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

What is Nutrition?

Nutrition is the set of processes by which the body obtains the substances it needs to live. It involves several stages:

• Collection of nutrients through digestion.
• Collection of oxygen through breathing.
• Distribution of nutrients and oxygen through the bloodstream.
• Elimination of waste through excretion and expulsion of carbon dioxide in the breath.

What is Digestion?

Digestion is the process by which foods are broken down into simple substances that can be used by the body. It has these phases:

• Digestion
• Absorption
• Waste Removal

Apparatus Involved in Nutrition

The digestive, respiratory, circulatory, and excretory systems are involved.

Parts of Dentition

Molars, canines, and incisors.

Digestive Tube

It is a muscular tube of different thicknesses... Continue reading "Human Nutrition, Digestion, and Body Systems" »

Mollusks

Triploblasty, coelomates, not segmented. Bilateral symmetry. Soft body (head, visceral mass, foot). Limestone shell. Complete digestive tube (mouth-anus). Radula (in most). Open circulatory system (closed in cephalopods). Excretory system: 1 or 2 metanephridia. Ganglionic nervous system. Asexual or larval reproduction.

• Bivalves: Mussels
• Gastropods: Snails
• Cephalopods: Cuttlefish

Annelida

Triploblasty, coelomates. Bilateral symmetry. Elongated cylindrical body with rings or metamerism. Closed circulatory system. Ganglionic nervous system. Cutaneous respiration. Excretory system: metanephridia. Sexes separate or hermaphrodites. With or without a larval stage.

• Polychaetes: Marine worms
• Oligochaeta: Earthworms
• Hirudinea: Leeches

Arthropods

Triploblasty,... Continue reading "Animal Kingdom Classification: A Comprehensive Guide" »

Heart Failure

Heart failure is the inability of the heart to pump sufficient blood volume into the peripheral circulation, resulting in a diminished cardiac output.

Classification

Location: Left, right, or general.

Pathophysiological Impact:

• Anterograde Heart Failure: Reduced volume expelled.
• Retrograde Heart Failure: Increased resistance to pumping.

Presentation: Acute or chronic.

Etiology

• Cardiac Ischemia and Myocardial Infarction: Affect contractility.
• Valvular and Congenital Heart Disease: Affect pre- and afterload.
• High Blood Pressure: Affects afterload.
• Renal Failure: Affects preload.

Mechanisms

• Decreased Myocardial Contractility
• Systolic Overload: Hypertension and valvular stenosis.
• Diastolic Overload: Valvular heart disease and shunt.
• Effects on Myocardium:

Hypothalamus Connections

• Humoral, Arteries → Hypothalamus
• Hippocampus (Fornix) → Mammillary Nuclei
• Amygdala (Stria Terminalis, Fugo Amygdala-Ventral Bundle) → Nuclei Chiasmatic and Tuberal
• Septal Nuclei (Medial Telencephalic Beam Lateral) ↔ Hypothalamus
• Brain Stem (Dorsal Longitudinal Fasciculus) → Hypothalamus

Hypothalamic Pathways

• Medial Forebrain Bundle
• Posterior Longitudinal Fasciculus
• Mammillothalamic Fasciculus
• Mammillomesencephalic Fasciculus (Tract of Gudden)
• Stria Terminalis
• Hypothalamohypophyseal Tract
• Descending Hypothalamic Fasciculus
• Hypothalamothalamocortical Fasciculus

Thalamus Nuclei and Pathways

Arquithalamus Nuclei

• Lateral Reticular Substance: Thalamic Reticular Nucleus (Gated Area of Arnold) (responsible for modulating dorsal thalamus)

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