Introduction to anatomy & physiology

What is Anatomy?

The word is taken from the Ancient Greek ἀνατέμνειν, anatemnein:

• ana, “separate, apart from“
• temnein, “to cut up, cut open”

It is the study of the structure of living organisms. We study anatomy by:

• Inspection - looking, palpation, auscultation, percussion
• Dissection - cadavers, comparative anatomy
• Exploratory Surgery
• Imaging - X-ray, CT, Ultrasound, MRI, PET
• Gross anatomy - structure that can be seen with the naked eye by surface observation, dissection, radiology
• Histology - microscopic anatomy seen with a microscopy (light, electron etc.)

What is Physiology?

From the Ancient Greek, φύσιςλογία:

• physis, “nature” or “origin”
• logia, “study of”

In other words it is the study of the function of living things. It is possible to study physiology from scientific experimentation on the single cells to the whole organism.

Levels of Structure

What is Human?

Our Chordate Characteristics Phylum

1. Pharyngeal arches, a series of bulges that develop in the pharyngeal (throat) region. Pharyngeal pouches between these open and form gill slits in fish and amphibians, but not in humans.
2. Tail that extends beyond the anus. The small bones of the coccyx (“tailbone”) remain after birth as a remnant of this.
3. Notochord, a dorsal, flexible rod found only in the embryo.
4. A dorsal hollow nerve cord, a column of nervous tissue that passes along the dorsal (upper) side of the body and has a central canal filled with fluid.

The first three of these features are found only in the embryo and fetus; only the nerve cord persists through life, as the spinal cord and brain. Other chordates include fish, lizards and birds.

Our Vertebrate Characteristics Subphylum

Other Vertebrate include fish, reptiles, birds, mammals.

• A well developed brain and sensory organs.
• An internal skeleton
• A jointed vertebral column (spine).
• A protective, usually bony enclosure for the brain, called the cranium.

Our Mammalian Characteristics Class

Less than 0.2% of animals are mammals. Other mammals include rats, horses, dogs and monkeys.

• Mammary glands for nourishing the young with milk.
• Hair, which serves in most mammals to retain body heat.
• Endothermy, the ability to generate most body heat by metabolic means instead of having to warm up by basking in the sun or seeking other warm places.
• Heterodonty, the possession of varied types of teeth (incisors, canines, premolars, and molars) specialized to puncture, cut, and grind food. These varied teeth break food into small pieces, making chemical digestion faster. Rapid digestion is necessary to support the high metabolic rate needed to maintain endothermic animals.
• A single lower jawbone (mandible).
• Three middle-ear bones (known colloquially as the hammer, anvil, and stirrup).

Our Primate Characteristics Order

Here are a few of our primate characteristics

• Four upper and four lower incisors, the front cutting teeth.
• A pair of functional clavicles (collarbones).
• Only two mammary glands.
• Forward-facing eyes with stereoscopic vision.
• Flat nails in place of claws.
• Opposable thumbs that can touch the fingertips, enabling the hand to encircle and grasp objects.

Our Hominid Characteristics Family

Here are a few of our hominid characteristics

• Large brains, speech, tool making
• Bipedalism

Variation

There are variations in both Anatomy & Physiology:

• Normal variations
• Pathological variations pathology = study of disease

The Reference Human

The reference man is defined as a healthy male 22 years old, weighing 70 kg (154 lb), living at a mean ambient (surrounding) temperature of 20°C, engaging in light physical activity, and consuming 2,800 kilocalories (kcal) per day.

The reference woman is the same except for a weight of 58 kg (128 lb) and an intake of 2,000 kcal/day.

Homeostasis

Homeostasis is the body’s ability to detect change, activate mechanisms that oppose it, and thereby maintain relatively stable internal conditions

Dynamic equilibrium – physiological values fluctuate very closely around an average value

Negative Feedback

Negative Feedback is a process in which the body senses a change and activates mechanisms that negate or reverse it:

• Receptor: senses change
• Integrating (control) centre: processes signals, e.g. compares to reference values and triggers effectors
• Effector: carries out the corrective action
• Feedback loop

Positive Feedback

Positive Feedback is a physiological change leads to even greater change in the same direction. Used when a rapid change is needed, e.g. childbirth

The Anatomical Position

This position provides a precise and standard frame of reference for anatomical description and dissection. The person stands erect with the feet flat on the floor, arms at the sides, and the palms, face, and eyes facing forward.

Anatomical Terms

Here are some general terms of anatomical relationships:

Regions of the body

There are two main regions of the body:

• The axial region consists of the head, neck (cervical region), and trunk. The trunk is further divided into the thoracic region above the diaphragm and the abdominal region below it.
• The appendicular region of the body consists of the upper and lower limbs (also called appendages or extremities). The upper limb includes the arm (brachial region), forearm (antebrachial region), wrist (carpal region), hand (manual region), and fingers (digits). The lower limb includes the thigh (femoral region), leg (crural region), ankle (tarsal region), foot (pedal region), and toes (digits).

9 Regions of the Abdomen

To be completed soon