Zoology 101 Unit 3

Anatomy vs. Physiology

Anatomy is animal form; physiology is how those structures function.

Three Essential Animal Functions

Obtaining nutrients/oxygen, defending against the environment, and reproducing.

Convergent Evolution

The development of similar adaptations in unrelated species due to similar physical laws.

Skeletal/Muscle Needs in Large Animals

Larger animals require thicker skeletons and relatively more muscle mass.

Single-Celled vs. Multicellular Exchange

Single-celled organisms exchange directly; multicellular organisms require specialized surfaces.

Surface Area to Volume Ratio

The critical ratio governing chemical exchange capacity across cell membranes.

Interstitial Fluid

The fluid that connects body cells to specialized exchange surfaces.

Hierarchical Organization

Cells, Tissues, Organs, Organ System, Organism

Epithelial Cells

Covers body surfaces and lines cavities

Epithelial Tissue Functions

Protection, secretion, and absorption.

Three Shapes of Epithelial Cells

Cuboidal (dice), columnar (bricks), and squamous (tiles).

Connective Tissue

Tissue that binds and supports other tissues, consisting of sparse cells in a matrix.

Fibroblasts vs. Macrophages

Fibroblasts secrete protein fibers; macrophages carry out phagocytosis.

Three Connective Tissue Fiber Types

Collagenous (strength), reticular (joining tissues), and elastic (stretch/recoil).

Six Types of Connective Tissue

Loose connective tissue, fibrous connective tissue, bone, adipose, blood, and cartilage.

Muscle Tissue Filaments

Actin and myosin filaments, which are responsible for movement.

Muscle Tissue

Responsible for Movement, Contains actin and myosin filaments

Three Types of Muscle Tissue

Skeletal (voluntary), smooth (involuntary), and cardiac (heart).

Nervous Tissue

Functions in communication

Neurons vs. Glial Cells

Neurons transmit nerve impulses; glial cells support and nourish neurons.

Endocrine System

Uses slow, long-lasting hormones, affects multiple or specific targets, good for gradual whole body changes

Nervous System

Uses fast, short-lived nerve impulses, specific pathways and targets, good for immediate response

Homeostasis

The maintenance of a steady internal state despite external changes.

Homeostasis Set Point

Desired value. Can change with age or time (ex. circadian rhythm)

Homeostatic Control Loop

Stimulus → Sensor → Control Center → Response.

Negative Feedback

A control mechanism that reduces the stimulus (e.g., temperature regulation).

Positive Feedback

A control mechanism that amplifies the stimulus (e.g., childbirth).

Metabolism

All chemical reactions in cells

Anabolism vs. Catabolism

Anabolism builds molecules; catabolism breaks down molecules for energy.

Basal Metabolic Rate (BMR)

The energy needed at rest for basic, life-sustaining body functions.

pH Scale Ranges

< 7 is acidic (ex. stomach acid), 7 is neutral (ex. water), and > 7 is basic ( ex.baking soda).

Three Dietary Needs

Chemical energy, organic building blocks, and essential nutrients.

Essential Nutrients

Substances an animal requires but cannot assemble from simple organic precursors. Amino acids, fatty acids, vitamins, minerals

Amino Acids

8-9 must come from diet (complete vs incomplete proteins)

Fatty Acids

Certain unsaturated fats must be consumed

Vitamins

Organic, need in small amounts (fat and water soluble)

Minerals

Inorganic, needed in small amounts

Filter Feeders

Animals that sift small food particles from water (e.g., whales).

Substrate Feeders

Animals that live on or in their food source (e.g., caterpillars).

Fluid Feeders

Animals that suck nutrient-rich fluid from a living host (e.g., mosquitoes).

Bulk Feeders

Animals that eat relatively large pieces of food (e.g., humans).

Four Stages of Digestive Processing

1. Ingestion, 2. Digestion, 3. Absorption, 4. Elimination.

Intracellular vs. Extracellular Digestion

Intracellular occurs inside cells (ex. sponges). Extracellular occurs in the digestive tract (ex. most animals).

Oral Cavity

Teeth, Saliva (amylase), tongue from bolus

Pharynx and Esophagus

swallowing, peristalsis, and sphincters regulate flow

Amylase

An enzyme in saliva that initiates breakdown of carbohydrates.

Peristalsis

Alternating waves of muscle contraction and relaxation that push food down the esophagus.

Stomach

stores food, secretes gastric juice. Mucus protects the lining. chyme

Stomach Gastric Juice

A digestive fluid containing hydrochloric acid (HCl) and pepsin.

Chyme

The mixture of partially digested food and gastric juice.

