BLG111 Quiz 2: Chapters 19, 20, 21 Flashcards
Compare and contrast arteries, veins, and capillaries
Arteries: carry (mostly oxygenated) blood away from the heart; non-oxygenated blood is carried through the arteries during pulmonary circulation
Capillaries: have direct contact with tissue cells and directly serve cellular needs
Veins: carry (mostly deoxygenated) blood toward the heart; deoxygenated except for the pulmonary circulation and umbilical vessels of fetus
What are the forces acting across the capillary wall
See slide #49
Define Blood Vessels
Blood vessels consist of three layers: a smooth inner layer, a muscular layer, and a connective tissue layer. They deliver blood around the body and work very closely with the lymphatic system. Working together, they redistribute the fluids of the body.
All blood vessels consist of a central blood-containing space called a..?
Lumen
All walls of vessels, except capillaries, have three layers known as…?
Tunics.
1. Tunica intima: simple squamous epithelium that lines lumen of all vessels (great for diffusion)
2. Tunica media: middle layer composed of mostly smooth muscle and sheets of elastin (innervated by the sympathetic nervous system for constriction and dilation)
3. Tunica externa: composed mostly of loose collagen fibers that protect and reinforce wall and anchor it to surrounding structures
Arteries are divided into three groups, based on size and function - what are these three groups?
- Elastic arteries: thick-walled with large, low-resistance lumen (i.e., aorta)
- Muscular arteries: have thickest tunica media with more smooth muscle, but less elastic tissue (i.e., active vasoconstriction)
- Arterioles: smallest of all arteries, also called resistance arteries
Most capillary endothelial cells are joined by tight junctions with gaps called…?
Intercellular clefts that allow for passage of fluids and small solutes
What are the three types of capillaries?
- Continuous: least permeable and most common (i.e., skin, muscles, lungs, CNS, and brain)
- Fenestrated: endothelial cells contain swiss-cheese-like pores called fenestrations that allow for increased permeability; found in areas involved in active filtration (kidneys), absorption (intestines), or endocrine hormone secretion
- Sinusoidal: fewer tight junctions, usually fenestrated with larger intercellular cleft - blood flow is sluggish so allows time for modification of large molecules and blood cells (i.e., liver, bone marrow, spleen, adrenal medulla)
Why are veins called capacitance vessels?
Otherwise known as blood reservoirs, because they contain up to 65% of blood supply
Dilated and painful veins due to incompetent (leaky) valve are known as…?
Varicose veins
What is blood flow?
Volume of blood flowing through a vessel, organ, or entire circulation in a given period and is measured in ml/min; it is equivalent to cardiac output for entire vascular system
Define blood pressure
The force per unite area exerted on the wall of a blood vessel by blood
Define peripheral resistance
Is a measurement of the amount of friction blood encounters with vessel walls, generally in peripheral (systemic) circulation. There are three important sources of resistance: blood viscosity, total blood vessel length, and blood vessel diameter.
Blood flow (F) is directly proportional to _______; blood flow is inversely proportional to _______.
blood pressure gradient (P); peripheral resistance (R)
F = P/R
The blood pressure near the heart is considered…?
Pulsatile, it rises and falls with each heartbeat
Why is systemic pressure highest in the aorta?
- Elasticity of arteries close to the heart
- Volume of blood forced into them at any time
Define pulse pressure
The difference between systolic and diastolic pressure. 0.5 is diastole, 0.3 is systole of the 0.8 seconds in a heart beat.
What is the systolic pressure?
The pressure exerted in aorta during ventricular contraction. The left ventricle pumps blood into the aorta, imparting kinetic energy that stretches aorta which averages 120 mm Hg in a normal adult.
Define Mean Arterial Pressure (MAP)
The pressure that propels blood to the tissues. The heart, however, spends more time in diastole, so it is not just a simple average of diastole and systole.
Why is a low capillary pressure desirable?
- High BP would rupture fragile, thin-walled capillaries
- Most capillaries ae very permeable, so low pressure forces filtrate into interstitial spaces
Low venous blood pressure requires adaptations to help with venous return, what are these adaptations/
- Muscular pump: the contraction of skeletal muscles “milks” blood back toward the heart; valves prevent backflow
- Respiratory pump: pressure changes during breathing move blood toward the hear by squeezing abdominal veins as thoracic veins expand
- Sympathetic venoconstriction: under sympathetic control, smooth muscles constrict, pushing blood back toward the heart
How do neural controls impact blood pressure regulation?
- Cardiovascular center of the medulla: sympathetic innervation controls vasomotor tone and dilation
- Baroreceptors: sense changes in blood vessels and therefore blood pressure
- Chemoreceptor reflexes: sensitive to changes in blood gas measurements (i.e. increase in CO2, or decrease in pH or O2)
- Influence of higher brain centers (i.e., hypothalamus)
How do hormonal controls impact blood pressure regulation?
