Respiration

Cellular Respiration A reaction that occurs in the mitochondria of the cell that requires O2 and that breaks down the end products of glycolysis into CO2 and water while capturing large amounts of energy as ATP.

Cellular Respiration

What does diffusion mean?

3 requirements that facilitate diffusion in animal respiratory systems Respiratory surfaces must remain moist Respiratory surfaces must be very thin Respiratory system must have a large surface area in contact with the environment

Not all animals have lungs or gills Some animals breath through their skin Have thin, gas permeable skin that provides adequate surface area for the diffusion of gases Usually live in moist habitats Usually have low metabolic demands

Skin breathing animals Microscopic roundwormFlatworm Sea jelly (jellyfish) Earthworm

Gas exchange (animals with well-developed resp. systems) 1. Air or water is moved past a respiratory surface by bulk flow 2. O2 and CO2 are exchanged through the respiratory surface by diffusion 3. Gases are transported between the respiratory system and the tissues 4. Gases are exchanged between the tissues and the circulatory system by diffusion

Gas Exchange

Gills Respiratory structures of aquatic animals May be extensions of the body surface into the surrounding water Or may be elaborately folded or branched structures that increase surface area for gas exchange

Gills Fish gills Mexican axolotl Shark Mollusk

Terrestrial animals Transition from water to land - animals had to evolve respiratory structures that were: – Protected – Supported – Covered with a film of water Tracheae – insects Lungs – terrestrial vertebrates

Tracheae - insects Tracheae – elaborately branched internal tubes that convey air throughout the body Are reinforced with chitin and found throughout the body tissues Branch into microscopic tissues called tracheoles Which allow for gas exchange Spiracles – where air enters and leaves tracheae (series of openings)

Insect tracheael system

Terrestrial vertebrates use lungs Lungs – chambers containing moist respiratory surfaces that are protected within the body where water loss is minimized and the body wall provides support

Terrestrial vertebrates TadpolesBullfrog Coral snake Painted bunting Wildebeest

Human respiratory system Can be divided into 2 parts: – Conducting portion – Gas-exchange portion

Conducting portion Brings air to the lungs Air enters: Nose or mouth Pharynx Larynx Trachea Branches into 2 bronchi Brochioles Alveoli

Larynx Epiglottis – covers larynx and prevents food from entering Contains Vocal Cords which are bands of elastic tissue controlled by muscles

Human respiratory passage

Complications of the respiratory passages Smoking Normal lung tissue Smokers lung

Emphysema

Complications of the respiratory passages Choking - Heimlich maneuver

Complications of the respiratory passages Asthma

Gas exchange Alveoli – where gas exchange takes place Provides large surface area for diffusion Network of capillaries cover most alveolar surface Respiratory membrane – Single layer of epithelial cells on alveoli (innermost portion) – Single layer of endothelial cells that form the wall of each capillary

Respiratory membrane Diffusion of CO2 and O2 is a short distance between air and blood – only 2 layers of cells thick

Alveoli Surfactant lines alveoli Thin layer of oily fluid that reduces surface tension and prevents the alveoli from collapsing during exhalation

Gas exchange Deoxygenated blood coming from heart – Blood - High in CO2; Low in O2 – Arrives at the alveoli in the lungs – CO2 travels down concentration gradient through respiratory membrane into air Air in lungs – High in O2; Low in CO2 – O2 travels down concentration gradient through respiratory membrane into blood – Oxygenated blood returns to heart to be pumped throughout body In the tissues, O2 diffuses into cells because the concentration of O2 is lower in the cells than in the blood

Gas exchange

Transport of gases – CO2 CO2 transported in 3 different ways – A little is dissolved in plasma – Some loosely bound to hemoglobin (iron- containing protein in red blood cells) – Most forms bicarbonate ion – HCO 3 - Diffuses into plasma; helps maintain proper blood pH This reverses when capillaries flow past the alveoli CO2 wants to move down its concentration gradient into alveoli

Transport of gases – O2 O2 carried by hemoglobin in red blood cells Hemoglobin can carry up to 4 O2 molecules Removes O2 from plasma, allowing O2 to move down its concentration gradient from air to blood Hemoglobin bound to O2 changes its shape and color

Hemoglobin

Carbon monoxide (CO) poisoning

Breathing Involuntary 2 stages 1. Inhalation – Contracts diaphragm muscle – enlarges chest cavity – At rest, diaphragm domes upward – Rib muscles contract – lift ribs up and outward – As chest expands - lungs inflate – draws in air 2. Exhalation

Breathing Exhalation – Occurs automatically when muscles relax – Can also forcibly contract abdominal muscles to exhale additional air

Breathing