Talk Four:

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Human Biology (BIOL 104)

• Talk Four
• Tissues, Organs, and Organ Systems
• Chapter 4

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Tissues, Organs, and Organ Systems

• Every year tens of thousands of people develop a
  disease or suffer an injury that severely damages
  an organ or tissue.
• If only it were possible to replace those body
  parts!
• All body cells come from stem cells (more in
  later talks).
• Ah, back to the ethics stuff!!!!!
• Adults also have stem cells (less controversial)
• Adult stem cells are more limited than embryonic
  cells
• Active types show promise for regenerating
  cartilage and heart muscle damaged by a heart
  attack
• We will focus on the basic types of cells and
  tissues that make up the Human Body.

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Tissues

• Tissue
• Similarly specialized cells that perform a common
  function in the body.
• 4 main tissue types in the human body
• 1. Epithelial covers body surface and lines
  body cavities.
• 2. Connective binds and supports body parts.
• 3. Muscular Moves body parts
• 4. Nervous Receives, interprets and sends
  signals.

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1. Epithelial Tissue

• This covers the whole surface of the body.
• It is made up of cells closely packed and ranged
  in one or more layers.
• This tissue is specialized to form the covering
  or lining of all internal and external body
  surfaces.
• Epithelial tissue that occurs on surfaces on the
  interior of the body is known as endothelium.
• Epithelial cells are packed tightly together,
  with almost no intercellular spaces and only
  a small amount of intercellular substance.
• Epithelial tissue, regardless of the type, is
  usually separated from the underlying tissue by a
  thin sheet of connective tissue basement
  membrane.
• The basement membrane provides structural
  support for the epithelium and also binds it to
  neighboring structures.

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1. Epithelial Tissue

• 5 types
• A Squamous-flat-lungs and blood.
• B Cuboidal-cube-kidney tubes.
• C Columnar-pillars-Digestive tract.
• D Pseudostratified ciliated columnar-
  Respiratory tract.
• E Stratified squamous epithelium - esophagus

Used with permission from imgarcade.com
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Functions of Epithelial Tissue

• Protection
• Epithelial cells from the skin protect underlying
  tissue from mechanical injury, harmful chemicals,
  invading bacteria and from excessive loss of
  water.
• Sensation
• Sensory stimuli penetrate specialised epithelial
  cells. Specialised epithelial tissue containing
  sensory nerve endings is found in the skin, eyes,
  ears, nose and on the tongue.
• Secretion
• In glands, epithelial tissue is specialised
  to secrete specific chemical substances such as
  enzymes, hormones and lubricating fluids.
• Absorption
• Certain epithelial cells lining the small
  intestine absorb nutrients from the digestion of
  food.

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Functions of Epithelial Tissue

• Excretion
• Epithelial tissues in the kidney excrete waste
  products from the body and reabsorb needed
  materials from the urine. Sweat is also excreted
  from the body by epithelial cells in the sweat
  glands.
• Diffusion
• Simple epithelium promotes the diffusion of
  gases, liquids and nutrients. Because they form
  such a thin lining, they are ideal for the
  diffusion of gases (eg. walls of capillaries and
  lungs).
• Cleaning
• Ciliated epithelium assists in removing dust
  particles and foreign bodies which have entered
  the air passages.
• Reduces Friction
• The smooth, tightly-interlocking, epithelial
  cells that line the entire circulatory
  system reduce friction between the blood and the
  walls of the blood vessels.

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Cleaning, an extended example - the Trachea

• Windpipe connects larynx to primary bronchi.
• Held open by cartilage
• Goblet cell
• Makes mucus
• Mucosa contains layer of pseudostratified
  ciliated epithelium
• Sweep dirt and excess mucus upwards

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Basement Membrane

• Why doesn't our skin fall completely off our
  bodies?
• The results of gravity's constant downward pull
  on our faces, shoulders, backs, necks, chests,
  organs, legs and feet are obvious to most of us,
  especially as we age.
• Nowhere is this more obvious than our skin.
  Millions of dollars are spent every year to
  tighten that sagging, drooping skin.
• The occasional face-lift, a little Botox, creams,
  serums, and muscle exercises are part of this
  nations obsession.
• Meet the basement membrane.
• Epithelial Tissue is held to the body via a
  Basement membrane

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Basement Membrane

• The basement membrane serves as the anchor for
  the epithelium, attaching it to the connective
  tissue below.
• Your skin has three layers. The outer layer,
  called the epidermis, is composed of epithelial
  cells. 
• The middle layer is the dermis, and is composed
  of connective tissue such as
• blood vessels, sweat glands, sebaceous glands,
  and temperature sensors.
• The third layer is the subcutaneous, and is the
  lowest layer.
• The basement membrane lies between the epidermis
  and the dermis, keeping the outside layer tightly
  connected to the inside layer.

