BIO 211 Final Review: Human Anatomy and Physiology Study Notes

The Human Body: An Orientation

Introduction to Anatomy and Physiology

Anatomy and physiology are foundational sciences in understanding the structure and function of the human body. Anatomy focuses on the body's structures, while physiology explains how these structures work.

• Anatomy: Study of the structure of living organisms, including their location and function.

• Physiology: Study of the function of living organisms, focusing on processes and mechanisms.

• Histology: Study of microscopic tissues and cells.

• Embryology: Study of biological development from fertilization to birth.

Anatomical Position and Terminology

Standardized terms describe body positions and directions to avoid confusion.

• Anatomical Position: Upright stance, feet flat and slightly apart, arms at sides, palms forward, thumbs away from body, head and eyes forward.

• Directional Terms:

  • Superior: Above

  • Inferior: Below

  • Anterior (Ventral): Front/belly-side

  • Posterior (Dorsal): Back/backside

  • Proximal: Closer to point of attachment

  • Distal: Farther from point of attachment

  • Superficial: Closer to surface

  • Deep: Further from surface

• Regional Terms: Cephalic (head), cervical (neck), thoracic (chest), abdominal (belly), pelvic (pelvis), brachial (arm), antebrachial (forearm), carpal (wrist), manual (hand), femoral (thigh), crural (leg), tarsal (ankle), pedal (foot).

Body Cavities

The body is divided into major cavities that house organs.

• Dorsal Body Cavity:

  • Cranial: Encases the brain

  • Vertebral (Spinal): Contains spinal cord

• Ventral Body Cavity:

  • Thoracic: Contains heart and lungs

  • Abdominopelvic:

    • Abdominal: Digestive organs

    • Pelvic: Bladder, reproductive organs, rectum

Homeostasis and Feedback Mechanisms

Homeostasis maintains internal stability. Feedback mechanisms regulate physiological processes.

• Positive Feedback: Amplifies change (e.g., oxytocin in childbirth, blood clotting).

• Negative Feedback: Reverses change to maintain balance (e.g., temperature, blood glucose regulation).

Bones and Skeletal Tissues

Major Bones and Skeletal Divisions

• Axial Skeleton: Skull, vertebrae, rib cage

• Appendicular Skeleton: Limbs and girdles

Classification of Bones

• Long Bones: Limbs

• Short Bones: Cube-shaped (wrist, ankle), sesamoid (within tendons)

• Flat Bones: Thin, flat, curved (sternum, scapulae, skull)

• Irregular Bones: Vertebrae, hips

Bone Remodeling: Deposition vs Resorption

• Bone Deposition: Formation of new bone by osteoblasts

• Bone Resorption: Breakdown of bone by osteoclasts

• Regulation: Negative feedback for calcium homeostasis; responds to mechanical/gravitational forces

Tissue: The Living Fabric

Types of Tissue

• Epithelium: Covers/lines surfaces, forms glands; avascular, innervated

• Connective Tissue: Supports, protects, binds; typically vascular and innervated (cartilage is avascular and not innervated)

• Muscle: Movement; very vascular, innervated

• Nervous Tissue: Communication; highly vascular, innervated

Characteristics of Epithelium

• Polarity: Apical and basal surfaces

• Specialized Contacts: Tight junctions

• Supported by Connective Tissue

• Avascular but Innervated: No blood supply, has nerves

• Regeneration: High mitotic activity

Types of Cartilage and Locations

• Hyaline Cartilage: Nose, trachea, ends of long bones, costal cartilage

• Fibrocartilage: Intervertebral discs, knee menisci, pubic symphysis

• Elastic Cartilage: Ear

The Integumentary System

Skin Layers

• Epidermis: Stratified squamous epithelium

  • Stratum corneum

  • Stratum lucidum

  • Stratum granulosum

  • Stratum spinosum

  • Stratum basale

• Dermis: Connective tissue

  • Papillary layer: Areolar CT

  • Reticular layer: Dense irregular CT

• Hypodermis: Subcutaneous layer (adipose tissue, collagen)

Joints

Movements at Synovial Joints

• Gliding

• Angular Movements: Flexion, extension, hyperextension, abduction, adduction, circumduction

• Rotation: Medial (internal), lateral (external)

• Special Movements: Supination, pronation, dorsiflexion, plantar flexion, inversion, eversion

Tendons vs Ligaments

• Tendons: Connect muscle to bone

• Ligaments: Connect bone to bone

Muscles and Muscle Tissue

Types of Muscle Tissue

• Skeletal Muscle: Attached to bones, striated, voluntary, multinucleated, requires nervous stimulation

• Cardiac Muscle: Heart only, striated, involuntary, can contract without nervous stimulation

• Smooth Muscle: Walls of hollow organs, not striated, involuntary, can contract without nervous stimulation

Similarities: All types are contractile and contain actin and myosin.

