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106 Cards in this Set
- Front
- Back
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Evolutionary Convergence
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Reflects different species’ adaptations to a similar environmental challenge
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Sac Body Plan
Complex Body Plan |
Body walls that are only two cells thick, facilitating diffusion of materials
Highly folded internal surfaces for exchanging materials |
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Interstitial Fluid
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Fluid that fills the space between cells, allows for the movement of material into and out of cells
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Epithelial tissue
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Covers the outside of the body and lines the organs and cavities within the body; contains cells that are closely joined; shape may be cuboidal, columnar, or squamous; arrangement of epithelial cells may be simple, stratified, or pseudostratified
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Connective Tissue
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Binds and supports other tissues; contains sparsely packed cells scattered throughout an extracellular matrix, matrix consists of fibers in a liquid, jellylike, or solid foundation
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Connective Tissue Fibers
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Collagenous fibers provide strength and flexibility
Elastic fibers stretch and snap back to their original length Reticular fibers join connective tissue to adjacent tissues |
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Fibroblasts
Macrophages |
Cells contained in connective tissue:
secrete the protein of extracellular fibers involved in the immune system |
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Connective Tissue Types
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Loose connective tissue binds epithelia to underlying tissues and holds organs in place
Cartilage is a strong and flexible support material Fibrous connective tissue is found in tendons, which attach muscles to bones, and ligaments, which connect bones at joints Adipose tissue stores fat for insulation and fuel Blood is composed of blood cells and cell fragments in blood plasma Bone is mineralized and forms the skeleton |
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Muscle Tissue
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Consists of long cells called muscle fibers, which contract in response to nerve signals
Skeletal muscle, or striated muscle, is responsible for voluntary movement Smooth muscle is responsible for involuntary body activities Cardiac muscle is responsible for contraction of the heart |
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Nervous Tissue
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Senses stimuli and transmits signals throughout the animal
Neurons, or nerve cells, that transmit nerve impulses Glial cells, or glia, that help nourish, insulate, and replenish neurons |
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Regulator
Conformer |
Uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuation; endothermic animals generate heat by metabolism; homeotherm
Allows its internal condition to vary with certain external changes; ectothermic animals gain heat from external sources; poikilotherm |
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Mechanisms of homeostasis
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Fluctuations above or below a set point serve as a stimulus; these are detected by a sensor and trigger a response
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Acclimatization
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Adjustments to changes in external environment
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Exchange of Heat
Integumentary System |
Conduction, convection, radiation, and evaporation
Skin, hair, and nails; often involved in heat regulation mammals |
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Adaptations for Thermoregulation
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Insulation
Circulatory adaptations Cooling by evaporative heat loss Behavioral responses Adjusting metabolic heat production |
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Countercurrent Exchange
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Transfer heat between fluids flowing in opposite directions; important mechanism for reducing heat loss
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Bioenergetics
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The overall flow and transformation of energy in an animal; inversely related to body size among similar animals
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Metabolic rate
Basal metabolic rate (BMR) Standard metabolic rate (SMR) |
The amount of energy an animal uses in a unit of time
the metabolic rate of an endotherm at rest at a “comfortable” temperature the metabolic rate of an ectotherm at rest at a specific temperature |
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Torpor
Hibernation Estivation |
A physiological state in which activity is low and metabolism decreases
A long-term torpor that is an adaptation to winter cold and food scarcity Summer torpor, enables animals to survive long periods of high temperatures and scarce water supplies |
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Endocrine glands
Endocrine signals (hormones) |
Ductless and secrete hormones directly into surrounding fluid
Secreted into extracellular fluids and travel via the bloodstream |
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Chemical Signals
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Hormones
Local regulators Neurotransmitters Neurohormones Pheromones |
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Exocrine glands
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Have ducts and secrete substances onto body surfaces or into body cavities
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Local regulators
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Chemical signals that travel over short distances by diffusion; help regulate blood pressure, nervous system function, and reproduction
Paracrine signals act on cells near the secreting cell Autocrine signals act on the secreting cell itself |
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Neurotransmitters
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chemical signals that diffuse a short distance to bind to receptors on the target cell of neurons at synapses; play a role in sensation, memory, cognition, and movement
Synaptic signaling - synapse with a target cell Neuroendocrine signaling - synpase with a blood vessel |