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Basement Membrane

• Not even the effects of gravity can destroy this
  anchoring system.
• While skin may droop and sag, it will never
  completely fall off.
• Basement membrane is not found just in the skin.
• It has important functions all over the body.
• Any place you find epithelium and endothelium,
  the basement membrane will be sandwiched in
  between to hold the layers together.
• Basement membrane is composed of
• glycoproteins-sticky sugary proteins and protein
  fibers
• Collagen
• strong, elastic-stretchy

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2. Connective Tissue

• Supports, connects, or separates different types
  of tissues and organs of the body.
• Contains high quantities of a protein called
  collagen
• Connective tissue proper consists of loose
  connective tissue and dense connective
  tissue (which is further subdivided into dense
  regular and dense irregular connective tissues.)
• Special connective tissue consists of reticular
  connective tissue, adipose tissue, cartilage, bone
  , and blood.
• Other kinds of connective tissues include
  fibrous, elastic, and lymphoid connective tissues.

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2. Connective Tissue

• Dense connective tissue
• In skin and capsules around organs used as a
  support structure
• Adipose connective tissue
• Mainly cells filled with fat- under skin and
  kidneys
• Energy reserve, insolation, and padding
• Areolar connective tissue
• Found under the skin Elasticity and diffusions
  of solutes
• Compact bone
• Movement, support, and protection
• Blood
• Fluid blood plasma

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Functions of connective tissue

• Storage of energy
• Protection of organs
• Provision of structural framework for the body
• Connection of body tissues
• Connection of epithelial tissues to muscle fiber.
• Supply of hormones all over the body
• Nutritional support to epithelium
• Site of defense reactions
• Repair of body tissues

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Diseases of connective tissue

• Scurvy problems with sea voyages, lack of food
  other than salted meats.
• Symptoms include, swollen gums, loose teeth,
  small black-and-blue spots on the skin, and
  bleeding from small blood vessels are among the
  characteristic signs of scurvy.
• Caused when vitamin C (ascorbic acid) is lost
  from diet
• Vitamin C is needed to keep Iron reduced in blood
  cells to carry oxygen
• In 1795, the British Royal Navy provided a daily
  ration of lime or lemon juice to all its men.
  English sailors to this day are called "limeys",
  for lime was the term used at the time for both
  lemons and limes.

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Diseases of connective tissue

• Several heritable diseases result from mutations
  in the collagen

• Marfans Syndrom and Ehlers-Danlos syndromes -
  inherited disorder of connective tissue which
  affects many organ systems, including the
  skeleton, lungs, eyes, heart and blood vessels.
• All resulting from various mutation in collagen
  and other fibril associated proteins, ultimately
  affecting the structure and molecular interaction
  of connective tissue.

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3. Muscle tissue

• Is a soft tissue that composes muscles in bodies,
  and gives rise to muscles' ability to contract.
  This is opposed to other components or tissues in
  muscle such as tendons
• Muscle tissue varies with function and location
  in the body. In mammals the three types are 
• skeletal or striated muscle 
• smooth or non-striated muscle 
• cardiac muscle, which is sometimes known as
  semi-striated
• Smooth and cardiac muscle contracts
  involuntarily, without conscious intervention.

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Skeletal or striated muscle

• Striated in structure and under voluntary
  control, is anchored by tendons to bone and is
  used to effect skeletal movement such as
  locomotion and to maintain posture.
• An average adult male is made up of 42 of
  skeletal muscle and an average adult female is
  made up of 36 (as a percentage of body mass).

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Smooth or non-striated muscle 

• Smooth muscle, neither striated in structure nor
  under voluntary control, is found within the
  walls of organs and structures such as the
• esophagus
• stomach 
• intestines 
• bronchi
• uterus 
• urethra 
• bladder
• blood vessels 
• arrector pili in the skin (in which it controls
  erection of body hair).

