Macro Respiration Chapter 42

What you need to know The general characteristics of a respiratory surface. The pathway a molecule of oxygen takes from the air until it is picked up by the hemoglobin of a red blood cell.

Respiration Uptake of O2 and discharge of CO2 Respiratory Medium is the source of O2 Air (21% O2) Water (varies with temperature and salinity but always less than 21%) As temp and salinity increase, O2 decreases Gas diffuses based on gas pressure (partial pressure) Always from high to low (simple diffusion)

Respiratory Surfaces Always moist, single cell layer, epithelial tissue (skin cells) Lungs, air sacs, trachea In folding of body/skin *(favorable surface area to volume ratio) Reduces water loss for terrestrials Gills Outer folding of body/skin * Countercurrent exchange Skin

Types of Respiration Skin Breathing (worms) No specialized respiratory surface, high surface area to body volume required, they have to stay small, must live in moist environments

Types of Respiration Tracheal System (insects) Extensive branching tubes reach every cell, no circulatory system required, low efficiency, organisms are small and ectothermic

Types of Respiration Gills (organisms) Two or more, countercurrent exchange, high energy requirement

Types of Respiration Lungs (terrestrial vertebrates) Large surface area through intense in-folding Covered with moist epithelial tissue

Human Pulmonary System Flow of air into the body: Mouth or nose  Pharynx (throat)  Epiglottis (skin flap)  Larynx (voice box)  Trachea (windpipe)  Bronchi (2 bronchus: 1 to each lung)  Lungs which contain bronchioles (small tubules) and alveoli (tiny air sacs at the end of each bronchiole)

Functions of Organs Nasal cavity: cleans, moisturizes, and warms air Larynx: sound Epiglottis: separating food from air Cartilage flap that covers the entrance to the trachea, only opens when you breath Nervous system cross inhibition prevents swallowing and breathing at the same time

Functions of Organs Trachea & bronchi: ciliated epithelial cells which secrete mucus to trap and remove any remaining dirt/dust/debris particles Mucus is transported by cilia dispelling mucus out the throat and nose Cystic fibrosis is a recessive mutation leading to thick mucus which is a breeding ground for bacteria

Functions of Organs Lungs: spongy tissue with enormous surface area (football field) Right lung has 3 lobes, left lung has 2 Surrounded by capillaries Gases pass through 2 cell layers: alveoli cell and capillary wall cell

Gas Exchange Alveoli are tiny lung sacs 1 cell layer thick Gases diffuse from high to low concentrations (higher O2 in alveoli, higher CO2 in the blood)

Gas Transport Hemoglobin: quaternary protein, iron chelate in vertebrate erythrocytes (RBC) Myoglobin: similar to hemoglobin, O2 storing protein in muscles Hemolymph: protein/copper chelate in mollusks and arthropods Most CO2 is bound in the blood liquid as carbonic acid (HCO3-)

Mechanics of Breathing Diaphragm is a dome-shaped (relaxed) muscle separating the thorax from the abdomen When the muscle contracts it flattens, pulling down the lungs, which creates a vaccuum = inhalation Relaxation of the muscles = exhalation Vital Capacity = maximum volume of air in lungs

Control Inovluntary Blood chemistry influences breathing rate Medulla oblongata (brain stem) has O2 sensors

Respiratory Diseases Infections: ears, nose, throat, bronchi (bronchitus), lungs (pneumonia) Allergies: hayfever Asthma: extreme allergic reaction leading to the constriction of bronchi Emphysema: repeated infections and irritations leads to the replacement of alveoli with scar tissue CF, smoking, pollution Lung Cancer: mutated alveoli cells