Anatomy and Physiology Notes

Anatomical Position and Direction

• Anterior: Toward the front. Ex: The kneecap is on the anterior side of the leg.
• Posterior: Toward the back. Ex: The shoulder blades are located on the posterior side of the body.
• Superior: Toward the head. Ex: The hand is part of the superior extremity.
• Inferior: Toward the feet. Ex: The foot is part of the inferior extremity.
• Medial: Toward the midline. Ex: The chest is medial to the arm.
• Lateral: Away from the midline. Ex: The little toe is lateral to the big toe on the same foot.
• Proximal: Closer to the trunk of the body. Ex: The proximal end of the femur joins the pelvic bone.
• Distal: Further from the trunk of the body. Ex: The hand is distal to the shoulder.

Anatomical Planes

• Sagittal (Median): Vertical plane dividing the body into right and left halves.
• Frontal (Coronal): Vertical plane dividing the body into anterior (front) and posterior (back) halves.
• Transverse (Cross-section): Horizontal plane dividing the body into superior (upper) and inferior (lower) halves.

Levels of Organization

• Atom → Molecule → Macromolecule → Organelle → Cell → Tissue → Organ → Organ System → Organism

Tissue Types

• Epithelial Tissue
  • Covers body surfaces and organs.
  • Forms inner lining of body cavities.
  • Lines hollow organs.
  • Makes up glands.
  • Tightly packed cells attached to a basement membrane.
  • Lacks blood vessels.
• Connective Tissue
  • Binds structures.
  • Provides support and protection.
  • Serves as frameworks.
  • Fills spaces.
  • Stores fat.
  • Produces blood cells.
  • Protects against infections.
  • Helps repair damaged tissues.
• Muscle Tissue
  • Contractile tissue.
    • Skeletal muscle: Voluntary, striated.
    • Smooth muscle: Involuntary, no striations.
    • Cardiac muscle: Involuntary, striated.
• Nervous Tissue
  • Brain, spinal cord, and peripheral nerves.

Homeostasis

• Negative Feedback Loop: As a stimulus moves in one direction, the body works to move it in the opposite direction.
  • Ex: Body temperature, blood glucose levels.
• Positive Feedback Loop: As a stimulus moves in one direction, the body works to further move the stimulus in the same direction.
  • Ex: Labor contractions, blood clotting.

Integumentary System

• Consists of the skin and accessory structures (hair, nails, glands).
• Skin (Cutaneous Membrane)
  • Epidermis: Superficial layer, top of skin.
  • Dermis: Deep layer.
  • Epidermis lacks a blood supply; nutrients diffuse from the dermis.

Functions of the Integument

• Protection from the environment.
• Temperature maintenance (sweating, vasoconstriction/vasodilation).
• Synthesis and storage of nutrients (e.g., Vitamin D).
• Sensory reception (touch, pressure, pain, temperature).
• Excretion and secretion (salts, water, organic waste, milk).

Epidermis

• Outer layer of skin, epithelial tissue (stratified squamous).
• Cell membranes of older cells thicken and develop many desmosomes for tight connections.
• Keratinization: Cells harden and become tough, waterproof due to the protein keratin, eventually forming the stratum corneum.
• Melanocytes: Produce the dark pigment melanin.
• Melanin: Provides skin color and absorbs UV radiation.
• Layers (from superficial to deep): Stratum corneum → Stratum lucidum → Stratum granulosum → Stratum spinosum → Stratum basale.

Dermis

• Lies beneath the epidermis, binds it to underlying tissues.
• Loose connective tissue that nourishes the epidermis.
• Contains capillaries and nerves.
• Contains muscle fibers.

Burns

• 1st Degree: Injures only the epidermis (e.g., sunburn without blisters).
• 2nd Degree: Destroys some epidermis and some underlying dermis.
• 3rd Degree: Destroys epidermis, dermis, and accessory structures.