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Cardiac Muscle

• Cardiac muscle (myocardium), found only in the
  heart, not subject to voluntary control.
• Cardiac "striated" in that they contain
  sarcomeres and are packed into highly regular
  arrangements of bundles smooth muscle has
  neither.
• While skeletal muscles are arranged in regular,
  parallel bundles, cardiac muscle connects at
  branching, irregular angles (called intercalated
  discs).
• Heart cells must beat in unison. Intercalated
  Disks allow calcium to regulate united beating

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4. Nervous Tissue

• The main component of the two parts of the
  nervous system the brain and spinal cord of the
  central nervous system (CNS), and the branching
  peripheral nerves of the peripheral nervous
  system (PNS)
• Both regulate and control bodily functions and
  activity.
• It is composed of
• neurons, or nerve cells, which receive and
  transmit impulses
• neuroglia, also known as glial cells or more
  commonly as just glia.

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4. Nervous Tissue

• Glia assist the propagation of the nerve impulse
  as well as providing nutrients to the neuron.
• Nervous tissue is made up of different types of
  nerve cells, all of which having an axon, the
  long stem-like part of the cell that sends action
  potential signals to the next cell.
• Functions of the nervous system are sensory
  input, integration, control of muscles and
  glands, homeostasis, and mental activity.

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4. Nervous Tissue
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Tissues require cell junctions

• Type of structure that exists within the tissue
  of some multicellular organisms, such as Humans.
• Consist of multiprotein complexes that provide
  contact between neighbouring cells or between a
  cell and the extracellular matrix.
• They also build up the paracellular barrier of
  epithelia and control the transport of solutes.
  Cell junctions are especially abundant in
  epithelial tissues.
• Cell junctions are especially important in
  enabling communication between neighboring cells
  via specialized proteins called communicating
  junctions. Cell junctions are also important in
  reducing stress placed upon cells.

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Three types

• A Adhesion junction
• Cells within tissues and organs must be anchored
  to one another and attached to components of the
  extracellular matrix.
• Anchoring proteins extend through the plasma
  membrane to link cytoskeletal proteins in one
  cell to cytoskeletal proteins in neighboring
  cells as well as to proteins in the extracellular
  matrix

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Three types

• B Tight junction
• Found in epithelia, they act as barriers that
  regulate the movement of water and solutes
  between epithelial layers.
• There is evidence to suggest that the structures
  in which solutes pass through are somewhat like
  pores.
• Prevent the highly acidic gastric fluid in your
  stomach from leaking out and digesting proteins
  of your own body instead of those you consume as
  food.

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Three types

• C Communicating (GAP) junctions
• Allow for direct chemical communication between
  adjacent cellular cytoplasm through diffusion
  without contact of the extra cellular fluid.
• Protrudes across the cell membrane, and when 2
  adjacent cells interact, they form the gap
  junction channel.
• Play vital roles in the human body, including
  their role in the uniform contractile of the
  heart muscle.
• They are also relevant in signal transfers in the
  brain, and their absence shows a decreased cell
  density in the brain.
• Retinal and skin cells are also dependent on gap
  junctions in cell differentiation and
  proliferation.

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Organs and Organ Systems

• An organ is a collection of tissues joined in a
  structural unit to serve a common function
• Organs are composed of main tissue, parenchyma,
  and "sporadic" tissues, stroma.
• The main tissue is that which is unique for the
  specific organ, such as the specialized cells of
  the stomach,
• Sporadic tissues include the nerves, blood
  vessels, and connective tissues.
• Functionally related organs often cooperate to
  form whole organ systems.
• A hollow organ is a visceral organ that forms a
  hollow tube or pouch, such as the stomach or
  intestine, or that includes a cavity, like the
  heart or urinary bladder

Used with permission from imgarcade.com
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Organ Systems

• 1. Circulatory System The main function of this
  system is to transport nutrients and gasses to
  cells and tissues throughout body. This is
  accomplished by the circulation of blood.
• Cardiovascular comprised of the heart, blood,
  and blood vessels. The beating of the heart
  drives the cardiac cycle which pumps blood
  throughout body.
• Cardiovascular organs
• heart, blood vessels, blood
• Lymphatic This system is a vascular network of
  tubules and ducts that collect, filter, and
  return lymph to blood circulation.
• As a component of the immune system, the
  lymphatic system produces and circulates immune
  cells called lymphocytes.
• Lymphatic organs
• lymph vessels, lymph nodes, thymus, spleen,
  tonsils

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Organ Systems

• 2. Digestive System This system breaks down food
  polymers into smaller molecules to provide energy
  for the body.
• Digestive juices and enzymes are secreted to
  break down the carbohydrates, fat, and protein in
  food.
• Primary organs
• mouth, stomach, intestines, rectum
• Accessory organs
• teeth, tongue, liver, pancreas
• 3. Endocrine System This system regulates vital
  processes in the body including growth,
  homeostasis, metabolism, and sexual development.
  Endocrine organs secrete hormones to regulate
  body processes.
• Endocrine structures
• pituitary gland, pineal gland, thymus, ovaries,
  testes, thyroid gland

