Table of contents

1. Introduction to Anatomy & Physiology5h 43m

What is Anatomy & Physiology?
22m

Levels of Organization
13m

Variation in Anatomy & Physiology
12m

Introduction to Organ Systems
27m

Homeostasis
10m

Feedback Loops
11m

Feedback Loops: Negative Feedback
19m

Feedback Loops: Positive Feedback
11m

Anatomical Position
7m

Introduction to Directional Terms
3m

Directional Terms: Up and Down
9m

Directional Terms: Front and Back
6m

Directional Terms: Body Sides
12m

Directional Terms: Limbs
6m

Directional Terms: Depth Within the Body
4m

Introduction to Anatomical Terms for Body Regions
3m

Anatomical Terms for the Head and Neck
8m

Anatomical Terms for the Front of the Trunk
8m

Anatomical Terms for the Back
9m

Anatomical Terms for the Arm and Hand
9m

Anatomical Terms for the Leg and Foot
15m

Review- Using Anatomical Terms and Directions
12m

Abdominopelvic Quadrants and Regions
19m

Anatomical Planes & Sections
17m

Organization of the Body: Body Cavities
13m

Organization of the Body: Serous Membranes
14m

Organization of the Body: Serous Membrane Locations
8m

Organization of the Body: Thoracic Cavity
8m

Organization of the Body: Abdominopelvic Cavity
12m

2. Cell Chemistry & Cell Components12h 39m

Atoms- Smallest Unit of Matter
57m

Isotopes
39m

Introduction to Chemical Bonding
19m

Covalent Bonds
40m

Noncovalent Bonds
5m

Ionic Bonding
37m

Hydrogen Bonding
19m

Introduction to Water
7m

Properties of Water- Cohesion and Adhesion
7m

Properties of Water- Density
8m

Properties of Water- Thermal
14m

Properties of Water- The Universal Solvent
17m

Acids and Bases
12m

pH Scale
21m

Carbon
8m

Functional Groups
9m

Introduction to Biomolecules
2m

Monomers & Polymers
11m

Carbohydrates
23m

Proteins
28m

Nucleic Acids
34m

Lipids
28m

Microscopes
11m

Prokaryotic & Eukaryotic Cells
26m

Introduction to Eukaryotic Organelles
14m

Endomembrane System: Protein Secretion
30m

Endomembrane System: Digestive Organelles
14m

Mitochondria & Chloroplasts
21m

Endosymbiotic Theory
10m

Introduction to the Cytoskeleton
11m

Cell Junctions
8m

Biological Membranes
11m

Types of Membrane Proteins
8m

Concentration Gradients and Diffusion
9m

Introduction to Membrane Transport
16m

Passive vs. Active Transport
14m

Osmosis
30m

Simple and Facilitated Diffusion
17m

Active Transport
30m

Endocytosis and Exocytosis
15m

3. Energy & Cell Processes10h 8m

Introduction to Energy
15m

Laws of Thermodynamics
15m

Chemical Reactions
9m

ATP
22m

Enzymes
14m

Enzyme Activation Energy
9m

Enzyme Binding Factors
9m

Enzyme Inhibition
10m

Introduction to Metabolism
8m

Redox Reactions
15m

Introduction to Cellular Respiration
22m

Types of Phosphorylation
14m

Glycolysis
19m

Pyruvate Oxidation
8m

Krebs Cycle
16m

Electron Transport Chain
10m

Chemiosmosis
7m

Review of Aerobic Cellular Respiration
19m

Fermentation & Anaerobic Respiration
23m

Introduction to Cell Division
22m

Organization of DNA in the Cell
17m

Introduction to the Cell Cycle
7m

Interphase
18m

Phases of Mitosis
48m

Cytokinesis
16m

Cell Cycle Regulation
18m

Review of the Cell Cycle
7m

Cancer
13m

Introduction to DNA Replication
22m

DNA Repair
8m

Central Dogma
7m

Introduction to Transcription
20m

Steps of Transcription
19m

Genetic Code
25m

Introduction to Translation
30m

Steps of Translation
23m

Post-Translational Modification
6m

