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

Ovary

• Germinal Epithelium

  Cuboidal epithelium (modified peritoneal mesothelium)

• Tunica Albuginea

  Dense connective tissue

• Cortex

  Contains ovarian follicles at different stages of maturation

• Medulla

  Loose connective tissue, vessels, and smooth muscle

Uterine Tubes

• Mucosa

  Folded; simple columnar epithelium (ciliated and non-ciliated cells) + lamina propria (loose connective tissue)

• Muscular Layer

  Inner circular fibers, outer longitudinal fibers

• Serous Layer

  Mesothelium + loose connective tissue

Uterus

Fundus and Body

• Perimetrium

  Loose connective tissue + mesothelium

• Myometrium

  Smooth muscle (subserous, subvascular, vascular, submucosal strata)

• Endometrium

  a) Functional layer: undergoes cyclical changes
  b) Basal layer (approximately 1/3): simple columnar epithelium

Blood Components

Platelets

Platelets are tiny specialized cells that are activated whenever there is blood clotting or repair is needed. They are colorless and deform easily.

Blood Plasma Composition

Blood Plasma: Fluid formed by amino acids, carbohydrates, proteins, salts, lipids, hormones, antibodies, enzymes, and dissolved gases. Its two main components are water and proteins (albumin, globulin, and fibrinogen).

The Heart: Structure and Blood Flow

Heart Wall Layers

The endocardium consists of epithelial tissue lining that is continuous with the endothelium of blood vessels. The myocardium is the most voluminous layer, being composed of a special type of muscle tissue called cardiac muscle tissue. The pericardium forms the wall that surrounds the... Continue reading "Human Circulatory and Lymphatic Systems" »

Neothalamus Part II

Ventral Anterior Nucleus (VA)

Function: Regulates motor pathways.

Ventral Lateral Nucleus (VL)

• Inputs: Globus pallidus, Substantia nigra
• Outputs: Motor and premotor cortex

Anterior Thalamic Nuclei

Function: Limbic system relay, memory, behavior.

• Inputs: Mammillary nuclei (via mammillothalamic tract), Hippocampus (via fornix)
• Outputs: Cingulate gyrus and frontal cortex

Dorsomedial Nucleus (DM)

Function: Affect, cognition, judgment, memory, integration.

• Inputs: Hypothalamus, Globus pallidus, Amygdala, other thalamic nuclei
• Outputs: Prefrontal cortex (including frontal pole)

Subthalamus

Function Overview

Involved in facilitating automatic movements and inhibiting involuntary movements through basal ganglia loops.

Basal Ganglia Pathways &

Conjunctival Autoimmune Diseases

Autoimmune diseases associated with skin and mucocicatricial conditions that affect the cornea and conjunctiva:

• Ocular Cicatricial Pemphigoid: Chronic bilateral conjunctivitis that typically appears around 50 years of age, leading to fibrosis, keratinization, and symblepharon. Treatment includes corticosteroids, cyclophosphamide, and dapsone.
• Erythema Multiforme: Includes Stevens-Johnson syndrome (affecting skin and mucosa) and toxic epidermal necrolysis (Lyell's syndrome), often triggered by medication or an infectious process.

Neurotrophic Keratopathy

Etiology: Ablation of the fifth cranial nerve, infection (such as herpes), topical medications (anesthetics), systemic diseases (diabetes mellitus, vitamin A deficiency)... Continue reading "Understanding Common Eye Conditions and Treatments" »

Nervous System Coordination

Nervous coordination is carried out by the nervous system. Neurons are divided into three parts: the cell body, the dendrites, and the axon.

• The cell body contains the nucleus and other organelles.
• Dendrites are short, branch-like projections.
• The axon is a longer projection. It ends in a series of slender branches which widen slightly at the tip and are called axon terminals.

In general, axons are protected by a white substance called myelin. The axons of various neurons sometimes group together to form nerve fibers, and these in turn can group together to form nerves.

Neuron Connection: The Synapse

Neurons are connected to each other. The place where one neuron connects to another is called a synapse. A nerve impulse... Continue reading "Nervous and Endocrine Systems: Coordination and Regulation" »

Glycolysis: Preparatory Phase (Cytosol)

Glycolysis involves the breakdown of glucose in the cytosol.