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Organ Systems

• 4. Integumentary System This system protects the
  internal structures of the body from damage,
  prevents dehydration, stores fat and produces
  vitamins and hormones.
• Integumentary structures
• skin, nails, hair, sweat glands
• 5. Muscular System This system enables movement
  through the contraction of muscles.
• Structures
• muscles

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Organ Systems

• 6. Nervous System This system monitors and
  coordinates internal organ function and responds
  to changes in the external environment
• Structures
• brain, spinal cord, nerves
• 7. Reproductive System This system enables the
  production of offspring through sexual
  reproduction.
• It is comprised of male and female reproductive
  organs and structures which produce sex cells and
  ensure the growth and development of offspring.
• Male organs
• testes, scrotum, penis, vas deferens, prostate
• Female organs
• ovaries, uterus, vagina, mammary glands

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Organ Systems

• 8. Respiratory System This system provides the
  body with oxygen via gas exchange between air
  from the outside environment and gases in the
  blood.
• Respiratory organs
• lungs, nose, trachea, bronchi
• 9. Skeletal System This system supports and
  protects the body while giving it shape and form.
• Structures
• bones, joints, ligaments, tendons, cartilage

Both diagrams used with permission from
imgarcade.com
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Organ Systems

• 10. Urinary/Excretory Systems consists of the
  kidneys, ureters, urinary bladder, and urethra.
• The kidneys filter the blood to remove wastes and
  produce urine.
• The ureters, urinary bladder, and urethra
  together form the urinary tract, which acts as a
  plumbing system to drain urine from the kidneys,
  store it, and then release it during urination.
• Besides filtering and eliminating wastes from the
  body, the urinary system also maintains the
  homeostasis of water, ions, pH, blood pressure,
  calcium and red blood cells
• Structures
• kidneys, urinary bladder, urethra, ureters

Used with permission from imgarcade.com
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Organs and Organ Systems

• It is important to keep in mind that these organ
  systems don't just exist as individual units.
• The final product of these cooperating systems is
  one unit called the body.
• Each system depends on the others, either
  directly or indirectly, to keep the body
  functioning normally.

Used with permission from imgarcade.com
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The Skin an example of an organ system

• The skin is the largest organ in the human body.
• For the average adult human, the skin has a
  surface area of between 1.5-2.0 square meters
  (16.1-21.5 sq ft.), most of it between 23 mm
  (0.10 inch) thick.
• On average it weighs about 9 pound
• The average square inch (6.5 cm²) of skin holds
• 650 sweat glands
• 20 blood vessels
• 60,000 melanocytes
• more than 1,000 nerve endings

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The Skin an example of an organ system

• Skin performs the following functions
• Protection an anatomical barrier from pathogens
  and damage between the internal and external
  environment in bodily defense
• Sensation contains a variety of nerve endings
  that react to heat and cold, touch, pressure,
  vibration, and tissue injury
• Heat regulation Dilated blood vessels increase
  perfusion and heat loss, while constricted
  vessels greatly reduce cutaneous blood flow and
  conserve heat.

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The Skin an example of an organ system

• Control of evaporation the skin provides a
  relatively dry and semi-impermeable barrier to
  fluid loss.
• Loss of this function contributes to the massive
  fluid loss in burns.
• Aesthetics and communication Some trained
  professionals see our skin and can assess our
  mood, physical state and attractiveness.
• Storage and synthesis acts as a storage center
  for lipids and water, as well as a means of
  synthesis of vitamin D by action of UV on certain
  parts of the skin.

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The Skin an example of an organ system

• Excretion sweat contains urea, however its
  concentration is 1/130th that of urine, hence
  excretion by sweating is at most a secondary
  function to temperature regulation.
• Absorption the cells comprising the outermost
  0.250.40 mm of the skin are "almost exclusively
  supplied by external oxygen", although the
  "contribution to total respiration is
  negligible".
• Water resistance The skin acts as a water
  resistant barrier so essential nutrients aren't
  washed out of the body.

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Homeostasis

• Homeostasis is the property of a system in which
  variables are regulated so that internal
  conditions remain stable and relatively constant.
• Examples of homeostasis include the regulation
  of
• temperature
• balance between acidity and alkalinity (pH).
• It is a process that maintains the stability of
  the human body's internal environment in response
  to changes in external conditions.

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The End!