each bronchus splits into smaller branches called bronchioles
the bronchi and bronchioles are made from cartilage to keep them open when you breathe in preventing them from collapsing
each bronchiole leads to a bunch of air sacs called alveoli
gas exchange takes place in the alveoli
the lungs are surrounded by two pleural membranes which line a pleural cavity that is filled with pleural fluid to reduce friction between lungs and ribs when breathing
the nasal cavity warms and filters air
the trachea carries air to the bronchi
the bronchus brings air into right or left lung
the bronchioles are branched to carry air into many alveoli within lung
the lungs contain millions of alveoli to give a large surface area
the alveolus is the site of gas exchange
the diaphragm is a muscular sheet that contacts or relaxes to aid breathing
the ribs protect lungs and heart
intercostal muscles contract to lift ribs up and out
pleural membranes line thoracic cavity and cover outside of lungs
pleural fluid acts with pleural membranes to reduce friction when breating
increased volume = decreased pressure = air sucked in
in bell jar lung model:
lungs = balloons
trachea = glass tube
diaphragm = rubber sheet
ribs = bell jar
when we inhale:
diaphragm contracts and flattens
ribs move up and out
intercostal muscles contract to move ribs up
volume of lungs increases
pressure in lungs decreases
air forced into lungs as external air pressure is greater than internal
when we exhale:
diaphragm relaxes and domes
ribs move downand in
intercostal muscles relax to move ribs down
volume of lungs decreases
pressure in lungs increases
air forced out of lungs as internal air pressure is greater than external
alveoli have thin walls for a short diffusion pathway for gases
alveoli are surrounded by a network of blood capillaries which maintain the concentration gradient
the alveoli are moist, the layer of moisture dissolves the gases before they pass through
there are millions of alveoli for a large surface area
alveoli are well ventilated, oxygen in constant supply, to maintain the concentration gradient
the air we breath in has a higher concentration of oxygen than the air we breathe out because the oxygen is transported to the cells and used in cell respiration to produce energy
respiration in the cells produces CO2 as a waste product which is transported back to the lungs in the blood and breathed out
carbon dioxide diffuses from the blood into the alveoli via simple diffusion
oxygen diffuses from the alveoli into the blood via simple diffusion
respiratory systems in animals are designed to deliver oxygen to as surface so that it can be absorbed and then transported to the individual cells in the body, in the cells oxygen is used in cell respiration. to provide large amounts of energy
to gain energy plants also need to respire, to do this they use some of the glucose made in photosynthesis and oxygen, plant leaves are designed to help gases diffuse
adaptations of respiration achieved in plants:
large surface area, leaves are flat
thin, short distance for gases to travel through the stomata to the leaf cells
moist, moisture on the outer surface of cells especially the spongy layer of the leaf
permeable, cell membranes are permeable to gases in solution
diffusion gradient, maintaining a gradient is achieved by gases being used (high-low)
adaptations of respiration achieved in animals:
large surface area, millions of alveoli
thin, walls of alveoli are thin- short diffusion distance for gases to travel through
moist, gases are more easily transported in solution- layer of moisture on inner surface of alveolus
permeable, cell membranes are permeable to gases in solution
good blood supply, each alveolus has its own capillary network so that oxygen can reach blood quickly and CO2 can be passed from blood to alveolus
diffusion gradient, blood constantly and this maintains a gradient (high-low)
we get energy from food through cell respiration
the nutrients that we get from out digested food are oxidised to give CO2 and water and energy is released
glucose + oxygen -> CO2 + water + energy
C6H12O6 + 602 -> 6CO2 + 6H2O + energy
active transport is the movement of substances from and area of low concentration to an area of high concentration, against concentration gradient