Assignment 1 – (50 marks)
Discuss the importance of body fluids and which one is considered to be the body’s internal environment. (4 marks) * Body fluids carry chemical communicators which organize actions amid cells, carry nutrients to cells, and carry waste products away from cells. They are the primary transport system between cells. The internal environment of the body is extracellular fluid, which refers to all of the fluids outside of our cells in our bodies – such as blood plasma, interstitial fluid, lymph and transcellular fluid. These fluids make up approximately 1/4 of body weight.
Describe the three major types of lipids found in the body. (6 marks) * The three major types of lipids found in the body are triglycerides, phospholipids, and sterols (cholesterol). Triglycerides are fatty acids. Its functions include energy storage and the cushioning and insulating of the body and nerves. All nerves are wrapped in a myelin sheath; or lipid layer. Phospholipids are similar to triglycerides, but contain a phosphate group. It is a lipid bilayer – membranes in eukaryotic cells and the plasma membrane of cells. Sterols are made from lipids, but have no fatty acids in their structure. Cholesterol makes up sex hormones and carries lip-proteins.
Describe briefly what is occurring at each step in the figure. (3 marks) *

Name and briefly describe the cell shapes, arrangements, and functions of cell layers found in epithelial tissues. (3 marks) * In epithelial tissue, there are squamous cells, which are flat with the nucleus located near the upper surface. Cuboidal cells are cube-shaped (or hexagonal) with a central, round nucleus. Cuboidal cells absorb materials (ex: digested food) and produce secretions. Columnar cells have an oval-shaped nucleus near the basement membrane and are tall. They are thick, can absorb materials, and protect underlying tissues. Some may also have cilia to aid moving materials over surfaces. Transitional cells can be tall or flat, and can compress or extend to respond to body movement.
Describe the structural characteristics of the epidermis that relate to its protection function. Compare thick to thin skin. (6 marks)
Tight junctions work towards preventing bacterial invasion in epithelial cells, as well as keratin, which is a thick protective layer of the epidermis. Not only does keratin protect from bacterial invasion, but also blocks UV damage. The dermis is thinner in thick skin compared to thin. Thick skin also doesn’t have hairs, apocrine sweat glands, or sebaceous glands. It’s commonly found where there’s lots of abrasion. For example, palms, fingertips and soles of feet. In contrast, the dermis is thicker in thin skin than it is in thick. This makes thin skin easier to suture if injury is acquired. As well, thin skin has less eccrine sweat glands than thick skin.
Briefly describe the steps in endochondral ossification. (6 marks) * Firstly, in the center of hyaline cartilage, chondrocytes expand and form struts. These start to calcify, and the expanded chondrocytes die. This leaves cavities in the cartilage. Secondly, blood vessels grow around the cartilage. This is where osteoblasts are formed from cells in the perichondrium, which produce superficial bone around the shaft. This continues to grow and eventually turns into compact bone. This is referred to as appositional growth. Thirdly, blood vessels go into the cartilage carrying osteoblasts. At the primary ossification center, spongy bone develops. Fourthly, a marrow cavity is created. At the metaphysis, bone replaces cartilage. Fifthly, secondary ossification centers are created by the osteoblasts and capillaries entering the epiphyses. Lastly, spongy bone fills the epiphyses, and the remaining cartilage in the joint cavity is the articulation cartilage.
Choose the answer from the left column that best matches the description or term in the right column. (5 marks) facetsfissuresforaminacondylescrestsnasal bonesossiclestemporal bonesvomerzygomatic bonescervical vertebraecoccyxlumbar vertebraesacral vertebraethoracic vertebrafalse ribsfloating ribsmanubriumtrue ribsxiphoid process | along with thoracic vertebrae, make up primary curvature of spinelandmark for CPRprominent ridge found on sacrumsmallest bones in bodyattach directly to sternummany found in skull; allow passage of nerves and blood vesselsusually 5 of these, largest bodies, short rectangular spinous processessuperior portion of sternumtwo found on atlas, articulate with occipital condylesforms inferior portion of bony nasal septum |
Compare the pectoral and pelvic girdles. (4 marks) * In comparison of size, the pectoral girdle is much bigger than the lighter pelvic girdle. The pectoral girdle also has a more shallow socket, while the pelvic girdle has deeper, more ensured sockets for limb attachment. As well, the pectoral girdle has more flexibility, while the pelvic girdle bears more weight.
During an upper level anatomy lab at a university, students are given unpreserved joints and are asked to classify the joints they received functionally and structurally. How should the students proceed with identification and classification of the assigned joints? (7 marks) * Functionally, a joint that does not allow any movement can be classified as synarthrosis (ex: skull sutures). A joint that permits slight movement is known as amphiarthroses (ex: intervertebral disks). Freely movable joints are called diarthrosis (ex: elbow). Structurally, joints made of tough collagen fibers are referred to as fibrous joints (ex: syndesmosis that holds together the ulna and radius of the forearm). Joints that consist of a band of cartilage that binds bones are classified as cartilaginous (ex: joints between ribs and costal cartilage). Finally, a space filled with fluid between smooth cartilage pads at the end of articulating bones is known as a synovial joint. Synovial joints have a capsule of dense irregular connective tissue surrounding it that is lined with synovial membrane (ex: knee).
Answer to the following questions: a. Compare and contrast the functional and structural characteristics of muscular tissue. (3 marks) i. skeletal muscle tissue:
Description Long, cylindrical, striated fibers. Skeletal muscle fibers vary greatly in length, from a few centimeters in short muscles to 30–40 cm in longest muscles. A muscle fiber is a roughly cylindrical, multinucleated cell with nuclei at periphery. Skeletal muscle is considered voluntary because it can be made to contract or relax by conscious control.
Location Usually attached to bones by tendons.
Function Motion, posture, heat production, protection.

ii. cardiac muscle tissue:
Description Branched, striated fibers with usually only one centrally located nucleus (occasionally two). Attach end to end by transverse thickenings of plasma membrane called intercalated discs, which contain desmosomes and gap junctions. Desmosomes strengthen tissue and hold fibers together during vigorous contractions. Gap junctions provide route for quick conduction of electrical signals (muscle action potentials) throughout heart. Involuntary (not conscious) control.
Location Heart wall.
Function Pumps blood to all parts of body.

iii. smooth muscle tissue:
Description Fibers usually involuntary, non-striated (lack striations, hence the term smooth). Smooth muscle fiber is a small spindle-shaped cell thickest in middle, tapering at each end, and containing a single, centrally located nucleus. Gap junctions connect many individual fibers in some smooth muscle tissues (for example, in wall of intestines). Can produce powerful contractions as many muscle fibers contract in unison. Where gap junctions are absent, such as iris of eye, smooth muscle fibers contract individually, like skeletal muscle fibers.
Location Iris of eyes; walls of hollow internal structures such as blood vessels, airways to lungs, stomach, intestines, gallbladder, urinary bladder, and uterus.
Function Motion (constriction of blood vessels and airways, propulsion of foods through gastrointestinal tract, contraction of urinary bladder and gallbladder). *
Describe the process by which smooth muscle tissue contracts. (3 marks) * Smooth muscle tissue begins by contracting slower than skeletal muscle, but lasts much longer. It can also shorten and stretch to a greater extent than other muscle tissues. Smooth muscle actually contracts when it is excited by its own autorhythmic muscle fibers. The contractions are caused by sliding of myosin and actin filaments over one another. The hydrolysis of ATP provides the energy for this to be possible. In contrast to skeletal muscle, smooth muscle initiates its contraction by a calcium-regulated phosphorylation of myosin, instead of troponin.