Differences: Skeletal and cardiac are striated; only skeletal is voluntary.

Functional Unit: Sarcomere

• Sarcomere: Basic contractile unit of muscle, made of actin and myosin filaments

Events at the Neuromuscular Junction

1. Action potential arrives at axon terminal

2. Acetylcholine (ACh) released into synaptic cleft

3. ACh binds to sarcolemma receptors, causing depolarization

4. Action potential travels across sarcolemma and T-tubules

5. Sarcoplasmic reticulum releases Ca2+

6. Ca2+ binds to troponin, exposing myosin binding sites on actin

7. Myosin heads bind to actin (cross-bridge formation)

Role of ATP in Muscle Contraction

• ATP is required for myosin head detachment and re-cocking during cross-bridge cycling

• ATP is necessary for muscle relaxation

Fundamentals of the Nervous System and Nervous Tissue

Neurons vs Glial Cells

• Neurons: Excitable cells that transmit electrical signals (action potentials); structural units of the nervous system

• Glial Cells: Support, protect, nourish, and insulate neurons; maintain chemical environment; assist with myelination

Myelination

• Schwann Cells: PNS; form myelin sheath around axons; aid in nerve regeneration

• Oligodendrocytes: CNS; myelinate multiple axons

• Myelin: Whitish, fatty, insulating covering; increases speed of nerve impulse conduction

Action Potentials vs Graded Potentials

• Action Potentials: Rapid, all-or-none, long-distance signals; do not weaken over distance; occur when threshold is reached

• Graded Potentials: Short-distance, variable magnitude, can be depolarizing or hyperpolarizing; decay over distance

Generation of Action Potentials

• Resting membrane potential: $-70\ \mathrm{mV}$

• Depolarization: Stimulus opens voltage-gated Na+ channels

• Na+ influx causes rapid depolarization

• K+ channels open to repolarize membrane

• Sodium-potassium pump restores resting potential

Saltatory Conduction

• Action potentials jump between nodes of Ranvier in myelinated axons, increasing conduction speed

Organization of the Nervous System

• Central Nervous System (CNS): Brain and spinal cord; integration and control center

• Peripheral Nervous System (PNS): Cranial and spinal nerves; communication between CNS and body

Tracts, Nerves, Ganglia, Nuclei

• Tracts: Bundles of axons in CNS

• Nerves: Bundles of axons in PNS

• Ganglia: Neuron cell bodies in PNS

• Nuclei: Neuron cell bodies in CNS

Afferent vs Efferent Neurons

• Afferent (Sensory): Carry information from receptors to CNS

• Efferent (Motor): Carry impulses from CNS to muscles/glands

Somatic Motor System

• Controls skeletal muscles; voluntary

• One heavily myelinated neuron from CNS to muscle

• Neurotransmitter: Acetylcholine (ACh)

• Always stimulatory

Autonomic Nervous System: Sympathetic vs Parasympathetic

• Sympathetic: "Fight or flight"; thoracolumbar; short preganglionic, long postganglionic fibers; preganglionic neurons in T1-L2; neurotransmitter usually norepinephrine; increases heart rate, dilates pupils, bronchodilation

• Parasympathetic: "Rest and digest"; craniosacral; long preganglionic, short postganglionic fibers; both neurons release ACh; decreases heart rate, stimulates digestion

Cranial Nerves: Sensory, Motor, or Both

Number	Name	Type
I	Olfactory	Sensory
II	Optic	Sensory
III	Oculomotor	Motor
IV	Trochlear	Motor
V	Trigeminal	Both
VI	Abducens	Motor
VII	Facial	Both
VIII	Vestibulocochlear	Sensory
IX	Glossopharyngeal	Both
X	Vagus	Both
XI	Accessory	Motor
XII	Hypoglossal	Motor

Layers of the Meninges

• Dura Mater: Tough outer layer

• Arachnoid Mater: Middle, web-like layer

• Pia Mater: Thin, inner layer attached to brain/spinal cord

Spinal Cord Anatomy: Gray Matter vs White Matter

• Gray Matter: Neuron cell bodies, dendrites, unmyelinated axons (processing)

• White Matter: Myelinated axons forming tracts (transmission)

Reflex Arc

1. Sensory receptor detects stimulus

2. Sensory neuron carries impulse to CNS

3. Integration center processes information

4. Motor neuron carries response

5. Effector (muscle/gland) responds

Case Study: Multiple Sclerosis

• Multiple Sclerosis (MS): Autoimmune disease where the immune system attacks myelin in the CNS, leading to impaired nerve conduction, muscle weakness, and neurological symptoms.