Download 1 Unit 1: The Body as a Whole

Unit 1: The Body as a Whole
Structural and Functional Organization of the Human Body
I.
Levels of Organization in the Body
a)
b)
c)
d)
e)
f)
II.
Chemical – atoms combined to form molecules
Cellular – cells are made of molecules
Tissue – consists of similar types of cells
Organ – made up of different types of tissues
Organ system – consists of different organs that work closely together
Organismal – made up of the organ systems
Organ Systems of the Body
a) Integumentary System
• Forms the external body covering
• Composed of the skin, sweat glands, oil glands, hair, and nails
• Protects deep tissues from injury and synthesizes vitamin D
b) Skeletal System
• Composed of bone, cartilage, and ligaments
• Protects and supports body organs
• Provides the framework for muscles
• Site of blood cell formation
• Stores minerals
c) Muscular System
• Composed of muscles and tendons
• Allows manipulation of the environment, locomotion, and facial expression
• Maintains posture
• Produces heat
d) Nervous System
• Composed of the brain, spinal column, and nerves
• Is the fast-acting control system of the body
• Responds to stimuli by activating muscles and glands
e) Cardiovascular System
• Composed of the heart and blood vessels
• The heart pumps blood
• The blood vessels transport blood throughout the body
f) Lymphatic System
• Composed of red bone marrow, thymus, spleen, lymph nodes, and lymphatic vessels
• Picks up fluid leaked from blood vessels and returns it to blood
• Disposes of debris in the lymphatic stream
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• Houses white blood cells involved with immunity
g) Respiratory System
• Composed of the nasal cavity, pharynx, trachea, bronchi, and lungs
• Keeps blood supplied with oxygen and removes carbon dioxide
h) Digestive System
• Composed of the oral cavity, esophagus, stomach, small intestine, large intestine, rectum,
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anus, and liver
Breaks down food into absorbable units that enter the blood
Eliminates indigestible foodstuffs as feces
i) Urinary System
• Composed of kidneys, ureters, urinary bladder, and urethra
• Eliminates nitrogenous wastes from the body
• Regulates water, electrolyte, and pH balance of the blood
j) Male Reproductive System
• Composed of prostate gland, penis, testes, scrotum, and ductus deferens
• Main function is the production of offspring
• Testes produce sperm and male sex hormones
• Ducts and glands deliver sperm to the female reproductive tract
k) Female Reproductive System
• Composed of mammary glands, ovaries, uterine tubes, uterus, and vagina
• Main function is the production of offspring
• Ovaries produce eggs and female sex hormones
• Remaining structures serve as sites for fertilization and development of the fetus
• Mammary glands produce milk to nourish the newborn
l) Organ System Interrelationships
• The integumentary system protects the body from the external environment
• Digestive and respiratory systems, in contact with the external environment,
take in
nutrients and oxygen
• Nutrients and oxygen are distributed by the blood
• Metabolic wastes are eliminated by the urinary and respiratory systems
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Cells, Body fluids & concept of homeostasis
I.
Cell Theory
• The cell is the basic structural and functional unit of life
• Organismal activity depends on individual and collective activity of cells
• Biochemical activities of cells are dictated by subcellular structure
• Continuity of life has a cellular basis
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II. Structure of a Typical Cell Membrane
a) Plasma Membrane
• Separates intracellular fluids from extracellular fluids
• Are selectively permeable
• Plays a dynamic role in cellular activity
• Glycocalyx is a glycoprotein area abutting the cell
that provides highly specific
biological markers by which cells recognize one another
b) Fluid Mosaic Model
• Double bilayer of lipids with imbedded, dispersed proteins
• Bilayer consists of phospholipids, cholesterol, and glycolipids
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- Glycolipids are lipids with bound carbohydrate
- Phospholipids have hydrophobic and hydrophilic bipoles
Some proteins are integral; span entire membrane. Include transport proteins (permeases).
Some are peripheral; include receptor proteins for hormones, matrix of structural proteins that
attach to membrane and provide shape, etc
c) Functions of Membrane Proteins
• Transport
• Enzymatic activity
• Receptors for signal transduction
• Intercellular adhesion
• Cell-cell recognition
• Attachment to cytoskeleton and extracellular matrix
d) Passive Membrane Transport
• Diffusion
i) Simple diffusion – nonpolar and lipid-soluble substances
- Diffuse directly through the lipid bilayer
- Diffuse through channel proteins
Examples: ethanol (alcohol, contains both polar and non-polar regions); also fatty
acids, glycerol, steroids, etc & nonpolar gases like O2)
ii) Facilitated diffusion – large, polar molecules such as simple sugars
- Combine with protein carriers (i.e. protein-mediated transport)
• Osmosis
i) Occurs when the concentration of a solvent is different on opposite sides of a
membrane
ii) Diffusion of water across a semipermeable membrane
iii) Osmolarity – total concentration of solute particles in a solution
• Filtration
i) The passage of water and solutes through a membrane by hydrostatic pressure
ii) Pressure gradient pushes solute-containing fluid from a higher-pressure area to a
lower-pressure area
e) Active Transport
• Uses ATP to move solutes across a membrane
• Requires carrier proteins
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Example: Na+, K+ ATPase in nerve cells. Pumps Na+ to outside, K+ in, maintains
electrical potential against diffusion. When nerve cell "fires", momentary gates open
to let diffusion occur. Then pumps are turned back on to restore potential.
f) Types of Active Transport
• Symport system
• Antiport system
• Primary active transport
• Secondary active transport
g) Vesicular Transport
• Transport of large particles and macromolecules (proteins, nucleic acids,
polypeptides & polysaccharides) across plasma membranes
• Exocytosis
• Endocytosis
• Receptor-mediated transport
Certain important molecules or ions are not brought into cell by transport processes,
but by receptor-mediated endocytosis
III. Homeostasis
Cell survival depends upon some basic requirements, such as consumption of oxygen, release
of carbon dioxide and nitrogenous waste, breakdown down of nutrients, maintenance of ionic
equilibrium, an ability to respond to local extracelluar change, and in some cases cell division.
These cellular requirements are reflected in the air we breathe, the food we eat, and the waste we
excrete.
Homeostasis is the maintenance of relatively constant conditions within the body's internal
environment. Many physiological parameters, such as blood glucose and body temperature, are
precisely regulated by a homeostatic mechanism. Regulation of a physiological event usually
occurs via a feedback mechanism. Negative feedback is more common and is the response of the
system in a direction opposite to the change that set it in motion. The end result of negative
feedback is to bring a deviation in a physiological event back into line. Conversely, positive
feedback is a response which further enhances the change that set it in motion. Fast forward
mechanisms cause changes in a physiological variable before they are actually needed.
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