Thursday, August 19, 1999

Structure and Function of the Human Body week 5

Explain how adaptation relates to our thermoreceptors and touch receptors. What is referred pain and how could it be dangerous?
Thermoreceptors and touch receptors are both nerves. The thermoreceptors Referred pain is when the perception of pain coming from parts of the body that aren't actually stimulated. It's dangerous, because you don't know where the real dangerious areas really point too. If you didn't have touch receptors, you wouldn't know what information like location, shape, size, texture and movement. (pg 309)
Explain why olfaction and gustastion are considered “chemical” special senses (think of how these two senses work). Explain the importance of hair cells with the sense of hearing and equilibrium. Lastly, compare and contrast rod and cone cells' location, function, and overall amount.
Both olfaction and gustastion occurs as dissolved chemicals stimulate olfactory receptors. The hiding of an odorant changes the permeability of the receptor membrane, producing action potentials. The gustatory are actually chemically based tasted receptors of the tongue which tastes chemicals. Taste buds have gustatory cells which tends to slither microvilli to the taste poor. The poors are more sensitive to acids. (pg 313- 315)
Hair cells are simple mechanoreceptors which are complex structure of the inner ear and the different arrangements of accessory structures of the inner ear and the different arrangements of accessory structures. (pg 329)
Rod cells do not discriminate among colors of light. They help us see in dim light. Cone c ells provide color vision. Cones give humans sharper colors. Rod cells are found on the side while cones are found on the bottom (pg 320)
Explain how the body maintains homeostasis of serum (blood calcium) levels through the use of the thyroid and parathyroid glands.
Fibrin is large insoluble strands. The fibrin fibers interact and provide framework for blood clots. The steps not taken to prevent clotting in a plasma sample, fibrinogen will convert to fibrin. The fluid left over is called serum. The liver synthesizes more than 90% of the plasma proteins including albumins and fibrinogen and globulins. Antibodies are produced by the plasma cells and fibrinogen and plasma proteins clot the blood preserving homeostasis of serum (pg 384)
Explain the role the hypothalamus and pituitary gland have in the regulation of the endocrine system. What would happen if there were no negative feedback control on growth hormone and thyroid hormone?
The hormonal secretion is controlled by negative feedback mechanisms. The stimulus triggers the production of hormone worse direct or indirect effects that reduce the intensity of the stimulus. The simplest case, endocrine activity may be controlled by humoral stimuli - changes in the composition of the exetracelluar fluid. The control of blood calcium levels are controlled by two hormones, parathyroid hormone and calcitinin. The calcium levels are the blood decline, parathyroid hormone is released and the response of target cells elevate blood calcium levels. The blood rise, calcitonin is released and the response of target cells lower blood calcium levels. The endocrine activity is also controlled by hormonal stimuli or changes in the levels of circulating stimuli. The hypothalamus provides the highest level of endocrine control by acting as an important link between the nervous and endocrine systems. (pg 350).
The control of the calcitonin secretion is independent of the hypothalamus gland and pituitary gland. C cells produce hormone calcitonin. Physiologic effects of growth hormone are direct effects and indirect effects. The glands within the endocrine system simulate release of a hormone from thyroid glands are shut off. If too much negative feedback occurred there would be hormone imbalance , because too much of the hormone would be. The hypothalamus secretes TRH. This causes the tituitary to release THS. THS will cause the thyroid hormone to secrete T4. In many parts of the world, inadequate dietary iodine intake leads to the inability to synthesize thyroid hormones. The calcitonin inhabits osteoclasts and stimulates calcium excretion in at the kidneys. C-cells are endocrine cells sandwiched between the follicle cells and their basement membrane. If there was too much negative feedback, the kidneys would fail. If negative feedback occurs, there could be a loss of bone mass. Calcitonin is most important during childhood in controlling muscle cells and nerve cell activities. Thyroid hormones are stored in the colloid of follicle. There would be too much energy utilization, oxygen consumption, growth and development for most cells. There would be more calcium concentration in body fluids in the bones and kidneys.
Explain how the nervous system, general senses, and endocrine system work together to maintain homeostasis. Remember the 3 steps of the nervous system function: afferent (input/sensory) information, analysis, and efferent (output/motor) information. This will be helpful along with remembering what homeostasis is.
The nervous system regulates the breathing, urinary, and digestive systems. The heart rate and breathing are controlled by the nervous system. Hormones are less energetically expensive, the lymphatic system ability to fight infection. Second, the respiratory system maintains oxygen and pH levels. The exposure to drugs, alcohol and toxins kick the excretory functions and test these substances to accumulate damage of the body's cells. A body that lacks nutrients will induce the body to compensate or become sick.
Make sure you provide citations and references for your answers!

