PowerLecture: Chapter 4

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PowerLectureChapter 4

• Tissues, Organs, and Organ Systems

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Learning Objectives

• Understand the various levels of animal
  organization (cells, tissues, organs, and organ
  systems).
• Know the characteristics of the various types of
  tissues. Know the types of cells that compose
  each tissue type and cite some examples of organs
  that contain significant amounts of each tissue
  type.
• Describe how the four principal tissue types are
  organized into an organ such as the skin.

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Learning Objectives (contd)

• Explain how the human body maintains a rather
  constant internal environment despite changing
  external conditions.

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Impacts/Issues

• Stem Cells

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Stem Cells

• Stem cells are the first to form when a
  fertilized egg starts dividing.
• Adults have stem cells in some tissues such as
  bone marrow and fat these cells have shown some
  promise as therapy.
• Embryonic stem cells can be coaxed
• to differentiate into many different
• types of cells, which can replace
• damaged or worn out body cells
• perhaps to an extent greater than
• adult stem cells.

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Stem Cells

• The human body is an orderly assembly of parts
  (anatomy).
• A tissue is an aggregation of cells and
  intracellular substances functioning for a
  specialized activity.
• Various types of tissues can combine to form
  organs, such as the heart.
• Organs may interact to form organ systems such as
  the digestive system.
• Homeostasis allows for the stable functioning
  (physiology) of all our combined parts.

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Video New Nerves
CLICKTO PLAY

• From ABC News, Biology in the Headlines, 2005 DVD.

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How Would You Vote?

• To conduct an instant in-class survey using a
  classroom response system, access JoinIn Clicker
  Content from the PowerLecture main menu.
• Should researchers be allowed to start embryonic
  stem cell lines from human embryos that are not
  used for in vitro fertilization?
• a. Yes, most unimplanted embryos are destroyed
  anyway the potential of stem cells is too great
  to ignore.
• b. No, any human embryo has the potential to
  become a human and so deserves protection from
  destruction.

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Section 1

• Epithelium The Bodys Covering and Linings

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Epithelium

• Epithelial tissue covers the surface of the body
  and lines its cavities and tubes.
• One surface is free and faces either the
  environment or a body fluid the other adheres to
  a basement membrane, a densely packed layer of
  proteins and polysaccharides.
• Cells are linked tightly together there may be
  one or more layers.

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Fig. 4.1a, p. 69
free surface of epithelium
simple squamous epithelium
basement membrane
connective tissue
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Animation Structure of Epithelium
CLICKTO PLAY
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Epithelium

• There are two basic types of epithelia.
• Simple epithelium is a single layer of cells
  functioning as a lining for body cavities, ducts,
  and tubes.
• Simple epithelium functions in diffusion,
  secretion, absorption, or filtering of substances
  across the cell layer.
• Pseudostratified epithelium is a single layer of
  cells that looks like a double layer most of the
  cells are ciliated examples are found in the
  respiratory passages and reproductive tracts.
• Stratified epithelium has many layersas in human
  skin.

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Animation Types of Simple Epithelium
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Table 4.1, p. 68
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Epithelium

• Both simple and stratified epithelium can be
  subdivided into groups based on shape at the
  tissue surface
• Squamous epithelium consists of flattened cells
  examples are found in the lining of the blood
  vessels.
• Cuboidal epithelium has cube-shaped cells
  examples are found in glands.
• Columnar epithelium has elongated cells examples
  are found in the intestine.

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Fig. 4.2b-d, p. 70
cilia
columnar cells
basement membrane
TYPE Simple squamous DESCRIPTION
Friction-reducing slick, single layer of
flattened cells COMMON LOCATIONS Lining of
blood and lymph vessels, heart air sacs of
lungs peritoneum FUNCTION Diffusion
filtration secretion of lubricants
TYPE Simple cuboidal DESCRIPTION Single layer
of squarish cells COMMON LOCATIONS Ducts,
secretory part of small glands retina kidney
tubules ovaries, testes bronchioles FUNCTION
Secretion absorption
TYPE Simple columnar DESCRIPTION Single layer
of tall cells free surface may have cilia,
mucus-secreting glandular cells,
microvilli COMMON LOCATIONS Glands, ducts gut
parts of uterus small bronchi FUNCTION
Secretion absorption ciliated types move
substances
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Epithelium

• Glands develop from epithelium.
• Glands are secretory structures derived from
  epithelium that make and release specific
  substances, such as mucus.
• Glands are classified according to how their
  products reach the site where they are used.
• Exocrine glands often secrete through ducts to
  free surfaces they secrete mucus, saliva,
  earwax, milk, oil, and digestive enzymes for
  example.
• Endocrine glands have no ducts but distribute
  their hormones via the blood.