Small Intestine

Duodenum, Absorption, Fats

Duodenum

The first part of the small intestine where chyme mixes with digestive juices. (pancreas, liver, gallbladder)

Absorption

Villi and microvilli increase surface area

Fats

Absorption added by the lymphatic system

Large Intestine

Colon, Cecum, Rectum/Anus

Colon Function

Water recovery, aided by microbes

Cecum

Fermentation (appendix in humans)

Rectum/Anus

Feces storage and elimination

Dietary Influence on Alimentary Canals

Herbivores generally have longer alimentary canals than carnivores to digest plant matter.

Ruminants

Animals with specialized stomach chambers containing microbes to break down cellulose.

Energy Storage Forms

Glycogen (in liver and muscle) and fat in adipose cells.

Diffusion Distance Limitation

Diffusion is only efficient over small distances.

Gastrovascular Cavities

Used by simple animals (e.g., cnidarians, flatworms) for digestion and circulation.

Circulatory Systems Function

Transport gases, nutrients, and wastes in complex animals.

Open Circulatory System

A system where hemolymph bathes organs directly (e.g., insects).

Closed Circulatory System

A system where blood is confined to vessels (e.g., annelids, vertebrates).

Advantages of Open vs. Closed Systems

Open requires less energy; closed is more efficient and supports larger size.

Cardiovascular System Components

The heart and blood vessels (arteries, veins, and capillaries).

Sequence of Blood Flow

Arteries → Arterioles → Capillaries → Venules → Veins.

Arteries vs. Veins Distinction

Defined by direction of blood flow, not oxygen content.

Single Circulation

Circulatory pattern in fish featuring a two-chambered heart.

Double Circulation

Circulatory pattern in amphibians, reptiles, and mammals with pulmonary and systemic circuits.

Pulmonary vs. Systemic Circuit

Pulmonary goes right heart to lungs; systemic goes left heart to body.

Advantage of Double Circulation

Maintains higher blood pressure than single circulation.

Vertebrate Heart Chambers by Class

Fish: 2 chambers; Amphibians/Reptiles: 3 chambers; Mammals/Birds: 4 chambers (complete separation of oxygenated/deoxygenated blood).

Systole vs. Diastole

Systole is heart contraction; diastole is heart relaxation.

Heart Valves Function

Prevent backflow of blood (AV and semilunar valves).

Sinoatrial (SA) Node

The pacemaker that sets the heart's contraction rhythm.

Capillaries

Thin walls specialized for chemical and gas exchange.

Arteries

Thick, elastic walls designed to withstand high pressure.

Veins

Lower pressure vessels containing valves to prevent backflow.

Systolic vs. Diastolic Blood Pressure

Systolic is pressure during contraction; diastolic is pressure during relaxation.

Vasoconstriction vs. Vasodilation

Vasoconstriction increases blood pressure; vasodilation decreases blood pressure.

Normal Human Blood Pressure

Approximately 120/70 mm Hg.

Forces Driving Capillary Exchange

Driven by blood pressure and osmotic pressure.

Lymphatic System in Circulation

Assists the circulatory system by returning lost fluid to blood.

Atherosclerosis

Cardiovascular disease characterized by plaque buildup in arteries.

Heart Attack vs. Stroke

Heart attack: blocked coronary arteries; stroke: blocked/ruptured brain arteries.

Cardiovascular Risk Factors

High LDL/low HDL, smoking, poor diet, inactivity, and hypertension.

Cardiovascular Prevention andTreatments

Lifestyle (exercise, healthy diet, no smoking), Medications (statins (lower LDL) antihypertensives), Surgical (stents to open blocked arteries)

Gas Exchange

The uptake of molecular oxygen (O₂) and the discharge of carbon dioxide (CO₂).

Partial Pressure

The pressure exerted by a particular gas in a mixture; drives diffusion (high to low) across respiratory surfaces.

Respiratory Media Comparison

Air has high O₂ and low density (easier to breathe); water has lower O₂ and high density (requires more efficient respiratory adaptations).

Respiratory Surface Characteristics

Varys by species (gills, skin, trachea, lungs). Must be moist, thin, and have a large surface area for efficient diffusion.

Gills

Outfoldings of the body surface suspended in water, specialized for gas exchange. Use ventilation to move water over the gills.

Countercurrent Exchange in Fish Gills

Blood flows opposite to water, maintaining a partial pressure gradient to maximize O₂ absorption.

Tracheal System

A network of air tubes (trachea) in insects that delivers O₂ directly to body cells. Independent of the circulatory system. Larger insects use ventilation to meet O2 demands.

Lungs

Infoldings of the body surface specialized for gas exchange (occurring in alveoli), requiring circulatory transport.

Mammalian Air Pathway

Nostrils → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli.

Alveoli

Site of gas exchange with capillaries