Comprehensive Study Notes for Anatomy and Physiology: Muscular, Skeletal, Integumentary, and Nervous Systems

Muscular System

Types of Muscle Contraction

Muscle contractions are essential for movement and stability. There are two primary types:

• Isotonic Contraction: The muscle tone remains constant while the muscle length changes. This allows for movement, such as lifting objects.

• Isometric Contraction: The muscle length remains constant while the tension changes. This is important for maintaining posture.

Functional Contractile Units

• Sarcomeres: The basic contractile units of muscle fibers. They are responsible for muscle contraction through the sliding filament mechanism.

Muscle Types Comparison

Muscle tissue is classified into three types, each with distinct characteristics:

Type	Appearance	Location	Control	Function
Skeletal	Striated	Attached to skeleton	Voluntary	External movement
Cardiac	Striated	Heart	Involuntary	Circulation of blood
Smooth	Non-striated	Organs, vessels, airways	Involuntary	Internal movement (peristalsis, vasodilation/constriction)

Flexor vs Extensor Muscles

• Flexor: Decreases the angle between two bones (e.g., bending the elbow).

• Extensor: Increases the angle between two bones (e.g., straightening the knee).

Muscle Attachments

• Point of Origin: Attached to stationary bone.

• Point of Insertion: Attached to moving bone.

Role of ATP in Muscle Contraction

• ATP (Adenosine Triphosphate): Provides energy for cross-bridge cycling between actin and myosin, enabling contraction and relaxation.

Electrolytes in Muscle Movement

• Sodium: Maintains fluid balance and osmotic pressure.

• Potassium: Maintains resting membrane potential.

• Calcium: Initiates contraction by binding to troponin.

• Magnesium: Stabilizes ATP for energy release.

Muscle Injuries

• Strain: Tears or injury in muscles and tendons.

Skeletal System

Bone Types and Structure

Bones are classified by shape and function:

Type	Shape	Location
Long	Longer than wide	Arms, legs
Short	Cube-like	Wrists, ankles
Flat	Thin, flat or curved	Skull, ribs, sternum
Irregular	Odd-shaped	Hip bones, vertebrae

Bone Anatomy

• Epiphyses: Widened ends of long bones containing the epiphyseal plate (growth plate).

• Fossa: Groove or shallow depression in bone.

• Osteocyte: Mature bone cell maintaining bone structure.

• Osteoblast: Bone-forming cell.

• Osteoclast: Bone-resorbing cell.

• Osteon (Haversian System): Cylindrical unit in compact bone, facilitating nutrient and oxygen supply.

Bone Composition

• Main minerals: Calcium and phosphorus.

Bone Conditions

• Osteoporosis: Increased bone porosity and decreased density, common in older adults.

Appendicular vs Axial Skeleton

• Appendicular: Includes pelvis, clavicles, scapulae.

• Axial: Includes skull, vertebral column, rib cage.

• Clavicle: Articulates with the manubrium (top bone of sternum), connecting the two divisions.

Common Spinal Curvatures

• Lordosis: Inward curvature of cervical and lumbar spine.

• Kyphosis: Excessive forward curvature, leading to hunchback.

Carpal and Metacarpal Bones

• Carpal bones: Make up the wrist.

• Metacarpals: Form the palms of the hands.

Major Cranial Bones

• Sphenoid

• Temporal (x2)

• Parietal (x2)

• Ethmoid

• Occipital

• Frontal

Integumentary System

Skin Layers

Layer	Description
Epidermis	Thin, outermost layer; five strata on palms/soles, four elsewhere; contains keratin and melanocytes.
Dermis (Corium)	Middle layer; contains collagen, elastin, blood vessels, nerves, glands, hair follicles.
Hypodermis (Subcutaneous Fascia)	Deepest layer; elastic and fibrous tissue, adipose tissue; attaches skin to muscles.

Strata of Skin

• Stratum basale: Deepest epidermal layer.

• Stratum lucidum: Extra layer on palms and soles.

Burn Degrees

Degree	Depth	Symptoms	Healing Time
First	Epidermis	Red, painful, no blister	2-3 days
Second	Epidermis + part of dermis	Pain, redness, blistering	10-14 days or 4-14 weeks if deeper
Third	All skin layers	Leathery, variable color, no pain	Potentially life-threatening
Fourth	To bone/muscle/tendon	No pain, may require amputation	Severe

Glands of the Skin

• Merocrine/Eccrine: Cool skin surface.

• Sebaceous: Secrete sebum, limit bacterial growth.

• Apocrine: Secrete sweat at hair follicles in groin, anal region, armpits.

Other Skin Features

• Cuticle: Fold of tissue covering nail root.

• Carotene: Yellow pigment, precursor to vitamin A.

• Turgor: Skin's ability to return to normal after stretching.

Nervous System

Central vs Peripheral Nervous System

System	Components	Function
Central	Brain, spinal cord	Controls basic functions, responds to changes
Peripheral	All nerves outside CNS	Connects CNS to body; motor and sensory fibers

Somatic vs Autonomic Nervous System

• Somatic: Receives/interprets touch; controls voluntary skeletal muscles.

• Autonomic: Controls involuntary muscles, heart, glands; includes sympathetic and parasympathetic divisions.

Sympathetic vs Parasympathetic

Division	Neurotransmitter	Effects
Sympathetic	Norepinephrine	Fight or flight: increased heart rate, blood pressure, sweating, dry mouth
Parasympathetic	Acetylcholine	Rest and digest: decreased heart rate, increased digestion, pupillary constriction

Neuron Structure and Function

• Dendrite: Branches carrying information to neuron cell body.

• Myelin Sheath: Protects nerve fibers, enables rapid signal transmission.

• Acetylcholine: Neurotransmitter in synapses.

• Acetylcholinesterase: Enzyme breaking down acetylcholine.

• Polarized: Neuron at rest, negative charge inside.

• Depolarized: Neuron becomes less negative, more positive.

Sensorineural Conduction

• Sensorineural: Sensory cells send nerve impulse to temporal lobe, interpreted as sound.

Layers of the Meninges

• Dura mater: Thick, outer layer.

• Arachnoid mater: Wispy, middle layer.

• Pia mater: Innermost layer, fused to neural tissue, contains blood vessels.

Other Nervous System Features

• Thalamus: Relays and processes information to cerebrum.

• Vagus nerve: Mixed nerve; motor for autonomic organs, sensory for viscera and taste buds.

Sensory System

Eye Anatomy

• Choroid: Spongy membrane of blood vessels between sclera and retina.

• Pupil: Round opening in iris allowing light into eye.

• Tears: Secreted by lacrimal glands; lubricate and cleanse eye.

Ear Anatomy

• Three bones of inner ear: Vestibule chamber, cochlea, semicircular canals.

Taste Sensations

• Umami: Fifth taste sensation, triggered by glutamates; "savory" taste.

Other Key Terms and Structures

• Fibroblast: Cell from which connective tissue is created.

• Gyri: Convulsions of cerebral hemispheres.

• Mastoid process: Bulge behind ear, part of temporal bone; attachment site for sternocleidomastoid muscles.

• Trapezius muscle: Located at top of shoulder along neck.

• Epiphyseal plate: Thin band of cartilage; site of bone growth.

Pathology and Clinical Relevance

Tetanus

• Bacteria: Clostridium tetani

• Effect: Causes rigid paralysis.

Jaundice

• Cause: Liver disease; inability to excrete bilirubin.