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Neurohormones
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Hormones that originate from neurons in the brain and diffuse through the bloodstream
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Pheromones
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Chemical signals that are released from the body and used to communicate with other individuals in the species
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Classes of molecules function as hormones in vertebrates
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Polypeptides (proteins and peptides)
Amines derived from amino acids Steroid hormones |
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Lipid-soluble hormones
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(steroid hormones) pass easily through cell membranes; receptors for lipid-soluble hormones located inside cells; hormones diffuse across cell membranes, travel in the bloodstream bound to transport proteins, and diffuse through the membrane of target cells
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Water-soluble hormones
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(polypeptides and amines) do not pass easily through cell membranes; water-soluble receptors are on the cell surface; secreted by exocytosis, travel freely in the bloodstream, and bind to cell-surface receptors
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Signal Transduction
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Binding of a hormone to its receptor initiates a signal transduction pathway leading to responses in the cytoplasm, enzyme activation, or a change in gene expression
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Epinephrine
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multiple effects in mediating the body’s response to short-term stress, binds to receptors on the plasma membrane of liver cells, triggers the release of messenger molecules that activate enzymes and result in the release of glucose into the bloodstream
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Lipid-soluble hormone
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The response is usually a change in gene expression: enter target cells and bind to protein receptors in the cytoplasm or nucleus. Protein-receptor complexes then act as transcription factors in the nucleus, regulating transcription of specific genes
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The same hormone may have different effects on target cells that have
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Different receptors for the hormone
Different signal transduction pathways Different proteins for carrying out the response |
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Types of local regulators:
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Cytokines and growth factors
Nitric oxide (NO) Prostaglandins - help regulate aggregation of platelets, an early step in formation of blood clots |
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Pancreas
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The pancreas has clusters of endocrine cells called islets of Langerhans with alpha cells that produce glucagon and beta cells that produce insulin
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Insulin
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Insulin reduces blood glucose levels by
Promoting the cellular uptake of glucose Slowing glycogen breakdown in the liver Promoting fat storage |
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Glucagon
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Glucagon increases blood glucose levels by
Stimulating conversion of glycogen to glucose in the liver Stimulating breakdown of fat and protein into glucose |
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Type I diabetes mellitus
Type II diabetes mellitus |
(insulin-dependent) is an autoimmune disorder in which the immune system destroys pancreatic beta cells
(non-insulin-dependent) involves insulin deficiency or reduced response of target cells due to change in insulin receptors |
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Ecdysone
Juvenile hormone |
Promotes molting (in the presence of juvenile hormone) and development (in the absence of juvenile hormone) of adult characteristics; released by prothoracic glands
promotes retention of larval characteristics |
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Oxytocin
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Induces uterine contractions and the release of milk; example of positive feedback
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Antidiuretic hormone (ADH)
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Enhances water reabsorption in the kidneys
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Tropic hormone
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Regulates the function of endocrine cells or glands
Thyroid-stimulating hormone (TSH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Adrenocorticotropic hormone (ACTH) |
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Nontropic hormones
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Target nonendocrine tissues;
produced by the anterior pituitary Prolactin (PRL) - stimulates lactation in mammals Melanocyte-stimulating hormone (MSH) - skin pigmentation and fat metabolism |
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Growth hormone (GH)
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Secreted by the anterior pituitary gland;promotes growth directly and has diverse metabolic effects
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Thyroid gland
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Consists of two lobes on the ventral surface of the trachea; produces two iodine-containing hormones: triiodothyronine (T3) and thyroxine (T4); stimulate metabolism and influence development and maturation (Graves’ disease - hyperthyroidism)
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Homeostasis of calcium (Ca2+)
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Parathyroid hormone (PTH) is released by the parathyroid glands - increases the level of blood Ca2+
It releases Ca2+ from bone and stimulates reabsorption of Ca2+ in the kidneys It also has an indirect effect, stimulating the kidneys to activate vitamin D, which promotes intestinal uptake of Ca2+ from food Calcitonin is released by the thyroid gland - stimulates Ca2+ deposition in bones and secretion by kidneys |
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Adrenal glands
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The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline)
