bio 3 Flashcards
(137 cards)
1
Q
what is the purpose of the digestive system?
A
To mechanically and chemically digest food into monomers and simple components for absorption and later use as a source of energy, carbon chains and amino acids.
2
Q
Human are heterotrophs os they cannot___
A
make their own energy/food
3
Q
What are the two types of digestion?
A
Physical digestion: chewing, churning in stomach, breaking of food into smaller pieces and emulsification of fats by bile.
chemical: all breakdown of food that involves the breaking of bonds through the use of digestive enzymes.
4
Q
If the liver, pancreas and gallbladder are accessories to digestive organs, why are they part of digestive system outline? what do each do that is important to digestion?
A
The liver manufactures bile. The gall bladder concentrates and stores bile (but does NOT manufacture it). The pancreas secretes bicarbonate into the duodenum to neutralize the acidic chyme coming from the stomach. The pancreas also secretes six pancreatic digestive enzymes.
all essential to digestion
5
Q
What is saliva?
A
provides lubrication and amylase –> first digestive enzyme to which food is exposed to.
6
Q
Digestion begins in the mouth with the physical digestion of all food types and the chemical digestion of _____ only (via the enzyme ____)
A
carbohydrates; alpha amylase.
7
Q
Where is epiglottis?
A
u shaped fly that covers trachea when we eat food or swallow and lets air pass through when breathing.
8
Q
Where does the first stage of protein digestion happen?
A
stomach.
9
Q
Proteins in the stomach undergo _____ , a reaction catalyzed by the enzyme _____ . This enzyme begins as ____ , an example of a
zymogen. Zymogens are inactive enzyme precursors.
A
hydrolysis
pepsin
pepsinogen
10
Q
What are the four cell types of stomach lining?
A
1) mucous neck cells: make and secrete alkaline mucus to provide protection to neck cells from the stomach acidity.
2) chief cells: make and secrete zymogen pepsinogen into gastric pits/ stomach lumen.
3) parietal cells: secrete HCL, responsible for extreme acuity of stomach (pH=2) and turning pepsin into pepsinogen.
4) G- cells: make and secrete gastrin. Gastrin is released into the BLOOD and not gastric pit or stomach lumen like the others. Gastrin circulates back to parietal and chief cells and stimulate release of HCL and pepsinogen POSITIVE FEEDBACK.
11
Q
Is gastrin a peptide, a steroid, or a tyrosine derivative? Is gastrin likely to bind at a membrane receptor? If so, where would the receptor be?
A
peptide because it has to be soluble in blood
receptor on outside of membrane.
12
Q
In addition to pepsin, what other molecule assists in protein metabolism in the stomach?
A
The acid in the stomach denatures proteins. Recall from the Biology 1 lesson that acid is a protein denaturing agent.
13
Q
What prevents the tissues lining the stomach from being digested by pepsin?
A
The lining cells of the stomach are protected by a thick layer of mucus secreted by the mucus cells that line the gastric pits, one of four cell types present.
14
Q
What is the function of the liver?
A
metabolic brain of human body. It regulated blood concentrations of many different solutes, plays key roles in the metabolism of proteins, fats, and carbohydrates, detoxify chemicals, recycles metabolites and manufactures several key biomolecules.
Key functions:
- produces bile
-filters blood to remove toxins, drugs, metabolites, bacteria, etc.
-produces blood plasma proteins, including albumin, fibrinogen,
- regulated amin acid levels in the blood
-produces cholesterol and lipoproteins and packages them for transport (LDL, HDL, etc).
15
Q
What does the pancreas and liver release when there’s low blood glucose levels?
A
alpha cells in pancreas secrete glycogen, which stimulates glycogenolysis in the liver (breakdown of glycogen stored in the liver to form free glucose for release into the blood.
16
Q
What does the pancreas and liver release when there’s high blood glucose levels?
A
beta cells in pancreas release insulin, which stimulates glycogenesis in the liver and synthesize glycogen in liver,
17
Q
Insulin also stimulates the uptake of glucose from the blood into the cells. Finally, the liver converts lactate, glycerol, amino acids, and some TCA-cycle intermediates into glucose. Q9. This process, by which the liver makes new glucose, is called ___________________.
A
Gluconeogenesis
18
Q
What is the function of the pancreas?
A
- Pancreas is both an endocrine and an exocrine gland.
- It secretes a bicarbonate rich solution, which neutralizes the stomach acid, decreasing acidity of intestine pH=6.
- Secretes trypsin, chymotrypsin, pancreatic amylase, lipase, ribonuclease and deoxyribonuclease.
