A cat's skeleton is made up of more than 290 bones, which makes up approximately 12&13; percent of its body weight. The bones provide structural support and protect vital organs; they also store minerals, produce red and white blood cells, and facilitate movement.
Muscles
Muscles make up approximately 45% of a cat's body mass. There are three basic types of muscles: skeletal muscles, smooth muscles, and cardiac muscles. Skeletal muscles are responsible for voluntary movement and are attached to the bones. Smooth muscles are found in the walls of internal organs and are responsible for involuntary movements, such as digestion and respiration. Cardiac muscle is found in the heart and contracts and relaxes to pump blood throughout the body.
Digestive System
A cat's digestive system begins at the mouth and includes the teeth, tongue, esophagus, stomach, small intestine, and large intestine (colon). The teeth are used to cut and grind food, the tongue helps to mix and swallow food, and the esophagus carries food to the stomach. The stomach secretes digestive juices that break down food into smaller molecules, and the small intestine absorbs nutrients from food. The large intestine absorbs water from waste products and forms feces, which are excreted through the anus.
Respiratory System
The respiratory system of a cat includes the lungs, trachea, and nose. The lungs are where oxygen is absorbed into the bloodstream, and carbon dioxide is removed from the bloodstream. The trachea carries air to and from the lungs, and the nose helps to warm, humidify, and filter the air.
Circulatory System
The cat's heart, blood, and blood vessels form the circulatory system. The heart pumps oxygen-rich blood throughout the body via the arteries. The blood then flows back to the heart through the veins. This constant flow of blood delivers oxygen, nutrients, and hormones to all of the cells and tissues in the body.
Nervous System
The nervous system of a cat is made up of the brain and nerves. The brain is the cat's control center, processing sensory information, controlling movement, and regulating sleep and wakefulness. Nerves are bundles of fibers that carry electrical signals from the brain and spinal cord to all of the cells in the body.
Urinary System
The urinary system includes the kidneys, ureters, bladder, and urethra. The kidneys filter waste products and water from the blood. The ureters carry urine from the kidneys to the bladder. The bladder stores urine and the urethra allows urine to exit the body.
Reproductive System
The reproductive system of a cat consists of different organs, depending on whether it is a male or female. In male, it consists of the testes, which produce sperm; the epididymis, which stores and matures sperm; the vas deferens, which carry sperm; the seminal vesicles, which produce seminal fluid; and the prostate gland, which produces prostatic fluid. In females, it consists of the ovaries, which produce eggs; the fallopian tubes, which carry eggs from the ovaries to the uterus; the uterus, where the fertilized eggs implant and develop; and the cervix, which is the passageway between the uterus and vagina.
Immune System
The immune system of a cat is responsible for protecting the cat's body from foreign invaders, such as bacteria, viruses, and parasites. It is made up of white blood cells, antibodies, and other immune system components.