Trigger the release of glucose and fatty acids into the blood Increase oxygen delivery to body cells Direct blood toward heart, brain, and skeletal muscles, and away from skin, digestive system, and kidneys Catecholamines - secreted in response to stress-activated impulses from the nervous system The adrenal cortex releases a family of steroids called corticosteroids in response to stress - glucocorticoids and mineralocorticoids |
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Glucocorticoids
Mineralocorticoids |
Glucocorticoids, such as cortisol, influence glucose metabolism and the immune system
Mineralocorticoids, such as aldosterone, affect salt and water balance |
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Sex hormones
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The testes primarily synthesize androgens, mainly testosterone, which stimulate development and maintenance of the male reproductive system - causes an increase in muscle and bone mass and is often taken as a supplement to cause muscle growth, which carries health risks
Estrogens, most importantly estradiol, are responsible for maintenance of the female reproductive system and the development of female secondary sex characteristics In mammals, progestins, which include progesterone, are primarily involved in preparing and maintaining the uterus |
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Pineal gland
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The pineal gland, located in the brain, secretes melatonin - primary functions of melatonin appear to relate to biological rhythms associated with reproduction
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Parthenogenesis
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The development of a new individual from an unfertilized egg; involves the doubling of chromosomes after meiosis
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Sexual reproduction
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Sexual reproduction results in genetic recombination, which provides potential advantages:
An increase in variation in offspring, providing an increase in the reproductive success of parents in changing environments An increase in the rate of adaptation A shuffling of genes and the elimination of harmful genes from a population |
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Spermatheca
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In many insects, the female has a spermatheca in which sperm is stored during copulation
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Cloaca
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A cloaca is a common opening between the external environment and the digestive, excretory, and reproductive systems; common in nonmammalian vertebrates
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Female Reproductive System
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The female gonads, the ovaries, lie in the abdominal cavity. Each ovary contains many follicles, which consist of a partially developed egg, called an oocyte, surrounded by support cells. Ovulation expels an egg cell from the follicle, the remaining follicular tissue grows within the ovary, forming a mass called the corpus luteum, which secretes hormones that help to maintain pregnancy
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Male Reproductive System
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The male gonads, or testes, consist of highly coiled tubes surrounded by connective tissue. Sperm form in these seminiferous tubules. Leydig cells produce hormones and are scattered between the tubules.From the seminiferous tubules of a testis, sperm pass into the coiled tubules of the epididymis. During ejaculation, sperm are propelled through the muscular vas deferens and the ejaculatory duct, and then exit the penis through the urethra.
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Semen
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Semen is composed of sperm plus secretions from three sets of accessory glands
The two seminal vesicles contribute about 60% of the total volume of semen The prostate gland secretes its products directly into the urethra through several small ducts The bulbourethral glands secrete a clear mucus before ejaculation that neutralizes acidic urine remaining in the urethra |
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Human Sexual Response
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Vasocongestion, the filling of tissue with blood
Myotonia, increased muscle tension The sexual response cycle has four phases: excitement, plateau, orgasm, and resolution |
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Spermatogenesis differs from oogenesis
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In oogenesis, one egg forms from each cycle of meiosis; in spermatogenesis four sperm form from each cycle of meiosis
Oogenesis ceases later in life in females; spermatogenesis continues throughout the adult life of males Oogenesis has long interruptions; spermatogenesis produces sperm from precursor cells in a continuous sequence |
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Gonadotropin-releasing hormone (GnRH)
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Secreted by the hypothalamus and directs the release of FSH and LH from the anterior pituitary
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FSH
LH |
FSH promotes the activity of Sertoli cells, which nourish developing sperm and are located within the seminiferous tubules
LH regulates Leydig cells, which secrete testosterone and other androgen hormones, which in turn promote spermatogenesis |
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Sertoli cells
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Sertoli cells secrete the hormone inhibin, which reduces FSH secretion from the anterior pituitary
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Follicular Phase
Luteal Phase |
Follicle growth and an increase in the hormone estradiol characterize the follicular phase of the ovarian cycle
The follicular phase ends at ovulation, and the secondary oocyte is released Following ovulation, the follicular tissue left behind transforms into the corpus luteum; this is the luteal phase |
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Uterine Cycle
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Thickening of the endometrium during the proliferative phase coordinates with the follicular phase
Secretion of nutrients during the secretory phase coordinates with the luteal phase Shedding of the endometrium during the menstrual flow phase coordinates with the growth of new ovarian follicles |
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Human Chorionic Gonadotropin (hCG)
Trophoblast |
The embryo releases this hormone to prevent menstruation
The outer layer of the blastocyst, mingles with the endometrium and eventually forms the placenta |
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Fetus