19
Q
what is function of trypsin, chymotrypsin, pancreatic amylase, lipase, ribonuclease and deoxyribonuclease
A
- Trypsin and chymotrypsin are both proteases that cleave peptide bonds at specific amino acid sequences.
- Pancreatic amylase catalyzes the hydrolysis of carbohydrates.
- Lipase catalyzes the hydrolysis of fats.
- Ribonuclease and deoxyribonuclease catalyze the hydrolysis of RNA and DNA respectively. Some students find this odd, thinking “Who eats DNA and RNA?” While it’s true we don’t think of either as a food group, anything made of living cells—plant, fungi, animal, etc.– will contain both of these polynucleotides.
20
Q
what is function of gallbladder?
A
stores and concentrates bile, but does not produce bile.
21
Q
where is bile produced?
A
liver
22
Q
Is bile’s action an example of physical or chemical digestion?
A
Bile emulsifies fats, but it does not break any bonds—therefore it is an example of physical rather than chemical digestion.
23
Q
What happens in the small intestine?
A
where majority of all digestion and absorption occurs; digestion in duodenum, absorption primarily in jejunum and ileum.
24
Q
Provide definition for:
villi, microvilli, lacteal and brush border.
how do they intertwine?
A
The villi are finger-like projections of the wall of the small intestine. They are hollow and contain both blood vessels and a single lymphatic vessel called a lacteal. Fats are absorbed into the lymph system via the lacteals and carbohydrates and proteins are absorbed into the blood. The villi dramatically increase the surface area available for absorption. Further, each epithelial cell lining a villus contains fingerlike projections of the cell membrane called microvilli.
The brush border is a name given to the microvilli and the collection of mucus and digestive enzymes intermingled within them.
25
What happens in large intestine?
"water absorption" , "vitamin absorption".
26
As a review from the Biology 1 Lesson, the relationship between humans and the E. coli in the colon is an example of what type of inter-species relationship?
mutualism
27
A disease or illness that inhibits the normal function of the large intestine will most likely result in ____ .
diarrhea, constipation, vitamin deficiency
28
Describes digestion:
Include the following terms: mouth, pharynx, epiglottis, esophagus, peristalsis, stomach, pepsin, gastric pits, small intestine (i.e., duodenum, jejunum, and ileum), bile, pancreatic enzymes, villi, microvilli, large intestine, colon (i.e., ascending, transverse, descending, and sigmoid), and rectum.
The most important roles of the mouth in digestion are to break up food into small pieces by chewing and to mix it with saliva, which contains the enzyme alpha-amylase and some specific classes of antibodies. The saliva lubricates the food, which aids its passage down the esophagus. Amylase initiates carbohydrate digestion. The pharynx ensures the bolus is delivered to the esophagus without entering the nasal cavities or the larynx, but no digestion of any kind occurs here and nothing is added to the bolus. The epiglottis is an upward-oriented cartilaginous flap that folds down over the opening to the larynx during swallowing to prevent food from entering the larynx. The esophagus utilizes peristalsis to push the bolus down and into the stomach. Peristalsis is the rhythmic contraction of smooth muscle in the wall of the gastrointestinal track that moves food forward. Once again, no digestion occurs in the esophagus and nothing is added. Food enters the stomach by passing through the cardiac sphincter, which is located at the junction of the esophagus and the stomach. The churning of the stomach continues physical digestion. The stomach is lined with gastric pits. Chief cells are one of four cell types lining these pits, which are, in turn, lined with four cell types. Chief cells, one of these cell types, release pepsinogen, a zymogen that will be converted to its active form, pepsin, by the low pH of the stomach lumen. Pepsin will hydrolyze proteins. Another of these cell types lining the gastric pits, the parietal cells, secrete the HCl that lowers the pH of the stomach to about 2. The partially digested food mix, now referred to as chyme, passes through the pyloric sphincter and into the upper portion of the small intestine, called the duodenum. The common bile duct and the pancreatic duct both release products into the duodenum. As a result, the duodenum receives bile from the liver and gallbladder, and, from the pancreas, a bicarbonate-rich solution and six digestive enzymes: trypsin and chymotrypsin digest protein, pancreatic amylase digests carbohydrates, lipase digests fats, and ribo- and deoxynuclease digest RNA and DNA. The bicarbonate ions are important because they raise the pH of the chyme to around 6—a necessary step because the enzymes just listed could not function at the much lower pH of the mixture arriving from the stomach. The chyme progresses through the small intestine to its middle section, the jejunum, and then to the final section, the ileum. There are no distinct
boundaries marking these three sections. Most digestion occurs in the duodenum and most absorption (of food molecules, not water) occurs in the jejunum and ileum. The lining of the small intestine features finger-like projections called villi that increase the surface area for absorption. Individual epithelial cells along each villus have microvilli—long fingerlike projections of the cell membrane on their apical surface. Each villus’ center is filled with blood vessels and a single lymph vessel called a lacteal. Fats are absorbed into the lacteal, NOT the blood vessels. Carbohydrates and proteins are absorbed into the blood vessels. The ileum empties into the large intestine on the right side of the abdomen (anatomical right) slightly above a blind (dead-end) pouch called the cecum. The appendix is attached to the cecum. The colon rises upward along the right wall of the abdomen (ascending colon), traverses across the abdomen (transverse colon) and then descends along the left wall (descending colon). The final segment of the colon is somewhat twisted and is therefore appropriately named the sigmoid colon. The primary function of the colon is the absorption of water and vitamins. The colon contains resident commensal bacteria that secrete vitamin K, thiamin, riboflavin, and vitamin B12. The rectum is the final segment of the large intestine. It connects to the anus and stores feces.