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Section 2

• Connective Tissue Binding, Support, and Other
  Roles

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Connective Tissue

• Connective tissue binds together, supports, and
  anchors body parts it is the most abundant
  tissue in the body.
• Fibrous connective tissues and specialized
  connective tissues are both found in the body.
• Fiber-like structural proteins and
  polysaccharides secreted by the cells make up a
  matrix (ground substance) around the cells that
  can range from hard to liquid.

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Connective Tissue

• Fibrous connective tissues are strong and
  stretchy.
• Fibrous connective tissue takes different forms
  depending on cell type and the fibers/matrix
  produced.

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Fig. 4.2a-d, p. 70
Loose connective tissue
Dense, regular connective tissue
Dense, irregular connective tissue
Cartilage
collagenous fiber
ground substance with collagen fibers
collagenous fibers
collagenous fibers
fibroblast
fibroblast
elastic fiber
cartilage cell (chondrocyte)
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Connective Tissue

• Types and examples of fibrous connective tissue
• Loose connective tissue supports epithelia and
  organs, and surrounds blood vessels and nerves
  it contains few cells and loosely arrayed thin
  fibers.
• Dense, irregular connective tissue has fewer
  cells and more fibers, which are thick it forms
  protective capsules around organs.
• Dense, regular connective tissue has bundled
  collagen fibers lying in parallel such
  arrangements are found in ligaments (binding bone
  to bone) and tendons (binding muscle to bone).
• Elastic connective tissue contains fibers of
  elastin this tissue is found in organs that must
  stretch, like the lungs.

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Animation Soft Connective Tissues
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Connective Tissue

• Cartilage, bone, adipose tissue, and blood are
  specialized connective tissues.
• Cartilage contains a dense array of fibers in a
  rubbery ground substance cartilage can withstand
  great stress but heals slowly when damaged.
• Hyaline cartilage has many small fibers it is
  found at the ends of bones, in the nose, ribs,
  and windpipe.
• Elastic cartilage, because of its elastin
  component, is able to bend yet maintain its
  shape, such as in the external ear.
• Fibrocartilage is a sturdy and resilient form
  that can withstand tremendous pressure such as in
  the disks that separate the vertebrae.

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Connective Tissue

• Bone tissue is composed of collagen, ground
  substance, and calcium salts minerals harden
  bone so it is capable of supporting and
  protecting body tissues and organs.
• Adipose tissue cells are specialized for the
  storage of fat most adipose tissue lies just
  beneath the skin.

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Fig. 4.2ef, p. 71
compact bone tissue
nucleus
blood vessel
cell bulging with fat droplet
bone cell (osteocyte)
TYPE Bone tissue DESCRIPTION Collagen fibers,
matrix hardened with calcium COMMON LOCATIONS
Bones of skeleton FUNCTION Movement, support,
protection
TYPE Adipose tissue DESCRIPTION Large, tightly
packed fat cells occupying most of matrix COMMON
LOCATIONS Under skin, around heart,
kidneys FUNCTION Energy reserves, insulation,
padding
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Animation Specialized Connective Tissues
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Connective Tissue

• Blood is a fluid connective tissue involved in
  transport plasma forms the fluid matrix and
  blood proteins, blood cells, and platelets
  compose the fiber portion of the tissue.