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The first trimester is the main period of organogenesis, development of the body organs
All the major structures are present by 8 weeks, and the embryo is called a fetus |
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Rhythm Method or Natural Planning
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Refrain from intercourse when conception is most likely; it has a pregnancy rate of 10–20%
Coitus interruptus, the withdrawal of the penis before ejaculation, is unreliable |
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Barrier methods
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Barrier methods block fertilization with a pregnancy rate of less than 10%
A condom fits over the penis A diaphragm is inserted into the vagina before intercourse |
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Sterilization
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Permanent and prevents the release of gametes
Tubal ligation ties off the oviducts Vasectomy ties off the vas deferens |
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Assisted Reproductive Technologies
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In vitro fertilization (IVF) mixes eggs with sperm in culture dishes and returns the embryo to the uterus at the 8 cell stage
Sperm are injected directly into an egg in a type of IVF called intracytoplasmic sperm injection (ICSI) |
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Preformation
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The idea that the egg or sperm contains a miniature infant, or “homunculus,” which becomes larger during development
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Post-fertilization
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Cleavage: cell division creates a hollow ball of cells called a blastula
Gastrulation: cells are rearranged into a three-layered gastrula Organogenesis: the three layers interact and move to give rise to organs |
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Acrosome
Acrosomal Reaction |
The tip of the sperm releases hydrolytic enzymes that digest material surrounding the egg
Triggered when the sperm meets the egg |
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Fast Block
Cortical Reaction Cortical Granules Slow Block |
Gamete contact and/or fusion depolarizes the egg cell membrane and sets up a fast block to polyspermy
Fusion of egg and sperm also initiates the cortical reaction This reaction induces a rise in Ca2+ that stimulates cortical granules to release their contents outside the egg These changes cause formation of a fertilization envelope that functions as a slow block to polyspermy |
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Egg Activation
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The sharp rise in Ca2+ in the egg’s cytosol increases the rates of cellular respiration and protein synthesis by the egg cell
With these rapid changes in metabolism, the egg is said to be activated The sperm nucleus merges with the egg nucleus and cell division begins |
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Zona Pellucida
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In mammalian fertilization, the cortical reaction modifies the zona pellucida, the extracellular matrix of the egg, as a slow block to polyspermy
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Clevage
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Fertilization is followed by cleavage, a period of rapid cell division without growth
Cleavage partitions the cytoplasm of one large cell into many smaller cells called blastomeres The blastula is a ball of cells with a fluid-filled cavity called a blastocoel |
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Yolk
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The polarity is defined by distribution of yolk (stored nutrients)
The vegetal pole has more yolk; the animal pole has less yolk The eggs and zygotes of many animals, except mammals, have a definite polarity |
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Grey Crescent
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The three body axes are established by the egg’s polarity and by a cortical rotation following binding of the sperm
Cortical rotation exposes a gray crescent opposite to the point of sperm entry |
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Holoblastic cleavage
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Complete division of the egg, occurs in species whose eggs have little or moderate amounts of yolk, such as sea urchins and frogs
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Meroblastic cleavage
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Incomplete division of the egg, occurs in species with yolk-rich eggs, such as reptiles and birds
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Gastrulation
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Rearranges the cells of a blastula into a three-layered, germ layers, of the embryo, called a gastrula, which has a primitive gut
The ectoderm forms the outer layer The endoderm lines the digestive tract The mesoderm partly fills the space between the endoderm and ectoderm |
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Gastrulation in the sea urchin embryo
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The blastula consists of a single layer of cells surrounding the blastocoel
Mesenchyme cells migrate from the vegetal pole into the blastocoel The vegetal plate forms from the remaining cells of the vegetal pole and buckles inward through invaginationThe newly formed cavity is called the archenteron This opens through the blastopore, which will become the anus |
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Gastrulation in the frog
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The frog blastula is many cell layers thick
Cells of the dorsal lip originate in the gray crescent and invaginate to create the archenteron Cells continue to move from the embryo surface into the embryo by involution These cells become the endoderm and mesoderm The blastopore encircles a yolk plug when gastrulation is completed The surface of the embryo is now ectoderm, the innermost layer is endoderm, and the middle layer is mesoderm |
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Gastrulation in the chick
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The embryo forms from a blastoderm and sits on top of a large yolk mass
During gastrulation, the upper layer of the blastoderm (epiblast) moves toward the midline of the blastoderm and then into the embryo toward the yolk The midline thickens and is called the primitive streak The movement of different epiblast cells gives rise to the endoderm, mesoderm, and ectoderm |
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Notochord
Neural Plate Neural crest cells |