29
What are different places carbohydrates digested and into what?
carbohydrates digestion begins in the mouth with salivary amylase. --> through small intestine to be broken down into monomers BEFORE absorption. they enter bloodstream and travel to the LIVER via hepatic portal vein.
30
What are different places proteins are digested and into what?
Proteins are first digested in the stomach and is completed by the time they get to the small intestine, where they are small peptides and amino acids before absorption. They enter the blood stream and travel to the liver
31
What are different places lipids are digested and into what?
Digestion begins in small intestine (duodenum) and is complete by the end of the small intestine. Can only be broken down by bile and lipase which are in small intestine.
Triglycerides ar broken down to small peptides and amino acids before absorption. They enter the LACTELAS in to to travel in blood or lymph, all lipids must be either:
1) bind to protein carrier like albumin
2) from into a chylomicron or micelle.
32
The lining of the human stomach contains G-cells, cells that are primarily responsible for the secretion of the peptide hormone, gastrin. Some mammals have stomach linings that lack G-cells completely. It is likely that these mammals:
A) have developed immunity to the effects of gastrin.
B) consume a diet high in carbohydrates.
C) consume a diet high in proteins.
D) evolved in an environment where the presence of gastrin was a competitive advantage.
B- Gastrin stimulates the parietal cells to secrete HCl. That HCl serves two purposes: 1) It denatures proteins in the stomach, and 2) it activates pepsinogen to pepsin. Both functions are closely related to the digestion of proteins, so answer B is very plausible.
33
What is the function of the immune system?
Protect the body from infection and disease; destroy pathogens invading the body.
34
What are monocytes and what do they mature into?
Monocytes, a type of white blood cell, mature into macrophages, which phagocytize pathogens and cellular debris. Phagocytosis by macrophages is non-specific and a type of innate immunity, but macrophages also present antigens from pathogens they consume for recognition by B and T cells, an aspect of acquired immunity.
35
What are the three types of granulocytes?
| what do they all have in common?
neutrophils, basophils, eosinophils. all granulocytes are short-lived, do not reside permanently in the tissues, circulate in the blood, and are recruited to areas of infection of inflammation.
36
what are neutrophils?
stain a neutral pink.
Neutrophils are phagocytes that are recruited to areas of infection and inflammation by chemotaxis. They live for only about 5 days, but are the most abundant of all white blood cells. The pus created at a wound is mostly dead neutrophils.
37
what are basophils
stain dark blue- least common white blood cell. Their granules contain mostly histamine, which they release along with other chemicals when activated. These chemicals promote inflammation and are integral in the allergic response, so many associate basophils with allergies.
38
what are eosinophils?
recruited to areas of parasitic invasion, particularly multicellular parasites, where they release their granules containing peroxidases and other enzymes that digest tissue. This would destroy the pathogen but could also destroy host tissue
39
What are mast cells?
mast cells are permanent resident cells within many tissues. They are activated by allergens and other antigens to release histamine and other chemical mediators. They are usually associated with severe allergic reactions, including anaphylactic shock.
40
what are dendritic cells?
Dendritic cells are professional antigen-presenting cells. They efficiently phagocytize pathogens and present those antigens on their surface to stimulate other immune cells. Dendritic cells are white blood cells (leukocytes), but are not lymphocytes. They can form from monocytes (which also differentiate into macrophages) or independently in their own cell line from a blood cell precursor.
