If one considers the blood to be an organ, then our blood does not have a nerve supply. Now the blood vessels do, of course. Other parts of the body that are not truly organs, but are not supplied with nerves are: fingernails, and hair (shafts, not follicles). These tissues don't have a nerve supply.
Conversely, solid organs, such as the lungs, liver, and spleen, have fewer free endings and are not highly sensitive to pain. Hence, they can deteriorate without the individual's becoming very aware of it.
Skin, blood vessels, muscles, all internal organs, bone (but not bone marrow) all have innervation by some part of the nervous system.
The tongue, lips, and fingertips are the most touch- sensitive parts of the body, the trunk the least.
Sponges are the only multicellular animals without a nervous system. They do not have any nerve cells or sensory cells. However, touch or pressure to the outside of a sponge will cause a local contraction of its body.
Armour, in 1991, discovered that the heart has its "little brain" or "intrinsic cardiac nervous system." This "heart brain" is composed of approximately 40,000 neurons that are alike neurons in the brain, meaning that the heart has its own nervous system.
The brain has no nociceptors – the nerves that detect damage or threat of damage to our body and signal this to the spinal cord and brain. This has led to the belief that the brain feels no pain.
The brain itself does not feel pain because there are no nociceptors located in brain tissue itself. This feature explains why neurosurgeons can operate on brain tissue without causing a patient discomfort, and, in some cases, can even perform surgery while the patient is awake.
The sensory nerves in your organs have pain receptors called nociceptors. They send signals to the spinal cord and brain to alert you of illness or injury.
The forehead and fingertips are the most sensitive parts to pain, according to the first map created by scientists of how the ability to feel pain varies across the human body.
Have you ever had that feeling of butterflies in your stomach? It's just your nerves, literally. Your gut contains a large, but often forgotten, system of nerves. Collectively called the enteric nervous system, this system in the gut contains up to five times as many neurons as the number of neurons in the spinal cord.
Bones are discrete organs made up of bone tissue, plus a few other things. The main misconception about bones then, is that they are made up of dead tissue. This is not true, they have cells, nerves, blood vessels and pain receptors.
The human body contains special nerve endings called sensory receptors that enable you to “feel” things. These receptors are not located only in your skin. They're also found in muscles, joints, blood vessels and internal organs.
Cartilage does not contain nerves; it is aneural.
The lung, like many other organs, is innervated by a variety of sensory nerves and by nerves of the parasympathetic and sympathetic nervous systems that regulate the function of cells within the respiratory tract.
The part of the body that has the most nerve endings is probably the fingertips. Each fingertip contains approximately 3,000 nerve endings called Meissner's corpuscles, which are designed to detect light touch and vibration.
Congenital insensitivity to pain and anhydrosis (CIPA) is a very rare and extremely dangerous condition. People with CIPA cannot feel pain [1]. Pain-sensing nerves in these patients are not properly connected in parts of brain that receive the pain messages.
The brain itself doesn't feel pain. Though the brain has billions of neurons (cells that transmit sensory and other information), it has no pain receptors. The ache from a headache comes from other nerves — inside blood vessels in your head, for example — telling your brain something is wrong.
Organs are usually transplanted because the recipient's original organs are damaged and cannot function. The brain is the only organ in the human body that cannot be transplanted. The brain cannot be transplanted because the brain's nerve tissue does not heal after transplantation.
Managing pain
Many people (but not all) with a terminal illness may experience pain. Pain can be due to a variety of reasons such as pressure on an internal organ, damage to nerves or lack of blood supply.
Without nerve cells, we wouldn't know if it's dark or light, hot or cold. We wouldn't be able to touch anything or feel if someone is touching us. We wouldn't be able to smell or taste anything and would have no idea that we have an upset stomach or that we have cut ourselves.
Our Circulatory System and Nervous System We could not live without them! Our circulatory and nervous system are connected through organ and bodily functions. Our brains control these functions through our nervous system.
Injured nerve cells in the central nervous system typically do not regenerate. However, this part of the nervous system can reorganize in response to an injury. This is called "plasticity." Luckily, the brain has a lot of built-in redundancy.