Respiratory & Circulatory Systems

Nasal Cavity

Uppermost part of respiratory system; functions to warm and moisten air

External Nares

Nostrils

Pharynx

Throat

Epiglottis

Piece of cartilage in the throat that protects the airway during swallowing (in green)

Oropharynx

Space behind the mouth

Larynx

Voice box; located just above trachea and esophagus

Bronchi

Large tubes air travels down to reach the lungs

Lungs

Bronchioles

Small branches of the bronchi; delivers air to the alveoli

Alveoli

Tiny air sacs of the lungs where gas exchange takes place

Diaphragm

Muscle sitting below the lungs that controls breathing

Carina

Location where the bronchi split into left and right

Blood flow step 1

Oxygen-poor blood enters the right atrium through both the superior vena cava and the inferior vena cava

Blood flow step 2

As the atrium contracts, blood flows downward through the open tricuspid valve and empties into the right ventricle

Blood flow step 3

The right ventricle contracts and pushes blood through the pulmonary valve which leads to the pulmonary arteries

Blood flow step 4

The pulmonary arteries allow the blood to enter into either the left or right lung where gas exchange teakes place at the capillary level of the alveoli

Blood flow step 5

Oxygen-rich blood returns through the pulmonary veins and enters into the left atrium

Blood flow step 6

The left atrium contracts and squeezes the blood downward through the open mitral valve which empties into the left ventricle

Blood flow step 7

The left ventricle contracts and sends blood upward through the aortic valve into the aorta

Blood flow step 8

The aorta delivers blood to the rest of the body