Biology Flashcards
1
Q
G1 phase of interphase in the cell cycle
A
cells create organelles for energy and protein production (mitochondria, ribosomes, and ER)
2
Q
S phase of cell cycle
A
the cell replicates its genetic material so that each daughter cell will have identical copies (in this stage humans still have 46 chromosomes, even though there are 92 chromatids)
3
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G2 stage of cell cycle
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cell checks to ensure that there are enough organelles and cytoplasm for 2 daughter cells and the cell checks to make sure that DNA replication proceeded correctly to avoid passing on an error to daughter cells that may further pass on the error to their progeny
4
Q
M phase
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consists of mitosis along w/ cytokinesis, divided into 4 phases (prophase, metaphase, anaphase, & telophase)
5
Q
Cytokinesis
A
splitting of the cytoplasm and organelles btwn the 2 daughter cells
6
Q
Prophase (mitosis)
A
the chromosomes condense, the nuclear membrane dissolves, nucleoli disappear, centrioles migrate to opposite sides of the cell, and the spindle apparatus begins to form. The kinetochore of each chromosome is contacted by a spindle fiber
7
Q
Metaphase (mitosis)
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chromosomes line up along the metaphase plate (equatorial plate)
8
Q
Anaphase (mitosis)
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sister chromatids are separated and pulled to opposite poles
9
Q
Telophase (mitosis)
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the nuclear membrane reforms, the spindle apparatus disappears, and cytosol and organelles are split btwn the two daughter cells through cytokinesis
10
Q
Meiosis
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occurs in gametocytes (germ cells) and produces up to four identical haploid sex cells, has one round of replication and two rounds of division
11
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Spermatogenesis
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spermatogonium - (S stage)- primary spermatocytes - (meiosis I) - secondary spermatocytes - (meiosis II) - spermatids - (maturation) - spermatozoa
12
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Oogenesis
A
one haploid ovum and a variable # of polar bodies formed
oogonium - birth - primary oocytes - ovulated egg is each month is a secondary oocyte - if fertilized it becomes an ovum
13
Q
Gonadotropin-releasing hormone (GnRH)
A
from the hypothalamus, causes the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
14
Q
LH
A
in females- causes ovulation, signals the corpus luteum to secrete progesterone
in males- causes interstitial cells to produce testosterone
15
Q
FSH
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in females- stimulates the development of the ovarian follicles, and secrete estrogen
in males- stimulates the sertoli cells and triggers spermatogenesis (sperm maturation)
16
Q
Veins
A
carry oxygenated blood
17
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Arteries
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carry deoxygenated blood
18
Q
Ectoderm
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outer most germ layer, gives rise to the integument (epidermis, hair, nails), epithelia of the nose, mouth, and lower anal canal, lens of the eye, nervous system (adrenal medula), and inner ear
19
Q
Mesoderm
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middle layer, gives rise to musculoskeletal, circulatory, and most of the excretory systems, gonads, muscular and connective tissue layers of the digestive and respiratory systems and the adrenal cortex
20
Q
Endoderm
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innermost layer, forms the epithelial linings of the digestive and respiratory tracts, including the lungs, the pancreas, thyroid, bladder, and distal urinary tracts, parts of the liver
21
Q
Teratogens
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substances that interfere w/ development causing defects or even death of the developing embryo (ex: alcohol, prescription drugs, viruses, bacteria, and environmental chemicals)
22
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Stages of embryonic development
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morula -> blastulation (implantation) ->gastrulation ->differentiation -> neurulation
23
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induction
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the ability of one group of cells to influence the fate of nearby cells
24
Q
Cell specialization
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Specification (the cell is reversibly designated as a specific cell type) -> Determination (cell is committed to a particular cell lineage) -> Differentiation (the cell assumes the structure, function, and biochemistry of that cell type)
25
Potency of stem cells
Totipotent (cells can differentiate into any cell type), Pluripotent (cells can differentiate into any cell type except for those found in placental structures), Multipotent (cells can differentiate into multiple types of cells within a particular group)
26
Autocrine
act on the same cell that secreted the signal in the first place