1. Glucose + ATP → ADP + Glucose 6-phosphate (G6P) + Pi (Enzyme: Hexokinase) (Irreversible)
2. Glucose 6-phosphate ↔ Fructose 6-phosphate (F6P) (Enzyme: Phosphoglucose Isomerase) (Reversible)
3. Fructose 6-phosphate + ATP → Fructose 1,6-bisphosphate (F1,6BP) + ADP + Pi (Enzyme: Phosphofructokinase) (Irreversible)
4. Fructose 1,6-bisphosphate ↔ Glyceraldehyde 3-phosphate (G3P) + Dihydroxyacetone Phosphate (DHAP) (Enzyme: Aldolase) (Reversible)
5. Dihydroxyacetone Phosphate ↔ Glyceraldehyde 3-phosphate (G3P) (Enzyme: Triose Phosphate Isomerase) (Reversible)

Glycolysis: Payoff Phase

Oxidation of Glyceraldehyde 3-phosphate and subsequent steps leading to pyruvate,... Continue reading "Cellular Respiration Pathways Summary" »

Work of the Cell: Metabolism and Disease

Metabolism: The set of biochemical transformations that occur in living cells. It has two parts: anabolism and catabolism.

Anabolism

Anabolism is the part of metabolism dedicated to the production of molecules that comprise cells from nutrients.

Catabolism

Catabolism is the part of metabolism involved in the production of energy that the cell constantly needs to perform its functions. It uses organic nutrients.

Nutrients are essential substances that cells need but are unable to synthesize; therefore, they must be obtained through diet.

Healthy Lifestyles

Healthy lifestyles include:

• Personal hygiene
• Domestic hygiene
• Occupational hygiene
• Proper eating habits
• Adequate sleep
• Regular exercise
• Avoiding drugs
• Avoiding a sedentary

Understanding the Human Immune System

Innate and Acquired Immunity

The immune system is a complex network of organs and structures responsible for defending the body from toxic microbial aggression. It operates through two primary mechanisms:

• Innate (Natural) Immunity:
  • Passive: Represented by maternal antibodies.
  • Active: Involves antigen-antibody reactions.
• Acquired Immunity:
  • Active: Developed through vaccines.
  • Passive: Achieved via the administration of antibodies, such as those found in antibiotics.

Key Components of the Immune System

The immune response involves several processes, including:

• Chemotaxis: The attraction of immune cells to the site of infection.
• Diapedesis: The movement of immune cells out of blood vessels.
• Phagocytosis: The process of

Cellular Components: Cytoplasm and Cytosol

The cytoplasm is the material or protoplasm within a living cell, excluding the nucleus. It comprises the *cytosol* (also known as the hyaloplasm or cytoplasmic matrix), a gelatinous substance composed of ions and dissolved inorganic and organic molecules in water, and various organelles such as centrioles, ribosomes, endoplasmic reticulum, Golgi apparatus, mitochondria, and chloroplasts (in plant cells). These structures play specific roles in cellular function.

The cytosol is the site of various chemical reactions of metabolism, including the first stage of cellular respiration (glycolysis) and the synthesis of several substances.

The Cytoskeleton

In eukaryotic cells, the cytoskeleton is a complex network... Continue reading "Cell Structures: Cytoplasm, Cytoskeleton, Centrioles, Cilia, Flagella" »

Tumors

In normal tissues, cells divide to replace old or damaged cells. This balance can be disrupted, leading to tumor formation. Tumors are defined as a mass of disorganized tissue. Most tumors are benign, meaning they grow locally and do not spread.

Malignant Tumors: Cancer

Cancer is a malignant tumor whose cells can spread from the initial tumor site to other parts of the body. These cells have two key characteristics:

1. Invasiveness: Ability to penetrate and spread through adjacent tissues.
2. Metastasis: Capacity to enter the blood and lymph systems, travel to other parts of the body, and form secondary tumors.

Cancer Treatment

• Surgery: Removal of the tumor mass.
• Radiotherapy: Use of radiation to shrink cancer cells.
• Chemotherapy: Administration of