Early in vertebrate organogenesis, the notochord forms from mesoderm, and the neural plate forms from ectoderm
The neural plate soon curves inward, forming the neural tube The neural tube will become the central nervous system (brain and spinal cord) Neural crest cells develop along the neural tube of vertebrates and form various parts of the embryo (nerves, parts of teeth, skull bones, and so on) Neural crest cells develop along the neural tube of vertebrates and form various parts of the embryo (nerves, parts of teeth, skull bones, and so on) Lateral to the somites, the mesoderm splits to form the coelom |
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Extraembryonic membranes
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The chorion functions in gas exchange
The amnion encloses the amniotic fluid The yolk sac encloses the yolk The allantois disposes of waste products and contributes to gas exchange |
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Inner cell mass
Trophoblast |
Develops into the embryo and forms the extraembryonic membranes
The outer epithelium of the blastocyst, initiates implantation in the uterus, and the inner cell mass of the blastocyst forms a flat disk of cells |
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Convergent extension
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Cell crawling, a morphogenetic movement in which cells of a tissue become narrower and longer; driven by cytoskeleton
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Cell adhesion molecules
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Located on cell surfaces contribute to cell migration and stable tissue structure
One class of cell-to-cell adhesion molecule is the cadherins, which are important in formation of the frog blastula |
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Cell migration
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Several kinds of glycoproteins, including fibronectin, promote cell migration by providing molecu
lar anchorage for moving cells |
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Differentiation
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During early cleavage divisions, embryonic cells must become different from one another
If the egg’s cytoplasm is heterogenous, dividing cells vary in the cytoplasmic determinants they contain After cell asymmetries are set up, interactions among embryonic cells influence their fate, usually causing changes in gene expression This mechanism is called induction, and is mediated by diffusible chemicals or cell-cell interactions |
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Totipotent
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Can develop into all the cell types in the adult
As embryonic development proceeds, potency of cells becomes more limited |
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Hans Spemann and Hilde Mangold
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Concluded that the blastopore’s dorsal lip is an organizer of the embryo
The Spemann organizer initiates inductions that result in formation of the notochord, neural tube, and other organs |
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Vertebrate Limb Formation
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Inductive signals play a major role in pattern formation, development of spatial organization
The molecular cues that control pattern formation are called positional information This information tells a cell where it is with respect to the body axes It determines how the cell and its descendents respond to future molecular signals |
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Apical Ectodermal Ridge (AER)
Zone of Polarizing Activity (ZPA) |
One limb-bud organizer region; thickened ectoderm at the bud’s tip
Mesodermal tissue under the ectoderm where the posterior side of the bud is attached to the body Hox genes also play roles during limb pattern formation |
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Sensory reception
Sensory receptors |
Detection of stimuli by sensory receptors
Detect stimuli outside and inside the body |
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Sensory transduction
Receptor potential |
The conversion of stimulus energy into a change in the membrane potential of a sensory receptor
Change in membrane potentia |
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Transmission
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After energy has been transduced into a receptor potential, some sensory cells generate the transmission of action potentials to the CNS
Sensory cells without axons release neurotransmitters at synapses with sensory neurons Larger receptor potentials generate more rapid action potentials |
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Amplification
Sensory adaptation |
The strengthening of stimulus energy by cells in sensory pathways
A decrease in responsiveness to continued stimulation |
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Categories of sensory receptors
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Mechanoreceptors
Chemoreceptors Electromagnetic receptors Thermoreceptors Pain receptors |
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Mechanoreceptors
Chemoreceptors |
Sense physical deformation caused by stimuli such as pressure, stretch, motion, and sound
Transmit information about the total solute concentration of a solution; when a stimulus molecule binds to a chemoreceptor, the chemoreceptor becomes more or less permeable to ions |
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Electromagnetic receptors
Thermoreceptors Pain receptors / nociceptors |
Detect electromagnetic energy such as light, electricity, and magnetism
Respond to heat or cold, help regulate body temperature by signaling both surface and body core temperature A class of naked dendrites in the epidermis; respond to excess heat, pressure, or chemicals released from damaged or inflamed tissues |
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Statocysts
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Contain mechanoreceptors that detect the movement of granules called statoliths; maintain equilibrium using sensory organs called statocysts
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Hearing
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The perception of sound in the brain from the vibration of air waves; vibrations create pressure waves in the fluid in the cochlea that travel through the vestibular canal; pressure waves in the canal cause the basilar membrane to vibrate, bending its hair cells; bending of hair cells depolarizes the membranes of mechanoreceptors and sends action potentials to the brain via the auditory nerve
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Volume
Pitch |
the amplitude of the sound wave
the frequency of the sound wave |