41
what are the three types of lymphocytes?
T cells, B cells, and natural killer cells.
42
what are natural killer cells?
Natural killer cells recognize infected or cancerous cells and release cytotoxic granules that destroy the cell.
43
What are T cells?
T cells are lymphocytes that mature in the thymus and participate in cell-mediated immunity.
- require receptor
- do NOT produce antibodies
44
What are B cells?
B-cells are lymphocytes that mature in the bone marrow and lymph tissues and participate in humoral immunity. B-cells produce antibodies,
45
What are plasma cells?
Plasma cells are formed when a B-cell binds its matching antigen and is activated (with the help of helper T-cells) to undergo mitosis. The division of the B-cells produces mostly plasma cells—clones of the original B-cell that act as “antibody factories,” making and secreting soluble copies of that antibody
46
What are memory B cells?
A few B cells will differentiate into memory B cells that remain in the body, allowing the immune system to mount a more efficient secondary immune response if there is a later infection by the same pathogen.
- humoral immunity
47
What are helper T cells?
“help” other immune system cells, such as B-cells and cytotoxic T-cells, to perform their function. The way they “help” other cells is usually to secrete chemicals, such as cytokines, that activate (i.e., “turn-on”) functions or activities in the cell that is being “helped”
48
What are suppressor T cells?
Suppressor T-cells (a.k.a., regulatory T-cells) suppress the body’s own immune system—which helps prevent severe allergic reactions or autoimmune disease and aids in turning off an immune response once an infection has been eliminated.
49
What are Killer T- cells?
Killer (or cytotoxic) T-cells target infected and cancerous versions of the body’s own cells and destroy them.
50
what is part of humoral immunity?
antibody- mediated immunity, includes cytokines, and memory cells. Humoral immunity components are found in both innate and adaptive immune system.
51
what is innate immunity?
The body’s non-specific attack of pathogens. All forms of innate immunity are
present at birth, NOT acquired in any way.
o Includes all immune responses that are NOT specific to one particular virus, bacteria, pathogen, etc. Examples include: skin, stomach acid, enzymes in the mucus and saliva, digestive enzymes, blood chemicals, fevers, inflammation, and non-specific phagocytosis.
52
what is adaptive/ acquired immunity?
A specific response to one particular virus, bacteria or other pathogen based upon prior exposure. There are two types of acquired immunity: humoral and cell-mediated.
53
what happens during an inflammatory response?
first, macrophages, mast cells, dendritic cells which are in all tissues will be activated when there's damage and release chemicals like histamines, leukotrienes, prostaglandins, which increase blood flow to the injury site and create redness/ heat + increase permeability of veins and lymph vessels, which uses plasm and interstitial fluid to flood the infection site and result in swelling (aka. Edema).
54
what are the different part of an antibody?
-disulfide bonds between heavy/ light chains.
- hypervariable region on end of chain.
- constan region
55
what's primary response?
The immune system's first exposure and reaction to a pathogen.
56
what's secondary response?
the immune system's response to that same pathogen during subsequent exposures.
57
What is cell mediated immunity?
T cell immunity - T cells are made in bone marrow but mature in thymus and are self tested against proteins found in host. All T cells matching for self proteins are destroyed. and the remaining ones differentiate.
58
when you see "cell mediated " think ...?
Self attack of diseased cells. - T cells
59
when you see "humor" think...?
antibodies and primary. secondary response - b-cells.
60
what is antigen presentation?
process by which a cell that has engulfed an antigen or microbe, (via receptor-mediated endocytosis or phagocytosis) takes protein segments of that microbe, and “presents” them on MHC (Major Histocompatability Complex) proteins embedded in its own cell membrane. This makes the engulfed antigen/foreign proteins available for other cells to “see.” ***Macrophages, dendritic cells, and B-cells*** “present” antigens in this way.
61
2) Exposure to an environmental toxin causes a genetic defect in the normal mechanism that manufactures new antibodies. If a person were exposed to a virus for the first time shortly after such an exposure, and was unable to manufacture new antibodies as a result:
A) viral antigens would not be recognized or bound by an antibody due to the host’s inability to manufacture new antibodies to match the pathogenic antigens.
B) viral antibodies would be bound by host antigens that were created as a match to those antibodies prior to the environmental exposure.
C) the antibody producing function of the host would be repaired by insertion of viral DNA into the host genome.
D) viral antigens would be bound by host antibodies created before the first exposure to the virus.
