Understanding the Human Body: A Detailed Guide to Organ Size, Mass, and Function Across the Lifespan

Muscles

 **Size**

: Varies among different muscles

 **Mass**

: Approximately 35 kg in total¹

 **Function**

: Enable movement, maintain posture, and produce heat

Skin

**Size**

: Up to 1.95 square meters

 **Mass**

: Approximately 4.5 kg (without subcutaneous tissue) to 15 kg (with subcutaneous tissue)¹

**Function**

: Protection, sensation, thermoregulation, and vitamin D synthesis

 Intestines

 **Size**

: About 8 meters long combined

 **Mass**

: Around 2 kg¹

**Function**

: Digestion, absorption of nutrients, and excretion of waste

Liver

 **Size**

: Roughly the size of a football

**Mass**

: Between 1.4 to 2 kg¹

 **Function**

: Metabolism, detoxification, protein synthesis, and digestion

Brain

 **Size**

: Varies among individuals

**Mass**

: Around 1.36 kg on average¹

**Function**

: Central control of the body, cognition, sensations, and coordination

Lungs

 **Size**

: Varies among individuals

 **Mass**

: Not specified

 **Function**

: Gas exchange, maintaining acid-base balance

Heart

**Size**

: Similar to the size of a closed fist

**Mass**

: Approximately 0.3 kg¹

 **Function**

: Pumping blood throughout the body

Kidneys

**Size**

: About the size of a computer mouse

 **Mass**

: Approximately 0.16 kg each¹

 **Function**

: Filtration of blood, waste excretion, regulation of blood pressure

Joints

**Size and Mass**

: Varies significantly among different joints

 **Function**

: Allow movement and provide mechanical support

 Spleen

 **Size**

: Roughly the size of a fist

 **Mass**

: About 0.15 kg¹

**Function**

: Filters blood, recycles old red blood cells, stores white blood cells and platelets

 Pancreas

**Size**

: About 15 cm long

**Mass**

: Approximately 0.1 kg¹

 **Function**

: Produces digestive enzymes and hormones like insulin and glucagon

Thyroid

 **Size**

: 5 cm in height, 3 cm in width, and 2 cm in thickness

 **Mass**

: 15-30 grams¹

**Function**

: Regulates metabolism, heart rate, and body temperature

Joints

**Size and Mass**

: Varies significantly among different joints

 **Function**

: Provide movement and mechanical support

 Bones

**Size and Mass**

: Varies among the 206 bones in the human body

**Function**

: Provide structure, protect organs, anchor muscles, and store calcium

Eyes

**Size**

: About 2.5 cm in diameter

**Mass**

: Approximately 7.5 grams each

**Function**

: Provide vision

Ears

**Size**

: External ear is about 6 cm in height

**Mass**

: Not specified

**Function**

: Collect sound and aid in balance and body position

 Gallbladder

**Size**

: Roughly 8 cm in length

**Mass**

: About 40 grams

 **Function**

: Stores and concentrates bile produced by the liver

Adrenal Glands

**Size**

: About 5 cm in length

**Mass**

: 4-5 grams each

**Function**

: Produce hormones that help regulate metabolism, immune system, blood pressure, and response to stress

Bladder

**Size**

: Can hold about 400-600 ml of urine

**Mass**

: Not specified

**Function**

: Stores urine before it is excreted from the body

Aging can have various effects on the size and mass of human organs, as well as their function. Here are some key points regarding how aging affects organs:

Cellular Changes

 :As we age, cells become larger and less able to divide and multiply. There's an increase in pigments and fatty substances inside the cell (lipids), and many cells lose their ability to function or begin to function abnormally¹.

Tissue Atrophy

: Many tissues lose mass, a process known as atrophy. Some tissues may also become lumpy (nodular) or more rigid¹.

Connective Tissue Stiffness

: Connective tissue becomes stiffer, making organs, blood vessels, and airways more rigid¹.

Decreased Organ Function

: Aging organs slowly lose function, although most people do not notice this loss immediately because organs typically have a reserve ability to function beyond usual needs¹.

 Reduced Cell Count

: In some organs, cells die and are not replaced, leading to a marked decrease in the number of cells, which can affect the organ's ability to function normally⁵.

It's important to note that these changes vary widely among individuals and can be influenced by factors such as genetics, lifestyle, and overall health. While aging is a natural process, maintaining a healthy lifestyle can help mitigate some of the negative effects on organ size, mass, and function.