The connection between the structure and purpose of body parts is clear in their contribution to overall bodily function. For instance, the hand is designed for grasping, the heart for pumping blood, and the mouth for chewing food. Molecules combine to create organelles, which then form cells. Likewise, multiple cells join together to create tissues or tissue layers, and several tissues come together to form an organ.
Organs and organ systems are essential components of an organism, encompassing various characteristics that define life. These characteristics include movement, responsiveness, growth, reproduction, respiration, digestion, absorption, circulation, assimilation, and excretion. Additionally, aspects related to metabolism such as the necessity for water, food, oxygen, heat and pressure contribute to the vitality of living organisms. Comparing our personal requirements for survival to those outlined in this chapter is crucial.
The coordination of cells, organs, and organ systems is essential for maintaining homeostasis. Homeostasis ensures a stable internal environment and protects the body from external factors. Despite changes in the external surroundings, these components work together to keep our bodies stable. Additionally, homeostasis requires a significant amount of metabolic energy.
Our body’s physiological control system can be compared to a room with heating and cooling facilities regulated by a thermostat set at 20 degrees Celsius. Like how temperature is controlled in the room for comfort, our physiological control system operates through negative feedback. This means that sensors within us detect any deviations from the desired internal state and initiate reactions to restore it back to its optimal condition, similar to adjusting the temperature in the room.
If the temperature drops below or exceeds the set control temperature, the furnace or air conditioner will activate respectively until the desired temperature is achieved. This response to changes in temperature is a form of negative feedback, which prompts a corresponding reaction from the utility.
The hypothalamus in our brain contributes to regulating body temperature. It stimulates sweat glands to secrete watery perspiration that helps dissipate heat and cool down our body when we become overheated.
The body maintains homeostasis by regulating blood pressure and blood glucose levels. It achieves this by dilating and constricting blood vessels. When the body becomes colder, it widens the blood vessels in the skin to allow heat-carrying blood to reach the surface, thus releasing more heat externally. Conversely, when body temperature increases, it narrows the blood vessels to decrease blood flow and retain heat in deeper tissues. Similar mechanisms are involved in controlling blood glucose levels, where adjusting vessel size is vital for achieving balance. However, there are differences in triggers and responses between these processes. Moreover, apart from regulating vessel size, the body generates heat through muscle contractions like shivering whenever necessary.
Sensory receptors in the walls of blood vessels and the pancreas have distinct mechanisms for regulating blood pressure and glucose levels, respectively. Blood pressure is influenced by factors like blood volume and pumping rate, while the pancreas utilizes chemicals such as insulin or glucagon to regulate glucose levels.
The body can be categorized into two parts: axial and ventricular. The axial part includes the head, neck, and trunk, whereas the ventricular part comprises the upper and lower limbs.
Within the axial part of the body, several cavities exist including the cranial cavity, spinal cavity, thoracic cavity, and abdominal cavity.
Viscera refers to organs located within both the thoracic and abdominal cavities.
The mediastinum is positioned between the lungs in the thorax region. It separates this area into two compartments containing each lung separately. The mediastinum contains significant structures such as heart, esophagus, trachea, and thymus.
The head possesses various cavities along with their respective contents.
The oral cavity consists of the teeth and tongue, while the nasal cavity includes the nasal septum and sinuses (such as the sphenoid and frontal sinuses). The orbital cavities contain the eyes, including associated skeletal muscles and nerves. Middle ear cavities house the bones of the middle ear.
To locate each organ: a) the liver and spleen are housed in the abdominal cavity, b) the heart, trachea, and esophagus can be found in the thoracic cavity, c) the brain resides in the cranial cavity, d) rectum and urinary bladder are located in pelvic cavity e) spinal cord is within spinal cavity.
Lastly, it’s important to distinguish between a parietal membrane and a visceral membrane.
The wall of a cavity is lined by a parietal membrane, while a visceral membrane covers organs. In terms of maintaining homeostasis, each organ system makes a general contribution. The integument system functions to cover the body, the skeletal and muscular systems provide support and facilitate movement, the nervous and endocrine systems integrate and coordinate body functions, the cardiovascular and lymphatic systems transport fluids, and the digestive, respiratory, and urinary systems absorb nutrients, supply oxygen and eliminate carbon dioxide, and expel waste. Additionally, the reproductive systems are responsible for producing and transporting sex cells.