Skeletal System

• Functions:
  • Support: Structural support for the entire body.
  • Storage: Stores calcium and phosphate.
  • Blood cell production: RBCs, WBCs, and other blood elements are made in red marrow.
  • Protection: Protects vital organs.
  • Leverage: Levers for movement; muscles attach to bones.

Bone Structure

• Bone (osseous tissue): Connective tissue with specialized cells and a matrix of extracellular protein fibers and ground substance.
  • 2/3 weight of bone is from calcium phosphate (hydroxyapatite).
  • 1/3 weight is collagen fibers and cells.

Types of Bones

• Long bones: Longer than they are wide (e.g., femur, humerus, ulna, radius, tibia, fibula).
• Short bones: Roughly equal dimensions (e.g., carpal and tarsal bones).
• Flat bones: Thin and relatively broad (e.g., parietal bones in the skull, ribs).
• Irregular bones: Not classified as above (e.g., sacrum).
• Sesamoid bones: Bone embedded in a tendon (e.g., patella).

Long Bone Structure

• Diaphysis: Central shaft.
• Epiphysis: Ends of the bone.
• Articular cartilage: Covers ends of epiphysis.
• Compact bone: Solid and dense, forms diaphysis.
• Spongy bone: Less dense, found in epiphyses.
• Periosteum: Outer, fibrous surface, contains collagen fibers that connect bone to muscle and bone to bone.
• Endosteum: Lines medullary cavity that contains the bone marrow.
• Osteon: Basic functional unit of compact bone.

Bone Cells

• Osteocytes: Mature bone cells (contained in lacunae).
• Osteoclasts: Dissolve bony matrix, release stored calcium and phosphate.
• Osteoblasts: Produce new bone by making new bone matrix, deposit calcium salts into new bone.
• Central canal (Haversian canal): Where blood vessels and nerves run through osteon.
• Osteoblast becomes an osteocyte when completely surrounded by calcified matrix.

Skeletal System Diseases

• Osteoporosis: Bone mass and density decrease, increased osteoclast activity.
• Osteogenesis imperfecta: Brittle bone disease, genetic, defective in collagen matrix.
• Arthritis: Damages cartilage that articulates between joints.
• Rheumatoid arthritis: Autoimmune disease that causes arthritis.

Ribs and Sternum

• Rib pairs 1-7: True ribs (attached directly to the sternum).
• Rib pairs 8-12: False ribs (attached to cartilage or not attached at all).
• Rib pairs 11 and 12: Floating ribs.

Joint Classification

• Joint: Where two bones articulate (come in contact with one another, cartilage, or with teeth).
  • Synovial: Filled with synovial fluid, fully movable (e.g., shoulder, elbow, hip, knee).
  • Cartilaginous: Two bones held together by cartilage, slightly movable (e.g., symphysis pubis).
  • Fibrous: Bones fit tightly together, no or very little movement (e.g., sutures in cranium).

Muscular System

• Functions:
  • Movement.
  • Maintain posture and body position.
  • Support soft tissue.
  • Guard entrances and exits.
  • Maintain body temperature.

Muscle Types

• Cardiac Muscle
  • Found only in the heart.
  • Composed of cardiomyocytes joined by intercalated discs.
  • Intercalated discs allow cardiac muscle cells to contract in sync.
  • Has more mitochondria than skeletal muscle; exclusive for aerobic respiration.
• Skeletal Muscle
  • Made up of bundles of fascicles.
  • Each fascicle is made of muscle fibers.
  • A muscle fiber is one muscle cell (multinucleate).
  • A muscle fiber is made of myofibrils.
  • Myofibrils are bundles of myofilaments made of actin (thin) and myosin (thick).

Connective Tissue of Skeletal Muscle

• Fascia: Connective tissue that separates individual muscles.
• Epimysium: Surrounds the entire muscle.
• Perimysium: Surrounds the muscle fascicle.
• Endomysium: Surrounds each muscle fiber and ties adjacent muscle fibers together.
• Tendons: Bands of collagen fibers that attach skeletal muscle to bones.

