Notes, summaries, assignments, exams, and problems for Biology

Lymphedema Clinical Presentation

• Increased limb volume:
  • Worsens during the day and is lower at night.
  • Decreases with elevation.
• Lower extremity involvement:
  • Often respects the sole of the foot.
  • Typically begins in the ankle.
  • Can progress to resemble an elephant's foot (elephantiasis), which is usually painless.

Temporal Clinical Classification of Ischemic Stroke

Transient Ischemic Attack (TIA)

• Episode of focal neurological deficit, short-term.
• Total recovery within 24 hours.
• No cerebral parenchymal necrosis.
• Current definitions often include standard imaging tests.

Reversible Ischemic Neurological Deficit (RIND)

• Neurological deficit lasting 24 hours and less than 4 weeks.

Established Stroke

• Focal neurological deficit remains unchanged since its onset.

Progressive

Stem cells (or stem cells) are cells that have not completed their differentiation, either by being part of an embryo a few days old, or by being part of nature's reserves of immature cells in the adult organism.

Characteristics of Stem Cells

The key characteristics of stem cells are:

1. Self-renewal: The ability to produce more stem cells.
2. Differentiation: The origination of daughter cells of various types, which are converted by differentiation into specialized cell types.

Different Types of Stem Cells

Stem cells can be classified into the following types:

Totipotent Cells

There are about two hundred types of specialized cells, and all of them originate from unspecialized stem cells or differentiated cells. The first cell of every living thing, the... Continue reading "Stem Cells: Types, Characteristics, and Applications" »

Cellular Respiration: Energy Production in Cells

Understanding Cellular Respiration

Cellular respiration is often associated with the exchange of gases. The utilization and disposal of gases occur within the confines of individual cells in animal or plant bodies, or within the single cell of unicellular organisms. This process is known as cellular respiration. During cellular respiration, the breaking of chemical bonds follows a sequence of steps catalyzed by various enzymes, allowing for a gradual release of energy. This energy is not transformed into light; instead, it is partly "packaged" into ATP molecules, while the remainder is dissipated as heat.

Stages of Cellular Respiration

The first stage, Glycolysis, occurs in the cytoplasm's matrix,... Continue reading "Cellular Respiration and Cell Cycle: Fundamental Biological Processes" »

The endosymbiotic theory explains the process of moving from a prokaryotic cell, which lacks most organelles, through symbiogenetic additions.

The Three Stages of Endosymbiosis

1. A bacterium that uses sulfur as an energy source merges with a swimming bacterium to form a new entity. The result was the first eukaryotic cell. The nucleoplasm of animal cells, plants, and fungi would be the result of the union of these two bacteria. A baseline characteristic of both cells was added: a new, more complex morphology. DNA remained confined to an inner core separated from the rest of the cell by a membrane.
2. This new organization was still anaerobic, unable to metabolize oxygen, as this gas was poisonous to it. Therefore, they lived in environments where oxygen,

Understanding Fertilization

Fertilization is the union of an egg and sperm, occurring within the female genital tract, specifically in a fallopian tube. The immediate result of this union is the formation of a single-celled organism called the zygote. The fallopian tube connects the ovaries, where ova (eggs) are produced, to the uterus, the structure within which the development of the zygote begins.

Stages of Human Embryonic Development

Embryonic development is the set of profound changes that occur in any living being throughout its early life. In humans, as in many other living beings, it commences with the formation of the zygote. This initial development, often referred to as prenatal development, concludes at the time of birth. Postnatal

Digestive System Components

Salivary Glands

These glands help moisten the food bolus. Saliva moistens food to aid swallowing and begins the process of food degradation. The main salivary glands are:

• Parotid
• Submandibular (formerly Submaxillary)
• Sublingual

Pharynx

Located just after the mouth, the pharynx serves as a junction for both the respiratory and digestive systems.

Esophagus

The esophagus is a long, muscular tube connecting the pharynx to the stomach. It ends at the cardia, regulated by the lower esophageal sphincter.

Stomach

A thick-walled muscular sac located on the left side of the upper abdomen, below the ribs. It churns food and mixes it with digestive juices.

Small Intestine

A long, coiled tube (approximately 6-7 meters) where most nutrient... Continue reading "Human Digestive & Circulatory System Anatomy" »

The Human Sensory System

The Sense of Smell (Olfaction)

The sense of smell is located in the nasal cavity, which is lined by the olfactory mucosa. This mucosa is divided into two main regions:

• Red Olfactory Mucosa (Respiratory Region): Lining the inner half of the nasal cavity, this region contains numerous capillaries that warm and humidify the inhaled air.
• Yellow Olfactory Mucosa (Olfactory Region): Located at the top of the nasal cavity, this specialized region contains the olfactory receptors. These receptors are composed of hair cells that receive and transmit chemical stimuli. They are capable of detecting over 3,000 different gaseous substances. When stimulated, they send nerve impulses via the olfactory nerve to the olfactory bulb and then

Radiography: First Imaging Technique

Radiography is the first imaging technique developed. It is based on the use of X-rays. X-rays are a type of radiation with much energy, which causes some objects to pass through easily. Abuse of X-rays poses a risk of producing cancer. This technique is not recommended for pregnant women and small children.

Computerized Tomography (CT)

Computerized Tomography (CT) is based on taking multiple X-rays of a body area with a special device where the X-ray rotates around the patient. All images are combined using a PC. This technique provides detailed images of the body's interior. Its major drawback is that it requires using large amounts of radiation.

Magnetic Resonance Imaging (MRI)

Magnetic Resonance Imaging (

Egg Proteins

Dispersion containing particles uniformly distributed in a protein solution or plasma, identified as areas of yolk granules, low-density lipoprotein figures, and myelin.

Proteins and Lipoproteins of Particles

Fosvitin: A highly phosphorylated phosphoprotein rich in serine, serving as a phosphorus reserve for the embryo.

Plasma Proteins and Lipoproteins

• Livetin: Forms the globular fraction. Its components are related to plasma proteins.
• Low-density lipoproteins.
• Ovovitellin: A fraction rich in phosphorus and sulfur. The action of the enzyme chymosin on the clot causes dephosphorylation, producing heat and phosphorus-rich peptides.

Fresh Eggs

Fresh eggs are those with natural color and flavor, having undergone no manipulation beyond dry cleaning.... Continue reading "Egg Science: Composition, Quality, and Products" »

Invertebrate and Ruminant Digestive Systems

Invertebrate digestive systems are characterized by a transition from intracellular to extracellular digestion, with intermediate mixed mechanisms. These systems often feature structures that perform crushing and physical digestion. Key features include:

1. Transition from intracellular to extracellular digestion.
2. Structures for crushing and physical digestion.
3. Two openings in the digestive tract: mouth (food entry) and anus (waste).
4. Specialized body parts for ingestion, mastication, digestion, and chemical absorption.
5. Digestive glands, such as the hepatopancreas, which produce hydrolytic enzymes for chemical digestion.

Porifera

Porifera exhibit intracellular digestion. They have pores that allow water and food... Continue reading "Invertebrate and Ruminant Digestive Systems: A Comparative Study" »