BIOL 102 Unit 4: Animal Structures and Processes - Lecture Review Notes

Animal Processes Overview

Distinction between Animals and Plants:
- Animals consist of more diverse types of tissues and cell types compared to plants.
Four Types of Tissues in Animals:
  - Epithelial: Covers body surfaces and lines cavities.
  - Connective: Provides support and binds other tissues together; includes bone, blood, and adipose tissue.
  - Muscle: Facilitates movement; types include skeletal, cardiac, and smooth muscle.
  - Nervous: Transmits signals for communication; composed of neurons and supporting cells.
Functions of Tissues:
  - Epithelial: Protection, absorption, secretion, and sensation.
  - Connective: Structural support, storage, transport (e.g., blood).
  - Muscle: Movement.
  - Nervous: Coordination and control.
Identification of Tissue Types:
- Epithelial tissues are classified based on cell shape and layering (e.g., squamous, cuboidal, columnar).
Homeostasis:
  - Definition: The process of maintaining a stable internal environment despite external changes.
  - Importance: Vital for survival, allows for optimal functioning of organs and cells.
  - Types of Homeostasis:
    - Temperature regulation, pH balance, and osmoregulation.
  - Maintenance by the body can involve negative feedback mechanisms.

Integumentary System

Principal Functions:
- Protection against environmental hazards, regulation of body temperature, and sensation.
Principal Organs:
- Skin, hair, nails, and associated glands (e.g., sweat glands).
Principal Regions of the Integumentary System:
  - Epidermis: Outermost layer, composed mainly of keratinized epithelial cells.
  - Dermis: Below the epidermis, contains connective tissue, blood vessels, nerves, and glands.
  - Hypodermis: Also known as subcutaneous tissue, composed of loose connective tissue and fat.
Epidermis Structure:
- Principal Layers: Stratum corneum, stratum granulosum, stratum spinosum, stratum basale.
- Principal Tissue: Keratinized stratified squamous epithelium.
Principal Cells:
  - Keratinocytes: Produce keratin, a protective protein.
  - Melanocytes: Produce and distribute melanin, adding pigment and protecting from UV radiation.
  - Langerhans Cells: Immune cells present in the epidermis.
Cell Division in the Epidermis:
- Stem cells in the stratum basale divide to produce new keratinocytes.
Keratin Granules:
- Added in the stratum granulosum, crucial for waterproofing the skin.
Below the Epidermis:
- Dermis: Contains blood vessels, sensory receptors, and where sweat and oil glands are located.

Urinary System

Functions:
- Removal of waste products from the body, regulation of blood volume and pressure, and maintenance of electrolyte balance.
Major Functions:
- Excretion of nitrogenous wastes and osmoregulation.
Osmoregulation:
  - Definition: Regulation of water and salt concentrations in the body.
  - Vital organisms: Freshwater and marine animals.
  - Organs involved: Kidneys play a crucial role.
Osmoconformers vs. Osmoregulators:
- Osmoconformers: Match their body osmotic pressure to their environment (e.g., many marine invertebrates).
- Osmoregulators: Maintain constant internal conditions regardless of external environment (e.g., vertebrates).
Principal Organs in Vertebrates:
- Kidneys are responsible for osmoregulation.
Nitrogenous Wastes:
- Byproducts of protein metabolism, need to be excreted to prevent toxicity.
Fundamental Unit of the Urinary System:
- Nephron: Functional unit of the kidney; regions include glomerulus and renal tubule.

Nephron Structure and Function

Bowman's Capsule: Encapsulates the glomerulus, where filtration of blood occurs.
Glomerulus: Network of capillaries in the nephron, filtering blood to form filtrate.
Blood Vessel Functions:
- Afferent Arteriole: Brings blood to the glomerulus.
- Efferent Arteriole: Takes blood away from the glomerulus.
Urine Formation Steps:
  1. Filtration: Occurs in the glomerulus where blood is filtered to produce filtrate.
  2. Reabsorption: Useful substances are reabsorbed back into the bloodstream.
  3. Secretion: Additional wastes are secreted into the nephron for elimination.
Composition of Filtrate:
- Filtrate differs from afferent arteriole composition due to removal of water, ions, and small molecules.
Kidney Regions:
- Cortex: Outer region involved in filtration.
- Medulla: Inner region involved in the concentration of urine.
Collecting Duct: Final site of water reabsorption and urine concentration.
Urine Composition Compared to Blood:
- Urine contains excess water, urea, creatinine, and other wastes, lacking blood cells and proteins.
Urine Transport:
- Collected in renal pelvis, transported via ureter to bladder, stored until excretion through the urethra. This process is mostly involuntary but can be controlled voluntarily via the urethral sphincter.