A favorite MCAT principle is the fact that antibodies are never created “in response to” or “to match” antigens. Antibody creation is a random process. The sheer number of antibodies created, coupled with a somewhat flexible binding requirement, ensures that a foreign antigen will be bound by a host antibody. Answer A is false because it employs the false “created to match” premise. Answer B uses this same flawed reasoning and confuses antibodies with antigens. Answer C is illogical because viruses are far too simple to contain a complete set of genes for a complex process such as antibody production. Answer D is therefore the best choice.
62
What is the integumentary system?
Protection against abrasion, physical barrier to pathogens, vitamins D, synthesis, insulation, cushioning, prevention of water- loss, temperature regulation.
63
What are the three layers of skin?
1) epidermis: outermost layer made of mostly dead or dying keratinized cells.
2) dermis: contains blood vessels, hair follicles, sebaceous glands (oil), sudoriferous glands (sweat), and nerve endings. CONNECTIVE TISSUE.
3) Hypodermis for thermoregulation:
- blood vessels closer to the surface of the skin, dilate when heat needs to be release and constrict when heat needs to be retained-arrector pill muscle carse erection of hair follicles that traps an insulating layer of air next to the skin.
- subcutaneous fat provides insulation
- sweating, followed by evaporation of the water in the sweat, carries away a significant amount of heat due to the high heat of vaporization of water and its high specific heat capacity.
64
What is the function of the musculoskeletal system?
movement, support and stabilization generation of heat, aide to circulation and maintenance of homeostasis.
65
what are characteristics of skeletal muscles?
voluntary, striated, and multinucleate.
66
what are the attachments that join muscles/ bone and bone/bone?
tendons attach muscle to bone and ligaments attach bone to bone.
67
what is a muscle group called? what is each __ made up of?
fasciculi. Each is made up of muscle fibers. Around each muscle cell is a specialized cell membrane
68
What are the muscles and bones in the human body an example of in terms of physics?
A poor lever system that works at a mechanical disadvantage.
69
what is the cell membrane surrounds each muscle called?
sarcolemma
70
They are long bundles of proteins composed primarily of actin and myosin fibers, they are ....?
myofibrils
71
What are sarcomeres made up of?
repeated interconnected actin and myosin fibers
72
Interwoven bundles of myofibrils and muscle's ER are...
sarcoplasmic reticulum.
73
what part of muscle stores and release calcium to initiate contraction?
sarcoplasmic reticulum.
74
How do the thick filament, thin filament, actin, myosin, myosin heads work together and relate to sarcomere?
The basic component of the thick filaments is myosin, a motor protein. Myosin subunits form myosin fibers, which have a two moieties: a globular head and a tail. Two of these fibers intertwine to make up a myosin molecule, a dimer. Many myosin molecules form the long myosin filaments of the sarcomere. The heads protrude from the myosin filament at an angle in the relaxed conformation, referred to as “bent” in the sliding filament model. Myosin heads have a high affinity for actin and bind it unless the actin binding sites are blocked by tropomyosin. The thin filaments are microfilaments and are polymers of the protein actin. They feature troponin and tropomyosin.
75
What are the different lines on a sarcomere?
All of the following terms refer to portions of the sarcomere. The A band is the length of the myosin filaments and does NOT change during contraction. The I band is the distance between the ends of the myosin filaments in one sarcomere to the ends in the next sarcomere. It is also the lightest band when viewed under a microscope because only the thin actin filaments are present in this region. The I band will shorten during a contraction. The H zone is the distance between the ends of the actin filaments. The H zone will also shorten during a contraction. The Z lines (a.k.a. Z discs) appear as zigzag lines that define the edges of each individual sarcomere unit. The actin filaments are anchored here by the protein connection and stretch out in both directions. During a contraction the distance between Z lines decreases as the sarcomere shortens. The M line is the center of the myosin filaments. The distance between M lines between two sarcomeres will decrease during a contraction.
76
3) When a relaxed muscle fiber contracts, all of the following will occur, EXCEPT:
A) The density of thick filaments per cubic centimeter of muscle fiber increases.
B) The distance between Z discs decreases and the distance between M lines remains constant.
C) The distance between adjacent M lines and between adjacent Z discs both decrease.
D) Myosin heads bind to actin and dissociate from it multiple times during the same contraction.
B
Answer A is true because the myosin bundles move closer together as the length of the muscle fiber decreases. Answer C is true because as the entire muscle fiber shortens all repeating segments move closer to one another. Answer D is true because some myosin heads must release while others simultaneously bind to allow the myosin to “crawl” along the actin filament.
