Which of the following substances is released by activated platelets to recruit more platelets to the site of injury? 

What is the significance of increased sporadic DNA mutations in older adults? 

How can cancer-causing viruses contribute to cancer development? 

Which of the following is a characteristic of the adaptive immune system?

Which of the following is a common cause of rotator cuff injuries in the shoulder? 

Which part of the shoulder joint is often affected by degenerative diseases? 

A patient with seasonal allergies experiences symptoms upon exposure to pollen. What is the sequence of events leading to these symptoms? 

A 5-year-old boy presents with spontaneous joint bleeding and easy bruising. Laboratory tests show prolonged activated partial thromboplastin time (aPTT) and low factor VIII levels.  What is the most likely diagnosis? 

A 45-year-old male presents with pain and numbness in his right hand and forearm. He reports that his symptoms are worse with repetitive use of his hand and wrist. Physical examination reveals tenderness in the forearm muscles and a positive Tinel’s sign at the wrist.  What is the most likely diagnosis? 

An 80-year-old female with a history of recurrent infections is diagnosed with a late-stage cancer.   What role does immunosenescence play in her cancer progression?