Chapter 9 quiz

**Cardiac muscle tissue**

*  **is found in hearts**


* Makes up bulk of heart walls 


* Striated 
* Involuntary: cannot be controlled consciously 
* Contracts at steady rate due to heart's own pacemaker, but nervous system can increase rate 

1. **Skeletal muscle tissue**

is packaged into *skeletal muscle*: organs that are attached to bones and skin

**Skeletal muscle fibers**

are longest of all muscle and have striations (stripes)

Skeletal Muscle

Called voluntary muscle,  can be consciously controlled 

* Contract rapidly; tire easily; powerful 

**Smooth Muscle Tissue**

**found in walls of hollow organs** 

* Examples: stomach, urinary bladder, and airways 


* Not striated 
* Involuntary: cannot  be controlled consciously 

Muscle Cells

are Muscle fibers

**Excitability** (responsiveness)

*  **ability to receive and respond to stimuli** 

**Contractility**

**ability to shorten forcibly when stimulated** 

**Extensibility**

**ability to be stretched** 

**Elasticity**

*  **ability to recoil to resting length** 

* **Four important functions** 

Produce movement: responsible for all locomotion and manipulation 

* Example: walking, digesting, pumping blood 


2. Maintain posture and body position 
3. Stabilize joints 
4. Generate heat as they contract 

Three different features of skeletal tissues

* **nerve and blood supply, connective tissue sheaths, and attachments** 

**Nerve and Blood Supply**

* Each muscle receives a nerve, artery, and veins


* Consciously controlled skeletal muscle has nerves supplying every fiber to control activity 


* Contracting muscle fibers require huge amounts of oxygen and nutrients 


* Also need waste products removed quickly 

**Connective Tissue Sheaths** 

* Each skeletal muscle, as well as each ACh, is covered in connective tissue 
* Support cells and reinforce whole muscle 

**Epimysium**

*  Dense irregular connective tissue surrounding entire muscle; may blend with fascia 

**Perimysium**

* **fibrous connective tissue surrounding fascicles (groups of muscle fibers)** 

**Endomysium**

*  **fine areolar connective tissue surrounding each muscle fiber**

**Insertion** 

*  **attachment to movable bone** 

**Origin**

*  **attachment to immovable or less movable bone** 

**Direct (fleshy)**

*  **epimysium fused to periosteum of bone or perichondrium of cartilage** 

**Indirect**

connective tissue wrappings extend beyond muscle as rope like **tendon or sheetlike aponeurosis** 

Skeletal muscle fibers (Microanatomy)

are long, cylindrical cells that contain multiple nuclei 

**Sarcolemma**

muscle fiber plasma membrane

**Sarcoplasma**

*  muscle fiber plasma

**glycosomes**

 glycogen storage

**myoglobin**

* O2 storage 

Modified organelles

* **Myofibrils** 
* **Sarcoplasmic reticulum** 
* **T tubules**

**Myofibrils** 

* **are densely packed, rodlike elements** 


* Single muscle fiber can contain 1000s 
* Accounts for \~80% of muscle cell volume 

* **Striations**

* **stripes formed from repeating series of dark and light bands along length of each myofibril** 

**A bands**

* **dark regions** 

**H zone**

*  **lighter region in middle of dark A band**

**M line**

*  **Line protein (myomesin) that bisects H zone vertically** 

**I bands**

 lighter regions

**Z disc (line)**

*  **coin-shaped sheet of proteins on midline of light I band** 

**Sarcomeres**

* Orderly arrangement of actin and myosin myofilaments within sarcomere

**Actin myofilaments**

*  **thin filaments** 


* Extend across I band and part way in A band 
* Anchored to Z discs

Thick filaments

*  composed of protein and **myosin** that contains two heavy and four light polypeptide chains