Solve these clues to fill the grid.
- A mechanical device in a camera that controls size of aperture of the lens
- 2 Across
- A specialized bit of heart tissue that controls the heartbeat
- 4 Across
- Hypersensitivity reaction to a particular ___
- 8 Across
- Mucus-secreting ___ lining all body cavities or passages that communicate with the exterior
- 9 Across
- A chamber of the heart that receives blood from an atrium and pumps it to the arteries
- 12 Across
- Any of the smallest ___ ducts (plural)
- 13 Across
- A fourth state of matter distinct from solid or liquid or gas and present in stars and fusion
- 14 Across
- Respiratory disorder characterized by wheezing
- 16 Across
- Any of the minute blood vessels connecting arterioles with venules (plural)
- 1 Down
- A common disorder in which blood pressure remains abnormally high
- 3 Down
- Any chamber that is connected to other chambers or passageways
- 5 Down
- A mature ___ ___ that contains hemoglobin to carry oxygen to the bodily tissues (plural)
- 6 Down
- Tiny bits of protoplasm found in vertebrate blood (plural)
- 7 Down
- A blood vessel that carries blood from the heart to the body (plural)
- 10 Down
- One of the tubules forming the respiratory system of most insects and many arachnids
- 11 Down
- A deficiency of red blood cells
- 15 Down