Unit 6 Review Flashcards
Control Mechanisms of heart rate
Control of heartbeat: myogenic, nervous system (nerves and medulla oblongata), and endocrine system (adrenal glands)
Myogenic = signal for cardiac contraction arises in heart muscle itself
1. SA (sinoatrial) node in right atrium generates impulse, stimulating atria to contract (top to bottom)
2. Impulse reaches junction between atria and ventricles and activates AV node
3. AV node waits ~0.1 sec then sends signals causing ventricles to contract from the bottom – apex of heart – up, so that blood is pushed up and out of ventricles to arteries
*This sequence of events ensures delay
between atrial and ventricular contraction
(maximizing blood flow)
The RATE at which this sequence of events happens is your RESTING( myogenic) heart rate
Pacemaker (SA node) under control of autonomic nervous system (medulla oblongata of brainstem)
1. IF CO2 levels rise: medulla sends signal to SA node through CARDIAC NERVE to cause SA node to fire more frequently 2. As CO2 levels decrease: medulla sends signal to SA node through VAGUS NERVE to cause SA node to fire less frequently (decreasing heart rate/ returning to normal/ resting)
*Note: Adrenal gland (on top of kidney) can also speed up heart rate by releasing adrenaline into bloodstream
Production and function of antibodies
Macrophages identify “non-self” antigens and engulf/ ingest pathogens
Antigens (or pieces of them) from the pathogen remain in the macrophage and are presented on the macrophage cell membrane to helper-T cells which “activates” them
Helper-T cells release cytokines to activate specific B cells (B lymphocytes – produced in bone marrow) in the body that are able to produce the specific antibody that is needed for that specific pathogen
Because B cells exist in VERY small numbers in the bloodstream, once they are activated, they begin to divide rapidly so that there are enough of them to produce the proper antibody in large enough amounts to be effective –B cell cloning / clonal selection
B cell cloning produces TWO types of cells:
1. Antibody-secreting plasma cells make and secrete antibodies immediately to “target” the infection for destruction
Note: Antibodies are Y-shaped proteins that are SPECIFIC to one type of antigen and contain SPECIFIC antigen-binding sites
Antibodies bind to an antigen and “tag” it for phagocytosis and lysis or cause pathogen to agglutinate (stick together)
2. Memory cells: long-lived cells which do not secrete antibodies initially. Instead, they
remain in the bloodstream to provide LONG-TERM IMMUNITY - will secrete antibodies if a secondary infection occurs (providing your body with immunity from the same
pathogen should it invade again)
Role of valves in the mammalian heart
a. prevents backflow/ensures one-way flow/controls direction of flow
b. opening and closing of valves controls timing of blood flow «during cardiac cycle»
c. closed «semilunar» valves allow ventricles/chambers to fill with blood
OR
closed «semilunar» valves allow pressure in ventricles to rise «rapidly»
d. valves open when pressure is higher upstream/OWTTE/converse for closed valves
e. AV/bicuspid/tricuspid/mitral valves prevent backflow from ventricle to atrium
OR
AV/bicuspid/tricuspid/mitral valves open when pressure in atrium is higher «than in the ventricle»/when atrium is pumping/contracting
f. semilunar/aortic/pulmonary valves prevent backflow from artery to ventricle
OR
semilunar/aortic/pulmonary valves open when pressure in ventricle is higher «than in the artery»/when ventricle is pumping/contracting
Allow mpa, mpb, mpc or mpd if the point is made through the example of one specific valve.
How the structures of the alveoli are adapted to their function (including pneumocytes)
TRIM!!!
Thin wall – Single layer of cells (small diffusion distance)
Rich capillary network – maintain concentration gradients, and
only one cell thick too
Increased SA:V ratio – small, spherically shaped to increase
surface area and decrease volume
Moist – cells in lining secrete fluids to allow gases to dissolve so it
diffuses easier into blood (and to prevent alveoli from collapsing
on selves!)
Alveoli cells are pneumocytes:
Type I: Gas Exchange (flattened/ thin to increase SA)
Type II: Secrete pulmonary surfactant - decreases surface tension so all alveoli expand at same rate under unequal pressure (prevent cells from collapsing in on/ sticking to themselves) - cube shaped
