Table 41.1 — Epithelial tissue (the biggest memorization load)
5 rows| Type | Where it is | What it does | Cell type |
|---|---|---|---|
| Simple squamous | Lungs (alveoli), capillary walls, blood vessel lining | Thin sheet allowing easy diffusion | Epithelial cells |
| Simple cuboidal | Kidney tubules, some glands, covers the ovaries | Packed with transport channels; secretion and absorption | Gland cells |
| Simple columnar | Lining of stomach, intestines, parts of respiratory tract | Thicker layer — protection plus secretion and absorption | Epithelial cells (goblet cells present) |
| Pseudostratified columnar | Parts of the respiratory tract | Secretes mucus, heavily ciliated to sweep it along; protective | Gland cells and ciliated epithelial cells |
| Stratified squamous | Outer skin layer (epidermis) and mouth lining | Tough protective barrier; outer layers full of keratin | Epithelial cells |
Table 41.2 — Connective tissue
5 rows| Type | Where it is | What it does | Cells | Matrix |
|---|---|---|---|---|
| Loose connective tissue | Under the skin, between organs | Support, insulation, food storage; nourishes epithelium | Fibroblasts, macrophages, mast cells, fat cells | Ground-substance-rich, sparse collagen and elastin |
| Dense connective tissue | Tendons, ligaments, muscle sheaths, kidney, liver, skin dermis | Strong flexible connections; regular = parallel, irregular = multidirectional | Fibroblasts | Densely packed collagen, little ground substance |
| Cartilage | Spinal disks, joints, ear, nose tip, larynx, tracheal rings | Flexible support, shock absorption, low-friction load surfaces | Chondrocytes in lacunae | Organic; chondroitin ground substance, no blood vessels |
| Bone | Most of the skeleton | Shields organs, gives rigid anchorage for muscle | Osteocytes linked by canaliculi | Calcium phosphate crystals; central canals carry vessels |
| Blood | Circulatory system | Immune highway; hauls nutrients and wastes; organ-to-organ communication | Erythrocytes, leukocytes, platelets | Liquid plasma |
Table 41.3 — Muscle tissue
3 rows| Type | Striated? | Control | Nuclei per cell | Where | Special feature |
|---|---|---|---|---|---|
| Smooth | No | Involuntary | One, central | Blood vessel walls, stomach, intestines, eye iris | Spindle-shaped; some sheets self-excite, nerves only modulate |
| Skeletal | Yes | Voluntary | Many, at the cell edge | Attached to bone by tendons | Long fibers formed by fusion of many cells; contain myofibrils |
| Cardiac | Yes | Involuntary | One | Heart walls only (vertebrates) | Cells joined by intercalated disks (gap junctions); self-exciting |
The 11 organ systems and their five functional groups
11 rows| Functional group | System | Job | Key organs |
|---|---|---|---|
| Communication and integration | Nervous (incl. sensory) | Detect stimuli, integrate, drive the response | Brain, spinal cord, nerves, sense organs |
| Communication and integration | Endocrine | Chemical signals that regulate and fine-tune other systems | Hypothalamus, pituitary, thyroid, adrenal, pancreas, gonads |
| Support and movement | Skeletal | Rigid framework for muscles to pull against | Skull, sternum, pelvis, femur |
| Support and movement | Muscular | Produces movement | Biceps, quadriceps, gastrocnemius, and the rest |
| Regulation and maintenance | Digestive | Eating, nutrient absorption, solid waste elimination | Salivary glands, esophagus, liver, stomach, intestines |
| Regulation and maintenance | Circulatory | Pumps and distributes blood, nutrients, and other substances | Heart, arteries, veins |
| Regulation and maintenance | Respiratory | Takes in O₂ and expels CO₂ | Trachea, lungs |
| Regulation and maintenance | Urinary | Osmoregulation and control of body-fluid concentration | Kidney, ureter, bladder, urethra |
| Defense | Integumentary | First physical barrier against pathogens | Skin, hair, nails |