The female reproductive system supports prenatal development and childbirth. 20. Enumerate the key organs of each organ system and explain their functions. A. Integumentary system – includes the skin, hair, nails, sweat glands, and sebaceous glands. It serves as a protective layer for underlying tissue, regulates body temperature, contains sensory receptors, and synthesizes substances. B. Skeletal system – consists of bones, ligaments, and cartilages that connect bones. It provides a framework, shields against injury, facilitates muscle attachment, produces blood cells, and stores inorganic salts. C. Muscular system – encompasses the muscles of the body.The nervous system, consisting of the brain, spinal cord, nerves, and sense organs, controls body movement, posture maintenance, and heat production. It receives signals from sensory receptors and interprets them to elicit responses in muscles or glands.
In contrast, the endocrine system is made up of various glands including the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreas ovaries testes pineal gland and thymus. These glands secrete hormones that help regulate metabolism by stimulating target tissues.
Additionally, there is the cardiovascular system which involves the heart pumping blood throughout the body. This system also includes blood vessels that transport blood to and from different parts of the body.The blood carries a range of substances such as oxygen, nutrients, hormones, and wastes while also transporting lymphocytes to defend against disease-causing agents. The lymphatic system, which includes lymphatic vessels, lymph nodes, thymus, and spleen, moves lymph from tissue spaces to the bloodstream and removes specific fatty substances from digestive organs.
Furthermore, the digestive system is composed of various organs like the mouth, tongue, teeth, salivary glands,
pharynx, esophagus,stomach,liver gallbladder , pancreas , small intestine , large intestine. Its primary role is to receive food and break down nutrients into forms that can be utilized by cell membranes. Additionally,
it eliminates materials that have not been absorbed.
There are various organs in the body that produce hormones, while others have specific functions. The respiratory system is responsible for inhaling and exhaling air, which facilitates the exchange of gases between the blood and air. On the other hand, the urinary system filters waste from the blood, aiding in fluid and electrolyte balance. Additionally, reproductive systems play a vital role in enabling organisms to reproduce offspring, with the male reproductive system involved in maintaining and transporting male sex cells.
The female reproductive system is responsible for the production, maintenance, and transportation of female sex cells. It also supports the development and birth of offspring. This system consists of the ovaries, uterine tubes, uterus, vagina, clitoris, and vulva. Aging-related physical changes after 30 years can be described as follows: in their thirties, there is a decrease in female fertility; in their forties and fifties, adult disorders like high blood pressure and type 2 diabetes may occur; in their sixties, hair may turn gray or white while the skin develops deeper wrinkles and immune function decreases.
Age-related alterations in the skin, such as reduced elasticity, collagen, and subcutaneous fat content, can result in stiffening and wrinkling. These modifications take place at different levels of the body’s structure, including molecular, cellular, tissue, and organ levels. The stiffness of the skin is a consequence of decreased production of connective tissue proteins like collagen and elastic fibers. Wrinkles form due to lower levels of subcutaneous fat.
In addition to this, there are other age-related changes that involve variations in drug metabolism rates and limited cell divisions leading to an accumulation of mutations. Over time, DNA repair mechanisms become less efficient which increases susceptibility to damage caused by oxygen free radicals resulting in the formation of certain pigments. Metabolic processes slow down with age and can lead to a buildup of beta amyloid protein within the brain.
Tissue atrophy results in the shrinking of organs. Cells that have completed their division cycle can either enlarge or die. Slow cell division hinders wound healing and raises the risk of abnormal cell division, which is a major factor in causing cancer. As cells age, they become less effective at obtaining energy from nutrients and breaking down aged or damaged cell components. The buildup of beta myeloid in the brain can lead to Alzheimer’s disease. In general, metabolism decreases due to decreased function of the thyroid gland, resulting in impaired glucose utilization, reduced protein synthesis rate, and diminished production of digestive enzymes.
When examining the entire body, one can observe a decrease in metabolism, an increased sensitivity to cold, weight gain, and fatigue. In terms of specific body parts, their relative positions are as follows: Superior – The thoracic cavity is located above or superior to the abdominal cavity. Inferior – The neck is positioned below or inferior to the head. Anterior – The eyes are situated in front or anterior to the brain. Posterior – The pharynx is found behind or posterior to the oral cavity. Medial – The nose is positioned towards or medial to the eyes. Lateral – The ears are located on the sides or lateral to the eyes. Bilateral – The lungs are present on both sides or bilateral.
Epistolary- The right lung and the right kidney are epistolary.
i. Contractual- A patient with a fractured right leg would have to bear weight on the contractual left leg.
J. Proximal- The elbow is proximal to the wrist.
K. Distal- The fingers are distal to the wrist.
L. Superficial- The epidermis is the superficial layer of the skin.
M. Peripheral- I have good peripheral vision.
N. Deep- The dermis is the deep layer of the skin.
24. Sketch the outline of a human body and use lines to indicate each of the following sections:
a. Stagiest
b. Transverse
c. Frontal (See attached pages)
25.