Muscle Microanatomy

• Sarcolemma: Cell membrane of muscle fiber.
• Sarcoplasm: Cytoplasm of muscle fiber.
• Sarcoplasmic reticulum: Endoplasmic reticulum of muscle fiber; releases calcium ions when an action potential arrives.
• T-tubule: Network of narrow tubules that allow for action potential to move through the cell.
• Many mitochondria needed to make ATP.
• Motor Unit: All muscle fibers controlled by a single motor neuron.
• Muscle Tone: Resting tension of skeletal muscle; contractions don't cause enough movement.
• Atrophy: Skeletal muscle fibers become smaller and weaker when not used.

Types of Contractions

• Isotonic Contractions: Muscular contraction that changes muscle length.
  • Concentric: Contraction that shortens a muscle (e.g., lifting an object).
  • Eccentric: Contraction where the muscle length increases (e.g., lowering a dumbbell).
• Isometric Contractions: Tension continues to rise but the muscle does not change length (e.g., pushing against a wall).
  • Important for maintaining posture.

Skeletal Muscle Actions

• Origin and Insertion: The origin of a muscle stays stationary while the insertion moves.
• Agonist (Prime Mover): Muscle chiefly responsible for producing a particular movement.
• Antagonist: Muscles whose action opposes the movement produced by another muscle.
• Synergist: Muscles that contract to assist the prime mover.
  • Fixators: Synergists that stabilize the origin of a prime mover.

Muscle Metabolism

• How muscles get energy:
  • Aerobic Respiration: Requires oxygen, provides the most ATP energy from glucose.
    • Muscle cells store large amounts of glycogen (a polymer of glucose).
  • Anaerobic Respiration (Lactic Acid Fermentation): Doesn't require oxygen, provides very little energy.
    • Occurs when not enough oxygen gets to the muscle.
    • Ex: Sprinting.
  • Creatine Phosphate: Creates ATP by giving its phosphate group to the energy-depleted ATP.

Nervous System

• Functions:
  • Monitors internal and external environments.
  • Integrates sensory information.
  • Coordinates voluntary and involuntary responses of other organ systems.
  • Receive, Decide, React (Sensory, Integrative, Motor).
• Divisions:
  • Central Nervous System (CNS): Brain and spinal cord.
  • Peripheral Nervous System (PNS): All neural tissues outside of CNS, cranial and spinal nerves.

Peripheral Nervous System Divisions

• Sensory Division: Sensory receptors pick up information that travels to the CNS.
• Motor Division:
  • Somatic Nervous System: Conscious movement controlled by skeletal muscles.
  • Autonomic Nervous System: Involuntary response controlled by smooth muscle, cardiac muscle, glands.

Nervous Tissue

• Neuron: Basic unit of the nervous system.
  • Electrical signals pass through neuron for communication.
  • Consists of dendrite, cell body, axon (nerve fiber).
• Nerve: Bundle of axons.
• Action Potential: Electrical changes along a nerve cell membrane.
• Synapse: Space between a neuron and the cells that it communicates with.
• Neurotransmitters: Chemical messengers that convey information in the synapse.
  • Ex: Acetylcholine, dopamine, serotonin.
• Neuroglia: Cells that support the neuron.

Neuron Structure

• Dendrite: Receives signal.
• Cell body (soma): Contains nucleus.
• Axon: Transmits signal to target through axon terminals.
• Myelin sheath: Insulation covering that increases the speed of an action potential.
• Nodes of Ranvier: Gaps between the cells that are making up the myelin sheath.
• Neurotransmitters are released from the axon terminals.

Neuroglia

• Astrocytes: Maintain the blood-brain barrier.
• Oligodendrocytes: Create myelin sheath in CNS.
• Schwann cells: Create myelin sheath in PNS.
• Microglia: Phagocytes derived from WBC- engulf pathogens in CNS.
• Ependymal cells: Line fluid-filled cavities in CNS, make cerebrospinal fluid (CSF).

