Foundations of Human Anatomy & Physiology

Terminology in Anatomy & Physiology

Standardised language that allows health-care professionals to describe location, orientation and relationships of body parts with precision.

Directional Terms ("Where is it?")

• Superior (Cranial) – toward the head / above another structure

  • Example: The head is superior to the chest.

• Inferior (Caudal) – toward the feet / below another structure

  • Example: The stomach is inferior to the lungs.

• Anterior (Ventral) – toward the front of the body

  • Example: The chest is anterior to the spine.

• Posterior (Dorsal) – toward the back of the body

  • Example: The spine is posterior to the heart.

• Medial – toward the midline

  • Example: The nose is medial to the eyes.

• Lateral – away from the midline

  • Example: The ears are lateral to the nose.

• Proximal – closer to the point of attachment (used mostly for limbs)

  • Example: The elbow is proximal to the wrist.

• Distal – farther from the point of attachment

  • Example: The fingers are distal to the elbow.

• Superficial – nearer the body surface

  • Example: Skin is superficial to muscles.

• Deep – farther from the surface

  • Example: Bones are deep to the skin.

Body Planes ("How is it sliced?")

• Sagittal Plane – divides body into left & right halves

• Frontal (Coronal) Plane – divides body into anterior & posterior portions

• Transverse (Horizontal) Plane – divides body into superior & inferior portions
  Significance: orientation for imaging (MRI, CT), surgical approaches, and anatomical study.

Major Body Cavities

• Cranial cavity – houses the brain.

• Spinal (Vertebral) cavity – contains the spinal cord.

• Thoracic cavity – encloses heart and lungs; protected by rib cage.

• Abdominal cavity – holds digestive organs (stomach, intestines, liver, etc.).

• Pelvic cavity – contains urinary bladder, reproductive organs, part of large intestine.
  Clinical relevance: trauma assessment, infection spread, surgical entry points.

The Body Plan & Levels of Structural Organisation

Hierarchy shows how microscopic components build the macroscopic organism; structure always underpins function.

1. Chemical Level – atoms & molecules (e.g., water, glucose, $\text{DNA}$).

2. Cellular Level – cells (basic life units) with specialised organelles (mitochondria, nucleus).

3. Tissue Level – groups of similar cells working together. 4 primary tissue types:

   • Epithelial – covering & lining.

   • Connective – support, binding, transport.

   • Muscle – movement (skeletal, cardiac, smooth).

   • Nervous – rapid communication & control.

4. Organ Level – two or more tissue types forming a discrete structure (heart, lungs).

5. Organ-System Level – groups of organs cooperating for a common function (digestive system).

6. Organism Level – all systems integrated into one living human.

Key principle: each higher level depends on proper operation of the one below. Damage at a lower tier (e.g., molecular mutation) can cascade upward (disease).

Major Organ Systems & Core Functions

• Integumentary – protection, temperature regulation; components: skin, hair, nails.

• Skeletal – support, leverage, mineral storage, blood formation.

• Muscular – body movement, posture, heat generation.

• Nervous – fast control & communication via electrical impulses; brain, spinal cord, nerves.

• Endocrine – slower, hormone-based regulation (growth, metabolism).

• Cardiovascular – transport of gases, nutrients, wastes; heart & blood vessels.

• Lymphatic / Immune – fluid return, defense against pathogens.

• Respiratory – gas exchange; maintains $\text{pH}$ balance.

• Digestive – mechanical & chemical breakdown of food, nutrient absorption.

• Urinary – waste removal, electrolyte & water balance, $\text{pH}$ regulation.

• Reproductive – production of gametes & offspring; secondary sexual characteristics.

Interconnectedness example: Muscular activity increases (\text{CO}2) output → Respiratory & Cardiovascular systems accelerate to dispel (\text{CO}2) and deliver $\text{O}_2$.

Molecular Basis of Life

Chemistry underpins biology; understanding atoms & biomolecules explains cellular behaviour and, by extension, organ function.

Atoms & Elements

• Matter’s smallest functional units.

• Four dominant elements (≈$96\%$ body mass): Oxygen (O), Carbon (C), Hydrogen (H), Nitrogen (N).

Molecules & Compounds

• Molecules = atoms bonded together.

• Biomolecules – large, complex, life-essential molecules.

The Four Major Biomolecule Classes

1. Carbohydrates

   • Primary energy source (quick ATP).

   • Forms: Monosaccharides (glucose), Polysaccharides (starch, glycogen).

2. Proteins

   • Structure (collagen), catalysts (enzymes), transport (hemoglobin).

   • Built from 20 amino acids; sequence ⇒ shape ⇒ function.

3. Lipids

   • Long-term energy storage, insulation, cell membranes (phospholipids), signaling (steroids).

   • Examples: Triglycerides, phospholipids, cholesterol.

4. Nucleic Acids

   • Information storage & transfer.

   • DNA – hereditary blueprint; RNA – interprets code to build proteins.

Water – The Universal Solvent

• Comprises $60\text{–}70\%$ of total body weight.