Figure 4.3
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Table 4.2, p. 71
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Section 3

• Muscle Tissue Movement

Figure 4.4
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Muscle Tissue Movement

• Muscle tissue contracts in response to
  stimulation, then passively lengthens movement
  is a highly coordinated action.
• There are three types of muscle
• Skeletal muscle tissue
• attaches to bones for
• voluntary movement long
• muscle cells are bundled
• together in parallel arrays,
• which are enclosed in a
• sheath of dense connective tissue.

skeletal muscle
Figure 4.4a
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Muscle Tissue Movement
cardiac muscle

• Smooth muscle tissue contains
• tapered, bundled cells that function
• in involuntary movement it lines
• the gut, blood vessels, and glands.
• Cardiac muscle is composed of
• short cells that can function in units
• due to the signals that pass through
• special junctions that fuse the cells
• together cardiac muscle is only
• found in the wall of the heart.

smooth muscle
Figure 4.4b-c
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Animation Muscle Tissues
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Section 4

• Nervous Tissue Communication

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Nervous Tissue Communication

• Nervous tissue consists mainly of cells,
  including neurons (nerve cells) and support
  cells nervous tissue forms the bodys
  communication network.
• Neurons carry messages.
• Neurons have two types
• of cell processes (extensions)
• branched dendrites pick up
• chemical messages and pass
• them to an outgoing axon.

Figure 4.5a
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Nervous Tissue Communication

• A cluster of processes from different neurons is
  called a nerve.
• Nerves move messages throughout the body.
• Neuroglia are support cells.
• Glial cells (neuroglia) make
• up 90 percent of the nervous
• system. Neuroglia provide
• physical support for neurons.
• Other glial cells provide
• nutrition (astrocytes), clean-up,
• and insulation services (Schwann cells).

Figure 4.5b
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Table 4.4, p. 85
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Section 5

• Cell Junctions Holding Tissues Together

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Cell Junctions

• Epithelial cells tend to adhere to one another by
  means of specialized attachment sites.
• Tight junctions link cells of epithelial tissues
  to form seals that keep molecules from freely
  crossing the epithelium.
• Adhering junctions are like spot welds in tissues
  subject to stretching.
• Gap junctions link the cytoplasm of adjacent
  cells they form communication channels.

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Cell Junctions

• Sites of cell-to-cell contact are especially
  profuse when substances must not leak from one
  body compartment to another.

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Fig. 4.6, p. 74
cell
basement membrane
intermediate filaments
protein channel
plaques
TIGHT JUNCTION
ADHERING JUNCTION
GAP JUNCTION
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Animation Cell Junctions
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Section 6

• Tissue Membranes Thin, Sheetlike Covers

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Tissue Membranes

• Epithelium membranes pair with connective tissue.
• Mucous membranes line the tubes and cavities of
  the digestive, respiratory, and reproductive
  systems where embedded glands secrete mucus.
• Serous membranes such as those that line the
  thoracic cavity occur in paired sheets and do not
  contain glands.
• Cutaneous membranes are hardy and dryand better
  known as skin.

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Tissue Membranes

• Membranes in joints consist only of connective
  tissue.
• Synovial membranes line the sheaths of tendons
  and the capsule-like cavities around certain
  joints.
• Their cells secrete fluid that lubricates the
  ends of the moving bones.

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Fig. 4.7, p. 75
mucous membrane
serous membrane
synovial membrane
cutaneous membrane (skin)
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Section 7

• Organs and Organ Systems

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Organs and Organ Systems

• An organ is a composite of two or more tissue
  types that act together to perform one or more
  functions two or more organs that work in
  concert form an organ system.
• The major cavities of the human body are
  cranial, spinal, thoracic, abdominal, and pelvic.

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Fig. 4.8a, p. 76
cranial cavity
spinal cavity
thoracic cavity
abdominal cavity
pelvic cavity
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Animation Major Body Cavities
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52
Animation Directional Terms and Planes of
Symmetry
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Fig. 4.8b, p. 76
SUPERIOR (of two body parts, the one closer to
head)
distal (farthest from trunk or from point of
origin of a body part)
frontal plane (aqua)
midsagittal plane (green)
proximal (closest to trunk or to point of
origin of a body part)
ANTERIOR (at or near front of body)
POSTERIOR (at or near back of body)
transverse plane (yellow)
INFERIOR (of two body parts, the one farthest
from head)
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Organs and Organ Systems

• Eleven organ systems (integumentary, nervous,
  muscular, skeletal, circulatory, endocrine,
  lymphatic, respiratory, digestive, urinary, and
  reproductive) contribute to the survival of the
  living cells of the body.