77
What happens once the AP arrive at the neuromuscular junction?
1) ACh is released at neuromuscular junctions, initiating AP and
2) spreading it along muscle cell sarcolemmas and down T- tubules, which interface directly with sarcoplasmic reticulum (SR),
3) electrical impulse spreads from T- tubules to the SR, stimulating the SR to release calcium.
4) Calcium is pumped into SR and initiates muscle contraction.
78
What is the sliding filament mechanism?
Myosin filaments are bundle of individual myosin molecules. The globular myosin heads bind to the actin filaments to form myosin cross bridges responsible for the actual contractile mechanism.
Calcium binds to troponin which releases tropomyosin away from the active binding site on myosin and enables the myosin head to bind to actin filament. After binding, the myosin head releases ADP and Pi and pulls the actin filament forward.
After power stroke, ATP binds to the myosin head again facilitating its release from the actin filament and moving back to original position/ relaxing.
If Calcium is still around, the mechanism keeps going, otherwise, tropomyosin rebinds the myosin binding site.
79
What is the default low energy position for the myosin heads is ___
bent
80
What is ATP hydrolysis required for?
provides energy required to straighten or cock myosin heads into their high energy STRAIGHT position.
81
What happens to the muscle if no ATP is present ?
the myosin heads cannot detach from actin and the muscle will be stuck in a contracted position called "rigor".
82
What happens to the muscle if no Calcium is present?
Inability to contract.
83
what constitutes a motor unit?
Motor units can be small or large. One motor unit can innervate multiple muscle fibers but muscle fibers cannot have multiple motor units.
84
What motor unit are activated during small delicate movement?
very small motor units
85
what motor unit are activated during big contraction?
larger motor unit
86
What does the strength of a contraction depend on?
1) number of motor units being used
2) size of motor units being used
3) frequency of action potentials
87
What are important features of the skeletal muscle?
- store large amounts of glycogen
| - require lots of oxygen and even have myoglobin (their own oxygen storage muscle)
88
A common muscle relaxant acts on skeletal muscle by binding ATP and preventing it from interacting with the sarcomere. When this drug is present, which of the following is expected?
A) The myosin heads will not be able to bind to the actin filament.
B) The muscle fiber will remain in a flaccid state until ATP becomes available.
C) The myosin heads will be locked in the bent position.
D) The muscle fiber will be hyperstimulated by ADP.
ATP plays two important roles. First, it is required to release the myosin head from the actin binding site. Second, it must be hydrolyzed to move the myosin heads from their relaxed (bent) position to their high-energy (straight) position. Answer A is incorrect. Myosin can bind actin without ATP. Answer B is incorrect because muscles are locked in “rigor” if no ATP is available. ADP does not stimulate contraction, so Answer D is also false. Answer C is the only true statement.
89
What are characteristics of the cardiac muscle?
involuntary, striated, one nucleus.
90
How is the contraction of a cardiac muscle cell different from skeletal muscle cells?
Cardiac muscle cells have gap junctions (connect cytoplasm) and calcium calmodulin cascade activates an AP that i distributed at once throughout heart so that they all "beat" at the same time.
91
what type of muscle are cardia muscle?
smooth muscles
92
what are functions of bone?
physical support and movement, protection of vital structures and mineral storage and regulation of blood mineral concentration and blood cell formation.
93
what are osteocytes?
mature bone cells surrounded by mineral matrix
94
what are osteoclasts?
bone cells that break down and resorb bone matrix, releasing the component minerals (Ca+ and Phosphate) back into the blood.
95
what are osteoblasts?
immature bone cells that secrete collagen, organic compounds and minerals forming a bone matrix around themselves. --> eventually differentiate into osteocytes.
96
What two hormones regulate bone cells/ density?
The two hormones that regulate bone maintenance and blood calcium levels are parathyroid hormone (PTH) and calcitonin.
- Calcitonin tones your bone:
When blood levels are above normal, calcitonin inhibits osteoClast activity, which enables osteoBlast activity to continue. The calcium used by osteoblasts to build new bone matrix comes from the blood and therefore blood calcium levels decrease.
- Parathyroid hormone: stimulates osteoclast activity, resulting in the breakdown of bone matrix and release of the associated calcium into the blood --> blood calcium levels rises.
97
what is hematopoiesis?
name given to the formation and differentiation of blood cells in the bone marrow.
98
what is red bone marrow and yellow bone marrow?
Red bone marrow is where hematopoiesis occurs in the spongy bone.
Yellow bone marrow consists mostly of fat and fills the medullary cavity of long bones.
