7. Cellular Adaptations Flashcards
Psoriasis
common, chronic, relapsing/remitting, immune-mediated systemic disease characterized by skin lesions including red, scaly patches, papules, and plaques, which usually itch.
The five main types of psoriasis are plaque, guttate, inverse, pustular, and erythrodermic.
Plaque psoriasis, the most common form, typically manifests as red and white scaly patches on the top layer of the skin. Skin cells rapidly accumulate at these plaque sites and create a silvery-white appearance.
Plaques frequently occur on the skin of the elbows and knees, but can affect any area, including the scalp, palms of hands, and soles of feet, and genitals. In contrast to eczema, psoriasis is more likely to be found on the outer side of the joint. Fingernails and toenails are frequently affected (psoriatic nail dystrophy) and can be seen as an isolated sign. Inflammation of the joints, known as psoriatic arthritis, affects up to 30% of individuals with psoriasis.
The causes of psoriasis are not fully understood. It is not purely a skin disorder and can have a negative impact on many organ systems. Psoriasis has been associated with an increased risk of certain cancers, cardiovascular disease, and other immune-mediated disorders such as Crohn’s disease and ulcerative colitis. It is generally considered a genetic disease, thought to be triggered or influenced by environmental factors. Psoriasis develops when the immune system mistakes a normal skin cell for a pathogen, and sends out faulty signals that cause overproduction of new skin cells.
Injury to the skin can trigger local psoriatic skin changes known as the Koebner phenomenon.
Goitre in iodine deficiency
A low amount of thyroxine (one of the two thyroid hormones) in the blood, due to lack of dietary iodine to make it, gives rise to high levels of thyroid stimulating hormone (TSH), which stimulates the thyroid gland to increase many biochemical processes; the cellular growth and proliferation can result in the characteristic swelling or hyperplasia of the thyroid gland, or goiter.
In mild iodine deficiency, levels of triiodiothyronine (T3) may be elevated in the presence of low levels of levothyroxine, as the body converts more of the levothyroxine to triiodothyronine as a compensation. Some such patients may have a goiter, without an elevated TSH.
If goiter is untreated for around five years, however, iodine supplementation or thyroxine treatment may not reduce the size of the thyroid gland because the thyroid is permanently damaged.
Left ventricular hypertrophy
Thickening of myocardium in the left ventricle
While ventricular hypertrophy occurs naturally as a reaction to aerobic exercise and strength training, it is most frequently referred to as a pathological reaction to cardiovascular disease, or high blood pressure.
While LVH itself is not a disease, it is usually a marker for disease involving the heart.
Disease processes that can cause LVH include any disease that increases the afterload that the heart has to contract against, and some primary diseases of the muscle of the heart.
Causes of increased afterload that can cause LVH include aortic stenosis, aortic insufficiency and hypertension. Primary disease of the muscle of the heart that cause LVH are known as hypertrophic cardiomyopathies, which can lead into heart failure.
Long-standing mitral insufficiency also leads to LVH as a compensatory mechanism.
Benign prostatic hypertrophy
Benign prostatic hyperplasia (BPH), also called benign enlargement of the prostate (BEP), adenofibromyomatous hyperplasia and benign prostatic hypertrophy (technically incorrect usage), is a benign increase in size of the prostate.
BPH involves hyperplasia of prostatic stromal and epithelial cells, resulting in the formation of large, fairly discrete nodules in the transition zone of the prostate.
When sufficiently large, the nodules impinge on the urethra and increase resistance to flow of urine from the bladder. This is commonly referred to as “obstruction,” although the urethral lumen is no less patent, only compressed. Resistance to urine flow requires the bladder to work harder during voiding, possibly leading to progressive hypertrophy, instability, or weakness (atony) of the bladder muscle.
Although prostate specific antigen levels may be elevated in these patients because of increased organ volume and inflammation due to urinary tract infections, BPH does not lead to cancer or increase the risk of cancer.
BPH involves hyperplasia (an increase in the number of cells) rather than hypertrophy (a growth in the size of individual cells), but the two terms are often used interchangeably, even amongst urologists.