Respiratory System

Functions:
- Facilitates gas exchange (O2 intake and CO2 removal).
Organs for Aquatic vs. Terrestrial Organisms:
- Aquatic: Gills.
- Terrestrial: Lungs.
First Region of Respiratory System:
- Nasal Cavity: Filters, warms, and humidifies air before it enters lungs.
Key Respiratory Organs:
- Trachea, bronchi, bronchioles, and alveoli.
Gases Involved:
- O2 is utilized in cellular respiration and CO2 is a byproduct that is excreted.
Transport System:
- Circulatory system is primarily responsible for transporting gases.
Homeostatic Engagement:
- Maintains blood pH and gas concentrations.

Mechanics of Breathing

Gas Exchange:
- Gases enter lungs: Depleted in CO2, Elevated in O2; gases leave lungs: Elevated in CO2, Depleted in O2.
Blood CO2 Levels:
- Affect blood pH, increasing CO2 leads to lower pH, while decreasing CO2 increases pH.
Control of Ventilation:
  - Primarily involuntary but can be consciously controlled to an extent.
  - Intercostal Muscles: Aid in expanding and contracting the rib cage to facilitate breathing.
  - Diaphragm: Primary muscle of respiration, contracting increases thoracic cavity volume.
Monitoring Condition:
- Carbon dioxide levels in blood regulate ventilation rate.

Circulatory System

Purpose:
- Distributes nutrients, gases, hormones, and waste products throughout the body.
Prevalence of Circulatory Systems:
- Most multicellular organisms possess some form of circulatory system.
Materials Circulated:
- Oxygen, carbon dioxide, nutrients, hormones, and wastes.
Organs of the Circulatory System:
- Heart, blood vessels (arteries, veins, capillaries), and blood.

Blood Vessel Types and Functions

Types of Blood Vessels:
  - Arteries: Carry blood away from the heart; thick muscular walls.
  - Veins: Carry blood toward the heart; valves present to prevent backflow.
  - Capillaries: Site of exchange between blood and tissues; one cell thick.
Exchange Mechanism:
- Significant exchange occurs in capillaries between blood and surrounding tissues.
Blood Composition:
- Constituents: Red blood cells, white blood cells, platelets, and plasma (contains proteins, hormones).
- pH of Blood: Average pH is around 7.4; deviations may lead to acidosis or alkalosis.
pH Maintenance:
- Regulated by respiratory and renal functions; carbon dioxide levels directly impact blood pH.

Heart Structure and Function

Heart Characteristics:
- Normal Heart Rate: Approximately 60-100 beats per minute for adults.
- Primary Tissue of the Heart: Cardiac muscle.
Intercalated Discs:
- Specialized connections between cardiac cells that enable synchronized contractions.
Heart Conduction:
- SA Node: Functions as the pacemaker, initiating contraction.
- AV Node: Slows down the electrical impulse before it reaches the ventricles.
Blood Flow Pathway:
- Blood flows from the body to the right atrium via the vena cava, through the right ventricle, to the lungs via the pulmonary artery. It collects oxygen in the lungs and returns to the left atrium via the pulmonary veins, then enters the left ventricle, and is pumped out through the aorta.
Heart Strings (Chordae Tendineae):
- Connective tissue structures that anchor the valve leaflets to the papillary muscles.
Blood Transport Areas:
- Major areas include lungs, digestive organs, kidneys, and muscles.

Blood Pressure and Flow

Blood Pressure Differences:
- Veins have significantly lower pressure than arteries due to distance from the heart and valve presence.
Systole vs. Diastole:
- Systole: Contraction phase of the heart.
- Diastole: Relaxation phase of the heart.
Mechanisms of Venous Blood Flow:
- Muscle actions and valve proximity support flow toward the heart.

