The document discusses several key components of the immune and lymphatic systems:
- The tonsils are located in the back of the throat but their role in the immune system is unclear and they may be removed if causing issues.
- The thymus produces T cells and plays an important role in immune tolerance; it is most active in infants and children.
- The spleen filters old red blood cells and stores blood reserves; it can be removed if there is an increased infection risk.
- Red bone marrow produces new blood cells and makes up 4% of body weight in adults.
- Lymph nodes throughout the body filter foreign particles and contain white blood cells.
- Phagocytes are white blood cells
The document discusses several key components of the immune and lymphatic systems:
- The tonsils are located in the back of the throat but their role in the immune system is unclear and they may be removed if causing issues.
- The thymus produces T cells and plays an important role in immune tolerance; it is most active in infants and children.
- The spleen filters old red blood cells and stores blood reserves; it can be removed if there is an increased infection risk.
- Red bone marrow produces new blood cells and makes up 4% of body weight in adults.
- Lymph nodes throughout the body filter foreign particles and contain white blood cells.
- Phagocytes are white blood cells
The document provides an English grammar lesson on expressing past time. It covers topics like using the simple past tense with questions using where, why, when and what time. It discusses irregular verbs in groups 5, 6 and 7. It also covers using before and after in time clauses, when in time clauses, the present progressive and past progressive tenses, and using the past progressive with while. The document contains examples, exercises and short answers for students to practice each grammar concept.
The document provides an English grammar lesson on expressing past time. It covers topics like using the simple past tense with questions using where, why, when and what time. It discusses irregular verbs in groups 5, 6 and 7. It also covers using before and after in time clauses, when in time clauses, the present progressive and past progressive tenses, and using the past progressive with while. The document contains examples, exercises and short answers for students to practice each grammar concept.