99
what are compact bones versus spongy bones?
dense bone that surrounds the outside of all bones and constitutes the shafts of long bones. The interiors of flat and irregular bones, as well as the bulbous ends of the long bones, are filled with spongy bone.
Spongy bones have many open spaces, formed by the interwoven trabeculae. These spaces are filled with red bone marrow.
100
What are the three joint types of skeletal structures?
1) fibrous (skull bones)
2) cartilaginous (pubic symphysis, intervertebral discs)
3) Synovial (knee, elbow, etc.)
101
What are the three bone types?
1) Long bones (femur, humerus)
2) Short bones (tarsals, carpals)
3) Flat bones (skull, sternum)
4) Irregular bones (hip, vertebrae)
102
What is the anatomy of a long bone?
Two epiphyses (bulbous ends) cushioned by cartilage; the ends are filled with spongy bone and the shaft in between is made of compact bone; the center is a hollow cavity filled with yellow bone marrow.
103
What is hydroxyapatite?
inorganic compound of calcium, phosphate and hydroxide. It is the mineral matrix responsible for a bone's strength and is the form in which most all of the body's calcium is stored.
104
What is a cartilage?
- A connective tissue composed mostly of collagen
- no perfusion or innervation
- found in appendages suchh as the nose and ears, at the ends of long bones, between vertebrae and at almost any joint or articulation.
105
what's the difference between proximal and distal epiphysis?
proximal - near articular cartilage
distal- further from articular cartilage
106
What are (functions) of penis, testicles, scrotum, sperm, seminiferous tubules, epididymis, vas deferens, seminal vesicles, prostate gland, bulbourethral gland, and urethra.
the penis is the male copulatory organ. It can also be thought of as playing a dual role in excretion and ejaculation because the urethra runs through it. The testicles serve the primary functions of making, nurturing and storing sperm. The scrotum is the thin sack of skin in which the testes are located. The external location of the scrotum allows the testicles to exist at a temperature a few degrees lower than the normal human body temperature of 37°C. The optimum temperature for spermatogenesis is 35°C. Sperm cells are the male haploid gametes. They are produced in the seminiferous tubules of the testes and move to the epididymis, where they are nurtured, fully matured, and stored until ejaculation. The vas deferens is a duct that connects each testicle with the urethra. Beginning at the epididymis, it leads up the inside of the scrotum, into the pelvic cavity, past the seminal vesicles, through the prostate gland, and empties into the urethra before the urethra enters the penis.
107
What is the purpose of the acrosome?
break ovum and enables penetration
108
What is the ejaculation pathway?
sperm leave epididymis via vas deference, arches back up into pelvis and down toward penis, going through seminal vesicles, prostate glands and Cowper's gland which secrete various lubricants (fructose and alkaline) and nutrients for sperm to go in with as food and supplies and transportation in harsh vagina domain. vas deferent empties into urethra which goes through penis.
109
which phase of meiosis are eggs arrested at at birth?
prophase I - completed at puberty
110
what is an immature egg called?
oocyte
111
What starts the menstrual cycle?
1) FSH (from anterior pituitary) stimulates maturation of ovum and the follicle in the ovary
2) LH stimulates cells in the ovaries to secrete estrogen , which signals the uterine wall to proliferate and prepare for a potential pregnancy AND acts as negative feedback to hypothalamus to stop LH release.
3) Surge in estrogen happens right before ovulation, which causes surge in LH, which signals for ovulation and development of corpus luteum.
4) Corpus luteum begins secreting estrogen and high levels of progesterone to signal the uterine lining to prepare for implantation.
5) IF implantation occurs (or you are taking the pill) the corpus luteum continues to secrete estrogen and progesterone maintaining pregnancy.
IF no implantation occurs, then everything drops and dies off.
112
where does fertilization occurs ?
fallopian tubes
113
which part of the menstrual cycle illustrates positive feedback mechanism?
On approximately day 14 of the menstrual cycle, high estrogen levels stimulate a rapid increase in luteinizing hormone (LH).
114
Which part of menstrual cycle causes bleeding?
Drop in hormone levels after high levels of hormone
115
Which part of menstrual cycle causes ovulation?
rise in hormone (LH and estrogen)
116
Persistne low levels of estrogen and progesterone lead to ..?
menopause
117
what is cleavage in embryology?
mitosis without change in size
118
what is morula in embryology?
eight celled zygote
119
what is gastrulation in embryology?
at about week 2, cells migrate to form the three germ layers
120
What is neurulation in embryology?
at about week 3, the notochord forms from the mesoderm and induces the overlying ectoderm to form the neural plate, which becomes the neural tube and eventually the spinal cord.
