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Human Physiology
Study of how the human body functions.
Pathophysiology:
How physiological processes are altered in disease or injury.
Scientific Method
Confidence in rational ability, honesty and humility.
Formulate hypothesis.
Testing the hypothesis.
Analyze results.
Draw conclusion.
Homeostasis
Maintaining constancy of internal environment.
Dynamic consistency.
Maintained by negative feedback loops.
Feedback Loops
Sensor:
Detects deviation from set point.
Integrating center:
Determines the response.
Effector:
Produces the response.
Negative Feedback
Defending the set point.
Reverse the deviation.
Produces change in opposite direction.
Eating - increase Blood glucose
Pancreatic islets (of Langerhans)
increased insulin - Cellular uptake of glucose
lowering the blood glucose
Positive Feedback
Action of effectors amplifies the change.
Is in same direction as change.
Examples:
Oxytocin (parturition)
Voltage gated Na+ channels (depolarization)
Primary Tissues
4 Different Primary Tissues:
1. Muscle Tissue - Specialized for contraction.
3 Types of Muscle Tissue:
...Skeletal Muscle - Voluntary muscle.
Striated.
Attach to bones at both ends (tendons).
Arranged in parallel.
Grade contraction.
...Cardiac Muscle - Striated.
Found only in the heart.
Interconnected.
Intercalated discs.
Syncytium.
...Smooth Muscle - Not striated.
Gap junctions.
Calmodulin.
Peristalsis.
Syncytium.
2. Nervous Tissue
Neurons (nerve cells):
Specialized for conduction of action potentials.
Supporting cells:
Provide anatomical and functional support.
...Neuron
Dendrites: Receive input.
Cell body: Nucleus. , Metabolic center.
Axon: Conducts nerve impulses.
3. Epithelial Tissue
Types of Epithelial Tissue:
Cells that form membranes:
...Squamous Cells - Flattened in shape.
Adapted for diffusion and filtration.
Line all blood vessels.
...Columnar Cells - Taller column shaped cells.
Excretion, secretion and absorption.
May contain cilia.
Line digestive tract and respiratory passageways.
...Cuboidal Cells - Cube-shaped cells.
Excretion, secretion and absorption.
Line kidney tubules, salivary ducts, and pancreatic ducts.
4. Exocrine glands
Derived from cells of epithelial membranes.
Secretions are released through ducts.
Simple tubes or modified as acini.
Examples:
Tear glands
Sweat glands
Prostate glands
Endocrine glands
Lack ducts.
Secrete hormones into capillaries within the body.
May be discrete organs:
Primary functions are the production and secretion of hormones.
Connective Tissue
Large amounts of extracellular (ECF) material in the spaces between connective tissue cells.
4 Types of Connective Tissue:
Connective tissue proper - Loose connective tissue:
Scattered collagen and tissue fluid. - Dermis of skin
Dense fibrous connective tissue:
Regular arranged. - Collagen oriented in same direction. - Tendons
Irregularly arranged. - Resists forces applied in many directions.
Capsules and sheaths
Cartilage - Chondrocytes.
Supportive and protective tissue.
Elastic properties to tissues.
Precursor to many bones.
Articular surfaces on joints.
Bone - Hydroxyapatite crystals
Osteoblasts:
Bone-forming cells
Osteocytes:
Trapped osteoblasts: less active
Osteoclasts:
Bone resorbing cells
Blood - Classified as connective tissue.
Half its volume is plasma.
Organs:
Composed of at least two primary tissues.
Serve different functions of the organ.
Systems
Organs that are located in different regions of the body and perform related functions.
Examples:
Skeletal system
Cardiovascular system
GI system
Body-Fluid Compartments
65-75% of total body weight H20.
Intracellular compartment:
Fluid inside the cell.
2/3 of H20
Extracellular compartment:
1/3 H20
2 Subdivisions:
Blood plasma
Interstitial fluid
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