4. Tissues & Histology10h 3m

Introduction to Tissues & Histology
16m

Introduction to Epithelial Tissue
24m

Characteristics of Epithelial Tissue
37m

Structural Naming of Epithelial Tissue
19m

Simple Epithelial Tissues
1h 2m

Stratified Epithelial Tissues
55m

Identifying Types of Epithelial Tissue
32m

Glandular Epithelial Tissue
26m

Introduction to Connective Tissue
36m

Classes of Connective Tissue
8m

Introduction to Connective Tissue Proper
40m

Connective Tissue Proper: Loose Connective Tissue
56m

Connective Tissue Proper: Dense Connective Tissue
49m

Specialized Connective Tissue: Cartilage
44m

Specialized Connective Tissue: Bone
12m

Specialized Connective Tissue: Blood
9m

Introduction to Muscle Tissue
7m

Types of Muscle Tissue
45m

Introduction to Nervous Tissue
8m

Nervous Tissue: The Neuron
8m

5. Integumentary System2h 28m

Introduction to the Integumentary System
14m

Integumentary System: Thermoregulation
16m

The Epidermis: Cells
26m

The Epidermis: Layers
54m

The Dermis
23m

The Hypodermis
6m

Glands
3m

Hair
3m

Nails
2m

6. Bones & Skeletal Tissue2h 16m

An Introduction to Bone and Skeletal Tissue
18m

Gross Anatomy of Bone: Compact and Spongy Bone
7m

Gross Anatomy of Bone: Periosteum and Endosteum
11m

Gross Anatomy of Bone: Bone Marrow
8m

Gross Anatomy of Bone: Short, Flat, and Irregular Bones
5m

Gross Anatomy of Bones - Structure of a Long Bone
23m

Microscopic Anatomy of Bones - Bone Matrix
9m

Microscopic Anatomy of Bones - Bone Cells
25m

Microscopic Anatomy of Bones - The Osteon
17m

Microscopic Anatomy of Bones - Trabeculae
9m

7. The Skeletal System2h 35m

Introduction to the Skeleton
6m

The Skull
49m

The Spine
13m

The Thoracic Cage
11m

The Pectoral Girdle
11m

Bones of the Upper Limb
18m

The Pelvic Girdle
22m

Bone of the Lower Limb
21m

8. Joints2h 17m

Introduction to Joints
18m

Classification of Joints
27m

Structural Class: Fibrous Joints
39m

Structural Class: Cartilaginous Joints
23m

Structural Class: Synovial Joints
27m

Joint Movements

9. Muscle Tissue2h 33m

Introduction to Muscles and Muscle Tissue
17m

Structure of a Skeletal Muscle
26m

Sliding Filament Theory and the Sacromere
45m

Steps of Muscle Contraction
1h 3m

10. Muscles1h 11m

Origin and Insertion
11m

Muscle Actions
15m

Levers
15m

Fascicle Arrangements
15m

Muscle Naming
13m

11. Nervous Tissue and Nervous System1h 35m

Ions - Sodium and Potassium
19m

Resting Membrane Potential
11m

Change in Membrane Potential
6m

Properties of Graded and Action Potentials
9m

Graded Potentials
17m

Action Potentials
10m

The Refractory Period
8m

Propagation of Action Potentials
11m

12. The Central Nervous System1h 6m

Introduction to the Central Nervous System
18m

The Cerebrum
48m

13. The Peripheral Nervous System1h 26m

Introduction to the Peripheral Nervous System
5m

Organization of Sensory Pathways
16m

Introduction to Sensory Receptors
5m

Sensory Receptor Classification by Modality
6m

Sensory Receptor Classification by Location
8m

Proprioceptors
7m

Adaptation of Sensory Receptors
8m

Introduction to Reflex Arcs
13m

Reflex Arcs
15m

14. The Autonomic Nervous System1h 38m

Introduction to the Autonomic Nervous System
10m

Control of the ANS
11m

Sympathetic Nervous System
39m

Parasympathetic Nervous System
8m

Review of the Sympathetic and Parasympathetic Divisions
5m

Neurotransmitters of the ANS