Read chapters 9 - 10 ys/endocrine/hypopit/gh.html

Tuesday, August 17, 1999

Structure and Function of the Human Body week 3

Bone is a very active tissue. Please explain the pathway of how the bone cells get nutrients and oxygen from the blood vessels using the following terms: Periosteum, endosteum, lacunae, lamellae, canaliculi, perforating canals, osteon, Haversian canal (central canal) and trabeculae.
There are two types of bone tissue, compact bone (solid dense) and spongy bone (bone separated by spaces). Example, the humerus bone consists of compact bone (diaphysis and spongy bone) at each end or epiphysis. The periosteum is the outer layer of the bone where tendons and ligaments are attached; whereby, attaching muscle to bone and bone another. The main function of periosteum isolates bones to surrounding tissues provides a route to circulatory and nervous supply. It has an influence of growth and repair of the bone. The endosteum is found in the inner surface of the bone. The function of the endosteum is growth and repair of the bone. In compact bones, the functional unit is the osteon. Within the osteon, the bone cells (osteocytes) are layered around a central canal called haversian that contains some blood vessels. The bone cells are found in small pockets called lacunae which are found between calcifid matrix which is called lamellae which are cylindrical. The inter-connections inside the matrix have small channels called canaliculi that connect the lacunae with the nearby blood vessels. Nutrient and waste products are exchanged from the osteocytes through diffusion in the extracelluar fluid that surround the cells. Perforating canals provide a highway and linkage from the central canal to the periosteum and the marrow cavity.
In the spongy bone, has no osteons. Instead, the spongy bone consists of trabeculae which are lamellae that are shaped as thin rods that create an open network. Nutrients and waste are diffused between marrow and ostreocytes through small channels (canaliculi) that extend from the lacunae of the spongy bone end, where the triabeculea is exposed.

There are three main types of canals including canaliculi, Haversian canals and Volkmann's canals.

The canaliculi would join osteocytes. Second, the thicker canals are Haversian canals. In the center of the osteone are longitudinal directly through the bone. Third, the transverse tunnels are Volkmann canals. The Volkmann canals will go into the bone from the exterior; therefore, allowing vascularization to go into the osseous tissue.

Bone tissue being hard, it requires canals or tunnels to get the osteocytes nutrients to the cells. Osteocytes have long protrusions of their cytoplasm within the tunnels that contact other osteocytes. The Osteocytes are connected at these unions which can transport nutrient.
In general compare and contrast the three functional classifications of joints according to movement. What are two characteristics that make synovial joints unique and different from other joints? Which joint is stronger-the shoulder or hip joint and why is it?

Two characteristics that make synovial joints unique is they are found at the end of long bones. They are also unique in that they have fibrous joint capsule surrounding it. The hip joint is stronger, because the femur is the largest bone in the body and the hip joint was made for strength and stability. In comparison the shoulder has a higher range of movement; therefore, is weaker at the joint. (pg 174)

Please explain how the muscle cell’s anatomy of the cytoplasm is unique from other cells.
Cytoplasm has cytosol, which is dissolved in nutrients, ions, soluble, and insoluble proteins. Cytosol would contain higher concentration of potasiums ions and lower sodium ions. Likewise, extracellular fluid contains lower potassium-ion concentration. Cytosol contains high concentration of dissolved proteins like enzymes which regulate metabolic operations. It gives the cytosol it's consistency. Organelles directly connect to Cytosol. pg 72.
With your knowledge of how a muscle cell contracts please describe three mechanisms (problems) that could inhibit or disrupt the process of muscle contraction. Think about the process and the steps involved in muscle contraction.
The three mechanism are Concentric Contractions, Eccentric Contractions, Isometric Contraction. Muscle fiber generates tension through the action of actin and myosin cross-bridge cycling. While under tension, the muscle may lengthen, shorten or remain the same. Although the term contraction implies shortening, when referring to the muscular system, it means muscle fibers generating tension with the help of motor neurons.
Many sarcomeres work serially and in parallel to achieve the full contraction ability of the muscle. The sarcomere includes Actin and Myosin. Actin and Myosin are protein based filaments from opposite sides of the sarcomere. Once the muscle is at rest, both the Actin and myosin filaments overlap. When the muscle contracts, the filaments from the opposing sides slide so the pulling both walls of the sarcomere. When the muscle is fully contacted, the filaments overlap each other the most. The sliding motion is activated by calcium that floods the sarcomeres (at the end of a process that is triggered by a command from a motor nerve). The calcium reveals sites on the Actin filaments at which molecular 'whips' extending from the Myosin filaments, can throw themselves, attach, pull, and leave, using the muscle's energy reserves in the process. Each molecular whip works at its own time (much like cylinders in an internal combustion engine), so that in any given time, contact between the filaments is being made by some of the whips.
What is the difference between osteoarthritis and osteoporosis?
Osteoarthritis is a noninflammatory condition that occurs in obese people or people who have trauma joints. They are both over the age of 65. It has lost of cartilage and adjacent bone overgrowth. Osteoporosis is a metabolic condition with loss of trabecular bone. Osteoporosis normally happens in women over 65, because she had steroids, smoking, caffeine, thyroid replacement. The hip and vertebral fracture are at risk for women. (Krant, J, Healthcentral, 2006)