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biology 3 Flashcards

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MCAT flashcards
1
Q

What is the function of the digestive system?

A

mechanically and chemically digest food into monomers and simple components for absorption and later use as a source of energy

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2
Q

What are the 2 types of digestion?

A

physical (chewing)

chemical (digestive enzymes)

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3
Q

saliva provides __ and ___, which is the first digestive enzyme food is exposed to

A

lubrication, amylase

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4
Q

Digestion begins in the mouth w the physical digestion of all food types and the chemical digestion of ___ only (via the enzyme ____).

A

carbohydrates , alpha- amylases

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5
Q

What is the name of the reaction by which amylase catalyses carb breakdown?

A

hydrolysis

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6
Q

What is the structure that folds down over the opening of larynx?

A

epiglottis

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7
Q

What are the functions of the stomach?

A

food storage
mixing
first stage of protein digestion

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8
Q

Proteins in the stomach undergo ____, a reaction catalyzed by the enzyme ___. This enzyme begins as ___, an example of a zymogen.

A

Hydrolysis; pepsin; pepsinogen

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9
Q

What are the 4 types of lining cells in the stomach?

A

mucous neck cells - secrete alkaline mucus to provide protection

chief cells - secrete pepsinogen (into gastric pits)
parietal cells - secrete HCl (responsible for low pH)

G- cells - secrete gastrin - released into the blood

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10
Q

What kind of hormone is gastrin?

A

peptide hormone

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11
Q

In addition to pepsin, what other molecule assists in protein metabolism in the stomach?

A

acid

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12
Q

What are the main functions of the liver?

A

produces bile
filters the blood to remove toxins, drugs, metabolites, bacteria
produces blood plasma proteins
regulates amino acid levels in the blood

produces cholesterol and lipoproteins and packages them for transport

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13
Q

___ - this hormone stimulates glycogenolysis in the liver

A

glucagon

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14
Q

___ stimulates glycogenesis in the liver

A

insulin

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15
Q

What is the process called where the liver makes new glucose from lactate, glycerol, amino acids and some TCA- cycle intermediates?

A

gluconeogenesis

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16
Q

The ___ is both an endocrine and an exocrine gland

A

pancreas

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17
Q

What digestive enzymes does the pancreas secrete?

A

trypsin, chymotrypsin, pancreatic amylase, lipase, ribonuclease, and deoxyribonuclease

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18
Q

What is the pH of the small intestine?

A

about 6

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19
Q

Where do pancreatic secretions empty into?

A

upper end of duodenum (pancreatic duct is joined by bile duct)

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20
Q

What is the function of the gallbladder?

A

stores and concentrates bile, but does NOT produce bile

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21
Q

Is bile’s action an example of physical or chemical digestion?

A

physical - does not break any bonds

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22
Q

The majority of all digestion and absorption occurs in the ___

A

small intestine

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23
Q

In the small intestine, digestion occurs primarily in the ___ and absorption primarily in the ____

A

duodenum; jejunum and ileum

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24
Q

What is the brush border of the small intestine?

A

the name given to microvilli and the collection of mucus and digestive enzymes intermingled with them

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25
Q

What is the main function of the large intestine?

A

water absorption and vitamin absorption

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26
Q

What are suppressor T-cells?

A

suppress the body’s own immune system

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27
Q

What are mast cells?

A

permanent resident cells within many tissues , activated by allergens and other antigens to release histamine and other chemical mediators

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28
Q

What is the main function of bone marrow?

A

all erythrocytes and leukocytes are made here (B lymphocytes mature in the marrow, T lymphocytes migrate to thymus )

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29
Q

What is the main function of the spleen?

A

filters blood and breaks down and recycles parts of old RBCs

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30
Q

What is the main function of the thymus?

A

location where T-lymphocytes acquire immunocompetency, differentiate and mature

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31
Q

What is innate immunity?

A

The body’s non-specific attack of pathogens. All forms of innate immunity are present at birth, NOT acquired in any way.

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32
Q

Describe the inflammatory response in general terms (thorn gets stuck in skin)

A

thorn has bacteria that is detected by macrophages, mast cells and dendritic cells

they release histamines, leukotrienes and prostaglandins

these chemicals increase blood flow and increase permeability of veins and lymph vessels

neutrophils are recruited via chemotaxis

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33
Q

What is humoral immunity?

A

involves B cells and antibodies

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34
Q

one antibody will bind to __ antigen

A

one

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35
Q

What is the structure of an antibody?

A

2 heavy chains, 2 light chains
constant regions, hypervariable regions (at ends, where antigens bind)
2 disulfide bonds hold 2 heavy chains together
1 disulfide bond hold heavy and light chain together

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36
Q

What is the difference between primary and secondary response?

A

primary - immune system’s first exposure and reaction to a pathogen

secondary - the immune system’s response to that same pathogen during subsequent exposures

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37
Q

What is cell-mediated immunity?

