Sucrose

A separate lipoprotein lipase, on the capillary endothelial cells of the muscle and fat tissues, first releases free fatty acids from the triglycerides. The free fatty acids then enter the muscle or fat cells, where they may be reesteriiied to triglycerides. That's a lot of work, but then again, fatty acids are used as energy sources. Absorption of fat is completed by the end of the jejunum, but reabsorption of the bile salts occurs in the ileum in what is termed the enterohepatic...

The Digestive System

Efficient food intake requires gastrointestinal motility, digestion and absorption. Malfunction may occur in any of the above categories. After the teeth chew the food, thereby providing greater surface area for digestion, swallowing occurs through the combined action of the tongue and pharyngeal muscles. The upper third of the esophagus is under voluntary control, whereas the musculature in the lower portion becomes progressively more involuntary. Throughout the gastrointestinal (GI) tract,...

Inspiratory

Ease (Infant Respiratory Distress Syndrome), the newborn does not produce enough surfactant and hence the lungs cannot expand well due to the increased elastic resistance. The alveoli instead have a tendency to collapse (atelectasis). Hypoxia in adults can also cause a loss of surfactant (either by decreasing its production or increasing its destruction), leading to Adult Respiratory Distress Syndrome (shock lung syndrome), with attendant atelectasis. With increased elastic resistance, the work...

Isxjss

The Rosenbaum and Snellen charts are equivalent only in that they both project the same sized images on the retina. If order to clearly see the letters, however, the eyes must focus them. The attending was presbyopic and had difficulty focusing for near. Sam was myopic. He saw perfectly for near but could not focus for far. Both Sam and the attending had refractive errors. The patient had a non-refractive problem focusing worked fine for the patient. The patient's...

The Respiratory System

Pulmonary respiration entails the acquisition of oxygen and release of excess CO2. The process also adjusts the pH of the blood, since CO2 and water form a weak acid. The main muscle of inspiration is the diaphragm. Contraction and downward motion of the diaphragm causes a negative pressure in the chest, which draws in air. Other than the diaphragm, there are accessory muscles of inspiration (pectoralis major and minor, ser-ratus anterior, sternocleidomastoid, scalene muscles, levatores...

Blood Flow

Blood flow is the amount of blood that passes a particular point in the circulation per unit time. Cardiac output is blood flow that relates to the heart it is the number of liters of blood pumped by the heart per minute, generally about 5-6 liters min. This section is concerned with the factors that regulate blood flow through the heart (cardiac output) as well as the peripheral tissues. At superficial glance, it would seem that the factors that control blood flow should be the same as the...

Blood Pressure

Homeostasis is the tendency for the body to maintain itself in a stable state. Many control mechanisms accomplish this. For instance, at the biochemical level, end products of a chemical reaction chain may feed back to the beginning of the chain to suppress an overproduction of the end product. Buffers prevent the body pH from changing too radically. Negative feedback loops in the neuronal circuitry prevent the impulses along a neural pathway from having too much of an effect. Rather than rote...

Ganglion

In order to extend all over the body, the sympathetic system fibers leave the spinal cord at cord levels T1-L2, enter the paravertebral ganglion chain and then may travel up or down the chain for considerable distances prior to synapsing (Fig. 9-19). The sympathetic chain stretches from the foramen magnum to the coccyx and supplies the far reaches of the body with post-ganglionic sympathetic fibers. Parasympathetic fibers reach widespread areas via the vagus (Fig. 9-19). Fig. 9-19. Schematic...

Amblyopia and Strabismus

Amblyopia is a visual loss with no apparent gross pathology. There is no cloudiness of the cornea or lens, or apparent retinal lesions. Amblyopia is not corrected by glasses. It is a microscopic defect in the wiring of the retina-to-brain connections that results from disuse of one eye at an early age (generally before age 7). An adult who does not use an eye will not develop amblyopia. A child below age 7 who does not use an eye will develop amblyopia, and the condition may become irreversible...

Specific Hormones

ORIGIN Anterior pituitary gland (acidophil cells) REGULATED BY GH-releasing hormone (GHRH) and inhibiting hormone (somatostatin) from the hypothalamus. FUNCTION Promotes growth of bone and cartilage increases protein synthesis throughout the body promotes lipid breakdown to fatty acids, which can be use for energy decreases the use of glucose as an energy source, which raises blood glucose concentration and results in increased glycogen storage. GH appears to act indirectly by first inducing...

Blood Cells And Blood Coagulation

Pluripotential cells in the bone marrow differentiate into the major blood cells red cells, white cells and platelets. The chapter on the immune system discusses the white cells. The major stimulus to red blood cell (RBC) production is erythropoetin, which is produced in the kidney. Anemia (a decrease in the number or concentration of red blood cells, or amount or concentration of hemoglobin) is a common inducer of erythropoetin production. It is not the number or concentration of RBCs that...

Wavelength

Range, will stimulate all three cone types to different degrees, but mainly stimulate the green cone receptors. The degree of stimulation of each of the three cone types determines the strength of the neuronal impulses along that cone's connections with the nervous system. The key point is that the ability to distinguish hundreds of different colors does not require the presence of hundreds of different kinds of receptors. Each color is coded as a ratio of the relative strengths of the impulses...

Unconscious Proprioception

Understood by realizing that the first half of a pathway name commonly refers to where the pathway originates and the latter half refers to where the pathway terminates. E.g. the spinothalamic tract originates in the spinal cord and ends in the thalamus. As may be seen in the figure, a lesion injury of the pain-temperature pathway spinothalamic tract , whether within the brain stem or spinal cord, results in loss of pain-temperature sensation contralaterally i.e. on the opposite side of the...