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Paracrine
act on cells in the local area
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Juxtacrine
do not usually involve diffusion, but involve a cell directly stimulating receptors of an adjacent cell
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Endocrine
involve secreted hormones that travel through the bloodstream to a distant target tissue
30
Morphogens
molecules that cause determination of cells
31
Senescence
biological aging, caused by shortened telomeres
32
First trimester
heart beats at 22 days, then the eyes, gonads, limbs, and liver form---- by the end of eight weeks most of the organs have formed, the brain is fairly developed, and the embryo becomes known as a fetus
33
Second trimester
the fetus undergoes a tremendous amount of growth, it begins to move in the amniotic fluid, its face takes on a human appearance, and the toes and fingers elongate
34
Third trimester
seventh and eight months of pregnancy characterized by continued rapid growth and further brain development, antibodies are transported from mother to fetus, growth rate slows and fetus becomes less active due to less space
35
Parturition
vaginal childbirth, accomplished by rhythmic contractions of uterine smooth muscle coordinated by prostaglandins and the peptide hormone oxytocin
36
dendrites
appendages on neurons which receive incoming messages from other cells
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axon
a long appendage that terminates in close proximity to a target structure (a muscle, a gland, or another neuron)
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Oligodendrocytes
glial cells in the CNS that produce myelin around the axon
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Schwann cells
glial cells in the PNS that produce myelin around the axon
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Astrocytes
glial cells that nourish neurons and form the blood-brain barrier, which controls the transmission of solutes from the bloodstream into nerve tissue, in the CNS
41
Ependymal cells
glial cells that line the ventricles of the brain and produce cerebrospinal fluid, which physically supports the brain and serves as a shock absorber, in the CNS
42
Microglia
glial cells that are phagocytic cells that ingest and break down waste products and pathogens in the central nervous system
43
Resting membrane potential
is the net electric potential difference that exists across the cell membrane, is about -70 mV for neurons w/ the inside of the neuron being negative relative to the outside
-the 2 most important ions involved in this are potassium (K) and sodium (Na)
44
Na+/K+ ATPase
continually pumps sodium and potassium back to where they started: potassium into the cell and sodium out of the cell, to maintain their respective gradients
45
depolarization
raising the membrane potential, Vm, from its resting potential, caused by excitatory input
46
hyperpolarization
lowering the membrane potential from its resting potential, caused by inhibitory input
47
Sensory neurons
also called afferent neurons, transmit sensory info from sensory receptors to the spinal cord and brain
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Motor neurons
also called efferent neurons, transmit motor info from the brain and spinal cord to muscles and glands
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Interneurons
found between other neurons and are the most numerous of the three types of neurons, located predominantly in the brain and spinal cord and are often linked to reflexive behaviors
50
White matter
consists of axons encased in myelin sheaths
51
Gray matter
consists of unmyelinated cell bodies and dendrites
52
Peptide hormones
are made up of amino acids, ranging in size from quite small (such as ADH) to relatively large (such as insulin)
-charged & cannot pass through plasma membrane, bind to extracellular receptor
-use signaling cascade
-effects are usually rapid but short lived
-peptides are water-soluble, they can travel freely in the blood stream and usually do not require carriers
-most have names that end in -in or -ine
53
Steroid hormones
are derived from cholesterol and are produced primarily by the gonads and adrenal cortex
-derived from nonpolar molecules, they can easily cross the cell membrane so their receptors are intracellular (in cytosol) or intranuclear
-undergo conformational changes such as dimerization which allows them to directly bind to DNA
-effects are slower but longer lived than peptide hormones bc they participate in gene regulation
-not water-soluble, so they must be carried by proteins in the bloodstream to travel around the body
-most have names that end in -one, -ol, or -oid
54
Amino Acid-Derivative Hormones
include epinephrine, norepinephrine, triiodothyronine, and thyroxine
-derived from one or two amino acids, usually with a few additional modifications
-catecholamines (epinephrine and norepinephrine) bind to G protein-coupled receptors, while thyroid hormones bind intracellularly
-most have names that end in -in or -ine
55
Direct hormones
are secreted and then act directly on a target tissue
56
Tropic hormones
require an intermediary to act; usually originate in the brain and anterior pituitary gland, allowing for the coordination of multiple processes within the body
