Respiratory and Circulatory System

• Function of the respiratory system?

  To intake oxygen into blood, so it can be delivered to the cells for cellular respiration and to remove carbon dioxide produced as a waste from cellular respiration from the blood.
• Parts of the respiratory system?

  - Nasal cavity

  - Pharynx

  -Epiglottis

  -Larynx

  -Trachea

  -Bronchi

  -Bronchioles

  -Alveoli

  -Lungs

  -Pleural membranes/fluid

  -Ribs, intercostal muscles, diaphragm
• Structure of the nasal cavity?

  Contains mucous membranes and hairs
• Function of the nasal cavity?

  - Warms, humidifies/moistens and filters the air.

  - Hairs and mucous trap any debris, preventing it from entering the lungs
• Structure of the pharynx

  Muscular tube
• Function of the pharynx

  Passage way for air (and food/drinks). Air passes to the trachea (food/fluids pass into the oesophagus)
• Structure of the epiglottis

  Flaps of elastic cartilage
• Function of the epiglottis

  Blocks the trachea during swallowing to prevent food and drink entering the trachea
• Structure of the larynx?

  - Consists of cartilage

  - Contains vocal cords/mucous membranes which can be stretched.
• Function of the larynx

  - Connects the pharynx to the trachea

  - As air passes over the vocal cords, they vibrate and sound is produced.
• Structure of the trachea?

  - Contains C-shaped cartilage rings (to hold it open)

  - Contains ciliated epithelium that secretes mucus
• Function of the trachea


  - Filters and carries air into and out of the lungs.

  - Mucus traps dust and debris, preventing it from entering the lungs.

  - Cilia beat the mucus and debris to the pharynx so it can be swallowed and digested
• Function of the bronchi?

  - Carriers air deep into the lungs. The cartilage helps to hold the airways open.

  - Mucus and cilia work to together to trap and remove dust/other particles from the lungs, filtering the air.
• Structure of the bronchioles?

  - Contain smooth muscle

  - Contain cilia and mucus membranes

  - Do not contain cartilage
• Function of the bronchioles?

  - Controls flow of air into the lungs as they can expand to allow more air to enter the lungs when more oxygen is needed.

  - Cilia and mucus work together to filter the air
• Structure of the alveoli?

  - They are one cell thick (creating a short diffusion distance)

  - The membrane is moist (allowing the gases to dissolve)

  - There are many of them, creating a large surface area for gas exchange

  - They are surrounded by capillaries (maintaining a constant steep concentration gradient to allow for rapid diffusion)
• Function of alveoli?


  The site of gas exchange, oxygen diffuses through the alveoli into the capillaries and carbon dioxide diffuses out of the blood capillaries into the alveoli
• Function of the lungs and the pleural membranes/fluid?

  Pleural membranes and fluid hold the lungs against the inside of the chest and lubricate the surface allowing the surfaces to slide past each other during breathing.
• Structure of the ribs?

  Bone
• Function of the ribs?

  Site for muscle attachment and protection of lungs and heart
• Structure of the intercostal muscles?

  Skeletal muscle between the ribs
• Function of the intercostal muscles?

  Moves ribs to increase / decrease volume of the chest cavity during breathing
• Structure of the diaphragm?

  Band of skeletal muscle
• Function of the diaphragm?

  Contracts downwards to increase the size of the chest cavity, during breathing in
• Breathing (ventilation)?


  The process by which air is moved into and out of the lungs
• Respiration?


  The process by which cells obtain energy by breaking down glucose or other large molecules
• Mechanics of breathing?


  - Ventilation/breathing (movement of air in and out of the lungs).

  - Inspiration/inhalation/breathing in (movement of air into the lungs).

  - Expiration/exhalation/breathing out (movement of air out of the lungs).
• What happens during breathing?


  Air flows from places of higher pressure to places of lower pressure; air flows in and out of the lungs due to pressure differences.
• Inhalation/inspiration


  - For air to move into the lungs, the pressure in the lungs must be lower than atmospheric pressure.

  - We can decrease the pressure in the lungs by increasing the volume of the lungs
• Steps of inhalation/inspiration


  1. Diaphragm contracts and flattens

  2. External intercostal muscles contract, moving the ribs out and up

  3. Together this increase the volume of the chest / thoracic cavity

  4. This results in a decrease in pressure within the chest / thoracic cavity

  5. Therefore air moves into the lungs as air moves from areas of high pressure to low pressure
• Expiration


  For air to move into the lungs, the pressure in the lungs must be high compared to atmospheric pressure.
• Expiration steps


  1. Diaphragm relaxes and bulges upwards

  2. Intercostal muscles relax, moving the ribs down and in

  3. Together this decreases the volume of the chest / thoracic cavity

  4. This results in an increase in pressure within the chest / thoracic cavity

  5. Therefore air moves out the lungs as air moves from areas of high pressure to low pressure
• Features that aid gas exchange

  - Large surface area

  - Highly vascularised

  - Consistent blood supply

  - One cell thick

  - Moist

  - Ventilation
• How does large surface area, aid gas exchange?

  Microscopic alveoli increases surface area allowing for rapid diffusion
• How does highly vascularised , aid gas exchange?

  Increase volume of the blood transported to alveoli increasing rate of diffusion.
• How does consistent blood supply, aid gas exchange?

  Maintains concentration gradient by constantly moving oxygen away / bring deoxygenated to the alveoli
• How does one cell thick, aid gas exchange?

  Less distance for gas to travel increases rate of diffusion
• How does moist, aid gas exchange?

  Gasses need to dissolve before they diffuse. This prevents evaporation.
• How does ventilation, aid gas exchange?

  Maintains concentration gradient for rapid gas exchange by continually bringing in a high amount of oxygen
• Deoxygenated blood composition?


  Low in oxygen and high in carbon dioxide. It comes from the heart.