Human anatomy consists of the following:

The Skeleton

In an adult body, the skeletal structure consists of 206 distinct bones. The axial skeleton and the appendicular skeleton are the two main divisions of these bones. The axial skeleton extends parallel to the midline axis of the body and is composed of 80 bones located in the following regions:

• Skull
  Except for the mandible, the head is made up of 22 fused bones. These 21 fused bones are separate in children to allow for head and brain growth but combine in adults to provide additional strength and defence. The mandible retains its mobility as a jaw bone and forms the skull’s only movable joint with the temporal bone.
• Hyoid
  The hyoid is a tiny U-shaped bone located immediately under the mandible. The hyoid is the one bone in the body not connected to any other bone—it is a floating bone. The hyoid’s purpose is to maintain an accessible trachea and provide a bony attachment for the tongue muscles.
• Sternum and Ribs
  The sternum, or breastbone, is a small, knife-shaped bone situated in the anterior thoracic portion of the skeleton near the midline. The sternum is connected to the ribs by thin cartilage bands called costal cartilage.
• Column with Vertebrae
  The vertebral column of the human body is composed of twenty-six vertebrae. Each vertebra is called by the first letter of its area and superior-inferior axis location except for the sacrum and coccyx.

Structure and Functions of Skin Organs

The skin is the body’s primary tissue, covering a region of about 20 square feet. The skin defends us from bacteria and the elements, aids in temperature regulation, and provides tactile, thermal, and cold stimuli.

The skin is composed of three layers:

1. The epidermis, the outermost layer of skin, acts as a waterproof shield and determines the colour of our skin.
2. The dermis, which lies under the epidermis, is a dense connective tissue that includes hair follicles and sweat glands.
3. Subcutaneous fat and connective tissue comprise the broader subcutaneous tissue (hypodermis).

The pigment melanin is produced by special cells called melanocytes, which give the skin its colour. The epidermis contains melanocytes.

Human physiology consists of the following:

Respiratory System

The human body’s cells need a steady supply of oxygen to survive. The respiratory system supplies oxygen to the body’s cells when eliminating carbon dioxide, a waste product that may be fatal if left to build up.

The mechanism of breathing is composed of three main components: the airway, the lungs, and the respiration muscles.

• The airway, which comprises the nose, throat, pharynx, larynx, trachea, bronchi, and bronchioles, is responsible for transporting air between the lungs and the body’s exterior.
• The lungs act as the respiratory system’s functional components, supplying oxygen to the body and removing carbon dioxide.
• Finally, the respiratory muscles, which include the diaphragm and intercostal muscles, function in concert to serve as a piston, moving air into and out of the lungs with each intake.

Thermoregulation

Thermoregulation is a process by which mammals self-regulate their body temperature in response to external temperatures. Temperature control is a form of homeostasis and a mechanism for maintaining a constant internal temperature necessary for survival.

While the core body temperature is closely regulated within a limited range, minor variations in heat production and core body temperature occur daily due to circadian rhythm and menstruation factors. When an individual is unable to control his or her body temperature, a variety of pathologies arise. The human body maintains core temperature by four distinct mechanisms: vaporization, radiation, convection, and conduction.

In this chapter, we learned about the different anatomies and physiologies of the human body. This knowledge can be further used to assess the health and nutrition of the human body.

1. How is human anatomy defined?
   Human anatomy is the analysis of the human body’s systems.
2. What are the anatomical components of the human body?
   The head, spine, torso, arms, and legs are the main components of the human body.
3. What is the term for the examination of the human body?
   Physiology is the science of the human body’s functioning.
4. What is the proper term for human body parts?
   The human body comprises a head, spine, torso, two arms, two legs, and male and female genitals.
5. Which organ is the biggest in the human body?
   The skin is the biggest organ.