BIOL 1040 Lecture notes, chapters 43 and 45
BIOL 1040 Lecture notes, chapters 43 and 45 BIOL 1040
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This 5 page Class Notes was uploaded by Sarah Stewart on Thursday March 31, 2016. The Class Notes belongs to BIOL 1040 at Clemson University taught by Dr. William Surver in Fall 2016. Since its upload, it has received 13 views. For similar materials see General Biology II in Biology at Clemson University.
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Date Created: 03/31/16
Sarah Stewart BIOL 1040 Exam 3 notes Chapter 43: Reproduction and Embryonic Development Lecture given 3/29/16 Human Reproduction: • Both species must have a set of gonads, ducts for gamete transport, and structures for copulation Male Reproduction: • Testes produce sperm and male hormones • Epididymis stores sperm as they develop • Multiple glands contribute to semen: the seminal vesicles, the prostate gland, and the bulbourethral glands • During ejaculation: sperm is expelled from the penis, glands secrete into the urethra, and semen is formed and expelled • Sperm production is regulated by a negative feedback system • Involves the hypothalamus, anterior pituitary, and the testes • Testes is the organ affected by these hormones; produce sperm and androgens (sex hormones that cause lower voice) once male reaches puberty • LH is the luteinizing hormone that acts upon the cells in the testes, and FSH is the follicle stimulating hormone that makes the testes produce testosterone; these two hormones come from the female reproductive system Female Reproduction: • Meant to carry a pregnancy Sarah Stewart BIOL 1040 Exam 3 notes • Hormones synchronize cyclic changes in the ovary and uterus, approximately every 28 days; can be synchronized with other females • This cycle’s purpose is to prepare a women for a pregnancy, great variation between every woman • The hypothalamus signals the anterior pituitary to secrete FSH and LH o LH – stimulates growth of follicle, promotes ovulation and development of corpus luteum o FSH – stimulates growth of follicle • Trigger the growth of an ovarian follicle and ovulation • After ovulation, the follicle becomes the corpus luteum • The corpus luteum secrets estrogen and progesterone which o Stimulate the endometrium (uterine lining) to thicken o Prepare the uterus for implantation o Inhibit the hypothalamus, which reduces FSH and LH – negative feedback loop • Only about 30% of implantations are successes, most important time in the reproductive cycle • If the egg is fertilized, embryo releases hormones that maintain the uterine lining: menstruation does not occur o Embryonic stage is the first three months of pregnancy Sarah Stewart BIOL 1040 Exam 3 notes o Remaining 2 stages are the fetal development stage, embryo begins taking on human characteristics • If the egg is not fertilized, the drop in LH shuts down the corpus luteum and its hormones; menstruation is triggered and the hypothalamus and pituitary form a new follicle – estrogen/progesterone no longer inhibiting this Menstrual Cycle • Begins with ovulation; generally occurs around day 14 • LH and FHS levels spike, which stimulates the follicle to be released and to grow • The follicle grows and secretes estrogen; once the corpus luteum is formed by the follicle, it secretes progesterone and estrogen • Estrogen and progesterone promote the rapid thickening of the uterine wall o Estrogen - low levels inhibit pituitary, high levels stimulate hypothalamus o Progesterone – maintain endometrium, high levels inhibit hypothalamus and pituitary – sharp drops promote menstruation • If the egg is not fertilized, the lining is sloughed off and this is what causes menstrual bleeding Chapter 45: Population and Community Ecology Lecture given 3/31/16 • Population ecology is concerned with changes in population size and factors that regulate populations over time, such as immigration and emigration o Too many people on this earth to maintain a sustainable environment Sarah Stewart BIOL 1040 Exam 3 notes • Populations increase through birth and immigration to an area and decrease through death and emigration out of an area Population – a group of individuals of a single species that occupy the same general area; from a reproductive view it is a group of individuals that share common gene pool Population dynamics – the interactions between the biotic (living) and abiotic (nonliving) factors causes variation in population sizes • Individuals in a population rely on the same resources, are influenced by the same environmental factors, and are likely to interact and breed with each other • Population may be described by the number and distribution of individuals • 46.2 million living in poverty in the US (below $27,000) – most resources are consumed by relatively few people in developed countries Population density – the number of individuals of a species per unit area or volume; i.e. number of oak trees per square kilometer in a forest • Ecologists use a variety of sapling techniques to estimate population densities, not always easy to determine • Animals move around and densities vary in a population’s range, so you cant be completely confident in a density number Capture-recapture – sampling method that makes the assumptions that marking has no effect on mortality, marking has no effect on the likelihood of being captured, and that there is no immigration or emigration between the sampling times Sarah Stewart BIOL 1040 Exam 3 notes Dispersion pattern – the way individuals are spaced within an area; can be clumped, nearly uniform, or random Life history pattern – a set of adaptions that influence survival, fertility, and the age at first reproduction; a set of conditions pertaining to an individual’s schedule of reproduction, summarized in life tables/survivorship curves • Life tables o Track age-specific patterns o Population divided into age categories o Birth and mortality rates calculated for each age category o Each species has a characteristic life span, not all achieve it • Survivorship curves – used to plot a cohort’s age-specific survival in a habitat o Type I – high survivorship until late in life, then a large increase in death; elephants, humans o Type II – reflect a fairly constant death rate at all ages; lizards, small mammals, large birds o Type III – death rate highest early on, species that produce many small offspring and do little parenting; invertebrates