A

involves T cells, antigen presentation by MHC (major histocompatibility complex)

Helper T cells release chemicals that stimulate B and T cells

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38
Q

What are dendritic cells?

A

antigen presentation experts (highest concentration near membranes that interface w the external environment - such as skin)

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39
Q

Antibodies are NOT ___

A

created to match antigens (they are produced randomly)

40
Q

What are the functions of the integumentary system?

A

protection against abrasion, physical barrier to pathogens, vitamin D synthesis, insulation, prevention of water loss, temperature regulation

41
Q

the integumentary system includes - hair, nails ___

A

skin, oil and sweat glands located in the skin

42
Q

What are the 2 layers of the skin?

A

epidermis (avascular) and dermis (contains blood vessels, hair follicles, nerve endings, sebaceous and sudoriferous glands)

43
Q

blood vessels closer to the surface of the skin ___ when heat needs to be released and ___ when heat needs to be retained

A

dilate, constrict

44
Q

What muscle near the hair follicle causes goose bumps?

A

arrector pili muscle

45
Q

What are the main characteristics of skeletal muscle?

A

voluntary, striated and multinucleate

46
Q

___ attach muscle to bone ; ___ attach bone to bone

A

tendons, ligaments

47
Q

the joints formed by most muscles and bones are examples of hinges w a ____ system

A

poor lever; eg. for the biceps, it must create a force equal to 6x the weight of the object in the hand

48
Q

a muscle group is a bundle of many ___

A

fasciculi

49
Q

Each muscle fascicle is a bundle of many long, tubular cells called ___. around each muscle cell is a specialized cell membrane called the ___.

A

muscle fibers, sarcolemma

50
Q

Repeating units of actin and myosin fibers

A

sarcomeres

51
Q

bundles of myofibrils that are interwoven among portions of the muscle cell’s endoplasmic reticulum, called the ___

A

sarcoplasmic reticulum

52
Q

What is stored in the sarcoplasmic reticulum?

A

calcium

53
Q

What is the A and I band, H zone, Z line and M line in skeletal muscle?

A

A band - length of the myosin filaments and DOES NOT change during contraction

I band - distance between the ends of the myosin filaments in 1 sarcomere to the ends of the next sarcomere

H zone - distance between the ends of the actin filaments

Z line - appear as zig zags that define the edges of each individual sarcomere unit.

M line - center of the myosin filaments

54
Q

thick filaments in skeletal muscle are __

A

myosin

55
Q

thin filaments in skeletal muscle is __

A

actin

56
Q

What neurotransmitter is the ONLY neurotransmitter used at the neuromuscular junction?

A

acetylcholine

57
Q

Describe the arrival of an action potential

A

when acetylcholine is released from the neuromuscular junction the action potential spreads along the muscle cell sarcolemma and down T-tubules. The T-tubules interface directly w SR, stimulating the release of calcium. calcium initiates muscle contraction

58
Q

following contraction, is calcium pumped into, or out of, the SR?

A

After contraction is complete, calcium must be actively transported back into the sarcoplasmic reticulum and sequestered there until the next contraction.

59
Q

Is ACh used at the ganglia or the effector in the sympathetic nervous system?

A

ganglionic synapses

60
Q

In the sliding filament mechanism for muscles, the default is ___

A

low energy position for the myosin heads is bent

61
Q

In the sliding filament mechanism, how does the myosin head become straight?

A

ATP hydrolysis provides the energy required to straighten myosin heads into their high energy, straight position

62
Q

What molecule covers the myosin binding site on actin filaments?

A

tropomyosin is clamped onto actin by troponin

when calcium is released, it attaches to troponin, releasing the clamp

63
Q

After the power stroke of myosin, what happens?

A

ATP binds to the myosin head again facilitating its release from the actin filament

64
Q

If there is no ATP present in the muscle, what happens?

A

the myosin heads cannot detach from actin and the muscle will be stuck in contraction (rigor)

65
Q

What happens when there is no calcium in the muscle?

A

no rigor, inability to contract (flaccidity)

66
Q

What is the motor unit?

A

a group of muscle cells innervated by a single motor neuron

67
Q

the strength of a given contraction depends on the :

A
  1. number of motor units being used
  2. size of the motor units being used
  3. frequency of action potentials (stimulation)
68
Q

How do muscle cells store oxygen?

A

myoglobin (they also store energy by storing glycogen)

69
Q

skeletal muscle cells are suspended in __ phase and do not ___

A

G0; divide

70
Q

How is smooth muscle contraction different than other muscle?

A

contraction is initiated by calcium- dependent phosphorylation of the myosin head. Smooth muscle contraction is sometimes referred to as the “calcium-calmodulin cascade.”

71
Q

What does it mean when it is said that the heart is “auto-rhythmic”?

A

the SA node acts as a pacemaker for the heart, the action potential for each heart beat originates at the SA node, not a signal from the nervous system

72
Q

What is the difference between the single unit (unitary or visceral) and multi-unit smooth muscle types?