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Hypothalamus
-the bridge btwn the nervous and endocrine systems
-regulates the pituitary gland through tropic hormones
-controls the pituitary through paracrine release of hormones into a portal system that directly connects the two organs
-release of hormone regulated by negative feedback
58
Hormones released by the hypothalamus and the hormones released by the anterior pituitary in response
-Gonadotropin-releasing hormone (GnRH) -> follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
-Growth hormone-releasing hormone (GHRH) -> growth hormone (GH)
-Thyroid-releasing hormone (TRH) -> thyroid-stimulating hormone (TSH)
-Corticotropin-releasing factor (CRF) -> adrenocroticotropic hormone (ACTH)
*exception: prolactin-inhibiting factor (PIF), which is actually dopamine, is released by the hypothalamus and causes a decrease in prolactin secretion
59
Anterior pituitary
synthesizes and secretes seven different products, 4 are tropic hormones while the other three are direct hormones
-Tropic: the release of both follicle-stimulating hormone (FSH) and luteinizing hormone (LH) is stimulated by gonadotropin-releasing hormone (GnRH) form the hypothalamus, the release of adrenocorticotropic hormone (ACTH) is stimulated by corticotropin-releasing factor (CRF) from the hypothalamus; ACTH acts on the adrenal cortex, the release of thyroid-stimulating hormone (TSH) is stimulated by thyroid-releasing hormone (TRH) from the hypothalamus; TSH acts on the thyroid
-Direct: prolactin (stimulates milk production in the mammary glands, the release of dopamine from the hypophyseal amus decreases its secretion), Endorphins (decrease the perception of pain), Growth hormone (promotes the growth of bone and muscle)
60
Oxytocin
stimulates uterine contractions during labor, as well as milk letdown during lactation
61
Antidiuretic hormone (ADH or vasopressin)
increases reabsorption of water in the collecting ducts of the kidneys, secreted in response to increased plasma osmolarity, or increased concentration of solutes within the blood
62
Posterior pituitary
receives and stores two hormones produced by the hypothalamus: ADH and oxytocin--
-ADH: results in greater retention of water, which results in increased blood volume and higher blood pressure
-Oxytocin: secreted during childbirth and allows for coordinated contraction of uterine smooth muscle (Unusual in that it has a positive feedback loop: the release of it promotes uterine contraction; which promotes more oxytocin release, which promotes stronger uterine contractions, and so on)
63
Thyroid
controlled by thyroid-stimulating hormone from the anterior pituitary, 2 major functions: setting basal metabolic rate (T3 and T4-- increase cellular respiration) and promoting calcium homeostasis (calcitionin)
64
Calcitonin
-C cells (Parafollicular cells) produce calcitonin
-decreases plasma calcium levels in 3 ways: by increasing calcium excretion from the kidneys, by decreasing calcium absorption from the gut, and by increasing storage of calcium in the bone
--high levels of calcium in the blood stimulate secretion of calcitonin from the C-cells
65
Parathyroid glands
hormone produced by these glands is parathyroid hormones (PTH)
-PTH serves an antagonistic hormone to calcitonin, raising blood calcium levels; specifically, it decreases excretion of calcium by the kidneys, increases absorption of calcium in the gut (via vitamin D), and increases bone resorption, thereby freeing up calcium
-as levels of calcium rise, PTH secretion is decreased
-PTH also promotes phosphorous homeostasis by increasing the resorption of phosphate from bond and reducing reabsorption of phosphate in the kidney (thus promoting its excretion in the urine)
-also activates vitamin D, which is required for the absorption of calico and phosphate in the gut
-overall effect of PTH: a significant increase in blood calcium levels with little effect on phosphate
66
Adrenal cortex
secretes corticosteroids which are steroid hormones that can be divided into 3 functional classes: glucocorticoids, mineralocorticoids, and cortical sex hormones
-Glucocorticoids: regulate glucose levels and affect protein metabolism, release is under the control of adrenocorticotropic hormone (ACTH), ex: cortisol and cortisone which raise blood glucose by increasing gluconeogenesis and decreasing protein synthesis
-Mineralocorticoids: used in salt and water homeostasis; their most profound effects are on the kidneys, ex: aldosterone which increases sodium reabsorption in the distal convoluted tubule and collecting duct of the nephron, decreases the reabsorption of potassium and hydrogen ions in these same segments of the nephron promoting their excretion in the urine
-cortical sex hormones: androgens and estrogens, testes secrete large quantities of androgens so it plays a small role, but ovaries secrete far smaller amounts making females more sensitive to disorders of cortical sex hormone production
67
Renin-angiotensin-aldosterone system
decreased BP causes the juxtaglomerular cells of the kidney to secrete renin, which cleaves an inactive plasma protein, angiotensinogen, to its active form, angiotensin I. Angiotensin I is then converted to angiotensin II by angiotensin-converting enzyme (ACE) in the lungs. Angiotensin II stimulates the adrenal cortex to secrete aldosterone.
