| Contract and relax to cause movement | Skeletal muscles |
| What are cells in skeletal muscles and describe: | Muscle fibers:long, cylindrical |
| Nuclei in skeletal muscles | Many: peripheral (cell’s edges) |
| striated muscles | Skeletal, Cardiac |
| Can see visible lines on muscles (dark/light) | striated |
| Dark and light (striated) lines caused by: | Actin and myosin |
| Actin and myosin are proteins responsible for | Muscle contraction |
| Are skeletal muscles controlled by voluntary or involuntary movement? | Voluntary |
| Line hollow organs, allow substances to move through organs by squeezing | smooth muscle |
| Nucleus in smooth muscle cells (how many and where?) | One, centrally locates |
| Are smooth muscles striated? | No |
| Are smooth muscles controlled by voluntary or involuntary? | Involuntary |
| Only found in walls of the heart (makes up the heart) | Cardiac muscle |
| Is cardiac muscle striated? | Yes |
| Are cardiac cells branched? | Yes |
| Are skeletal cells branched? | No |
| Cardiac cells are joined together at unique junctions called: | Intercalated discs |
| How many/ where are(is) nucleus in cardiac cells | One in the center |
| Are cardiac muscles controlled by voluntary or involuntary movement? | Involuntary |
| Can INdirectly increase heart rate, but not directly-the ability to receive and respond to stimuli | Cardiac muscles |
| Muscles have a chemical stimulus (ex:hormone) ; the response is an electrical impulse that causes the muscle to respond (contract, etc.) | Excitability/Responsiveness |
| Ability to contract | Contractility |
| Extensibility | Ability to stretch farther |
| Ability to return to original size without being changed | Elasticity |
| Functions of muscles: | Produce movement |
| Muscles maintaining posture vs bones | Bones are framework/structure, but muscles keep you upright and fight gravity |
| Structures that allow or prevent substances going through or in and out, by opening and closing | Valves |
| Connective tissue covering over entire muscle, is found on all muscles | Epimysium |
| Connective tissue, attaches muscle to bone | Tendons |
| When a person dies, their body no longer produces ATP, so actin and myosin stay locked together, and muscles stiffen (reverses after 48 hrs as muscle proteins break down | Rigor mortis |
| Flow of ions through biological tissue creates electrical currents which act as signals | Electrophysiology |
| Plasma membranes of muscle cells have: | Resting membrane potential |
| Charge when muscles aren’t contracting | Resting membrane potential |
| Cells have a differing concentration of ions on either side of cell membrane because: | Cells are selectively permeable |
| Let certain things in or out | Selectively permeable |
| Resting membrane potential in most cells | -70 mv |
| Because there’s a lot of sodium outside the cell, and potassium inside the cell, there’s an uneven distribution of ions across the membrane, causing the membrane charge: the inside of the cell has a negative charge COMPARED to the outside | Membrane potential |
| the electrical impulse system/cycle:the local voltage change across the cell wall as a nerve impulse is transmitted | Action potential |
| Many action potential cycles together cause | the muscle to contract |
| First step of action potential | Acetylcholine |
| Bonds to receptor in muscle cell, signals it | Acetylcholine |
| Second step of action potential | Sodium (Na+) rushes into cell through Na+ channels (because of concentration gradient), so the charge in the membrane becomes more and more positive |
| Third step of action potential | The second step happens until cell reaches the charge needed for an electrical impulse |
| Charge needed for an electrical impulse | Threshold |
| Fourth step of action potential | Once the threshold is reached, potassium stops coming: potassium(K+) leaves the cell through K+ channels. As it leaves, the charge of the cell returns to regular (resting membrane potential) |
| Fifth step of action potential | Sodium goes back out of cell/potassium comes back in , through the Na+/K+ Pump (which is constantly active) |
| How many sodium’s are pumped out in step 5 for every 2 potassium’s pumped in? | 3s out: 2P in |
| The action potential electric current is needed for: | Actin/myosin to function |