A

Unitary smooth muscle is a group of smooth muscle fibers that are innervated by a single neuron and contract simultaneously as a single group

A multi-unit smooth muscle is innervated by multiple neurons and does not act as a single unit. Multi-unit smooth muscle is quite rare. It is found in some of the larger vessels such as the aorta, and in the retina of the eye.

73
Q

What are the functions of bone?

A

physical support and movement, protection of vital structures, mineral storage and regulation of blood mineral concentration and blood cell formation

74
Q

What are the 3 bone cell types? What do they do?

A

Osteocytes - mature bone cell
osteoclasts - break down and resorb bone matrix, releasing Ca and P back into blood
osteoblasts - immature bone cells that secrete collagen, organic compounds and minerals forming a bone matrix around themselves

75
Q

What are the two hormones that regulate bone maintenance and blood calcium levels?

A

parathyroid hormone and calcitonin

76
Q

What is the effect of parathyroid hormone and calcitonin on blood calcium levels?

A

calcitonin - inhibits osteoclast activity, there is a net increase of bone formation (reduces calcium in blood)

parathyroid hormone - stimulates osteoclast activity, breaks down bone matrix and releases calcium into the blood

77
Q

What is the difference between red and yellow bone marrow?

A

red - fills pockets of spongy bone

yellow - fills medullary cavity of long bones (consist of mostly fat)(no hematopoiesis)

78
Q

What are the three types of joint types?

A

fibrous (skull bones0
cartilaginous (pubic symphysis, intervertebral discs)
synovial (knee, elbow etc)

79
Q

What are the 4 types of bones?

A 
long bones (femur, humerus)
short bones (tarsals, carpals)
flat bones (skull, sternum)
irregular bones (hip, vertebrae)
80
Q

What inorganic compound is responsible for a bone’s strength and is the form in which most all of the body’s calcium is stored?

A

hydroxyapatite

81
Q

What is cartilage?

A

a connective tissue composed mostly of collagen (no perfusion or innervation)

82
Q

What is the ejaculation pathway?

A

SEVEN UP

seminiferous tubules, epididymis, vas deferens, ejaculatory duct, urethra, penis

83
Q

What is the male gamete?

A

sperm (contains lots of mitochondria)

84
Q

What is the acrosome?

A

membrane-bound structure on the tip of the head of each sperm. The acrosome contains hydrolytic enzymes that break down the otherwise impenetrable coating around the ovum.

85
Q

What is the specific purpose of each substance secreted into the ejaculate by the seminal vesicles, prostate gland, and bulbourethral gland?

A

seminal vesicles - release majority of fluids that make up semen, including fructose and alkaline fluids that make the semen basic (helps neutralize acidic environment of vagina)

prostate gland - secretes milky white fluid that is slightly acidic and contains proteases (better survival of sperm)

bulbourethral gland - secrete pre-ejaculate that lubricates and neutralizes any acidic urine in the urethra

86
Q

an egg in the female fetus is arrested at __ of meiosis at birth. __ is when meiosis 1 is completed.

A

prophase 1; puberty

87
Q

Meiosis 2 is not completed in the egg until ___

A

the sperm fertilizes the ovum

88
Q

an immature egg is called a __

A

oocyte

89
Q

Describe the menstrual cycle with the hormones involved?

A
  1. FSH stimulates the maturation of ovum and follicle
  2. LH stimulates the cells in ovaries to secrete estrogen, which signals the uterine wall to proliferate
  3. just before ovulation, estrogen levels increase, causing a spike in LH
  4. corpus luteum begins secreting estrogen and high levels of progesterone to prepare uterine lining for implantation
  5. if no fertilization occurs, corpus luteum degrades and menstrual lining sloughs off
90
Q

What causes menopause?

A

persistent low levels of estrogen/progesterone

symptoms - hot flashes, vaginal dryness, atrophy of breast tissue

91
Q

In embryology, what is cleavage?

A

mitosis without change in size

92
Q

What is a morula?

A

8 celled zygote

93
Q

What is gastrulation?

A

at about 2 weeks, cells migrate to form three germ layers

94
Q

What is neurulation?

A

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

95
Q

What is the difference between totipotent, pluripotent, and multi-potent?

A

totipotent - give rise to all of the cell types in the body

pluripotent - 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.

multi-potent - develop into more than one cell type, but are further differentiated and more limited than pluripotent cells; adult stem cells and cord blood stem cells are considered multi-potent

96
Q

What are the 3 germ layers?

A

ectoderm - epidermis, nails, tooth enamel, lens of the eye, pituitary gland, central, peripheral and autonomic nervous systems.

mesoderm - dermis, muscle, bone, connective tissues, kidneys, genitalia and most internal organs EXCEPT the liver and pancreas.

endoderm - the entire digestive tract, thyroid, parathyroid, urinary bladder, the lining ONLY of the lungs, the liver and pancreas.

mcat (15 decks)

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