Primary Study Areas

In this text, we study the skeletal system from four different viewpoints a. Bone As Tissues. This aspect of the human skeletal system was discussed in paragraph 2-11 and will not be further discussed here. b. Bone As An Individual Organ. Section II of this lesson discusses bone as an individual organ. c. Articulations (Joints)--Arthrology. Section III of this lesson introduces the study of joints, or arthrology. d. The Human Skeleton. Section IV of this lesson discusses the human skeleton as a...

Exercises Lesson

The following exercises are to be answered by completing the incomplete statement or by writing the answer in the space provided at the end of the question. After you have completed all the exercises, turn to Solutions to Exercises, at the end of the lesson and check your answers. 1. The human urogenital systems are made up of the u_ organs, which produce the fluid called_, and the_, or_, organs of male and female humans, which together can produce a 2. The urinary system is...

The Anatomical Position

The anatomical position is an artificial posture of the human body (see figure 1-2). This position is used as a standard reference throughout the medical profession. We always speak of the parts of the body as if the body were in the anatomical position. This is true regardless of what position the body is actually in. The anatomical position is described as follows a. The body stands erect, with heels together. b. Upper members are along the sides, with the palms of the hands facing forward....

Secondary Sex Organs

The epididymis is a coiled tube whose function is to aid in the maturation of spermatozoa. Its coiled length is only about one and one-half inches. Its uncoiled length is about 16 feet. When coiled, it extends downward along the posterior side of each testis. Its lining secretes a nutritive medium for spermatozoa. It receives spermatozoa from the testes in an immature state. As the spermatozoa pass through the nutrient, they mature. b. Ductus (Vas) Deferens. The ductus deferens...

The Human Brain

The human brain has three major subdivisions brainstem, cerebellum, and cerebrum. The CNS is first formed as a simple tubelike structure in the embryo. The concentration of nervous tissues at one end of the human embryo to produce the brain and head is referred to as cephalization. When the embryo is about four weeks old, it is possible to identify the early forms of the brainstem, cerebellum, and cerebrum, as well as the spinal cord. As development continues, the brain is located within the...

The Motor Pathways

They descend the neuraxis in bundles of a number of specific neuron processes called motor fiber tracts. Commands originating in the right half of the brain leave the CNS through peripheral nerves on the left side. Commands from the left half of the brain leave the CNS on the right side. Therefore, the right half of the brain controls the left side of the body and the left half of the brain controls the right side of the body. For example, the actions of the...

General

Control Systems of the Human Body. The structure and function of the human body is controlled and organized by several different systems. (1) Heredity environment. The interaction of heredity and environment is the fundamental control system. Genes determine the range of potentiality and environment develops it. For example, good nutrition will allow a person to attain his full body height and weight within the limits of his genetic determination. Genetics is the study of heredity. (2)...

Lesson Assignment

After completing this lesson, you should be able to 8-2. Identify the function and major parts of the human urinary system. 8-3. Describe the kidney, including its gross internal structure and the structure of the nephron. 8-4. Describe the ureters, the urinary bladder, and the urethra. 8-5. Identify general characteristics of both the male and female genital systems. 8-6. Describe the ovaries, the uterine tubes, the uterus, the vagina, the external genitalia, and secondary sexual...

Fat Connective Tissue

A large fraction of the volume of a fat cell is occupied by a droplet of fat. This droplet has its own membrane, in addition to the outer membrane of the cell. The remaining components of the fat cell, including the nucleus, are found in an outer layer of cytoplasm surrounding the droplet of fat. b. Matrix. Fat connective tissue has a matrix of lipid (oil or fat). There may be yellow fat CT or brown fat CT. c. Functions. Fat CT acts as a packing material among the organs, nerves,...

Solutions To Exercises Lesson

The four basic components of any circulatory system are a vehicle, conduits, a motive force, and exchange areas. The vehicle is the substance which actually carries the materials being transported. A conduit is a channel, pipe, or tube through which a vehicle travels. If we say that a force is motive, we mean that it produces movement. Systems providing a motive force are often known as pumps. Exchange areas exist so that materials being transported may be eventually exchanged with a part of...