Hormones regulate BP in short term via changes in peripheral resistance or long term via changes in blood volume.
1. Adrenal medulla hormones (epinephrine and norepinephrine) increase CO and vasoconstriction
2. Angiotensin II stimulates vasoconstriction
3. ADH in high levels can cause vasoconstriction
4. Atrial natriuretic peptide decreases BP by antagonizing aldosterone, causing decreases in blood volume
How do the kidneys regulate arterial blood pressure independently of hormones?
- Increase in BP or blood volume causes the elimination of more urine, thus reducing BP
- Decreased BP or blood volume causes kidneys to conserve water, and BP rises
What is tissue perfusion and what is it involved in?
Blood flow through body tissues; involved in:
1. Delivery of O2 and nutrients to, and removal of wastes from, tissue cells
2. Gas exchange (lungs)
3. Absorption of nutrients (digestive tract)
4. Urine formation (kidneys)
What is an extrinsic control?
sympathetic nervous system and hormones control blood flow through the whole body. controls how quickly fluid gets to certain tissues
What is an intrinsic control?
Blood flow is adjusted locally to meet specific tissue requirements (i.e., organs regulate their own blood flow by varying resistance of their own arterioles)
What are the four ways molecules use to travel across capillaries?
- Diffuse directly through endothelial membranes
- Pass through clefts
- Pass through fenestrations
- Active transport via pinocytotic vesicles or caveolae
What is hydrostatic pressure?
The force exerted by fluid pressing against wall; in capillaries this pressure tends to force fluid through capillary walls. It is greater at the arterial end (35 mm Hg) than at the venule end (17 mm Hg) keeping flow unidirectional
What is colloid osmotic pressure?
A “sucking” pressure created by non-diffusible plasma proteins pulling water back in the capillary
What is the lymphatic system?
The lymphatic system returns interstitial fluids and plasma proteins leaked from blood vessels back to the blood and consists of three parts:
1. Network of lymphatic vessels
2. Lymph: fluid in vessels
3. Lymph nodes: cleanse lymph
Why do lymphatic vessels have increased permeability?
- Endothelial cells overlap loosely to form one-way mini valves
- Mini valves are anchored by collagen filaments to matrix, so increases in ECF volume opens mini valves even more
What do lymphoid cells consist of?
- Immune system cells (i.e., lymphocytes, macrophages, dendritic cells)
- Supporting cells that form lymphoid tissue structures
What are lymphocytes?
Cells of the adaptive immune system that mature into one of two main types: T cells or B cells
What is an antigen?
Anything the body perceives as foreign, will launch an attack
What is the difference between T and B cells?
T cells manage immune response, some also attack and destroy infected cells; B cells produce plasma cells, which secrete antibodies
What are antibodies?
Antibodies mark antigens for destruction by phagocytosis or other means. They are also called Immunoglobulins (Igs) and are grouped into one of five Ig classes.
What are the primary lymphoid organs?
Areas where T and B cells mature. T and B cells originate in bone marrow, but only B cells mature there, T cells mature in Thymus.
What are secondary lymphoid organs?
Areas where mature lymphocytes first encounter their antigen and become activated (i.e., nodes, spleen, MALT, diffuse lymphoid tissue)
What are the two main functions of lymph nodes?
- Cleansing the lymph: macrophages remove and destroy microorganisms and debris that enter lymph
- Immune system activation
What is the function of the spleen?
The largest lymphoid organ is a site of lymphocyte proliferation and immune surveillance and response. Also cleanses the blood of aged blood cells and platelets, macrophages remove debris.
What is MALT?
Mucosa-associated lymphoid tissue that protects from pathogens trying to enter the body, can be found in Tonsils, Peyer’s patches, and Appendix
What are the two intrinsic systems of the immune system?
- Innate (nonspecific) defense system
- Adaptive (specific) defense system
What is the first line of defense in innate/non-specific immunity?
Surface barriers such as skin and mucous membranes provide a physical barrier as well as protective chemicals (i.e., acid, enzymes)
What is the second line of defense in innate/non-specific immunity?
The second line of defense is necessary if microorganisms invade deeper tissues, it includes:
1. Phagocytes
2. Natural Killer cells
3. Inflammatory responses (i.e., macrophages, WBCs, inflammatory chemicals)
4. Antimicrobial proteins (i.e., interferons and complement proteins)
5. Fever
What is opsonization?
When the immune system uses antibodies or complement proteins as opsonins that coat pathogens; they act as “handles” for phagocytes to grab on to, enhancing phagocytosis
What are Natural Killer cells?
