the study of body function

1. 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].

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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