14. Smooth and Cardiac Muscle

Smooth and cardiac muscle activity is …, but …

similar to, but distinct from skeletal muscle activity

What is universal across all three muscle tissue types?

• muscle cells have receptors (for NTs/ or hormones)

• changes in muscle membrane potential initiate contraction

• high intracellular Ca2+ proximately triggers contraction

• myosin-acting binding and power stroke generates the actual muscle contraction (sliding filament mechanism)

What are the main differences that exist across muscle cell types?

1. does the nervous system drive contraction entirely, or does it have broader reasons why it can contract?

   1. skeletal muscles when healthy only contract when stimulated by motor neurons

2. whether muscle cells respond to one or more NT / hormones, or can even contract on their own (smooth, cardiac)

smooth muscle contractions are controlled by more … than skeletal muscles

variable inputs (nervous, endocrine, and local factors)

what are some of the inputs that influence smooth muscle contractile activity?

• neurotransmitters released by autonomic neurons (skeletal contract from somatic neuron NTs/hormones)

• hormones

• locally induced changes in the chemical composition of their environment (extracellular fluid surrounding the cell)

• stretch