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

Cellular Immune Response

The cellular immune response occurs against: microorganisms with intracellular growth and development (bacteria, fungi, viruses, protozoa); cells that are foreign to an organism from another individual (e.g., transplanted organs); and tumor cells. This response involves cytotoxic T cells and helper T cells, which collaborate with antigen-presenting macrophages.

Activation Process

Recognition of Antigen: T lymphocytes recognize antigens only when they are bound to MHC molecules on cell surfaces. When a macrophage detects an extracellular antigen, it activates, phagocytoses the antigen, and processes its proteins into linear peptides. These peptides bind to MHC class II molecules, which are then transported to the macrophage... Continue reading "Cellular and Humoral Immune Responses: Mechanisms & Activation" »

Abdominal Wall Anatomy: Key Structures

Bony Landmarks

• Sternum
• 4th Rib
• Vertebrae
• Ilium
• Ischium

Muscles of the Abdominal Wall

Anterior and Lateral Muscles

• Pectoralis major
• Serratus anterior
• External oblique abdominis
• Internal oblique abdominis
• Latissimus dorsi
• Rectus abdominis
• Pyramidalis
• Cremaster (in males)
• Transversus abdominis
• Diaphragm (superior aspect)
• Teres major
• Rhomboids
• Trapezius

Posterior Muscles

• Quadratus lumborum
• Psoas major
• Psoas minor
• Piriformis
• Ischiococcygeus
• Obturator internus
• Levator ani

Vasculature of the Abdomen

Arteries

Anterior Wall & Related Arteries

• Axillary artery
• Subclavian artery
• Subscapular artery
• Internal thoracic artery (lateral to the sternum)
• Lateral thoracic artery (under the arm)
• Thoracodorsal artery
• Anterior intercostal arteries
• Musculophrenic

Medications by System

Nervous System Medications

Adrenaline (SNA): Used in cases of asthma, allergies, and premature births (fenoterol). Also used in Parkinson's disease (dopamine) and inhibition of milk secretion (bromocriptine). Dopamine increases blood pressure.

• Parasympathetic Cholinergic Drugs: Produce parasympathetic stimuli.
• Acetylcholine: Causes vasodilation in the heart.
• Indirect Cholinergics: Prevent acetylcholine from being metabolized (e.g., Physostigmine, Neostigmine). Used in glaucoma, crosses the blood-brain barrier (BBB), and can be lethal in high doses.
• Anticholinergics: Block the effects of acetylcholine (e.g., Atropine, Scopolamine).

Respiratory System Medications

Most commonly used drugs include oxygen and cough modifiers. They... Continue reading "Medications: Nervous, Respiratory, Circulatory & Digestive Systems" »

Primary Meristem

Located at the tips of juvenile plant organs such as roots, shoots, and buds, the primary meristem is responsible for the plant's growth in length.

Root

The root has several distinct parts: the suberized zone, the zone of absorption, the growth area, and the root cap.

The growth zone, located near the root tip, contains meristematic tissue. This tissue can have one, two, or three meristematic cells. If there is one cell, it gives rise to all other cells. If there are three cells, they multiply and differentiate into the root cap and epidermis (lower cells), the cortex (middle cells), and the vascular cylinder (upper cells).

Shoot

Shoots do not grow in the opposite direction of roots. Shoots have nodes, internodes, and buds.

Buds... Continue reading "Plant Growth and Anatomy: Meristems, Tissues, and Structures" »

Catabolic and Anabolic Metabolism

Catabolic metabolism is oxidized when it loses electrons. It is a set of molecular processes that transform complex molecules into simpler ones. The energy molecule ATP stores energy. Energy is released during the oxidation of molecules, especially if O₂ is the ultimate acceptor (aerobic) or if another acceptor is used (anaerobic). Fermentation is the incomplete oxidation of energy molecules. For example, glucose activates Bacillus, and the initial product in the muscles is lactic acid. Alcohol fermentation starts with glucose in yeast, and the final product is ethyl alcohol. Putrefaction of proteins into simpler molecules is performed by some organisms.

Anabolism is a set of reduction reactions in which it is... Continue reading "Cellular Metabolism and Biodiversity: From Molecules to Ecosystems" »

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" »