A Skeletal Coverings

The bones of the cranium form a spherical case around the brain. The cranial cavity is the space inclosed by the bones of the cranium. (2) Spinal cord. The vertebrae, with the vertebral foramina, form a cylindrical case around the spinal cord. The overall skeletal structure is the vertebral column (spine). The vertebral (spinal) canal is the space inclosed by the foramina of the vertebrae. b. Meninges (Fibrous Membranes). The brain and spinal cord have three different membranes...

Cerebrospinal Fluid

A clear fluid called cerebrospinal fluid (CSF) is found in the cavities of the CNS. CSF is found in the ventricles of the brain (para 11 -9d), the subarachnoid space (para 11-11b(2)), and the central canal of the spinal cord (para 11 -10b(1)). CSF and its associated structures make up the circulatory system for the CNS. a. Choroid Plexuses. Choroid plexuses are special collections of arterial capillaries found in the roofs of the third and fourth ventricles of the brain. The choroid plexuses...

Rectum Anal Canal And Anus

However, this six-inch tubular structure would actually look a bit wave-like from the front. From the side, one would see that it was curved to conform the sacrum (at the lower end of the spinal column). The final storage of feces is in the rectum. The rectum terminates in the narrow anal canal, which is about one and one-half inches long in the adult. At the end of the anal canal is the opening called the anus. Muscles called the anal sphincters aid in the retention of...

Anterior Pituitary Gland

The anterior pituitary gland originates from the roof of the embryo's mouth. It then attaches itself to the posterior pituitary gland. b. The anterior pituitary gland is indirectly connected to the hypothalamus by means of a venous portal system. By portal, we mean that the veins carry substances from the capillaries at one point to the capillaries at another point (hypothalamus to the anterior pituitary gland). c. In the hypothalamus, certain chemicals known as releasing factors are...

Typical Spinal Nerve

In the human body, every spinal nerve has essentially the same construction and components. By learning the anatomy of one spinal nerve, you can understand the anatomy of all spinal nerves. a. Parts of a Typical Spinal Nerve (figure 11-8). Like a tree, a typical spinal nerve has roots, a trunk, and branches (rami). Figure 11-8. A typical spinal nerve with a cross section of the spinal cord. Figure 11-8. A typical spinal nerve with a cross section of the spinal cord. (1) Coming off of the...

Body Types

No two human beings are built exactly alike, but we can group individuals into three major categories. These groups represent basic body shapes. MESOMORPH body type between the two others, muscular type Ectomorphs, slim persons, are more susceptible to lung infections. Endomorphs are more susceptible to heart disease.

The Human Spinal Cord

Referring to figure 4-4, you can see that the typical vertebra has a large opening called the vertebral (or spinal) foramen. Together, these foramina form the vertebral (spinal) canal for the entire vertebral column. The spinal cord, located within the spinal canal, is continuous with the brainstem. The spinal cord travels the length from the foramen magnum at the base of the skull to the junction of the first and second lumbar vertebrae. (1) Enlargements. The spinal...

Cardiovascular Circulatory Patterns

See figure 9-4 for an illustration depicting cardiovascular circulatory patterns. Figure 9-4. Cardiovascular circulatory patterns. Figure 9-4. Cardiovascular circulatory patterns. a. General. The human cardiovascular circulatory system is described as a closed, two-cycle system. (1) It is closed because at no place is the blood as whole blood ever outside the system. (2) It is two-cycle because the blood passes through the heart twice with each complete circuit of the body. In the pulmonary...

CSystemic Cycle

The oxygen-saturated blood is moved from the left atrium into the left ventricle. When the left ventricular wall contracts, the pressure closes the mitral valve, which prevents blood from returning to the left atrium. The contraction of the left ventricular wall therefore forces the blood through the aortic semilunar valve into the aortic arch. Upon relaxation of the left ventricular wall, the back pressure of the aortic arch forces the aortic semilunar valve...