CNS Structure - Meninges

• Dura mater: Outermost layer, tough and contains blood vessels.
• Arachnoid mater: Weblike, underneath is subarachnoid space that contains cerebrospinal fluid.
• Pia mater: Innermost, delicate layer.
• Cerebrospinal Fluid (CSF): Fluid that bathes the brain (ventricles, subarachnoid space).
  • Protects (absorbs shock) and circulates nutrients.

Brain Regions

• 6 Major Regions:
  • Cerebrum
  • Diencephalon
  • Midbrain
  • Pons
  • Medulla Oblongata
  • Cerebellum

Cerebrum

• Site where conscious thought and intellectual functions originate.
• Memory storage and retrieval and complex movements.
• Divided into left and right hemispheres, divided by longitudinal fissure.
• Pass information between hemispheres through corpus callosum.
• Surface of cerebrum is called the cerebral cortex, made of gray matter (unmyelinated).
• Cerebral cortex has sulci (grooves) and gyri (bulges).

Cerebral Lobe Functions

• Frontal Lobe: Intellectual process for concentration, planning, problem-solving; motor areas initiate voluntary movement.
• Parietal Lobe: Sensory areas for temperature, touch, pressure, and pain from the skin.
• Temporal Lobe: Sensory areas for hearing.
• Occipital Lobe: Sensory areas for vision.

Diencephalon

• Thalamus: Selective gateway for sensory impulses (other than olfactory).
• Hypothalamus: Contains centers involved with emotions, autonomic functions, and hormone production.
  • Regulates heart rate and blood pressure, body temperature, electrolyte balance, control of hunger, sleep and wakefulness, stimulates pituitary.

Brainstem

• Midbrain
  • Processes visual and auditory information and generates involuntary motor responses.
  • Control of eye movements.
  • Reticular formation regulates many involuntary functions.
• Pons
  • Group of nerves that connects the cerebellum to the cerebrum.
• Medulla Oblongata
  • Relays sensory information to the thalamus and other brain stem centers.
  • Contains major centers that regulate autonomic functions, such as heart rate, blood pressure, respiration, and digestive activities.
  • Connects to the spinal cord.
  • Contains cardiovascular centers and respiratory rhythmic centers.
• Cerebellum
  • Adjusts voluntary and involuntary motor activities on the basis of sensory information and stores memories of previous movements.
  • Adjusts postural muscles of the body to maintain balance.
  • Programming and fine-tuning movements controlled at conscious and subconscious levels.
  • Heavily affected by alcohol.

PNS Nerve Types

• Efferent Neurons (Motor Neurons): Signal effector cells in muscles and glands to react to stimuli.
• Afferent Neurons (Sensory Neurons): Take in information from inside and outside the body through sensory organs and receptors.
• Interneurons: Neurons inside the CNS that are interposed between sensory and motor neurons.
• Spinal Nerves: 31 pairs in total that extend from the side of the spinal cord.
• Cranial Nerves: 12 pairs in total.
• Dermatome: Area of skin in which sensory nerves derive from a single spinal nerve root.

Autonomic Nervous System

• Divided into the sympathetic and parasympathetic divisions
  • Sympathetic: Fight or flight.
  • Parasympathetic: Rest or digest.

General and Special Senses

• General Senses
  • Temperature, pain, touch, pressure, vibration, and proprioception (body position).
  • Scattered throughout the body.
• Special Senses
  • Olfaction (smell).
  • Gustation (taste).
  • Vision.
  • Equilibrium (balance).
  • Hearing.

Receptor Types

• Pain: Nociceptors are free nerve endings.
• Temperature: Thermoreceptors are free nerve endings.
• Mechanoreceptors: Sensitive to stimuli that distort their cell membranes.
  • Tactile receptors: touch.
  • Baroreceptors: pressure.
  • Proprioceptors: Position of joints, tension in tendons and ligaments and state of muscular contraction.
• Chemoreceptors: Detect chemicals.
• Photoreceptors: Detect light.