| Defense | Lymphatic / immune | Antibodies and attack cells against invaders | Lymph nodes, thymus, spleen, bone marrow, lymphatic vessels |
| Reproduction and development | Reproductive | Produces gametes and maintains biological continuity | Testis, vas deferens, penis / ovary, fallopian tube, uterus, vagina |
Endotherms vs ectotherms and how each regulates temperature
8 rows| Feature | Endotherm | Ectotherm |
|---|---|---|
| Heat source | Own metabolism | Environment; metabolism contributes little |
| Metabolic rate | High | Low (a lizard needs ~10% of a same-sized mouse) |
| Thermal conductivity | Low — insulated by fur, feathers, blubber | High — little or no insulation |
| Cold response | Vasoconstriction, shivering and nonshivering thermogenesis, epinephrine, TSH → thyroxine | Bask in the sun, orient the body toward light, shiver flight muscles (moths) |
| Heat response | Vasodilation, sweating or panting, ear flapping (elephants) | Move to shade, dive, reduce blood flow to the surface |
| Special trick | Brown fat with UCP1; torpor and hibernation | Countercurrent heat exchange in tuna, swordfish, some sharks |
| Advantage | Sustained high-energy activity | Very low food and energy requirement |
| Cost | Constant high food intake | No sustained high-energy activity |
Exam traps
11 pairsQuestions get built out of near-misses. If you can state each difference in one sentence, you will not lose those points.
*Negative* feedbackvs*Positive* feedback
Negative feedback pushes the value BACK toward set point and is what maintains homeostasis. Positive feedback pushes it FARTHER away and amplifies change. Only clotting and childbirth are the standard positive examples.
*Endotherm / ectotherm*vs*Homeotherm / poikilotherm*
Endo/ecto is about the HEAT SOURCE (do you make it metabolically?). Homeo/poikilo is about CONSTANCY of temperature. A deep-sea fish is a poikilotherm with a very steady temperature, which is why warm-blooded and cold-blooded are inaccurate.
*Simple* epitheliumvs*Stratified* epithelium
Simple = ONE layer, every cell touches the basement membrane, built for diffusion. Stratified = TWO OR MORE layers, only the basal layer touches, built for protection.
*Pseudostratified* epitheliumvsTrue *stratified* epithelium
Pseudostratified only LOOKS layered. Every cell still touches the basement membrane; they just do not all reach the free surface. It is a simple epithelium.
*Cardiac* musclevs*Smooth* muscle
Both are involuntary with ONE nucleus per cell. But cardiac is STRIATED, is heart-only, and has intercalated disks. Smooth is unstriated, spindle-shaped, and lives in the viscera.
*Cardiac* musclevs*Skeletal* muscle
Both are striated. Cardiac cells are small, single-nucleus, and joined by intercalated disks. Skeletal fibers are long, MULTINUCLEATE (formed by fusion), and voluntary.
*Exocrine* glandvs*Endocrine* gland
Exocrine secretes through a DUCT to a surface or lumen (sweat, saliva). Endocrine secretes into the BLOOD (thyroid, pituitary, pancreatic islets). Ducts are the tell.
*Chondrocyte* vs *osteocyte* vs *fibroblast*vsWhich tissue makes which cell
Chondrocyte = cartilage (in a lacuna). Osteocyte = bone (in canaliculi network). Fibroblast = connective tissue proper (loose and dense). Rheumatoid arthritis hits joint-lining CHONDROCYTES.
*Dense regular* connective tissuevs*Dense irregular* connective tissue
Regular = collagen in PARALLEL, pulls in one direction → tendons and ligaments. Irregular = collagen in MANY directions, resists stress from any angle → organ capsules and sheaths.
*Neuron*vs*Neuroglia*
Neurons conduct impulses and have cell body, dendrites, and axon. Neuroglia do NOT conduct — they support, nourish, protect, and regulate. A virus attacking neuron structures would spare glia.
*Shivering* thermogenesisvs*Nonshivering* thermogenesis
Shivering = antagonistic MUSCLES contracting against each other; ATP hydrolysis makes heat. Nonshivering = BROWN FAT with UCP1 uncoupling electron transport, so energy leaves as heat rather than ATP.