19m

Visceral Reflex Arcs
4m

15. The Special Senses2h 41m

Introduction to Special Senses
11m

Structure of the Eyeball
11m

Fibrous Layer of the Eyeball
10m

Vascular Layer of the Eyeball
28m

Optic Components of the Eyeball
9m

Inner Layer of the Eyeball
44m

The Lens and Focusing Light on the Retina
22m

Rods, Cones, and Light
23m

16. The Endocrine System2h 48m

Introduction to the Endocrine System
44m

Membrane Bound Receptors and Secondary Messengers
48m

Intracellular Receptors and Direct Gene Action
11m

The Hypothalamus and Pituitary Gland
43m

Hormone Review Table
19m

17. The Blood3h 22m

Introduction To Blood
22m

Erythrocytes
11m

Erythrocytes: Hemoglobin
33m

Leukocytes
1h 4m

Platelets: Hemostasis
1h 11m

18. The Heart3h 42m

Electrical Conduction System of the Heart
55m

Cardiac Action Potentials
1h 1m

Electrocardiogram (ECG)
34m

Cardiac Cycle
1h 11m

19. The Blood Vessels3h 35m

Introduction to Blood Vessels
13m

Types of Blood Vessels
9m

General Blood Vessel Structure
25m

Arteries
24m

Capillaries
49m

Veins
26m

Anastomoses
23m

Introduction to Hemodynamics
44m

20. The Lymphatic System3h 16m

Introduction to the Lymphatic System
26m

Lymphatic Vasculature
49m

Lymphoid Cells & Tissues
15m

Overview of Lymphoid Organs
8m

Primary Lymphoid Organs
24m

Secondary Lymphoid Organs: Lymph Nodes
26m

Secondary Lymphoid Organs: The Spleen
25m

Secondary Lymphoid Organs: MALT
18m

21. The Immune System14h 37m

Introduction to the Immune System
10m

Introduction to Innate Immunity
17m

Introduction to First-Line Defenses
5m

Physical Barriers in First-Line Defenses: Skin
13m

Physical Barriers in First-Line Defenses: Mucous Membrane
9m

First-Line Defenses: Chemical Barriers
24m

First-Line Defenses: Normal Microbiota
7m

Introduction to Cells of the Immune System
15m

Cells of the Immune System: Granulocytes
28m

Cells of the Immune System: Agranulocytes
26m

Introduction to Cell Communication
5m

Cell Communication: Surface Receptors & Adhesion Molecules
16m

Cell Communication: Cytokines
27m

Pattern Recognition Receptors (PRRs)
48m

Introduction to the Complement System
24m

Activation Pathways of the Complement System
23m

Effects of the Complement System
23m

Review of the Complement System
13m

Phagocytosis
17m

Introduction to Inflammation
18m

Steps of the Inflammatory Response
28m

Fever
8m

Interferon Response
25m

Review Map of Innate Immunity

Introduction to Adaptive Immunity
32m

Antigens
12m

Introduction to T Lymphocytes
38m

Major Histocompatibility Complex Molecules
20m

Activation of T Lymphocytes
21m

Functions of T Lymphocytes
25m

Review of Cytotoxic vs Helper T Cells
13m

Introduction to B Lymphocytes
27m

Antibodies
14m

Classes of Antibodies
35m

Outcomes of Antibody Binding to Antigen
15m

T Dependent & T Independent Antigens
21m

Clonal Selection
20m

Antibody Class Switching
17m

Affinity Maturation
14m

Primary and Secondary Response of Adaptive Immunity
21m

Immune Tolerance
28m

Regulatory T Cells
10m

Natural Killer Cells
16m

Review of Adaptive Immunity
25m

22. The Respiratory System3h 20m

Introduction to Lung Physiology
15m

Pressure in the Lungs and Pleural Cavity
25m

Ventilation
43m

Lung Volumes and Capacities
34m

Law of Partial Pressure
29m

Respiration
51m

23. The Digestive System3h 5m

Introduction to the Digestive System
34m

The Stomach
44m

The Gallbladder