68
Adrenal medulla
responsible for the production of the sympathetic hormones epinephrine and norepinephrine- secreted directly into the bloodstream
-Epinephrine: can increase the breakdown of glycogen to glucose (glycogenolysis) in both liver and muscle, as well as increase the basal metabolic rate
-both increase HR, dilate the bronchi and shunt blood flow to the systems that would be used in a sympathetic response
69
Pancreas
-has both exocrine and endocrine functions, secretes substances directly into ducts
-islets of Lanagerhans contain 3 distinct types of cells: alpha (secrete glucagon), beta (secrete insulin), and delta cells (secrete somatostatin)
-Glucagon: secreted during times of fasting, when glucose levels are low glucagon increases glucose production by triggering glycogenolysis, gluconeogenesis, and the degradation of protein and fat
-when blood glucose concentrations are high, glucagon release is inhibited
-Insulin: is antagonistic to glucagon and is therefore secreted when blood glucose levels are high, induces muscles and liver cells to take up glucose and store it as glycogen for later use, stimulates anabolic processes such as fat and protein synthesis, in excess insulin will cause hypoglycemia which is characterized by low blood glucose concentration
-Somatostatin: an inhibitor of both insulin and glucagon secretion, high blood glucose and amino acid concentrations stimulate its secretion, also produced by the hypothalamus where it decreases growth hormone secretion
70
Tricuspid valve
valve between the right atrium and the right ventricle
71
Mitral or bicuspid valve
valve between the left atrium and the left ventricle
72
Normal human heart rate
60-100 bpm
73
Cardiac output
the total blood volume pumped by a ventricle in a minute
-is the product of heart rate and stroke volume
-CO = HR X SV
-for humans, CO is about 5 liters per minute
74
Arteries
carry blood away from the heart, the largest is the aorta in the systemic circulation
-most contain oxygenated blood (only the pulmonary arteries and umbilical arteries contain deoxygenated blood)
75
Veins
except for the pulmonary and umbilical veins, all carry deoxygenated blood, thin-walled inelastic vessels that transport blood to the heart
76
Circulation
deoxygenated blood enters the heart from the body via the vena cavae
-deoxygenated blood enters the right atrium, travels through the tricuspid valve, and enters the right ventricle
-on contraction, blood from the right ventricle passes through the pulmonary valve and enters the pulmonary arteries, where it travels to the lungs and breaks into smaller vessels and undergoes gas exchange
-Blood travels to the pulmonary venules and enters into the pulmonary veins which carry the blood to the left side of the heart
-oxygenated blood enters the left atrium, travels through the mitral valve and enters the left ventricle
-on contraction, blood from the left ventricle passes through the aortic valve and enters the aorta
-from the aorta, blood enters arteries, then arterioles, and then capillaries
-after gas and nutrient exchange occurs at the capillaries, the blood enters the venules which lead to the larger veins. The veins then empty into either the SVC or IVC for return to the right side of the heart
77
Normal blood pressure
between 90/60 and 120/80
78
Oxygen saturation
the percentage of hemoglobin molecules carrying oxygen, healthy oxygen saturation level is above 97 percent
79
Innate immunity
is composed of defenses that are always active against infection, but lack the ability to target specific invaders; for this reason, it is also called nonspecific immunity
80
Adaptive or specific immunity
refers to the defenses that target a specific pathogen, is slower to act, but can maintain immunological memory of an infection to mount a faster attack in subsequent infections
81
Granulocytes
neutrophils, eosinophils, and basophils
82
Agranulocytes
lymphocytes and monocytes
83
Complement system
proteins in the blood that punch holes in the cell walls of bacteria, making them osmotically unstable
-considered a nonspecific defense bc it cannot be modified to target a specific organism over others
84
Interferons
proteins that prevent viral replication and dispersion
