Understanding Inheritance, Anatomy, and Anatomical Positions
Inheritance and Mendelism
In 1854, work began on plants to understand the principles regulating the transmission of characteristics from parents to descendants. A pure line is a group of living things that produce offspring with the same traits, generation after generation.
Mendel’s First Law
Mendel’s first law states that if you cross two pure breeds for a particular character, the descendants of the first generation are all equal to each other (both phenotype and genotype) and equal (in phenotype) to a parent.
Mendel’s Second Law
Mendel’s second law is also called the law of separation or disjunction of alleles. A backcross serves to differentiate individuals.
Mendel’s Third Law
This law, known as the independent inheritance of characters, refers to the case of covering two different characters. Each character is transmitted following the previous laws, regardless of the presence of another character.
Dihybridism
Dihybridism is the crossing of two different characters for the same species.
Anatomy and Anatomical Positions
Anatomy
Anatomy is the study of the structure, function, and classification of human beings.
Anatomical Position
The anatomical position is standing erect, head erect without inclination, eyes open looking straight ahead at the same level, arms extended, palms outstretched, feet parallel, and heels together.
Headaches
Superior: What is up, or closer to the head.
Parallel
Parallel: What is at the same level as the ground reference point, either together or separately. Examples: Ears, eyes, elbows, knees, heels, legs, arms.
Ventral (Anterior)
Ventral (Anterior): What is forward of that line, is looking forward. Examples: The eyes, knees, palms of the hands.
Dorsal (Posterior)
Dorsal (Posterior): What is back of that line, is looking back. Examples: The elbows, buttocks, heels, back of hands, neck.
Medial (Proximal)
Medial (Proximal): What is close to that line, which is near the midline.
Lateral (Distal)
Lateral (Distal): What is far from that line, because it is on the side of the midline.
Anatomical Cuts
Lines which have been described generate the possibility of cutting through them in order to observe internal structures of the human body.
Coronal Cut
It is the cut that is made through the longitudinal plane, passing through the ears. It divides the body into two unequal parts, front and rear. It’s called coronal because it passes through the coronal suture (frontal bone joint with the two parietal bones).
Ripping Cuts
These cuts are made through the parietal lines parallel to the longitudinal middle or coronal plane.
- They are longitudinal lines but also before or after the coronal line.
Medial Upper Cut
This cut can be made in the anatomical position.
The midline is perpendicular to the longitudinal plane, dividing the body into two equal parts.
A cut is made through this line.
It separates equally all pairs of the human body structures, such as eyes, ears, upper limbs, lower limbs, and internal structures such as ovaries, kidneys, etc.
Sagittal Cut
These are made in a line drawn parallel to the midline. Cuts made lateral to the midline certainly do not divide the body into two equal halves.
Transverse Cut
This cut is made horizontally and perpendicular to the medial section. It passes through the navel and divides the body into upper and lower halves.
Cross Sections
These are all the cuts made parallel to the transverse cut, either higher or lower than this.