Biology Test Study Notes

Structure and Function of Cartilage and Bone

• Cartilage

  • Specialized connective tissue
  • Strong and flexible, designed to withstand compression
  • Composed of cells (chondrocytes) surrounded by a matrix
  • Chondroblasts secrete the extracellular matrix and often become trapped in lacunae
  • Matrix includes glycoprotein-rich ground substance and collagen
  • Lacks blood vessels, allowing oxygen and nutrients to reach cells by diffusion, resulting in slow healing

• Bone

  • Specialized connective tissue
  • Comprised of organic molecules (collagen fibers, polysaccharides) and inorganic molecules (mostly hydroxyapatite)
  • Osteoblasts secrete enzymes producing calcium
  • Some osteoblasts become trapped within the matrix and differentiate into osteocytes
  • Osteocytes reside in lacunae connected by canaliculi
  • Bone types include compact, medullary, and spongy

Growth in Epiphyses

• Endochondral Bone Development

  • Occurs in vertebrae, ribs, and long bones at the epiphyses
  • Epiphyses contain growth plates with young cartilage cells that undergo mitosis to thicken, leading to longitudinal growth

• Intramembranous Development

  • Occurs between membranes, mainly in flat bones
  • Calcified bone replaces outer cartilage covering and inner cartilage
  • Results in latitudinal growth

Bone Remodeling

• Continuous process of osteoblasts depositing new bone and osteoclasts resorbing it
• Stimulated by mechanical stress and hormonal changes
• Osteoporosis results when bone resorption exceeds deposition, resulting in fragile bones

Structure of Human Skeletal Muscle

• Each skeletal muscle is made up of bundles of muscle fibers (cells)
• Structure hierarchy: Muscle → Muscle fibers → Myofibrils (segmented into sarcomeres) → Myofilaments (actin and myosin)

Muscles Producing Movement at Joints

• Antagonist Muscles
  • Flexors and extensors of limbs interact to produce joint motion
  • One attachment (origin) is stable while the other (insertion) moves during contraction
  • Muscle contractions are reversible

Sliding Filament Mechanism of Muscle Contraction

• Initiated by action potentials from motor neurons, causing depolarization of muscle cell membranes
• Sarcomeres contract as actin and myosin filaments slide past one another
• Requires ATP for the process

Muscle Fiber Types

• Fast Twitch

  • Fewer capillaries and mitochondria
  • Rapid power generation
  • White fibers

• Slow Twitch

  • More capillaries and mitochondria
  • Sustained energy production
  • Red fibers

Human Nutrition Requirements

• Essential Nutrients: Carbohydrates, proteins, fats
• Basal Metabolic Rate (BMR): Minimum calorie intake required for basic bodily functions; typically needs to be 50-60% higher for proper functioning

Structure and Function of Human Digestive System

• GI Tract
  • Approximately 8m long, extending from mouth to anus
  • Accessory organs play additional roles (liver, gallbladder, pancreas, salivary glands)
• Ingestion
  • Begins in the mouth with mechanical chewing and chemical breakdown via saliva
• Digestion
  • Stomach and small intestine involved; acidic gastric juice forms chyme in the stomach
  • Enzymes from the pancreas and bile from the gallbladder break down nutrients
• Absorption
  • Primarily occurs in the small and large intestine; nutrients transported via the portal vein to the body

Major Digestive Enzymes

• Amylase: Saliva and pancreas; breaks down carbohydrates
• Pepsin: Active in stomach; denatures proteins
• Lipase: Saliva and pancreas; breaks down fats
• Trypsin and Chymotrypsin: Active in small intestine for protein breakdown
• Lactase: Active in small intestine; breaks down lactose

Accessory Organs and Their Functions

• Liver: Produces bile essential for fat digestion
• Gallbladder: Stores bile
• Pancreas: Produces enzymes and hormones like insulin
• Salivary Glands: Secrete saliva to aid digestion

Variations in Vertebrate Digestive Systems

• Non-Ruminant Herbivore: Simple stomach, larger cecum
• Ruminant Herbivore: Four-chambered stomach
• Insectivore: Short intestine, no cecum
• Carnivore: Short intestine and colon

Hormones and Appetite Regulation

• Leptin: Reduces appetite
• Ghrelin: Increases appetite
• Insulin: Promotes glucose uptake
• Cholecystokinin (CCK): Stimulates gallbladder and pancreas in response to fatty acids

