Blood is everywhere how is this possible?
Vessels that leave the heart are pumped with blood and divide and split to all the major parts of the body; limbs, head, guts, major organs, body wall, skeleton, and muscles
Stuff moves in and out of blood:
Diffusion inside organs, muscles, structures, bones, and big vessels divide into smaller and smaller vessels and then into network-like capillary beds. This is where diffusion can happen rapidly. Then to get blood back to the heart capillaries feed into smaller veins into larger and larger veins into major veins that return to the heart.
Capillaries Infiltrate every tissue of the body:
Why?- Because the cell that make up every tissue need oxygen for cellular respiration, nutrients for cell metabolism, Immune cells nearby to eliminate invading microbes, and removal of waste from cell metabolism
Capillaries:
-arteries bring blood from heart/veins take blood to heart
-network of capillaries really connect artery to vein
-diffusion of needed substances only happen in microscopic thin walled capillaries.
Heart pumps blood:
-if more oxygen is needed heart pumps faster
- brain and guts are big users of oxygen
- muscles under activity are bigger users of oxygen
-during exercise more oxygen is needed so heart pumps faster
- pulse is the measure of how fast heart is pumping
*most common places to check pulse are rist and neck
Blood Pressure:
measures force of blood against wall of vessels
systolic pressure- highest point, as blood is being forced out of heart by contraction of heart muscle
diastolic- lowest point, between heart beats, when heart is inactive
Normal values of adult blood pressure- 95-135/50-90
hypertension- greater than 135 and greater than 90
hypotension- less than 95 and less than 50
Oxygen for cell Respiration:
Why do cells need oxygen?
cell respiration breaks down glucose to make high energy ATP bonds that can be used for cell metabolic reactions.
-glycolysis can happen without oxygen fermentation
-citric acid cycle
-elcectron transport chain
-every step of respiration catalyzed by proteins that are coded for DNA
How does oxygen get into the blood?
-oxygen diffuses into blood through lungs in lungs bronchioles branch and branch finally ending in tiny sacs called alveoli, each alveoli is surrounded by capillaries
-oxygen diffuses across super thin epithelial tissue of alveolus, across super thin epithelial tissue of capillaries, across red blood cell membrane and is held by hemoglobin protein molecules in red blood cells
Blood Cells:
Red blood cells are one of several types of blood cells, each second 3 million new red blood cells are formed by a special kind of mitosis, they have no nucleus or organelles, they are full of hemoglobin
White blood cells fight invading microbes as part of the immune system.
lymphocytes-recognize invaders
monocytes- engulf microbes
basophils- release substances that trigger the other cells
What are foreign invaders?
Bacteria are prokaryotic cells. Most life on earth is bacteria, most is not disease causeing, but immune system must recognize which dont casue disease
Viruses are escaped parts of DNA of different organisms. They can't live independent of the cells they escape from.
How do immune cells recognize invaders?
Invaders are bacteria, viruses, and any other substance that is not part of our body. During fetal and child development immune cells are exposed to out body's own cells and the proteins that they have on their surfaces. Thus happens mostly in the thymus and bone marrow. Those immune cell precursors that attack our own cells are eliminated. Those that recognize other cells contunue to develop T cells and B cells. This process is called clonal selection
The T cells and B cells recognize foreign proteins that are invaders but have been selected so that they don't recognize and try to kill the body's own cells
Antibody editing by clonal selection or deletion:
Variety of B cells produced by random recombinations of genes for variable regions of antibody.
During B cell development certain clonal lines are eliminated because their antibodies glom onto the body's own antigens
B cell production and clonal selection occurs in bone marrow during early years of life
Antibodies:
-are highly variable proteins that are produced by B cells in order to recognize the foreign proteins on the invaders called antigens
-are free in blood stream, when on surface of B cells they are called BCRs or B cell receptors, T cells also make variable proteins TCRs or T cell receptors
How do immune cells actually get rid of invaders?
-Phagocytes move through blood and into connective tissue (part of the inflamation responses cells and fluid move out of capillaries into surrounding aleolar tissues) then the macrophages actually engulf and dissolve the invading microbes.
There are several different sources of macrophages: cells in skin, phagocytes in blood, microglial cells in central nervous system
Non specific Immunity- does not rely on T and B cells or antibodies
specific immunity- based on specific antibodies that recognize the invader, they kill or engulf the invading microbes
AIDS- acquired immuen deficiency syndrome
HIV- human immune deficiency syndrome
*AIDS is caused by HIV virus
How is HIV transmitted?
Virion- loose virus, doesn't live long outside the body
-through blood and body fluid contact
-other std's are more easily transmitted but aren't as fatal
HIV infects helper T cells:
Type 1- stimulate cytotoxic T-cells
Type 2- stimulate cytotoxic B- cells
-helper T cells recognize antigens, but cant do anything about it on their own, they secrete cytokines to direct what kind of immune response should be activated. For most infections Helper T cells are crucial for robust response
In AIDS these cells are killed as they themselves present viral antigens and invite cytotoxic T cells or macrophages to ingest them, without helper T's good responses to infections cant be maintained
Immune response- complicated because HIV infects cells of immune system, HIV doesn't kill just lowers the body defenses as T cell levels drop.
http://www.city-data.com/forum/health-wellness/161657-flu-shots-yay-nay-9.html
The picture to your right is healthy T cells that help protect our body from invaders. The picture on the left is T cells that have been infected by AIDS.
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