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Animation Organ Systems of the Human Body
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Section 8

• The Integument Example of an Organ System

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The Integument

• Humans have an outer covering called the
  integument, which includes the skin and the
  structures derived from epidermal cells including
  oil and sweat glands, hair, and nails.
• The skin performs several functions
• The skin covers and protects the body from
  abrasion, bacterial attack, ultraviolet
  radiation, and dehydration.

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The Integument

• It helps control internal temperature.
• Its receptors are essential in detecting
  environmental stimuli.
• The skin produces vitamin D.
• Epidermis and dermisthe two layers of skin.

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Fig. 4.10b, p. 79
outer epidermal layer (all dead cells)
keratinized cells being flattened
rapidly dividing cells of epidermis
dermis
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The Integument

• Epidermis refers to the thin, outermost layers of
  cells consisting of stratified, squamous
  epithelium.
• Keratinocytes produce keratin when the cells are
  finally pushed to the skin surface, they have
  died, but the keratin fibers remain to make the
  outermost layer of skin (the stratum corneum)
  tough and waterproof.
• Deep in the epidermis are melanin-producing cells
  (melanocytes) melanin, along with carotene and
  hemoglobin, contribute to the natural coloration
  of skin.
• Langerhans cells and Granstein cells are two
  important cells in skin that contribute to immune
  function.

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The Integument

• The dermis is the thicker portion of the skin
  that underlies the epidermis.
• The dermis is mostly dense connective tissue,
  consisting of elastin and collagen fibers.
• Blood vessels, hair follicles, nerve endings, and
  glands are located here.
• The hypodermis is a subcutaneous layer that
  anchors the skin fat is also stored here.

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Fig. 4.10a, p. 78
melanocyte
smooth muscle
sweat pore
sebaceous gland
Langerhans cell
keratinized layer
living layer
hair shaft
EPIDERMIS
keratinocyte
Granstein cell
DERMIS
HYPODERMIS
adipose cells
nerve fiber
hair follicle
pressure receptor
sweat gland
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Animation Structure of Human Skin
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The Integument

• Sweat glands and other structures are derived
  from epidermis.
• Sweat glands secrete a fluid (mostly water with a
  little dissolved salt) that is useful in
  regulating the temperature of the body.
• Oil (sebaceous) glands function to soften and
  lubricate the hair and skin acne is a condition
  in which the ducts become infected by bacteria.

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The Integument

• Hairs are flexible, keratinized structures rooted
  in the skin and projecting above the surface
  growth is influenced by genes, nutrition, and
  hormones.

Figure 4.11
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The Integument

• Sunlight permanently damages the skin.
• Ultraviolet (UV) radiation and the light from
  tanning beds stimulate melanin production in
  skin, resulting in a tan too much UV exposure,
  however, can damage the skin.
• UV light can activate proto-
• oncogenes in skin cells, leading
• to cancer.
• Rates of skin cancer are on the
• rise due to continued destruction
• of the atmospheric ozone layer that normally
  protects the Earth from too much UV light.

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Section 9
Homeostasis The Body in Balance
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Homeostasis The Body in Balance

• The internal environment A pool of extracellular
  fluid.
• The trillions of cells in our bodies are
  continuously bathed in an extracellular fluid
  that supplies nutrients and carries away
  metabolic wastes.
• The extracellular fluid consists of interstitial
  fluid (between the cells and tissues) and plasma
  (blood fluid).

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In-text Fig., p. 80
Interstitial (tissue) fluid
Cell
Blood
Blood vessel
Extracellular fluid
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Homeostasis The Body in Balance

• The component parts of an animal work together to
  maintain the stable fluid environment
  (homeostasis) required for life.
• Homeostasis requires the interaction of sensors,
  integrators, and effectors.
• Homeostatic mechanisms operate to maintain
  chemical and physical environments within
  tolerable limits and to keep the body close to
  specific set points of function.

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Homeostasis The Body in Balance

• Homeostatic control mechanisms require three
  components
• Sensory receptor cells detect specific changes
  (stimuli) in the environment.
• Integrators (brain and spinal cord) act to direct
  impulses to the place where a response can be
  made.
• Effectors (muscles and glands) perform the
  appropriate response.

