Basic Anatomy, Homeostasis and Disease Human Anatomy-Unit I-Part A

How the Human Body is Studied General Anatomy is the study of body structure Physiology is the study of how the body functions These terms are almost always taken together Directions in the body A universal system has been designed to designate position and direction in the body All terms assume the body is in an anatomical position, meaning: Standing upright Face front Arms at sides with palms forward Feet Parallel

How the Human Body is Studied Directional Terms Superior-above in the transverse plane Inferior-below in the transverse plane The heart is superior to the intestine, but inferior to the brain Ventral-location towards the belly (anterior plane) Dorsal-towards the back (anterior plane) The stomach is ventral to the kidneys, the kidneys are dorsal to the stomach Anterior-towards the frontside of (frontal plane) Posterior-towards the backside of (frontal plane) The nose is anterior to the ear.

How the Human Body is Studied Cranial-near the head Caudal-nearer the tail The heart is cranial to the stomach, but caudal to the forehead. Medial-towards the midline (saggital plane) Lateral-away from the midline (saggital plane) The heart is medial, the kidneys lateral Proximal-near the trunk Distal-farther from the trunk The part of your thumb that joins your hand is proximal, the tip of the thumb is distal.

How the Human Body is Studied Planes of Division Used to visualize internal structures. The planes are: Frontal (coronal)-a cut made giving you an anterior (ventral) and a posterior (dorsal) view. Sagittal-a cut giving you left and right sections Transverse-a horizontal cut that leaves you a superior and inferior part

How the Human Body is Studied Planes of Division Many diagnoses require tissue specimens to be looked at. Tissue may be cut in three ways: Cross sectional-to give you round slices Longitudinal-to give long slices Oblique-an angled, cross sectional cut Internally the body is also divided into cavities which contain the various organs. They include: Dorsal-contains the cranial (brain) cavity, and the spinal cavity Ventral-contains the thoracic, abdominal, and pelvic cavities

Homeostasis General Homeostasis All chemical reactions that living things undergo make up their metabolism Those reactions which involve breakdown are called catabolic Those that build up are anabolic Homeostasis Living things attempt to maintain a steady state with both their internal and external environment This steady state is known as homeostasis (literally “staying the same”) Homeostasis is maintained by feedback

Homeostasis How feedback works Feedback is a control system based on information returning to a source When feedback fails, the body is said to be in a homeostatic imbalance Moderate imbalance causes illness and disease Severe imbalance will cause death How feedback works Most feedback systems work by keeping body conditions within a set normal range by reversing any upward or downward shift In negative feedback, the body will attempt to reverse negative or positive changes

Homeostasis The body may also use positive feedback to regulate itself In positive feedback, a given action promotes more of the same An example involves childbirth, uterine contractions, and oxytocin The nervous and endocrine systems are mostly involved in feedback and the maintenance of homeostasis. They coordinate with other body systems as well.

Disease Definition-a homeostatic imbalance, involving an abnormality of the structure or function of a part, organ, or system Categories of disease: Infection-caused by infectious organisms (called pathogens) such as bacteria and viruses Degenerative-involve degeneration (breaking down) of tissues in an organ system Nutritional-may be due to a lack of essential substances, as well as the excessive intake of substances Metabolic-any disruption to anabolic or catabolic reactions.

Disease Causes of disease Immune-any problem with the immune system Neoplasm-any disease involving growth or tumors Psychiatric disorders-mental disorders Causes of disease Outside factors that enter into the production of a disease are called predisposing factors Predisposing factors to disease include age, gender, heredity, living conditions, emotional disturbance, physical and chemical damage, and preexisting illnesses

Diseases Studying Disease Etiology is the study of the cause of any disease Diseases are classified based on their severity and duration as follows: Acute- severe but short lasting Chronic- less severe but last longer Subacute-intermediate, between the two Communicable diseases can be transmitted between people, this can lead to an epidemic Epidemics can stay in a particular region (endemic) or prevalent through the whole world (pandemic)

Diseases Treatment and Prevention Before treatment can begin, a doctor must first decide exactly what is wrong. This is termed diagnosis Before diagnosis, the doctor first must know what is wrong (symptoms) as well as predisposing conditions (history) Once a diagnosis is made, the doctor will tell the patient what will happen. This is called the prognosis. The course of treatment for disease is known as therapy In recent years, doctors and health care workers have been working towards stopping disease before it happens. This is known as prevention.

Diseases Areas for prevention include: Quitting smoking Reducing alcohol intake Improved diet Weight control exercise