What is connective tissue?
This type of tissue blood is classified as because it contains cells suspended in a matrix.
What is the thoracic duct?
This duct drains the entire lower body and left upper body into the left subclavian vein.
What is the tunica intima?
This layer of arteries and veins is made of simple squamous epithelium.
What is the absence of mitochondria?
This is the reason RBCs cannot use the oxygen they carry.
What is the thymus?
This organ shrinks after puberty but is essential for T-cell maturation.
What is the right ventricle?
This chamber pumps blood to the lungs.
What is the tricuspid valve?
This valve prevents backflow from the right ventricle into the right atrium.
What is the SA node?
This part of the heart’s conduction system is known as the “pacemaker.”
What are the papillary muscles?
These muscle structures contract to keep the AV valves from prolapsing into the atria.
What is the aortic semilunar valve?
This valve opens during ventricular systole to allow blood into the aorta.
What are the nasal conchae?
These structures in the nasal cavity warm, clean, and humidify air by creating turbulence.
What is fibrinogen?
This solute in plasma is essential for blood clot formation.
What is the spleen?
These lymphatic organs contain red pulp for RBC recycling and white pulp for immune responses.
What are veins (especially the vena cava)?
This type of blood vessel has the lowest pressure in the body.
What is albumin?
This plasma protein helps maintain osmotic pressure and regulate water balance.
What are veins?
These vessels carry blood back to the heart and contain valves.
What is tracheal cartilage?
This cartilage is C-shaped to prevent airway collapse while allowing the esophagus to expand.
What are alveolar type II cells?
This cell type secretes surfactant to prevent alveolar collapse.
What is the epiglottis?
This structure prevents food from entering the trachea during swallowing.
What is simple squamous epithelium?
This tissue type forms the alveolar walls and allows rapid diffusion.
What are skeletal muscle pumps and one-way valves?
These two mechanisms help blood return to the heart through veins despite low pressure.
What is a connective tissue capsule?
Tonsils lack this type of capsule so they can directly sample pathogens entering the throat.
What are the pharynx → larynx → trachea → bronchi → bronchioles?
Air travels in this sequence after the nasal cavity before reaching the alveoli.
What is complete separation of oxygenated and deoxygenated blood?
This advantage is gained by having a four-chambered heart instead of a two- or three-chambered one.
What are intercalated discs?
These specialized cell-to-cell junctions in cardiac muscle allow electrical signals to spread rapidly so the heart can contract as a unit.