Arrange in the proper sequence the following events as they occur in the ossification of long bone development. Cartilage starts to break down and the periosteum begins to develop. Osteoblasts secrete osteoid to make hard bones. Blood vessels transport osteoblasts into the area to be ossified. Chondroblasts create a model of long bones from hyaline cartilage. Osteoblasts become osteocytes as the bone lengthens and widens.  

New sperm cell synthesis takes place in the ______________ and matures in the _______________.

Which one of the following statements is TRUE regarding Schwann cells? 

Which of the following is capable of producing an action potential (AP) in the human body? Select ALL that apply.   

Using the figure (A to D) above, 1) Identify the structure at the cellular level. 2) Identify the structure at the organ level. 3) Identify the structure that links the muscle to the bone. 4) Out of four human tissue types what tissue surrounds the fascicle? tissue.

Based on this illustration, match the right description with the left numbered muscle.

For an action potential to be generated, a minimum membrane voltage (-55mV) referred to as the ________, must be reached.

Tina was helping her grandmother cook dinner. The savory aroma of garlic and onions filled the warm kitchen. As she reached out to adjust the pot on the stove, her fingers touched the hot metal lid—sizzling, blistering heat surged through her skin. Instantly, neurons in her fingertips detected the dangerous temperature and fired off electrical signals. These signals raced through her peripheral nerves to her . There, the message was relayed by , the messengers in the spinal cord. Without even waiting for the brain to process the pain, the interneurons sent an urgent command to her arm muscles through the neurons. In a reflexive flash, Tina’s hand jerked back. She gasped, cradling her stinging fingers, the scent of cooked onions still lingering as her brain finally caught up: “That was hot!”

The following events are associated with muscle contraction. Write down the correct order in which these events occur, following the initiation of a contraction by a nerve impulse. Use a comma in between your answers ex) 1, 2, 3, 4, 5 T-tubules transmit electrical impulses throughout the muscle cell. Myosin contacts actin and pulls it toward the center of the sarcomere. Acetylcholine binds to receptors on the muscle. Troponin-tropomyosin complex shifts to expose myosin heads binding sites. Calcium is released from the sarcoplasmic reticulum.

All of the following teeth are found in adult vertebrates except