Cardio Flashcards
T/F: smooth muscle has 1 nucleus
True
______capillaries have pores and are seen in liver/spleen/lymph/bone marrow/some endocrine glands
Sinusoidal
Where do we get the name “striated muscle”?
Highly organized arrangement of filaments within the muscle cell
(this gives a characteristic alteration of light and dark bands when viewed in longitudinal section)
Derivations of “sarco”, “myo”, and “mys” are generally used in relation to _____.
muscle
Define sarcolemma
Muscle cell membrane
Define sarcoplasm
Cytoplasm of muscle cells
Define sarcoplasmic reticulum
Highly specialized membrane system derived from the muscle endoplasmic reticulum
Why is smooth muscle referred to as involuntary?
It is regulated by the autonomic nervous system, hormones, or local physiological conditions
Where is smooth muscle found (7)?

- GI tract
- Wall of urinary tract
- Reproductive system
- Blood vessels
- Gland ducts
- Respiratory system
- Dermis
Describe the shape and the nucleus location of smooth muscle cells.
- Fusiform shape
- Single nucleus located in the thickest central portion of the cell

Describe the nucleus of a fusiform - shaped cell in longitudinal cross section when contracted vs. relaxed?
Contracted: cork screw appearance
Relaxed: round

Describe the histological appearance of multiple smooth muscle cells in cross section.
- Packed with the narrow part of one cell lying adjacent to the thick (nucleus - containing) portion of another cell.
- In cross-section we see a range of diameters, the thickest having a nucleus in the center

Which organelles are present adjacent to each pole of a smooth muscle cell nucleus?
- Polyribosomes
- RER
- Golgi
- Mitochondria
Do smooth muscle cells contain T tubules?
No
Describe the sarcoplasmic reticulum of smooth muscle cells (3).
- Continuous w/RER
- Rudimentary and scattered throughout the sarcoplasm
- Contains Calcium binding proteins (Calsequestrin)
Define caveolae.
Structures involved in calcium sequestration
(near cell surface & look like pinocytotic vesicles)
Why is smooth muscle “smooth” and not “striated”?
Myofilaments are NOT arranged in an organized manner, as striated muscle is.
What are the three types of filaments found in smooth muscle sarcoplasm?
- Thin filaments
- Intermediate filaments
- Thick elements
What are thin filaments of smooth muscle cells coposed of?
Actin and tropomyosin (NO TROPONIN)
What are intermediate filaments of smooth muscle sarcoplasm composed of?
Desmin
What are thick filaments of smooth muscle sarcoplasm composed of?
Myosin
What is unique about the arrangement of thick and thin filaments in smooth muscle?
- *Thick filament**: myosin heads all along the length of the filaments
- *Thin filaments:** longer & 3 xs more than skeletal m.
(casual intermingled association between filaments, not as structured as skeletal m.)
Where do the thin and intermediate filaments insert?
- dense bodies
- dense plaques
Define dense bodies
- Small, poorly defined densities in the cytoplasm
- Possess Alpha actin and other proteins






















