• Roles: solvent, temperature buffer (high heat capacity), lubricant, reactant/product in metabolic reactions, transport medium (blood plasma).

ATP – Cellular Energy Currency

• Adenosine Triphosphate stores energy in high-energy phosphate bonds.

• Generated mainly via aerobic cellular respiration in mitochondria.

• Hydrolysis: $\text{ATP} \rightarrow \text{ADP} + \text{P}_i + \text{energy}$ fuels cellular work (muscle contraction, active transport, biosynthesis).

Characteristics of Life

Criteria distinguishing living organisms; failure of any often signals pathology.

1. Organization – hierarchical structure from atoms → organism.

2. Metabolism – all chemical reactions.

   • Anabolism – synthesis/building (e.g., protein construction).

   • Catabolism – breakdown (e.g., digestion, glycolysis).

3. Responsiveness (Irritability) – detect & respond to stimuli (hand withdraws from heat).

4. Growth – increase in size & cell number; includes developmental changes.

5. Reproduction – cell division for growth/repair & production of offspring.

6. Movement – of organism (locomotion) and internal substances (blood flow, peristalsis).

7. Differentiation – unspecialised cells (stem cells) become specialised (neurons, myocytes).

8. Homeostasis – maintenance of stable internal conditions.

9. Excretion – removal of metabolic wastes (urea, $\text{CO}_2$, sweat).

Clinical implication: loss of homeostasis underlies many diseases; responsiveness deficits highlight nervous system disorders, etc.

Homeostasis

Dynamic equilibrium enabling optimal cellular function despite external fluctuations.

Why It Matters

• Ensures enzymes & cellular processes operate within narrow limits (temperature, $\text{pH}$).

• Imbalances lead to pathology (hyperthermia, diabetes, acidosis).

Common Homeostatic Variables & Normal Ranges

• Body temperature ≈ $37^\circ \text{C}$

• Blood glucose ≈ 70\text{–}110\, \text{mg·dL}^{-1}

• Blood pressure ≈ $120/80\, \text{mmHg}$

• Arterial pH ≈ $7.35\text{–}7.45$

Mechanisms Maintaining Balance

1. Receptor (Sensor) – detects stimulus (e.g., thermoreceptors in skin).

2. Control Center – processes information & sets response threshold (often brain or endocrine gland).

3. Effector – executes corrective action (sweat glands, muscles, glands).

Feedback Types

• Negative Feedback (dominant) – reverses deviation, restoring set point.

  • Example sequence: rising blood sugar → pancreatic β-cells release insulin → glucose uptake by cells → blood sugar drops to set point.

• Positive Feedback – amplifies change, driving process to completion.

  • Example: Stretch of cervix → hypothalamus releases oxytocin → stronger uterine contractions → more stretch … until birth.

Relationship to earlier topics: relies on nervous & endocrine systems (organ-system level) and on molecular mediators (chemical level) such as hormones & second messengers.

Integrative Summary & Real-World Relevance

• Structure ↔ Function Principle: The finely tuned anatomy (alveolar sacs, joint articulation) enables specific physiology (gas exchange, movement).

• Clinical Cross-talk: Understanding directional terms and planes is vital for imaging ("lesion is inferior & posterior to the left hepatic lobe on axial CT").

• Biochemistry Connection: Cellular ATP demand links diet (carbohydrates/lipids), oxygen delivery (cardiovascular/respiratory), and organelle health (mitochondria).

• Homeostatic Breakdown: Chronic hyperglycaemia (failure of glucose homeostasis) underlies diabetes mellitus – illustrating why negative feedback integrity is critical.

• Ethical / Practical Angle: Knowledge of body organisation and homeostasis guides safe intervention limits (e.g., fluid resuscitation, temperature management in neonates).

Mastery of these foundational concepts forms the scaffold for deeper exploration of pathophysiology, clinical diagnostics, and therapeutic strategies.

Terminology in Anatomy & Physiology Standardised language that allows health-care professionals to describe location, orientation and relationships of body parts with precision. ### Directional Terms ("Where is it?") - Superior (Cranial) – toward the head / above another structure - Example: The head is superior to the chest. - Inferior (Caudal) – toward the feet / below another structure - Example: The stomach is inferior to the lungs. - Anterior (Ventral) – toward the front of the body - Example: The chest is anterior to the spine. - Posterior (Dorsal) – toward the back of the body - Example: The spine is posterior to the heart. - Medial – toward the midline - Example: The nose is medial to the eyes. - Lateral – away from the midline - Example: The ears are lateral to the nose. - Proximal – closer to the point of attachment (used mostly for limbs) - Example: The elbow is proximal to the wrist. - Distal – farther from the point of attachment - Example: The fingers are distal to the elbow. - Superficial – nearer the body surface - Example: Skin is superficial to muscles. - Deep – farther from the surface - Example: Bones are deep to the skin. ### Body Planes ("How is it sliced?") - Sagittal Plane – divides body into left & right halves - Frontal (Coronal) Plane – divides body into anterior & posterior portions - Transverse (Horizontal) Plane – divides body into superior & inferior portions

Significance: orientation for imaging (MRI, CT), surgical approaches, and anatomical study. ### Major Body Cavities - Cranial cavity – houses the brain. - Spinal (Vertebral) cavity – contains the spinal cord. - Thoracic cavity – encloses heart and lungs; protected by rib cage. - Abdominal cavity – holds digestive organs (stomach, intestines, liver, etc.). - Pelvic cavity – contains urinary bladder, reproductive organs, part of large intestine.