Blood Constituents and Functions

Blood Composition:
- Constituents: Plasma (55%), red blood cells (40-45%), white blood cells and platelets (<1%).
Stem Cells: Unspecialized cells that give rise to all blood cell types; primarily found in the bone marrow.
Blood Cell Types and Functions:
  - Red Blood Cells (Erythrocytes): Transport oxygen via hemoglobin; lose nuclei to enhance oxygen transport efficiency.
  - White Blood Cells (Leukocytes): Involved in immune response; include various types (neutrophils, lymphocytes).
  - Platelets (Thrombocytes): Role in blood clotting.
Hemoglobin Role:
- Binds oxygen in the lungs and releases it in tissues; also assists in CO2 transport.

Blood Typing and Immunity

ABO Blood Typing System:
- Four blood types: A, B, AB, O, determined by presence of antigens on cell surfaces and antibodies in plasma.
Rh Factor:
- Indicates the presence or absence of D antigen; Rh+ is more common.

Lymphatic System

Function:
- Returns excess interstitial fluid to the bloodstream, supports immune function.
Flow of Lymph:
- Driven by muscle contraction and pressure changes in the thoracic cavity.
Major Organs:
- Lymph nodes, spleen, thymus gland.
Fluid Return to Circulation:
- Fluid is returned via lymphatic vessels which join the circulatory system at the thoracic duct.
Absorption of Compounds:
- Fatty acids and fats are absorbed from the intestines and transported to the bloodstream.
Contrast with Circulatory System:
- Lymphatic system is open-ended and does not circulate blood like the circulatory system.

Immune Response Mechanics

Role of Thymus and Spleen:
- Thymus: Maturation of T lymphocytes.
- Spleen: Filters blood, removes old cells, immune function.
White Blood Cell Roles:
- First Responders: Neutrophils; initiate immune response.
- Lymphocytes: B and T cells involved in adaptive immunity.

Inflammatory Response

Recognition Signs:
- Redness, heat, swelling, and pain in the affected area due to increased blood flow and immune activity.
Protective Proteins:
- Antibodies and complement proteins acting against pathogens.

Digestive System

Purpose:
- Break down food into macromolecules for energy, growth, and repair.
Digestive System Structure:
- Tube-like structure with specialized regions (e.g., mouth, stomach, intestines).
Mouth Organs and Role:
- Teeth (chewing) and salivary glands (amylase secretion).
Bolus Formation:
- A cohesive ball of chewed food that is formed during swallowing.
Esophagus Role:
- Transports bolus to stomach via peristalsis. The esophageal sphincters regulate movement.

Stomach Function

Muscularized Layer:
- More muscularized than other sections to aid in food mixing and grinding.
Stomach Environment:
- Acidic (pH around 1.5-3.5); facilitates enzyme action and kills pathogens.
Mucus Role:
- Protects stomach lining from acid damage.
Digestive Enzymes Secretion:
- Gastric acid (HCl), pepsinogen, others necessary for protein digestion.
Digested Fluid:
- Chyme is produced after food processing in the stomach.

Small Intestine Functions

Three Regions:
  - Duodenum: Receives digestive juices and bile for initial breakdown.
  - Jejunum: Main site for nutrient absorption.
  - Ileum: Absorbs remaining nutrients.
Villi and Microvilli:
- Increase surface area for absorption; specialized cells transport nutrients into the bloodstream.
Nutrient Capillary Bed Role:
- Capillaries receive absorbed nutrients; lacteals transport fats.
Hepatic Portal Vein Function:
- Transports nutrient-rich blood to the liver for processing.

Large Intestine and Nutrient Absorption

Principal Role:
- Absorbs water, remaining vitamins, and preparation of waste for excretion.
Resident Microbial Flora:
- Aid in digestion and vitamin production (e.g., vitamin K).
Appendix Location:
- Attached to the cecum, believed to play a role in immune function.
Rectum Role:
- Stores feces prior to elimination; under involuntary muscle control.

Liver and Pancreas Functions

Liver Role:
- Metabolic regulation, detoxification, and nutrient storage/processing (e.g., glucose regulation).
Urea Production:
- Produced in the liver as a waste product of protein metabolism.
Dietary Nutrient Roles:
  - Carbohydrates, proteins, fats: each perform essential functions; proportions vary:
    - Recommended carbohydrates: 45-65% of total calories.
    - Proteins: 10-35%; Fats: 20-35%.
Unsaturated vs. Saturated Fats:
- Unsaturated fats are better for health (reduce cholesterol levels).
Glycemic Index:**
- Measures how quickly foods affect blood sugar levels; low-index foods are preferable.
Vitamins and Minerals Differences:
- Vitamins are organic, while minerals are inorganic compounds; excess vitamins can lead to toxicity.