HEART DISORDERS

1. Pump failure => Alters pressure (flow) =>alters oxygen carrying capacity.
   1. Renin release (Juxtaglomerular cells) Kidney
   2. Converts Angiotensinogen => Angiotensin I
   3. In lungs Angiotensin I Converted => Angiotensin II
   4. Angiotensin II = powerful vasoconstrictor (raises pressure, increases afterload)
      1. stimulates thirst
      2. stimulates adrenal cortex to release Aldosterone
         (Sodium retention, potassium loss)
      3. stimulates kidney directly to reabsorb Sodium
      4. releases ADH from Posterior Pituitary
2. Myocardial Infarction

    

   1. Myocardial Cells die from lack of Oxygen
   2. Adjacent vessels (collateral) dilate to compensate
   3. Intracellular Enzymes leak from dying cells (Necrosis)
      1. Creatine Kinase CK (Creatine Phosphokinase) 3 forms
         1. One isoenzyme = exclusively Heart (MB)
         2. CK-MB blood levels found 2-5 hrs, peak in 24 hrs
         3. Lactic Dehydrogenase found 6-10 hours after. points less clearly to infarction
      2. Serum glutamic oxaloacetic transaminase (SGOT)
         1. Found 6 hrs after infarction, peaks 24-48 hrs at 2 to 15 times normal,
         2. SGOT returns to normal after 3-4 days
   4. Myocardium weakens = Decreased CO & SV (severe - death)
   5. Infarct heal by fibrous repair
   6. Hypertrophy of undamaged myocardial cells
      1. Increased contractility to restore normal CO
      2. Improved by exercise program
   7. Prognosis
      1. 10% uncomplicated recovery
      2. 20% Suddenly fatal
      3. Rest MI not fatal immediately, 15% will die from related causes
3. Congenital heart disease (Affect oxygenation of blood)
   1. Septal defects
   2. Ductus arteriosus
   3. Valvular heart disease
      1. Stenosis = cusps, fibrotic & thickened, Sometimes fused, can not open
      2. Regurgitation = cusps, retracted, Do not close, blood moves backwards

Levels of Organization:

CHEMICAL LEVEL - includes all chemical substances necessary for life (see, for example, a small portion - a heme group - of a hemoglobin molecule); together form the next higher level

CELLULAR LEVEL - cells are the basic structural and functional units of the human body & there are many different types of cells (e.g., muscle, nerve, blood)

TISSUE LEVEL - a tissue is a group of cells that perform a specific function and the basic types of tissues in the human body include epithelial, muscle, nervous, and connective tissues

ORGAN LEVEL - an organ consists of 2 or more tissues that perform a particular function (e.g., heart, liver, stomach)

SYSTEM LEVEL - an association of organs that have a common function; the major systems in the human body include digestive, nervous, endocrine, circulatory, respiratory, urinary, and reproductive.

There are two types of cells that make up all living things on earth: prokaryotic and eukaryotic. Prokaryotic cells, like bacteria, have no 'nucleus', while eukaryotic cells, like those of the human body, do.

The Nervous System Has Peripheral and Central Units

• The central nervous system (CNS) is the brain and spinal column
• The peripheral nervous system (PNS) consists of nerves outside of the CNS
• There are 31 pairs of spinal nerves (mixed motor & sensory)
• There are 12 pairs of cranial nerves (some are pure sensory, but most are mixed)

The pattern of innervation plotted on the skin is called a dermatome

The Nervous System Has Peripheral and Central Units

• The central nervous system (CNS) is the brain and spinal column
• The peripheral nervous system (PNS) consists of nerves outside of the CNS
• There are 31 pairs of spinal nerves (mixed motor & sensory)
• There are 12 pairs of cranial nerves (some are pure sensory, but most are mixed)

The pattern of innervation plotted on the skin is called a dermatome

An anti-diruetic is a substance that decreases urine volume, and ADH is the primary example of it within the body. ADH is a hormone secreted from the posterior pituitary gland in response to increased plasma osmolarity (i.e., increased ion concentration in the blood), which is generally due to an increased concentration of ions relative to the volume of plasma, or decreased plasma volume.

The increased plasma osmolarity is sensed by osmoreceptors in the hypothalamus, which will stimulate the posterior pituitary gland to release ADH. ADH will then act on the nephrons of the kidneys to cause a decrease in plasma osmolarity and an increase in urine osmolarity.

ADH increases the permeability to water of the distal convoluted tubule and collecting duct, which are normally impermeable to water. This effect causes increased water reabsorption and retention and decreases the volume of urine produced relative to its ion content.

After ADH acts on the nephron to decrease plasma osmolarity (and leads to increased blood volume) and increase urine osmolarity, the osmoreceptors in the hypothalamus will inactivate, and ADH secretion will end. Due to this response, ADH secretion is considered to be a form of negative feedback.

The pituitary gland is pea-sized structure located at the base of the brain. In humans, it consists of two lobes:

• the Anterior Lobe and
• the Posterior Lobe

The Anterior Lobe

The anterior lobe contains six types of secretory cells All of them secrete their hormone in response to hormones reaching them from the hypothalamus of the brain.

Thyroid Stimulating Hormone (TSH)

TSH (also known as thyrotropin) is a glycoprotein The secretion of TSH is

• stimulated by the arrival of thyrotropin releasing hormone (TRH) from the hypothalamus.
• inhibited by the arrival of somatostatin from the hypothalamus.