Nonphagocytic, large granular lymphocytes that can recognize and kill malignant cells through apoptosis
What are the steps of inflammatory response during injury?
- Leukocytosis: neutrophils enter blood from bone marrow
- Margination: neutrophils cling to capillary wall
- Diapedesis: neutrophils flatten and squeeze out of capillaries
- Chemotaxis: neutrophils follow chemical trail
What are interferons?
A family of immune-modulating proteins. Cells infected with viruses can secrete interferons that “warn” healthy neighboring cells
What are complement proteins?
The complement system consists of ~20 blood proteins that circulate in blood in inactive form; activation enhances inflammation and also directly destroys bacteria
What are the three characteristics of adaptive immunity?
- Specific: recognizes and targets specific antigens
- Systemic: not restricted to the initial site
- Memory: mounts an ever stronger attacked to “known” antigens
What are the two main branches of the adaptive system?
- Humoral (antibody-mediated) immunity
- Cellular (cell-mediated) immunity
What is Humoral immunity?
The production of antibodies produced by lymphocytes that circulate freely in body fluid, they will bind temporarily with the target cell and mark it for destruction
What is Cellular Immunity?
Involves lymphocytes that act against the target cell, may directly kill or indirectly kill by releasing chemicals that enhance inflammatory response
What is a self-antigen?
Pathogens have antigens that help us to detect them as foreign bodies; but we also have antigens - known as MHC proteins that are found in the cells, they tell our immune system that these cells belong to us - please do not kill them
What are major histocompatibility complexes?
They are self-antigens and unique to each individuals; there are two types: MHC I includes all cells of our body except RBCs (no nucleus), and MHC II includes antigen presenting cells, dendritic cells, and B lymphocytes
What are the three crucial cell types of adaptive immunity?
- B lymphocytes - humoral immunity
- T lymphocytes - cellular immunity
- Antigen-presenting cells
What are the five steps of lymphocyte development, maturation, and activation?
- Origin: both lymphocytes originate in red bone marrow
- Maturation: B cells mature in bone marrow, T cells in Thymus
- Seeding secondary lymphoid organs and circulation
- Antigen encounter and activation
- Proliferation and differentiation
A few remain as memory cells…
What are antigen-presenting cells and what are the three major types?
APCs engulf antigens and present fragments of antigens to T cells for recognition
1. Dendritic cells
2. Macrophages
3. B cells
Describe the Humoral Immune response
B cells are activated when pathogen antigens bind to surface receptors. Proliferation occurs with the help of the helper T cell. B lymphocyte proliferates through mitosis and transforms into plasma cells and produces antibodies. Clone cells that do not become plasma cells become memory cells.
What are the two types of active humoral immunity?
- Naturally acquired: formed in response to actual bacterial or viral infection
- Artificially acquired: formed in response to vaccine of dead or attenuated pathogens
What is passive humoral activity?
Occurs when ready-made antibodies are introduced into the body
1. Naturally acquired: antibodies delivered to fetus via placenta or to infant through milk
2. Artificially acquired: injection of serum, such as gamma globulin
What is IgM?
The first immunoglobulin class secreted by plasma cells during the primary response; readily activates complement
What is IgA?
Found in body secretions such as saliva, sweat, intestinal juice, and milk. Helps to stop pathogens from attaching tp epithelial cell surfaces (including mucous membranes and the epidermis)
What is IgD?
Found on the B cell surface and functions as a B cell antigen receptor
What is IgG?
The most abundant antibody in plasma, accounting for 75-85% of circulating antibodies. The main antibody of both secondary and later primary responses. Readily activates complement
What is IgE?
Stem end binds to mast cells or basophils. Antigen binding to its receptor end triggers these cells to release histamine and other chemicals that mediate inflammation and an allergic reaction.
What are the defensive mechanisms used by antibodies?
- Neutralization: masks dangerous parts of bacterial exotoxins, viruses
- Agglutination: cell-bound antigens
- Precipitation: soluble antigens
- Complement fixation
What is a CD4 cell?
CD4 cells usually become helper T cells that can activate B cells, other T cells, and macrophages
What is a CD8 cell?
CD8 cells become cytotoxic cells that are capable of destroying cells harboring foreign antigens
What are the steps of activation and differentiation of T cells?
- Antigen binding: T cell antigen receptors bind to antigen-MHC complex on APC surface. TCR must recognize both the MHC and foreign antigen is displays.
- Proliferation and differentiation
Define hypersensitivities
immune responses to perceived (otherwise harmless) threat that cause tissue damage. Different types are distinguished by:
1. Their time course
2. Whether antibodies or T cells are involved
Antibodies cause immediate and subacute hypersensitivity
T cells cause delayed hypersensitivity
