Aging is a complex process that affects every part of our body, from the surface of our skin to the intricate systems working underneath. In Part One of this series, we discussed the external and internal changes related to the musculoskeletal, cardiovascular and respiratory systems. However, many significant changes also occur within our immune, nervous and digestive systems: ones that can profoundly affect our quality of life as we grow older. In Part Two of the series, we’ll explore what these systems do, the changes that occur with age and how they can influence your health. 

Immune System 

When your partner or little one comes home with a sudden fever and sore throat that turns into the flu, you can thank your immune system if you manage to stay flu-free. (Of course, you may also end up cursing that same system if you catch the illness yourself.) 

The immune system plays a critical role in defending your body against pathogens like the cold and flu and helps you recover faster if you do get sick. It consists of several crucial parts, including: 

• White blood cells 
• Antibodies 
• Lymph nodes 
• Spleen 
• Tonsils and adenoids 
• Bone marrow 
• Skin 

Some components, such as the skin, tonsils and adenoids, serve as the first line of defense against germs, acting as protective barriers. However, if pathogens manage to get past these barriers, other parts of the immune system, like white blood cells and lymph nodes, spring into action, attacking harmful germs to eliminate the infection. 

As you age, your immune system’s response begins to slow. Your body produces fewer white blood cells and other cells that fight viruses and bacteria, making you more vulnerable to illnesses. Additionally, when you do get sick, recovery often takes longer due to the slower immune response.  

Nervous System 

The nervous system is the body’s communication hub. It transmits signals between the brain and the rest of the body and is responsible for voluntary actions, like talking or walking, and involuntary actions, like digestion. It also controls your thoughts and memories. 

The two main parts of the nervous system include: 

• Central Nervous System (CNS) 
  Made up of the brain and spinal cord, the CNS processes and interprets information and sends out instructions to the rest of the body. 

• Peripheral Nervous System (PNS) 
  Consisting of nerves that travel through the head, neck and body, the PNS works like a communication highway, carrying information to and from the CNS. 

As you age, your brain’s overall function begins to slow, making it more challenging to process new information or transition between tasks. Some older adults also experience memory decline, sometimes leading to cognitive disorders like dementia, with Alzheimer’s being the most common form. 

Furthermore, reflexes and response times may also slow due to less efficient neural communication. When signal transmission between the PNS and CNS becomes sluggish, it can lead to decreased coordination and difficulty with balance.  

Digestive System and Metabolic Changes 

The digestive system plays a crucial role in absorbing the nutrients from the food you eat, breaking it down and converting it into waste (a.k.a. feces) to be eliminated from the body during bowel movements. 

But how does the digestive system work? Here’s a breakdown: 

1. Food passes through your mouth and esophagus into the stomach, where it’s broken down into a more digestible form.  
2. It moves into the small intestine, a 22-foot-long tube that further processes the food, transforming it from a semi-solid state to a liquid form.  
3. The body absorbs essential nutrients like carbohydrates, proteins, fats and vitamins. 
4. Nutrients are sent to the liver, which processes them and produces the chemicals your body needs to function.  
5. The remaining waste continues to the large intestine (colon), where it is broken down further and eventually becomes stool.  
6. The feces are stored in the rectum until they’re expelled through the anus. 

Though this system functions efficiently, aging causes the digestive system to decline in several ways: 

• Your metabolism slows down, which can result in weight gain and constipation. 
• The production of digestive enzymes also slows down, making it more challenging to digest food. This can lead to more frequent bloating and indigestion. 
• Your body’s ability to digest nutrients also decreases, which may lead to vitamin deficiencies and an increased risk of conditions like osteoporosis and anemia. 

Take a Deep Dive Into the Functions of the Human Body at UF 

If you’re fascinated by the physiological effects of aging, considered a career in the medical sciences. From becoming a physician assistant to working in the biomedical devices industry, numerous career paths are available to those with a background in anatomy and physiology. 

The University of Florida proudly offers seven online graduate programs in the medical sciences. Many of them can be completed in as little as one year, and all allow you to study on your timeline. With year-round start dates, affordable tuition options and an education from Forbes’ No. 4 university in the nation, what’s stopping you from pursuing a career you’re passionate about?  

Explore our program offerings and choose the program that aligns with your goals. 

Sources:
https://medlineplus.gov/ency/article/004008.htm
https://www.lung.org/lung-health-diseases/how-lungs-work/lung-capacity-and-aging
https://www.health.harvard.edu/blog/surprising-findings-about-metabolism-and-age-202110082613
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2267679/