Clinical relevance: trauma assessment, infection spread, surgical entry points. ---

The Body Plan & Levels of Structural Organisation Hierarchy shows how microscopic components build the macroscopic organism; structure always underpins function. 1. Chemical Level – atoms & molecules (e.g., water, glucose, $\text{DNA}$). 2. Cellular Level – cells (basic life units) with specialised organelles (mitochondria, nucleus). 3. Tissue Level – groups of similar cells working together. 4 primary tissue types:

• Epithelial – covering & lining.

• Connective – support, binding, transport.

• Muscle – movement (skeletal, cardiac, smooth).

• Nervous – rapid communication & control. 4. Organ Level – two or more tissue types forming a discrete structure (heart, lungs). 5. Organ-System Level – groups of organs cooperating for a common function (digestive system). 6. Organism Level – all systems integrated into one living human. Key principle: each higher level depends on proper operation of the one below. Damage at a lower tier (e.g., molecular mutation) can cascade upward (disease). ---

Major Organ Systems & Core Functions - Integumentary – protection, temperature regulation; components: skin, hair, nails. - Skeletal – support, leverage, mineral storage, blood formation. - Muscular – body movement, posture, heat generation. - Nervous – fast control & communication via electrical impulses; brain, spinal cord, nerves. - Endocrine – slower, hormone-based regulation (growth, metabolism). - Cardiovascular – transport of gases, nutrients, wastes; heart & blood vessels. - Lymphatic / Immune – fluid return, defense against pathogens. - Respiratory – gas exchange; maintains $\text{pH}$ balance. - Digestive – mechanical & chemical breakdown of food, nutrient absorption. - Urinary – waste removal, electrolyte & water balance, $\text{pH}$ regulation. - Reproductive – production of gametes & offspring; secondary sexual characteristics. Interconnectedness example: Muscular activity increases $\text{CO}2$ output → Respiratory & Cardiovascular systems accelerate to dispel $\text{CO}2$ and deliver $\text{O}_2$ ---

Molecular Basis of Life Chemistry underpins biology; understanding atoms & biomolecules explains cellular behaviour and, by extension, organ function. ### Atoms & Elements - Matter’s smallest functional units. - Four dominant elements (≈$96\%$ body mass): Oxygen (O), Carbon (C), Hydrogen (H), Nitrogen (N). ### Molecules & Compounds - Molecules = atoms bonded together. - Biomolecules – large, complex, life-essential molecules. ### The Four Major Biomolecule Classes 1. Carbohydrates

• Primary energy source (quick ATP).

• Forms: Monosaccharides (glucose), Polysaccharides (starch, glycogen). 2. Proteins

• Structure (collagen), catalysts (enzymes), transport (hemoglobin).

• Built from 20 amino acids; sequence ⇒ shape ⇒ function. 3. Lipids

• Long-term energy storage, insulation, cell membranes (phospholipids), signaling (steroids).

• Examples: Triglycerides, phospholipids, cholesterol. 4. Nucleic Acids

• Information storage & transfer.

• DNA – hereditary blueprint; RNA – interprets code to build proteins. ### Water – The Universal Solvent - Comprises $60 ext{–}70\%$ of total body weight. - Roles: solvent, temperature buffer (high heat capacity), lubricant, reactant/product in metabolic reactions, transport medium (blood plasma). ### ATP – Cellular Energy Currency - Adenosine Triphosphate stores energy in high-energy phosphate bonds. - Generated mainly via aerobic cellular respiration in mitochondria. - Hydrolysis: $\text{ATP} \rightarrow \text{ADP} + \text{P}_i + \text{energy}$ fuels cellular work (muscle contraction, active transport, biosynthesis). ---

Characteristics of Life Criteria distinguishing living organisms; failure of any often signals pathology. 1. Organization – hierarchical structure from atoms → organism. 2. Metabolism – all chemical reactions.

• Anabolism – synthesis/building (e.g., protein construction).

• Catabolism – breakdown (e.g., digestion, glycolysis). 3. Responsiveness (Irritability) – detect & respond to stimuli (hand withdraws from heat). 4. Growth – increase in size & cell number; includes developmental changes. 5. Reproduction – cell division for growth/repair & production of offspring. 6. Movement – of organism (locomotion) and internal substances (blood flow, peristalsis). 7. Differentiation – unspecialised cells (stem cells) become specialised (neurons, myocytes). 8. Homeostasis – maintenance of stable internal conditions. 9. Excretion – removal of metabolic wastes (urea, $$\