Respiratory System Flashcards
Oxygen
● Without energy, you would not survive
● To get energy, we break down glucose using oxygen; this is called cellular respiration and it happens in the mitochondria
● The average adult uses almost a cup’s worth (230mL) of oxygen/minute at rest. During exercise, up to 20x more than that!
Cellular respiration
The equation for cellular respiration is:
glucose + oxygen —> carbon dioxide + water + energy
C6H12O6 + O2 ——> CO2 + H2 O + energy
Glucose: simple sugar, comes from the food we eat. absorbed via the digestive system, villi, capillaries, etc.
Oxygen: comes from the air we breathe. absorbed in the lungs. carbon dioxide: toxic! must exhale
water: for your cells
ATP: usable energy in biological systems
Respiration
To get oxygen to our cells, and carbon dioxide away from our cells, these 2 processes must happen; together, they are called respiration:
1. Gas Exchange
2. Breathing
Gas exchange
● Happens deep within the lungs.
● Lungs have thin membranes and a large surface area
○ Large surface area is due to many small air sacs (alveoli)
● The lungs’ moisture makes it easier for gases (dissolved in water) to move across them or to diffuse
● When we inhale, oxygen in air goes to lungs and into capillaries that surround the lungs. From there, it is carried in blood to our cells.
● Carbon dioxide moves in the opposite direction; cells → blood → capillaries around lungs → air in lungs → leaves body through mouth and nose
Diffusion
● Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration
Haemoglobin and Gas Transport
● Oxygen is carried by a protein called haemoglobin that is found in red blood cells
● Haemoglobin contains iron atoms that can bind the oxygen
● Oxygen bound to haemoglobin gives blood its bright red
colour
● Approx. 20% of CO2 is carried by haemoglobin. The remainder of CO2 is carried in the cytoplasm of RBCs in the form of carbonic acid
○ CO2 + H2O =carbonic acid H2CO3
During Intense Physical Activity…
● An increase in cellular respiration → increased CO2 in the blood → excess carbonic acid→ drop in pH of blood
● Chemical receptors in the brain 🧠 and some arteries detect drop in pH → signals are sent b/w the brain and the muscles of the respiratory system (intercostal muscles and diaphragm) → more contractions → forceful exhalation and inhalation → more CO2 released out and more O2 in
Nasal passages
● Hairs in nostrils trap large particles
● Blood vessels in the nasal cavity warm air
● Mucus moistens air & traps dirt
● Cilia on cells sweep away dirt which can either be
swallowed or coughed up
Throat
● Pharynx: tube that branches into the oesophagus (where food goes down) and the trachea (where air goes down)
● Epiglottis: a flap of tissue that covers the trachea when swallowing food; out of the way when no food present
Trachea
● Walls supported and kept open by cartilage rings
● Mucus moistens and cleans the air
Bronchi and bronchioles
○ Main function is to get air to and from the lungs
○ Cartilaginous rings hold the bronchi open but none in bronchioles
Lungs
● Pink-grey spongy organs
● Right lung is larger and has 3 lobes; left lung has 2 lobes making room for the heart
Pleural membrane
● Lungs are wrapped in a thin, slippery membrane called the pleura
● Two layers;
○ the outer pleura is attached to the ribs.
○ The inner pleura covers the lungs;
○ between those layers is fluid that lubricates and reduces friction when we breathe
● Because the lungs are “glued” to the ribs, the lungs expand as the ribs (chest) expand
Alveoli
● Very small, thin-walled, moist air sacs at the ends of the bronchioles
● Large surface area where gas exchange happens with the capillaries
● CO2 (carried by RBCs) diffuses from capillaries into alveoli;
● O2 diffuses from alveoli into capillaries;
● O2 will be picked up by RBCs
Breathing control
● There are specialised MEDULLARY CHEMORECEPTOR How does the medulla oblongata know
cells that are sensitive to the [CO ] and [H+] in the fluid 2
HOW and WHEN to change the
around them.
breathing rate???
● There are also carotid chemoreceptors (carotid is the major artery to the brain) and aortic chemoreceptors (aorta is the major artery to the body) that measure the amount of O2 getting to the important parts of the body.
● If the receptors record high levels of [CO2] and [H+] in the blood, the breathing rate will increase.
● If the receptors record low levels of [O2], the breathing rate will increase.
● Once breathing rate increases, [CO2] and [H+] levels will decrease and [O2 ] levels will increase.
● Chemoreceptors will stop sending messages, breathing rate returns to normal. ☺
