Human Biology: Nutrition, Cells, Tissues, Health, and Disease
Nutrition
Nutrition involves incorporating environmental matter and energy into cells to reproduce, replace damaged structures, and move. Waste products are urine and CO2. The following systems are involved: digestive, respiratory, circulatory, and excretory. Nutrition is not the same as digestion.
Organic Molecules
Organic molecules are made of atoms of carbon, oxygen, nitrogen, and phosphorus, and some contain sulfur. They can be very large and complex.
Inorganic Molecules
Inorganic molecules are much
Read MorePassive Immunity Transfer and Hypersensitivity Reactions in Animals
Passive Transfer of Immunity
A) Type of Placentation:
- Humans and Primates: Hemochorial placentation, maternal blood is in contact with the fetal trophoblast. There are only 2 layers of cells separating the maternal and fetal blood circulation. This allows the passage of IgG. At the time of birth, the newborn has an IgG titer similar to the mother’s.
- Dogs and Cats: Endotheliochorial placentation, the fetal chorionic epithelium is in contact with the endothelium of maternal capillaries. There are 3 cell
Cellular Responses and Nutrition: Metabolism, Movement, and Growth
Cellular Responses
At the molecular level, responses are varied, as all metabolic processes in cells occur as responses to stimuli. Cell behavior can be categorized into three types of responses:
Secretion
Beta cells and other specialized cells have a regulated secretion rate, controlled by specific couriers. Molecules are stored in secretory vesicles until a signal (e.g., calcium levels) triggers their release.
Proliferation and Cell Development
- If a cell receives survival signals, it renews its structures
Hematological Disorders: Causes and Diagnostic Tests
Pernicious Anemia: Causes and Lab Findings
Pernicious anemia is a type of megaloblastic anemia caused by vitamin B12 deficiency, primarily due to autoimmune destruction of gastric parietal cells, leading to a lack of intrinsic factor (IF). Intrinsic factor is necessary for vitamin B12 absorption in the ileum. In addition to IF antibodies, some individuals produce antibodies against the B12-IF complex, further impairing B12 absorption. This results in defective DNA synthesis in erythroid precursor
Read MoreEnzymes and Nucleic Acids: Essential Biomolecules
Enzymes
Concept: Enzymes are usually proteins that specifically catalyze certain biochemical reactions by binding to the molecule or metabolite that is going to transform, the substrate.
Chemical Nature: Some protein enzymes are not exclusively proteins but are associated with other molecules. The nature of these molecules depends on the enzyme’s activity. These associations are called conjugated enzymes or holoenzymes. Holoenzymes are composed of cofactors and the protein part of the enzyme, the
Read MoreHuman Blood, Lymphatic, and Urinary Systems: Composition and Functions
Blood Composition and Functions
Blood constitutes 8% of our body weight. It consists of blood plasma and cellular components suspended in plasma.
Plasma
Plasma is a liquid composed mostly of water, minerals, glucose, proteins (fibrinogen, albumin, and globulin), and other substances such as vitamins and hormones.
Cellular Components
The cellular component constitutes about 40% of the blood. This volume remains constant and is called hematocrit. Its decrease indicates anemia. There are three types:
- Red