Special Senses - Smell

• Paired olfactory organs are located in the nasal cavity on either side of the nasal septum.
• Each organ consists of olfactory epithelium that contains the olfactory receptors.
• Olfactory glands secrete mucus to cover the epithelium.
• Olfactory receptors are highly modified neurons.

Special Senses - Taste

• Taste receptors are distributed over the surface of the tongue and adjacent portions of pharynx and larynx.
• Taste receptors and specialized epithelial cells form taste buds.

Special Senses - Vision

• Lacrimal glands produce tears.
• Tears leave the eye through lacrimal canals to the lacrimal sac to the nasal cavity.
• Tears contain lysozyme that destroys bacteria.

The Special Senses -Ear

• Outer Ear
  • External ear and ear canal ceruminous glands make ear wax.
  • Tympanic membrane (eardrum).
• Middle Ear
  • Filled with ear.
  • Contains 3 bones: malleus, incus, stapes.
  • Auditory or Eustachian tube connects to the pharynx.
• Inner Ear (fluid-filled chamber with receptors for hearing and equilibrium)
  • Vestibule- receptors here provide sensations of gravity and linear acceleration.
  • Semicircular canals- respond to rotational movements.
  • Cochlea-receptors for hearing.

Endocrine System

• Function:
  • Communication is slower compared to the nervous system.
  • Hormones have specific target cells based on receptor structure.
• Glandular secretory cells release secretions internally rather than onto an epithelial surface.
• Hormones: Chemical messengers that are released in one tissue and transported by the bloodstream to reach target cells in their tissues.

Endocrine Glands

• Hypothalamus
  • Links the endocrine system to the nervous system.
  • Main endocrine function is to control the pituitary gland.
  • Functions:
    • Acts as an endocrine organ to secrete ADH and oxytocin.
    • Secretes releasing hormones (RH) and inhibiting hormones (IH).
    • Contains autonomic nervous system centers to control endocrine cells of adrenal medullae through sympathetic innervation.
• Pineal Gland
  • Produces melatonin.
  • Melatonin targets the brain to help regulate daily wake and sleep rhythm.
• Thyroid Gland
  • Butterfly-shaped gland in the neck.
  • Hormones produced:
    • T4 (thyroxine).
    • T3 (triiodothyronine) , difference in # of Iodine - T4 converts to T3 in liver
    • T3 affects a cell's metabolism by increasing energy utilization, oxygen consumption, growth, and development.
    • Calcitonin: Targets the bone and kidneys and will decrease calcium concentrations in body fluids.
• Parathyroid Gland
  • Releases Parathyroid Hormone (PTH).
  • Targets the bones and kidneys.
  • Effects: Increases calcium concentrations in the body fluids.
• Adrenal Glands
  • Sit on top of the kidneys.
  • Adrenal cortex produces corticosteroid hormones:
    • Mineralocorticoids.
    • Glucocorticoids.
    • Androgens.
  • The adrenal medulla produces Epinephrine and Norepinephrine

Cardiovascular System

• Functions of the blood:
  • Transportation of dissolved gases, nutrients, hormones, and metabolic wastes.
  • Regulation of pH and electrolyte composition of interstitial fluids.
  • Restrict fluid loss through damaged blood vessels-blood contains enzymes and factors to cause blood clotting.
  • Defense against toxins and pathogens -WBCs.
  • Stabilization of body temperature -blood absorbs heat from skeletal muscles and redistributes to other parts of the body.

Blood Vessels

• Blood flows through a network of blood vessels that extends between the heart and peripheral tissues.
  • Pulmonary circuit: Carries blood to and from the lungs.
  • Systemic circuit: Transports blood to and from the rest of the body.
  • Each circuit begins and ends in the heart.
  • Blood returning to the heart from the systemic circuit must complete the pulmonary circuit before reentering the system circuit.
• Arteries: Carry blood AWAY from the heart.
• Veins: RETURN blood to the heart.
• Capillaries: Small, thin-walled vessels between the smallest arteries and veins.

