Chapter 1

The Study of Body Function

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Human Physiology

Study of how the human body functions.

Pathophysiology: How physiological processes are

altered in disease or injury.

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Scientific Method

Confidence in rational ability, honesty and humility.

Formulate hypothesis. Testing the hypothesis. Analyze results. Draw conclusion.

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Homeostasis

Maintaining constancy of internal environment.

Dynamic consistency. Maintained by negative feedback

loops.

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Feedback Loops

Sensor: Detects deviation from set point.

Integrating center: Determines the response.

Effector: Produces the response.

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Negative Feedback

Defending the set point.

Reverse the deviation. Produces change in

opposite direction.

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Hormone insulin restores plasma [glucose].www.freelivedoctor.com

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Positive Feedback

Action of effectors amplifies the change.

Is in same direction as change. Examples:

Oxytocin (parturition) Voltage gated Na+ channels

(depolarization)

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Primary Tissues

4 Different Primary Tissues: Muscle Nervous Epithelial Connective

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Muscle Tissue

Specialized for contraction. 3 Types of Muscle Tissue:

Skeletal Cardiac Smooth

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Skeletal Muscle

Voluntary muscle. Striated. Attach to bones at

both ends (tendons).

Arranged in parallel. Grade contraction.

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Cardiac Muscle

Striated. Found only in

the heart. Interconnected. Intercalated

discs. Syncytium.

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Smooth Muscle

Not striated. Gap junctions. Calmodulin. Peristalsis. Syncytium.

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Nervous Tissue

Neurons (nerve cells): Specialized for conduction of action

potentials. Supporting cells:

Provide anatomical and functional support.

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Neuron

Dendrites: Receive input.

Cell body: Nucleus. Metabolic center.

Axon: Conducts nerve

impulses.

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Epithelial Tissue

Types of Epithelial Tissue: Cells that form membranes:

Squamous Columnar Cuboidal

Exocrine glands Endocrine glands

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Squamous Cells

Flattened in shape.

Adapted for diffusion and filtration.

Line all blood vessels.

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Cuboidal Cells

Cube-shaped cells.

Excretion, secretion and absorption.

Line kidney tubules, salivary ducts, and pancreatic ducts.

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Columnar Cells

Taller column shaped cells.

Excretion, secretion and absorption.

May contain cilia. Line digestive tract

and respiratory passageways.

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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

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Endocrine Glands

Lack ducts. Secrete hormones into capillaries

within the body. May be discrete organs:

Primary functions are the production and secretion of hormones.

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Connective Tissue

Large amounts of extracellular (ECF) material in the spaces between connective tissue cells.

4 Types of Connective Tissue: Connective tissue proper Cartilage Bone Blood

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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

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Cartilage

Chondrocytes. Supportive and protective tissue. Elastic properties to tissues. Precursor to many bones. Articular surfaces on joints.

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Bone

Hydroxyapatite crystals Osteoblasts:

Bone-forming cells Osteocytes:

Trapped osteoblasts: less active Osteoclasts:

Bone resorbing cells

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Blood

Classified as connective tissue. Half its volume is plasma.

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Organs

Organs: Composed of at least two primary

tissues. Serve different functions of the

organ.

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Systems

Organs that are located in different regions of the body and perform related functions.

Examples: Skeletal system Cardiovascular system GI system

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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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