Barrett’s oesophagus
abnormal change (metaplasia) in the cells of the lower portion of the esophagus. It is characterized by the replacement of the normal stratified squamous epithelium lining of the esophagus by simple columnar epithelium with goblet cells (which are usually found lower in the gastrointestinal tract).
Strong association (about 0.5% per patient-year) with esophageal adenocarcinoma, a very often deadly cancer, because of which it is considered to be a premalignant condition.
The main cause of Barrett’s esophagus is thought to be an adaptation to chronic acid exposure from reflux esophagitis.
Myositis ossificans
comprises two syndromes characterized by heterotopic ossification (calcification) of muscle.
In the first, and by far most common type, nonhereditary myositis ossificans, calcifications occur at the site of injured muscle, most commonly in the arms or in the quadriceps of the thighs.
The second condition, myositis ossificans progressiva (also referred to as fibrodysplasia ossificans progressiva) is an inherited affliction, autosomal dominant pattern, in which the ossification can occur without injury, and typically grows in a predictable pattern. Although this disorder can be passed to offspring by those afflicted with FOP, it is also classified as nonhereditary, as it is most often attributed to a spontaneous genetic mutation upon conception.
Most (i.e. 80%) ossifications arise in the thigh or arm, and are caused by a premature return to activity after an injury. Other sites include intercostal spaces, erector spinae, pectoralis muscles, glutei, and the chest. On planar x-ray, hazy densities are sometimes noted approximately one month after injury, while the denser opacities eventually seen may not be apparent until two months have passed.
The specific cause and pathophysiology are unclear - it may be caused by an interaction between local factors (e.g., a reserve of available calcium in adjacent skeletal tissue or soft tissue edema, vascular stasis tissue hypoxia or mesenchymal cells with osteoblastic activity) and unknown systemic factors. The basic mechanism is the inappropriate differentiation of fibroblasts into bone-forming cells (osteoblasts). Early edema of connective tissue proceeds to tissue with foci of calcification and then to maturation of calcification and osifications
Endometrial hyperplasia
a condition of excessive proliferation of the cells of the endometrium, or inner lining of the uterus.
Most cases of endometrial hyperplasia result from high levels of estrogens, combined with insufficient levels of the progesterone-like hormones which ordinarily counteract estrogen’s proliferative effects on this tissue. This may occur in a number of settings, including obesity, polycystic ovary syndrome, estrogen producing tumours (e.g. granulosa cell tumour) and certain formulations of estrogen replacement therapy.
Endometrial hyperplasia is a significant risk factor for the development or even co-existence of endometrial cancer, so careful monitoring and treatment of women with this disorder is essential.
Atrophy of disuse
Atrophy is partial or complete wasting away of a part of the body.
Causes of atrophy include mutations (which can destroy the gene to build up the organ), poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply to the target organ, excessive amount of apoptosis of cells, and disuse or lack of exercise or disease intrinsic to the tissue itself.
Hormonal and nerve inputs that maintain an organ or body part are referred to as trophic. Trophic describes the trophic condition of tissue. A diminished muscular trophic is designated as atrophy.
Atrophy is the general physiological process of reabsorption and breakdown of tissues, involving apoptosis. When it occurs as a result of disease or loss of trophic support due to other disease, it is termed pathological atrophy, although it can be a part of normal body development and homeostasis as well.
Osteoporosis of disuse
a decrease in bone mass that occurs in sedentary people or patients confined to bed for a long period.
Chronic eczema
Dermatitis
inflammation of the skin.
It is characterized by itchy, erythematous, vesicular, weeping, and crusting patches. The term eczema is also commonly used to describe atopic dermatitis/eczema.
In some languages, dermatitis and eczema are synonyms, while in other languages dermatitis implies an acute condition and eczema a chronic one.
The cause of dermatitis is unclear. One possibility is that the condition is caused by a dysfunctional interplay between the immune system and skin.
The term eczema is broadly applied to a range of persistent skin conditions. These include dryness and recurring skin rashes that are characterized by one or more of these symptoms: redness, skin swelling, itching and dryness, crusting, flaking, blistering, cracking, oozing, or bleeding. Areas of temporary skin discoloration may appear and are sometimes due to healed injuries. Scratching open a healing lesion may result in scarring and may enlarge the rash.