12m

Pancreas
22m

Duct System of the Liver, Gallbladder, and Pancreas
10m

Small Intestine
1h 0m

24. Metabolism and Nutrition4h 0m

Essential Amino Acids
5m

Lipid Vitamins
19m

Cellular Respiration: Redox Reactions
15m

Introduction to Cellular Respiration
22m

Cellular Respiration: Types of Phosphorylation
14m

Cellular Respiration: Glycolysis
19m

Cellular Respiration: Pyruvate Oxidation
8m

Cellular Respiration: Krebs Cycle
16m

Cellular Respiration: Electron Transport Chain
14m

Cellular Respiration: Chemiosmosis
7m

Review of Aerobic Cellular Respiration
18m

Fermentation & Anaerobic Respiration
23m

Gluconeogenesis
16m

Fatty Acid Oxidation
20m

Amino Acid Oxidation
17m

25. The Urinary System2h 39m

Introduction to the Urinary System
4m

The Kidneys
13m

The Nephron
25m

Blood Supply of the Kidneys
8m

Renal Physiology: Overview
6m

Renal Physiology Step 1: Glomerular Filtration
22m

Renal Physiology: Regulation of Glomerular Filtration
32m

Renal Physiology Step 2: Tubular Reabsorption
44m

26. Fluid and Electrolyte Balance, Acid Base Balance37m

Fluid Balance
21m

Electrolyte Balance
7m

Acid-Base Balance
8m

27. The Reproductive System2h 5m

Introduction to the Reproductive System
9m

Anatomy of the Male Reproductive System
26m

Anatomy of the Female Reproductive System
49m

Meiosis
39m

28. Human Development1h 21m

Introduction to Human Development
13m

Early Embryonic Development
10m

Implantation
10m

Extraembryonic Membrane Development
7m

Embryonic Development (Weeks 3-8)
24m

Placentation
15m

29. Heredity3h 32m

Overview of Human Genetics
14m

Patterns of Inheritance
1h 22m

Factors Affecting Gene Expression
1h 28m

Genetic Disorders
17m

Gene Therapy
10m

3. Energy & Cell Processes

Organization of DNA in the Cell

Anatomy & Physiology

3. Energy & Cell Processes

Organization of DNA in the Cell

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1:55 minutes

Problem 8

Textbook Question

Our somatic cell nuclei contain___pairs of chromosomes.
(a) 8
(b) 16
(c) 23
(d) 46

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Understand that somatic cells are all the body cells except the gametes (sperm and egg cells).

Recall that chromosomes come in pairs in somatic cells because one chromosome of each pair is inherited from each parent.

Identify the total number of chromosomes in human somatic cells, which is 46 chromosomes arranged in 23 pairs.

Recognize that the question asks for the number of pairs, not the total number of individual chromosomes.

Conclude that the correct number of chromosome pairs in human somatic cell nuclei is 23 pairs.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Somatic Cells

Somatic cells are all the body cells except the reproductive cells (gametes). They contain a full set of chromosomes, which carry genetic information necessary for the organism's growth and function.

Chromosome Pairs

Chromosomes in somatic cells exist in pairs called homologous pairs, where one chromosome of each pair is inherited from each parent. Humans typically have 23 pairs of chromosomes in their somatic cells.

Human Chromosome Number

Humans have a diploid chromosome number of 46 in somatic cells, arranged as 23 pairs. This number includes 22 pairs of autosomes and one pair of sex chromosomes, determining biological sex.

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