Midterm 3 Flashcards
What is the primary function of the endocrine system?
Integration and regulation of growth and development
What are the four chemical classifications of hormones?
Amines: derived from tyrosine and tryptophan
Polypeptides and proteins
Glycoproteins: long polypeptides bound to a carbohydrate
Steroids: lipids derived from cholesterol
What are the major endocrine glands?
Hypothalamus, pituitary, thyroid, parathyroid, adrenal, pancreas, ovary/testis
Describe how hormones are classified
polar: water soluble, must be injected if used as a drug
Nonpolar: insoluble in water, called lipophilic hormones, can enter target cells directly, can be taken orally in pill form
Distinguish prohormones and prehormones
Prohormones-inactive hormones that must be cut and spliced together to be active (proinsulin –> insulin)
Prehormones–inactive hormones that must be modified within their target cells
Distinguish synergistic, permissive, and antagonistic effects of hormones
Synergistic–occurs when 2 or more hormones work together to produce a particular effect. May be additive or complementary.
Permissive–occurs when one hormone makes the target cell more responsive to a 2nd one.
Antagonistic–occurs when hormones work in opposite directions
Describe hormone half life
Most hormones are removed within minutes to hours, thyroid hormones take days
Describe the significance of hormone concentration
Tissues only respond when hormone concentration is at a certain “normal” level. At higher concentration, effects may be different, which may result in binding of hormones to receptors of related hormones, sometimes causes widespread side effects.
what do flexor muscles do? what do extensor muscles do?
Flexor: decrease angle between bones
Extensor: increase angle between bones
What is a motor unit composed of?
Neuromuscular junction and somatic motor axon
What are the components of muscle fiber striations
I bands (light) and A bands (dark)
What are the two types of muscle fibers and what are they composed of?
Thick: protein myosin
thin: protein actin
What is the sliding filament theory
A and I bands do not shorten. Thin filaments slide towards each other, H bands DO shorten
What is a skeletal muscle twitch?
When muscle quickly contracts and relaxes after electrical shock
What is tetanus?
Increase in frequency of electrical shocks decreases relaxation time. Complete tetanus: no relaxation
What is treppe?
As voltage increases, # of muscle fibers uses increases. Staircase effect: when fresh muscle is stimulated with several shocks at max voltage and twitches are stronger
Distinguish isotonic and isometric contractions
Isotonic: muscle fibers shorten, tension is greater than load
Isometric: muscle fibers can’t shorten, load too great, can be voluntary.
Distinguish concentric vs eccentric contraction
Concentric: muscle fiber shortens
Eccentric: muscle fbier lengthens, ex. lowering dumbell after concentric contraction
List four muscle strength determinants
- # s of fibers recruited to contract
- frequency of stimulation
- Thickness of each muscle fiber
- Initial length of fiber at rest
Where do muscles get their energy?
Rest and mild exercise–fatty acids
Moderate exercise–glycogen
Heavy exercise–blood glucose (GLUT4 channels inserted into sarcolemma)
Differentiate between slow and fast twitch fibers
Slow-(type 1) slower contraction speed, can sustain contraction for long periods without fatigue, rich capillary supply, more mitochondria, more respiratory enzymes, more myoglobin
Fast (type 2)–faster contraction speed, fatigue fast, fewer capillaries, mitochondria, respiratory enzymes and less myoglobin
Intermediate (type 2a)–fast twitch but with high oxidative capacity
What are causes of muscle fatigue
- -Accumulation of extracellular K+, reducing membrane potential
- -Depletion of stored glycogen
- -reduced SR calcium release
- -lactic acid accumlation and lower pH
- -Increased concentration of PO4 due to phosphocreatine breakdown
- -Lack of ATP
- -Buildup of ADP
- -Fatigue for upper motor neurons, called central fatigue
What is hypertrophy?
Type 2 muscle fibers become thicker due to increased amount of actin and myosin (more sarcomeres)
What do satellite cells do?
Fuse to damaged muscle cells and repair them or fuse to each other to form new fibers
why does muscle decline with aging?
Reduced muscle mass and capillary blood supply, few satellite cells and increased myostatin production
What are the functions of the circulatory system?
Transportation, regulation and protection
What are the components of the circulatory system?
Cardiovascular and lymphatic systems
What is the blood composition? Volume, fluid portion, and cellular portion
5 L or 8% of body weight
Fluid portion: plasma 55% of total blood volume
Cellular portion: formed elements 45%
What makes up plasma?
plasma proteins, serum, gamma globulins
What are the characteristics of erythrocytes?
They are red blood cells, they carry oxygen, have a 120 day life span, contain hemoglobin and transferrin
What are the characteristics of leukocytes?
White blood cells, granular vs. aggranular, leukemia: increased number of immature leukocytes
What are the characteristics of platelets?
thrombocytes: smallest formed element, 5-9 day life span, clot blood, release serotonin
What is hematopoiesis? How many cells are produced in a day and where?
Process of blood formation. 500 billion cells produced a day in bone marrow.
What are some characteristics of hematopoeietic stem cells?
Undifferentiated, multipotent
What is leukopoiesis?
White blood cell formation, in myeloid and lymphoid tissues, interleukin
What is erythropoeisis?
Red blood cell formation, 2.5 million produced per second, erythropoietin
What is hepcidin?
Regulates iron metabolism
What are antigens?
Agglutinogens, found on surface of cells to help immune system recognize self cells. E.g. type A blood has the A antigen
What are antibodies?
Agglutinins, secreted by lymphocytes in response to foreign cells