The Heart

• Muscular chambers:
  • Right Atrium - receives blood from the systemic circuit.
  • Right ventricle - discharges blood into the pulmonary circuit.
  • Left Atrium - collects blood from the pulmonary circuit.
  • Left ventricle - ejects blood into the systemic circuit.
• Layers of the Heart
  • The heart lies in the pericardial cavity.
  • Pericardium - serous membrane that lines the pericardial cavity.
    • Parietal Pericardium - lines the inner surface of the pericardial sac, which surrounds the heart.
    • Visceral Pericardium - covers the outer surface of the heart.
  • Myocardium -muscular wall of the heart that contains cardiac muscle tissue.
  • Endocardium - simple squamous epithelium that lines inner surfaces, including values. The endocardium is continuous with the endothelial lining of the attached blood vessels.

The Heartbeat

• The electrical conduction coordinates the events of the cardiac cycle.
  • Sinoatrial node - depolarizes.
  • Electrical signal goes rapidly to the Atrioventricular node via internodal pathways.
  • Depolarization spreads through atria.
  • Depolarization moves rapidly through ventricular conducting systems via the apex of the heart: Bundle of His and right and left bundle branches and Purkinje fibers.

Blood Pressure

• Systolic pressure - pressure during ventricular systole (contraction).
• Diastolic pressure - minimum blood pressure at the end of ventricular diastole (relaxation).
• Peripheral resistance - resistance of the vessels to the flow of blood as a result of friction.
• Blood volume - the sum of the formed elements and plasma volume in the vascular system.

Lymphatic System

• Lymphatic system organization:
  • Lymphatic capillaries that extend into interstitial spaces carry lymph into larger lymphatic vessels.
  • Lymph-fluid-resembles plasma but lower concentration of suspended proteins.
  • Large lymph vessels lead to lymph nodes, lymph will eventually drain back into the venous system.
• Functions
  • Production, maintenance, and distribution of lymphocytes.
  • Return of fluid and solutes from peripheral tissues to the blood.
  • Distribution of hormones, nutrients, and waste products from their tissues of origin to the general circulation - enter bloodstream substances unable to directly may do so via lymphatic vessels.
  • Absorption of dietary fatty acids from small intestine to transport to circulatory system (occurs in lymphatic vessels in the small intestine).
• Lymphoid Organs
  • Lymph nodules- functional unit of a lymph node, can also be found on their own (EX : tonsils, peyer's patches).
  • Lymph nodes -small , oval organs that function like a filter
  • As antigens arrive it filters and purifies the lymph before it reaches the venous system ,they are detected and removed by T and B lymphocytes
  • Macrophage are also present to destroy and engulf foreign substances ,damaged cells and cellular debris
  • Thymys-lies behind sternum and is the site of T cell maturation
  • Spleen-removes abnormal blood cells and components, initiates immune response by Band T cells in response to antigens in circulating blood

Types of Lymphocytes

• T cells
  • Made in the bone marrow, Mature in the thymus, attack pathogens
• B cells
  • Made in the bone marrow, Mature in the bone marrow, recognize foreign antigens and produce antibodies
• Adaptive immunity
  • Antigen-chemical that causes an immune response
  • B lymphocytes-make antibodies when activated by antigens, memory B cells keep the memory of the antigen for any future infections
  • T lymphocytes -become activated when another cell "presents" the antigen to them, once activated- they can kill the pathogen with that specific antigen
  • TCELLS-activated by an antigen
  • B CELLS-activated by antigen
  • Cytotoxic T cells (Killer Tcells) - responsible for cell-mediated immunity, activated by exposure to antigens, theyKill the cell that is infected
  • Activated B cells divide several times and differentiate into plasma cells and memory B cells
  • Helper T cells- help coordinate specific and nonspecific defenses and stimulate cell-mediated immunity and antibody mediated immunity
  • Plasma cells-Produce antibodies that recognize the antigen
  • Memory + cells- remember the antigen
  • Memory B cells - remember the antigen for future exposure

Respiratory System

• Functions:
  • Provides large area for gas exchange between air and blood.
  • Moves air to and from the gas exchange surfaces of the lungs.
  • Protect respiratory surfaces from dehydration and temperature changes, provides nonspecific defenses against pathogens.
  • Produces sounds permitting speech.
  • Provides olfactory sensations to the central nervous system for the sense of smell.