121
What is totipotent cell differentiation?
cells can give rise to all of the cell types in the body, including extra embryonic or placental cells. Embryonic cells within the first few cell divisions after fertilization are the only cells that are totipotent.
122
what is pluripotent cell differentiation?
cells can give rise to all of the cell types that make up the body, but not extra embryonic cells. Undifferentiated embryonic stem cells are considered pluripotent.
123
what is multipoint cell differentiation?
cells can develop into more than once cell type, but are further differentiated and more limited than pluripotent cells; adult stem cells and cord blood stem cells ar considered multipoint.
124
what are the three germ layers?
ectoderm= outer layer like epidermis, nail, tooth enamel, lens of the eye, pituitary gland, ...
mesoderm= middle structures like dermis, muscle, bone, connective tissue, organs
endoderm= innermost layers like the digestive tract, thyroid, parathyroid, urinary bladder, lining only of lungs, liver and pancreas.
125
A woman suffering from a heritable hormone abnormality has above-normal levels of estrogen and progesterone in her blood, but little to no luteinizing hormone or follicle stimulating hormone. Based on this information alone, one would expect this woman to:
A) develop a thick uterine lining and have heavy menstrual flow.
B) develop a thick uterine lining but lack regular menses.
C) be at risk for multiple births.
D) exhibit an over-developed corpus luteum.
B
| The MCAT directly associates high estrogen/progesterone levels with the thickening of the uterine lining.
126
A disease that imparts a cell's ability to polymerize tubular would most directly affect:
a) cilia in the microvilli of the small intestine
b) ependymal cells in the cerebrospinal cavities
c) cell division in myocytes
d) pepsin manufacture in he linen cells of the stomach
B
127
Drastic changes in pH are uncommon with the body generally but fluctuations in pH are frequently encountered in the digestive tract. Which of following accurately represents?the pH of stomach, mouth and duodenum respectively as well as chemical associated with it.
a) ph=2, pepsin; pH=7, bicarbonate, pH=6 bicarbonate ions
b) ph=2, pepsin; pH=7, buffer, pH=6 bicarbonate ions
c) ph=3, HCl; pH=7, buffer, pH=5 enzymes
d) ph=2, HCl; pH=7, buffer, pH=5 enzymes
b) ph=2, pepsin; pH=7, buffer, pH=6 bicarbonate ions
128
Aging women are often prescribed estrogen supplements to help offset the effects of osteoporosis. which of the following is a possible side effect?
a) decreased pituitary activity due to negative feedback
b) inappropriate lactation
c) loss of female secondary characteristics
d) increased pituitary activity due to positive feedback
a
129
A chronic alcoholic who develops cirrhosis of the liver may expect problems with all of the following except:
a) digestion of fats
b) blood sugar levels
c) bile storage
d) uncontrolled bleeding
C
130
In mamalian skeletal muscle:
I) myfibrils are clustered in groups called fasciculi
II) T- tubules located in the sarcoplasmic reticulum allow for conduction of action potentials deep into muscle fiber
III) all cells are multinucleate.
III only
131
The formation of primary oocytes occurs in the ....?
seminiferous tubules
132
With respect to the physiology of mammalian bones:
I) osteocytes re mature bone cells that differentiate from osteoblasts
II) osteoclast activity is inhibited by parathyroid hormone
III) compact bone is one site of hematopoiesis
I only
133
During contraction of human muscle cell, a molecule of ATP is hydrolyzed into ADP and Pi in association with:
a) transition of the myosin from bent to straight position
b) transition of the myosin head from straight to bent position
A
134
What is path of the sperm from origin in male fertilization to egg of female?
epididymis, vas deference, urethra, vagina, cervix, uterus, fallopian tube
135
A student wishing to examine striated muscle could look in which of the following locations?
I. intercostal muscles
II. muscle tissue lining veins and arteries
III. cardiac muscle
IV. Arrestor pill muscles within the skin
I and III
136
Immediately before calcium enters the sarcomere through the sarcoplasreticulum, the relative state of the myosin head is best described as:
a) cocked and bonded to actin filament
b) relaxed and bound to actin filament
c) cocked and dissociated form actin filament
d) relaxed and dissociated from the actin filament
C
| cocked= straight
137
If you took an assay of a bone sample with hip fracture, what would you find:
a) phosphorous
b) calcium
c) oxygen
d) nitrogen
e) all of the above
E
