied with blood; blood gives off heat to the air filling the airways.

From the nasal cavity the air is transported through the pharynx to the trachea. The pharynx is where the respiratory and digestive systems intersect – food from the mouth is moved through the pharynx to the esophagus.

The air from the upper airways enters the larynx, the voice organ built of cartilage connected to each other flexibly through ligaments and muscles. There is a mobile cartilage between the pharynx and the larynx – epiglottis. It works like a valve, which when breathing and speaking is raised up, and this allows for the transport of inhaled air to the larynx and the trachea. During swallowing, the epiglottis drops and closes the entrance to the larynx, protecting the airways against food particles. Sometimes, when we take a deep breath while swallowing (willing to say something more loudly), the epiglottis does not manage to close itself and food along with the stream of air goes to the larynx. This causes irritation of the mechanical receptors in the larynx and a cough reflex.

The narrowest part of the larynx is the glottis, in which sounds are made. The mucosa creates transverse folds in it – vocal cords between which there is a true glottis. While talking, the vocal cords tighten and the true glottis decreases. The air leaves the lungs and vibrates the cords, resulting in a voice. The sounds of human speech arise with the participation of the larynx, tongue, palate, cheeks, lips and teeth.

From the larynx the air passes into the trachea. It has the shape of a tube reinforced from the front with half‑ringed cartilages, which protects its walls against collapsing. In the upper part of the chest, the trachea branches into two bronchi that lead the air into the lungs.

The lungs are the organs of gas exchange in the chest. From the outside, they are protected by a thin double membrane, called the pleura, filled with a small amount of fluid. It prevents damage to the lungs due to friction on ribs and other chest bones during breathing movements.

Inside the lungs, the bronchi branch out in the form of a tree, forming a system of increasingly smaller channels called bronchioles. At their ends there are alveoli. There are about 600 million of them and they have a total area of 90 mIndeks górny 2². The bubbles that are close together form a structure similar to a grape cluster. The alveoli are surrounded by a dense network of capillaries. Between them and the air from the alveoli there takes place gas exchange through diffusion. The passage of oxygen into the blood and carbon dioxide from the blood into the alveoli is very quick and efficient due to the fact that:

• the walls of the alveoli and the capillary blood vessels are composed of a thin, single‑layered epithelium;

• the network of capillaries covering the alveoli is very dense;

• the alveoli form a very large gas exchange surface.

One of the most important signs of life is breathing. In humans, this process includes lung ventilation, gas exchange and intracellular respiration. During ventilation the collection and removal of the air from the lungs takes place. Oxygen‑rich air enters the lungs during inhalation and then, depleted of some oxygen, it is removed outside during exhalation. The following are responsible for lung ventilation:

• intercostal muscles, expanding and constricting the chest;

• diaphragm – a flat respiratory muscle separating the chest from the abdominal cavity.

During inhalation, the diaphragm contracts and lowers, whereas the external intercostal muscles also relax contract and lift the ribs up. As a result, the volume of the chest increases, the alveoli expand and aspiration of the air into the lungs takes place. When exhaling, the diaphragm relaxes and lifts passively up, the intercostal muscles also relax. At the same time, the internal muscles contract, so the ribs are lowered and the air is pushed out. The movements of the diaphragm are automatic, but to a certain extent they can be consciously modified, e.g. during diving and singing.

Lung ventilation based on rhythmic inhalations and exhalations is a process that takes place without the participation of our consciousness. Its rate depends on the content of carbon dioxide in blood – an increase in its concentration increases the frequency of breaths. At rest, a person makes about 12‑16 breaths per minute, collecting and removing about 0.5 litres of air each time. The amount of air that can fit the lungs of an adult human is usually 4,500 ml for men and 3,200 ml for women. Lung capacity is an indicator of the body's efficiency and depends on age, sex, physical fitness and smoking.

Blood transports respiratory gases between the lungs and tissues. Transmission of oxygen from the lungs to blood, and carbon dioxide from blood to the lungs is called external gas exchange. After inhalation, oxygen concentration in the alveoli is higher than in the blood flowing into the lungs. As a result, according to the concentration difference, oxygen through diffusion passes through the walls of the alveoli and capillaries to plasma, and then to erythrocytes. Carbon dioxide diffuses into the alveoli the same way. Oxygen, entering an erythrocyte, creates an unstable connection with hemoglobin and oxyhemoglobin is formed. In this form, oxygen is transported to the body's cells. That is where internal gas exchange takes place. In the capillaries, the oxygen that reaches the body’s cells is detached from oxyhemoglobin and diffuses into cells. Carbon dioxide is transmitted from the body's cells to blood plasma in which it dissolves. Part of carbon dioxide is connected to hemoglobin in an unstable manner. It is transported to the alveoli with blood.

• The respiratory system consists of the upper and lower airways and lungs.

• In the airways there is a ciliated, mucus‑producing epithelium, thanks to which the air is purified, moisturized and heated.

• The true glottis is the place where our voice is created.

• Even lungs are the organs of gas exchange.

• The process of breathing in humans and other lung organisms consists of lung ventilation, gas exchange, intracellular respiration.

• Lung ventilation involves, among others, intercostal muscles and the diaphragm.

• Gas exchange in the lungs and tissues takes place by diffusion in accordance with the concentration difference.

• External gas exchange occurs between the alveoli and blood.

• Internal gas exchange occurs between blood and the body’s cells.

• Oxygen is transported in the form of oxyhemoglobin, and carbon dioxide mainly in a dissolved form in plasma.