Respiratory Tract

• UPPER RESPIRATORY TRACT
  • Nose-air enters the nasal openings.
  • Pharynx - throat
  • Larynx (voice box) -enlargement of airway that prevents foreign objects from entering the trachea and contains vocal cords
  • Glottis-narrow opening surrounded and protected by the larynx
  • Epiglottis projects the opening
• LOWER RESPIRATORY TRACT consists of always that carry airto and from the exchange surfaces of your lungs
  • Trachea-tough , flexible tube that is your airway , protected by tracheal cartilages
  • Bronchi - the trachea branches into the left and right bronchi
  • Bronchioles-branches off bronchi like a tree
  • Alveolar Ducts - respiratory bronchioles open into expansive chamber called alveolar ducts and these passages end at alveolar sacs
  • Alveoli - the exchange surfaces of the lungs
  • Air passing through the glottis vibrates the vocal cords and produces sound waves

Respiratory Tract Cells

• Mucus layer-traps dust, particles, pathogens.
  • Cilia sweep the mucus back to the throat to cough out or swallow
• Goblet cells- make mucus.

Respiratory Membrane

• Gas exchange occurs across the respiratory membrane:
  • Squamous epithelial cells lining the alveolus -> Endothelial cells lining an adjacent capillary.
• Alveolar macrophages-patrol the epithelium and phagocytize dust, debris, and pathogens that have reached alveolar surfaces.
• Surfactant cells-produce surfactant, an oily secretion that forms superficial coating over a thin layer of water on alveolar epithelium, prevents alveoli from sticking together during exhalation.

The Lungs

• Right and left lungs occupy the right and left pleural cavities, respectively.
• Each lung has distinct lobes.
• Each pleural cavity is lined by a serous membrane called the pleura.
  • parietal pleura covers the wall of the, cavity and the visceral pleura covers the outer surface of the lungs.
  • The space between parietal and visceral pleura is called the pleura cavity, it is filled with pleural fluid ,it provides lubrication and reduces friction when you breath.

Respiratory Physiology

• Step 1: Pulmonary ventilation - Breathing, movement of air into the lungs.
• Step 2: Gas exchange - Gas diffusion across respiratory membrane of alveoli.
• Step 3: Gas Transport-Transport of oxygen and carbon dioxide between alveoli capillaries and capillary beds in other tissues.

Lungs : Pressure + Airflow

• Air flows from an area of higher pressure to lower pressure.
• The diaphragm forms the floor of the thoracic cavity so it can increase/decrease size of cavity.
  • During Inhalation, the thoracic cage size increases and lowers the pressure inside the lungs.
  • During exhalation, the thoracic cage size decreases and will increase the pressure inside the lungs.

Volumes and Capacities

• Tidal volume - amount of air moved into or out of the lungs during a single respiratory cycle: - Only a small amount of air in the lungs is exchanged during a single quiet respiratory cycle.
• Expiratory reserve volume - the amount of air that could be voluntarily expelled beyond the tidal volume.
• Inspiratory reserve volume -amount of air that can be taken in over and above the tidal volume.
• Vital capacity-sum of inspiratory reserve volume + expiratory reserve volume + tidal volume .The maximum amount of air that can be moved into and out of the respiratory system in a single respiratory cycle.
• Residual Volume-Air remaining in respiratory passageways even after expiratory reserve volume has been exhausted.
• Total lung capacity-Total volume the lungs can hold: Vital capacity + residual volume.