--cause nearby cells to decrease production of both viral and cellular proteins
85
Cytokines
chemical substances that stimulate inflammation and recruit additional immune cells to the area
86
ADH and aldosterone
trigger the sensation of thirst, encouraging the behavior of fluid consumption
87
Glucagon and ghrelin
Glucagon secreted by the pancreas, ghrelin secreted by the stomach and pancreas
-stimulate feelings of hunger
88
Leptin and cholecystokinin
stimulate feelings of satiety (fullness90
89
The stomach secretes six products
1. HCI (kills microbes, denatures proteins, and converts pepsinogen into pepsin; an enzyme that partially digests proteins)
2. Pepsinogen (cleaved in the stomach to pepsin; an enzyme that partially digests to proteins)
3. Mucus (protects mucosa)
4. Bicarbonate (produces mucosa)
5. Water (dissolves and dilutes ingested material)
6. Intrinsic factor (required for normal absorption of vitamin B12)
90
Small intestines
consists of 3 segments: the duodenum (responsible for the majority of chem. digestion and has minor involvement in absorption), the jejunum, and the ileum (most absorption takes place in the jejunum and ileum)
91
Large intestines
absorbs water
-has a larger diameter, but shorter length than the small intestines
-the cecum (an out pocketing that accepts fluid exiting the small intestine), the colon (absorbs water and salts from the undigested material left over from the small intestines, primarily concentrates the remaining material to form feces), and the rectum (serves as a storage site for feces, which consists of indigestible material, water, bacteria)
92
Skeletal muscle
-responsible for voluntary movement and is therefore innervated by the somatic nervous system
-appears striated due to the arrangement of actin and myosin in sarcomeres
-red fibers: slow-twitch fibers, high myoglobin content and primarily derive energy aerobically, high mitochondria content, muscles that contract slowly but sustain activity
-white fibers: fast-twitch, contain much less myoglobin, lighter color, muscles that contract rapidly but fatigue quickly
93
Smooth muscle
-responsible for involuntary action, controlled by the autonomic nervous system
-found in the respiratory tree, digestive tract, bladder, uterus, blood vessel walls, etc,
-have a single nucleus in the center of the cell
-no striations
-myogenic activity (can contract w/o the nervous system input)
94
Cardiac muscle
-uninucleated but may contain two nuclei
-contraction in involuntary and innervated by the autonomic nervous system
-striated
-connected by intercalated discs which contain gap junctions
-myogenic activity (SA node -> AV node -> bundle of His -> purkinje fibers)
95
Thick filaments
organized bundles of myosin
96
Thin filaments
made of actin along with two other proteins: troponin and tropomyosin
97
Creatine phosphate
created by transferring a phosphate group from ATP to creatine (ADP) during times of rest. This reaction can then be reversed during muscle use to quickly generate ATP from ADP
creatine + ATP -> <-creatine phosphate + ADP
98
Axial skeleton
consists of the skull, vertebral column, rib cage, and hyoid bone (a small bone in the anterior neck used for swallowing); it provides the basic central framework for the body
99
Appendicular skeleton
consists of the bones of the limbs (humerus, radius and ulna, carpals, metacarpals, and phalanges in the upper limb; and femur, tibia and fibula, tarsals, metatarsals, and phalanges in the lower limb); the pectoral girdle (scapula and clavicle); and pelvis
100
Parathyroid hormone
a peptide hormone released by the parathyroid glands in response to low blood calcium, promotes resorption of bone, increasing the concentration of calcium and phosphate in the blood
101
Calcitonin
a peptide hormone released by the parafollicular cells of the thyroid in response to high blood calcium, promotes bone formation, lowering blood calcium levels
102
Endochondral ossification
hardening of cartilage into bone, mechanism by which most bones in the body are created
--occurs in long bones
103
Intramembranous ossification
undifferentiated embryonic connective tissue (mesenchymal tissue) is transformed into, and replaced by, bone
--occurs in bones of the skull