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Fig. 4.12, p. 80
STIMULUS (input into the system)
receptor (such as a nerve ending in the skin)
integrator (such as the brain or spinal cord)
effector (a muscle or gland)
RESPONSE to stimulus causes change. The change
is fed back to receptor. In negative feedback,
the systems response cancels or counters the
effect of the original stimulus.
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Homeostasis The Body in Balance

• Feedback mechanisms are important homeostatic
  controls.
• A common homeostatic mechanism is negative
  feedback.
• It works by detecting a change in the internal
  environment that brings about a response that
  tends to return conditions to the original state.
• It is similar to the functioning of a thermostat
  in a heating/cooling system.
• Positive feedback mechanisms may intensify the
  original signal childbirth is an example.

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Animation Negative Feedback at the Organ Level
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Animation Homeostatic Control of Temperature
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76
Fig. 4.13a, p. 81
sweat gland pore
dead, flattened skin cells
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Fig. 4.13b, p. 81
STIMULUS After overexertion on a hot, dry day,
surface temperature of body rises.
effectors Pituitary gland thyroid gland trigger
widespread adjustments in many body organs.
receptors In skin and elsewhere detect
the temperature change.
integrator The hypothalamus, a brain region,
compares input from the receptors against the set
point for the body.
RESPONSE Body temperature falls,receptors
initiate shifts in effector output.
Effectors These carry out specific responses,
including
Skeletal muscles in chest wall work to get
additional oxygen into lungs.
Smooth muscle in blood vessels dilates blood
transporting metabolic heat shunted to skin some
heat lost to surroundings.
Sweat glands secrete more, with cooling effect
on the brain especially.
Overall slowing of activity results in less
metabolically generated heat.
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Section 10
How Homeostatic Feedback Maintains the Bodys
Core Temperature
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How Homeostatic Feedback Maintains the Bodys
Core Temperature

• Humans are endotherms, heated from within by
  metabolic processes.
• Core temperature of the head and torso is roughly
  37?C (98.6?F).
• Above this temperature (41?C) proteins begin to
  denature below this temperature (35?C and below)
  the body stops functioning.

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Animation Human Thermoregulation
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Fig. 4.14a, p. 82
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Fig. 4.14b, p. 82
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Animation Heat Denaturation of Enzymes
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How Homeostatic Feedback Maintains the Bodys
Core Temperature

• Responses to cold stress.
• Cold responses are controlled by an area of the
  brain called the hypothalamus.
• Several things happen when the outdoor
  temperature drops
• Peripheral vasoconstriction occurs when the
  hypothalamus commands the muscles around blood
  vessels to contract this diverts blood flow away
  from the body surface.
• The pilomotor response causes your body hair to
  stand on end to trap air around the body to
  prevent heat loss.

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How Homeostatic Feedback Maintains the Bodys
Core Temperature

• Skeletal muscle contractions cause you to shiver
  in an attempt to generate heat.
• In babies, who cant shiver, hormones raise the
  rate of metabolism in a nonshivering heat
  production response this response occurs in a
  special type of adipose tissue called brown fat.
• If body temperature cannot be maintained, damage
  to the body occurs.
• Hypothermia is characterized by mental confusion,
  coma, and possibly death.
• Physical freezing can lead to frostbite and death
  of the affected tissues.

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How Homeostatic Feedback Maintains the Bodys
Core Temperature

• Responses to heat stress.
• Heat responses are also controlled by the
  hypothalamus.
• Peripheral vasodilation causes blood vessels to
  expand in the skin, allowing excess body heat to
  dissipate.
• Heat is also dissipated in sweat from sweat
  glands water and salts both are lost to cool the
  body.

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How Homeostatic Feedback Maintains the Bodys
Core Temperature

• Various levels of heat stress (hyperthermia) can
  be experienced
• Heat exhaustion occurs under mild heat stress
  blood pressure drops as fluid is lost and the
  person can collapse.
• Heat stroke occurs when the body ceases to be
  able to control temperature death is one
  possible outcome.
• A fever is a natural rise in core temperature
  used to fight off disease severe fevers,
  however, should be controlled to avoid serious
  damage to the body.

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Table 4.3, p. 83