Primary Sex Organs Testes

The primary sex organ of the human male is the testis. See figure 8-5 for an illustration of the male genital system. The testes are egg-shaped. Figure 8-5. The human male genital system. Figure 8-5. The human male genital system. a. Location. The paired testes lie within the scrotum. The scrotum is a sac of loose skin attached in the pubic area of the lower abdomen. The scrotum provides a site cooler than body temperature to maintain the viability of the spermatozoa. However, when the air is...

ADefinitions

(1) The peripheral nervous system (PNS) is that portion of the nervous system generally concerned with commands for skeletal muscles and other muscles made up of striated muscle tissue, as well as sensory information from the periphery of the body. The sensory information is carried to the CNS where it is processed. The PNS carries commands from the CNS to musculature. (2) A nerve is a collection of neuron processes, together and outside the CNS. (A fiber tract is a collection of neuron...

The Articular Disc

In three of the synovial joints of the human body, a special addition is seen. This addition is known as an articular disc. The joints with articular discs are the temporomandibular joint of the lower jaw, the sternoclavicular joint (at the sternum (breastbone)), and the ulnocarpal joint of the distal end of the forearm. a. An articular disc is a fibrocartilage plate. It is inserted between the articular surfaces of the bones of a synovial joint. In this way, it divides the synovial space into...

The Appendicular Skeleton

The appendicular skeleton is made up of the skeletal elements of the upper and lower members (often incorrectly referred to as the extremities). These members are appended (attached) to the axial skeleton. b. The general pattern of construction of the upper and lower members is the same as follows (1) Girdle. The girdle is the actual attaching part. It attaches (appends) the limb (the member less the girdle) to the axial skeleton. (2) Proximal limb segment. The proximal segment of the limb...

Components And Subdivisions Of The Human Respiratory System

See figure 7-1 for an illustration of the human respiratory system. a. Components. The components of the human respiratory system consist of air passageways and two lungs. Air moves from the outside of the body into tiny sacs in the lungs called alveoli (pronounced al-VE-oh-lie). b. Main Subdivisions. The main subdivisions of the respiratory system may be identified by their relationship to the voice box or larynx. Thus, the main subdivisions are as listed in table 7-1. Figure 7-1. The human...

Functions Of The Human Skeleton

The human skeleton serves the following functions a. Bodily Support. The skeletal system provides a framework for the human b. Protection. The skeleton protects certain soft structures within the human body. An example is the skull, which surrounds the brain. c. Motion. Muscles are attached to and move the bones. Bones provide leverage for motion. d. Formation of Blood Cells (Hematopoiesis). Blood cells are manufactured in the red bone marrow, mainly found in flat bones.

Development Of An Individual Bone

The human skeleton is preformed in the early fetus, but the early form is not of bony material. There are two types of bones according to their preformed basis membranous bones and cartilage bones. These are in the location and have the general shape of the adult bones they will later become. (1) Membranous bones. The outer skull bones are an example of membranous bones. Osteoblasts invade a membrane to form a center of ossification (formation of bone). Bone-forming activity spreads...

The Axial Skeleton

Regions Human Body

The axial skeleton is the central framework of the human body. It includes the skull, the vertebral column (spine), and the thoracic cage (chest or rib cage). Figure 4-3A. Anterior view of the human skeleton. Figure 4-3A. Anterior view of the human skeleton. Figure 4-3B. Posterior view of the human skeleton. Figure 4-3B. Posterior view of the human skeleton. a. Vertebral Column (Spine). The vertebral column, or spine, is made up of a vertical series of bony blocks called vertebrae. These...

AUni Axial Synovial Joints

1 In uni-axial synovial joints, motion occurs in only one plane. The joints of the fingers interphalangeal flex and extend in the sagittal plane. These are commonly referred to as hinge joints. 2 If a single rotatory rotational motion occurs around a post-like structure, the joint is a pivot joint. The atlas vertebra rotating around the dens tooth like projection of the axis vertebra at the top of the neck base of the skull is a pivot joint. b. Bi-Axial Synovial Joints. In bi-axial synovial...