Digestive System

• Digestion -mechanical and chemical breakdown of foods so that nutrients can be absorbed.
  • Mechanical digestion -physical breakdown
  • Chemical digestion-chemical breakdown
• organs perform these functions during digestion:
  • Ingestion - food enters the digestive tract.
  • Secretion- release of water, acids, enzymes, and buffers by the digestive tract and accessory organs.
  • Absorption-movement of nutrients, electrolytes, vitamins, and water across digestive epithelium.
  • Excretion - removal of waste products.

Digestive System Histology

• Mucosa-inner layer of the digestive tract that includes the mucous membrane, some loose connective tissue and small amount of smooth muscle.
• Submucosa-loose connective tissue,glands, blood Vessels, lymphatic vessels, nerves.
• Muscularis -Smooth muscle cells arranged in an inner circular layer and outer longitudinal layer.
• Serosa - a serous layer consisting of visceral peritoneum that covers the tube.

Esophagus

• Muscular tube peristalsis that begins at pharynx and ends at stomach at lower esophageal sphincter.

Stomach-Functions

• Temporary storage of ingested food.
• Mechanical digestion.
• Break down of proteins via pepsin enzyme.
• Breakdown of food due to acidic environment (HCI), but also protects against pathogens in food.
• Rugae: folds in the stomach that allow for expansion.

The Gastric Wall

• Stomach is lined by a mucus epithelium - the mucus layer protects the stomach lining acids, enzymes, and abrasive materials.
• Gastric glands contain:
  • Parietal cells-secrete HCI.
  • Chief cells -secrete pepsinogen, the Inactive form of pepsin. It is activated by HCI.

The Small Intestine

• Plays a key role in both digestion of food and absorption of nutrients.
  • Duodenum-receives chyme and exocrine secretion from pancreas and liver.
  • Jejunum-bulk of chemical digestion and nutrient absorption.
  • Ileum - last portion.

The Intestinal Wall

• Lining of the intestinal wall is composed of a series of fingerlike projections called villi.
• Each villi is covered with microvilli.
• Both increase surface area of absorption

Digestive Hormones

• Gastrin-targets stomach to produce acids, enzymes, increase motility; made in both stomach and duodenum.
• Secretin-released when the PH falls in the duodenum. When chyme enters the duodenum, secretin causes increase secretion of bile, and buffers by the liver and pancreas.
• Cholecystokinin (CCK)-secreted when chyme arrives in duodenum, especially when it contains lipids and partially digested protein.

Pancreas

• Produces pancreatic juice, a mixture of digestive enzymes and buffers.
• Pancreatic juice is made by pancreatic acinar cells.
  • Pancreatic amylase
  • Pancreatic lipase -> Nucleases -breaks down nucleic acids
  • Proteases

Large Intestine

• Functions:
  • Reabsorption of water and compaction of feces.
  • Absorption of important vitamins made by microbiome bacteria.
  • Storing fecal material prior to defecation.

Urinary System

• Functions:
  • Filters the blood to
    • Remove organic waste products generated by body.
  • Regulating blood volume and pressure - these can be adjusted by adjusting water lost in urine, releasing erythropoietin and renin
  • Regulating plasma concentrations of ions-sodium, potassium, chloride
  • HelpStabilize blood pH-stabilized by controlling loss of H^+ and bicarbonate ions.
  • Reabsorption of nutrients.

Urinary System Structures

• Kidney-filter blood to produce urine.
• Ureter-transports urine toward the urinary bladder.
• Urinary bladder-temporarily stores urine prior to elimination.
• Urethra-conducts urine to exterior of the body (longer in males).
• The Nephron -The structural and functional unit of the Kidney that produces urine.

Water, Electrolyte, Acid-Base Balance

• Water Balance
  • When the amount of water gained each day is equal to the amount lost to the environment.
• Electrolyte Balance
  • Electrolytes are ions