2. Thorax(胸廓) ■ The thorax is a closed compartment that is bounded at the neck by muscles and connective tissue and completely separated from the abdomen by the diaphragm Ribs Intercostal muse
2. Thorax（胸廓） ◼ The thorax is a closed compartment that is bounded at the neck by muscles and connective tissue and completely separated from the abdomen by the diaphragm
3. Alveoli(肺泡) Copyright o The McGraw-Hill Companies, Inc. Permission required for reproduction or display Left pulmonary artery Left main bronchus bronchia a Branch of Smooth muscle Respiratory Each of the clustered alveoli includes an abundance of pulmonary capillaries, thereby assuring that the ventilated air is brought into close proximity to the"pulmonary blood, allowing efficient and thorough gas exchange between the air and the blood
Each of the clustered alveoli includes an abundance of pulmonary capillaries, thereby assuring that the ventilated air is brought into close proximity to the “pulmonary” blood, allowing efficient and thorough gas exchange between the air and the blood. 3. Alveoli（肺泡）
a Capillaries EXtensive branching Respiratory bronchiole of alveoli produces Alveolus Alveolar duct lots of surface area Alveolus for exchange between Alveolus air and blood Alveolar air Type ll cell Basement Alveolar and capillary walls are thin permitting rapid Interstitium diffusion of gases ype I cell Alveolar air
Extensive branching of alveoli produces lots of surface area for exchange between air and blood. Alveolar and capillary walls are thin, permitting rapid diffusion of gases
Breathing is an active process ■ To inhale吸入 Contraction of external intercostal muscles肋间外肌→> elevation of ribs& sternum胸骨→ increased front-to- back dimension of thoracic cavity>lowers air pressure in lungs > air moves into lungs Contraction of diaphragm膈肌→> diaphragm moves downward >increases vertical dimension of thoracic cavity> lowers air pressure in lungs> air moves into lungs 个 Air Out
Breathing is an active process ◼ To inhale 吸入 – Contraction of external intercostal muscles肋间外肌→elevation of ribs & sternum胸骨 → increased front- to-back dimension of thoracic cavity → lowers air pressure in lungs → air moves into lungs – Contraction of diaphragm 膈肌→ diaphragm moves downward → increases vertical dimension of thoracic cavity → lowers air pressure in lungs → air moves into lungs
Breathing is an active process To exhale呼 Relaxation of external intercostal muscles diaphragm > return of diaphragm, ribs, sternum to resting position >restores thoracic cavity to preinspiratory volume>increases pressure in ungs→> air is exhaled Air Out
Breathing is an active process ◼ To exhale 呼气 – Relaxation of external intercostal muscles & diaphragm → return of diaphragm, ribs, & sternum to resting position → restores thoracic cavity to preinspiratory volume → increases pressure in lungs → air is exhaled