 TSH stimulates the thyroid gland to secrete its hormone thyroxine (T₄).

Some develop antibodies against their own TSH receptors making more T₄ causing hyperthyroidism. The condition is called thyrotoxicosis or Graves' disease.

Hormone deficiencies

A deficiency of TSH causes hypothyroidism: inadequate levels of T₄ (and thus of T₃ )..

Follicle-Stimulating Hormone (FSH)

FSH is a heterodimeric glycoprotein Synthesis and release of FSH is triggered by the arrival from the hypothalamus of gonadotropin-releasing hormone (GnRH).

FSH in females :In sexually-mature females, FSH (assisted by LH) acts on the follicle to stimulate it to release estrogens.

FSH in males :In mature males, FSH acts on spermatogonia stimulating (with the aid of testosterone) the production of sperm.

Luteinizing Hormone (LH)

LH is synthesized within the same pituitary cells as FSH and under the same stimulus (GnRH). It is also a heterodimeric glycoprotein

LH in females

In sexually-mature females, LH

• stimulates the follicle to secrete estrogen in the first half of the menstrual cycle
• a surge of LH triggers the completion of meiosis I of the egg and its release (ovulation) in the middle of the cycle
• stimulates the now-empty follicle to develop into the corpus luteum, which secretes progesterone during the latter half of the menstrual cycle.

LH in males

LH acts on the interstitial cells (also known as Leydig cells) of the testes stimulating them to synthesize and secrete the male sex hormone, testosterone.

LH in males is also known as interstitial cell stimulating hormone (ICSH).

Prolactin (PRL)

Prolactin is a protein of 198 amino acids. During pregnancy it helps in the preparation of the breasts for future milk production. After birth, prolactin promotes the synthesis of milk.

Prolactin secretion is

• stimulated by TRH
• repressed by estrogens and dopamine.

Growth Hormone (GH)

• Human growth hormone (also called somatotropin) is a protein
• The GH-secreting cells are stimulated to synthesize and release GH by the intermittent arrival of growth hormone releasing hormone (GHRH) from the hypothalamus. GH promotes body growth

In Child

• hyposecretion of GH produces dwarfism
• hypersecretion leads to gigantism

In adults, a hypersecretion of GH leads to acromegaly.

ACTH — the adrenocorticotropic hormone

ACTH acts on the cells of the adrenal cortex, stimulating them to produce

• glucocorticoids, like cortisol
• mineralocorticoids, like aldosterone
• androgens (male sex hormones, like testosterone

Hypersecretion of ACTH cause of Cushing's disease.

White Blood Cells (leukocytes)

White blood cells

• are much less numerous than red (the ratio between the two is around 1:700),
• have nuclei,
• participate in protecting the body from infection,
• consist of lymphocytes and monocytes with relatively clear cytoplasm, and three types of granulocytes, whose cytoplasm is filled with granules.

Lymphocytes: There are several kinds of lymphocytes, each with different functions to perform , 25% of wbc The most common types of lymphocytes are

• B lymphocytes ("B cells"). These are responsible for making antibodies.
• T lymphocytes ("T cells"). There are several subsets of these:
  • inflammatory T cells that recruit macrophages and neutrophils to the site of infection or other tissue damage
  • cytotoxic T lymphocytes (CTLs) that kill virus-infected and, perhaps, tumor cells
  • helper T cells that enhance the production of antibodies by B cells

Although bone marrow is the ultimate source of lymphocytes, the lymphocytes that will become T cells migrate from the bone marrow to the thymus where they mature. Both B cells and T cells also take up residence in lymph nodes, the spleen and other tissues where they

• encounter antigens;
• continue to divide by mitosis;
• mature into fully functional cells.

Monocytes : also originate in marrow, spend up to 20 days in the circulation, then travel to the tissues where they become macrophages. Macrophages are the most important phagocyte outside the circulation. Monocytes are about 9% of normal wbc count

Macrophages are large, phagocytic cells that engulf

• foreign material (antigens) that enter the body
• dead and dying cells of the body.

Neutrophils

The most abundant of the WBCs. about 65% of normal white count  These cells spend 8 to 10 days in the circulation making their way to sites of infection etc  Neutrophils squeeze through the capillary walls and into infected tissue where they kill the invaders (e.g., bacteria) and then engulf the remnants by phagocytosis. They have two types of granules: the most numerous are specific granules which contain bactericidal agents such as lysozyme; the azurophilic granules are lysosomes containing peroxidase and other enzymes

Eosinophils : The number of eosinophils in the blood is normally quite low (0–450/µl). However, their numbers increase sharply in certain diseases, especially infections by parasitic worms. Eosinophils are cytotoxic, releasing the contents of their granules on the invader.

Basophils : rare except during infections where these cells mediate inflammation by secreting histamine and heparan sulfate (related to the anticoagulant heparin). Histamine makes blood vessels permeable and heparin inhibits blood clotting. Basophils are functionally related to mast cells.  . The mediators released by basophils also play an important part in some allergic responses such as hay fever and an anaphylactic response to insect stings.

Thrombocytes (platelets):

Thrombocytes are cellular derivatives from megakaryocytes which contain factors responsible for the intrinsic clotting mechanism. They represent fragmented cells  which contain residual organelles including rough endoplasmic reticulum and Golgi apparati. They are only 2-microns in diameter, are seen in peripheral blood either singly or, often, in clusters, and have a lifespan of 10 days.