Components of Blood and Circulatory Functions

• Functions of Circulatory System
  • Transportation of oxygen, nutrients, and waste
  • Regulation of hormones and body temperature
  • Protection against pathogens and injury
• Composition of Blood
  • Plasma, erythrocytes (red blood cells), leukocytes (white blood cells)
• Erythropoietin (EPO): Stimulates red blood cell production

Evolution of the Chambered Heart

• Fish: Two-chambered heart, circulates blood to gills
• Amphibians: Three-chambered heart for separation of pulmonary circulation
• Mammals: Four-chambered heart with complete separation of oxygenated and deoxygenated blood

Blood Flow through Mammalian Circulatory System

1. Deoxygenated blood enters the right atrium
2. Blood flows to the right ventricle and is pumped to the lungs
3. Oxygenated blood returns to the left atrium
4. Blood is pumped from the left ventricle to the body

The Cardiac Cycle

• Systolic Phase: Heart contracts, blood is pumped out
• Diastolic Phase: Heart relaxes, fills with blood

Lymphatic System Function

• Lymphatic capillaries collect excess fluid from blood capillaries and return it to circulation

Gas Exchange Mechanisms

• Examples of evolutionary adaptations in respiratory systems
• Structure of human respiratory system facilitates gas exchange, with alveoli increasing surface area for diffusion

Inhalation and Exhalation

• Inhalation: Diaphragm contracts, thoracic cavity expands
• Exhalation: Diaphragm relaxes, thoracic cavity decreases in volume

Oxyhemoglobin Dissociation Curve

• Describes how hemoglobin releases oxygen under certain conditions (high temperature, low pH)

Nitrogenous Waste Comparison

• Ammonia: Highly toxic; requires large amounts of water
• Urea: Less toxic; requires less water than ammonia
• Uric Acid: Least toxic; conserves water

Kidney Function Overview

• Filtration: Removes water and small solutes
• Reabsorption: Returns substances back to bloodstream
• Secretion: Removes toxins from blood into filtrate

Urine Formation Process

• Filtration: Occurs at the glomerulus, forming filtrate
• Reabsorption: Takes place in nephron segments with selective solute absorption
• Secretion: Unwanted solutes are transferred from blood into the filtrate

ADH and Aldosterone Role in Blood Osmolarity

• ADH: Promotes water reabsorption, decreasing blood osmolarity
• Aldosterone: Promotes sodium reabsorption and indirectly increases blood volume

Human Innate Defenses

• Physical Barriers: Skin, mucosal systems of the digestive, urinary, and respiratory tracts
• Recognition: Pathogen recognition through signaling pathways triggers immune responses
• Inflammatory Response: Histamine release leads to increased blood flow and recruitment of neutrophils

Lymphatic System and Immunity

• Primary lymphoid organs are where lymphocytes are produced (bone marrow and thymus)
• Secondary organs include lymph nodes and the spleen, where lymphocytes encounter pathogens

Adaptive Immune Response

• Humoral Immunity: Involves B cells producing antibodies against free pathogens
• Cell-Mediated Immunity: Involves T cells targeting and destroying infected cells

Structure of Antibodies

• Y-shaped structure with variable binding sites for antigens

Immune System Malfunctions

• Autoimmune diseases: Immune system targets self-cells
• Immunodeficiency: Reduced immune response effectiveness
• Allergies: Overreaction to minor antigens

Sexual vs Asexual Reproduction

• Asexual: Offspring identical to parent (mitosis)
• Sexual: Unique offspring (meiosis)

Male Reproductive System Structure

• Testes in scrotum; sperm produced in seminiferous tubules
• Epididymis for sperm maturation; vas deferens carries sperm to urethra for ejaculation

Spermatogenesis Overview

• Spermatogenesis occurs in seminiferous tubules with Leydig cells producing testosterone
• Testosterone promotes sperm development and secondary sexual characteristics

Female Reproductive System Structure

• Ovaries produce eggs and hormones; fallopian tubes lead to the uterus
• Uterus is where embryo develops; vagina is entrance for sperm

Oogenesis Overview

• Oogenesis begins in fetal development; ovulation releases secondary oocytes
• Fertilization leads to embryo development

Female Reproductive Cycle Changes

• LH triggers ovulation; cyclic hormone changes regulate the reproductive process.