Organization of Placenta
Tutorials/exercises - 2 pages - Medical studies
From the electron microscopic studies of Wislocki and Dempsey (1955), data were provided that permitted a functional interpretation of the fine structure of the placenta. There are prominent microvilli on the syncytial surface, corresponding to the "brush border" described by light microscopy....
Embryonic and Placental Development
Tutorials/exercises - 2 pages - Medical studies
In a description of the earliest stages of the human blastocyst, the wall of the primitive blastodermic vesicle was characterized as consisting of a single layer of ectoderm. As early as 72 hours after ovum fertilization, the 58-cell blastula had differentiated into 5 embryo-producing cells and...
Immunological Acceptance of the Conceptus
Tutorials/exercises - 3 pages - Medical studies
Over the last half century, many attempts to explain the survival of the semiallogenic fetal graft have been proposed. One of the earliest explanations was based on the theory of antigenic immaturity of the embryo-fetus. This was disproved by Billingham (1964) who showed that transplantation...
Fetal Tissues of the Fetal-Maternal Communication System
Tutorials/exercises - 5 pages - Medical studies
The extravillous and villous trophoblasts are the embryonic-fetal tissues of the anatomical interface of the placental arm; the avascular fetal membranes—the amnion and chorion laeve—are the fetal tissues of the anatomical interface of the paracrine arm of this system. The placental...
The Decidua
Tutorials/exercises - 4 pages - Medical studies
This tissue is the specialized, highly modified endometrium of pregnancy. The transformation of secretory endometrium to decidua is dependent upon the action of estrogen and progesterone and other stimuli provided by the implanting blastocyst (or maternal platelets) during trophoblast invasion of...
Prementrual Syndromes
Tutorials/exercises - 2 pages - Medical studies
A variety of maladies, sometimes disabling, beset many ovulatory women in a recurrent manner during the luteal phase of each ovarian cycle. Although the biological basis for this association is not defined, evidence points to a causal relationship between progesterone secretion and withdrawal and...
Clinical Aspects of Menstruation
Tutorials/exercises - 2 pages - Medical studies
Menstruation is the periodic discharge of blood, mucus, and cellular debris from the uterine mucosa. Menses occur at more or less regular, cyclical, and predictable intervals from menarche to menopause except during pregnancy, lactation, anovulation, or pharmacological intervention. It is...
Delirium
Tutorials/exercises - 3 pages - Medical studies
Delirium, a clinical syndrome characterized as an acute disorder of attention and cognitive function, is the most frequent complication of hospitalization for elders and a potentially devastating problem. Delirium often is unrecognized despite sensitive methods for its detection, and its...
Intraneuronal Signaling Pathways
Tutorials/exercises - 7 pages - Biology
Prior to delineating the organization of specific intraneuronal signaling pathways, it is important to consider, in general terms, their role in helping neurons interpret and respond to the barrage of afferent stimulation impinging on them continuously. From an evolutionary perspective, second...
Ion Channels
Tutorials/exercises - 6 pages - Biology
Structure and Function of Voltage-Gated Ion Channels Voltage-gated ion channels allow the flow of ions in response to changes in membrane voltage and are key elements in neuronal excitation and inhibition. Although ion channels can usually pass more than a single type of ion, voltage-gated...
Neurotransmitter and Ion Channels
Tutorials/exercises - 3 pages - Biology
Classes of Neurotransmitters Much of the information transfer between neurons in the CNS occurs via chemical synapses. These synapses use a variety of messengers (neurotransmitters) that are released in a Ca2+-dependent fashion from presynaptic terminals and act on specific protein receptors to...
Sybaptic Plasticity
Tutorials/exercises - 4 pages - Biology
In its simplest form, the postsynaptic response to neurotransmitter release can be mediated by a single protein complex. For example, nicotinic acetylcholine receptors are self-contained stimulus-response modules that both detect a stimulus, acetylcholine, and generate a response, passage of ion...
Principles of Cellular Electrophysiology
Tutorials/exercises - 3 pages - Biology
Resting Membrane Potential In nerve cells, potassium ions (K+) are at higher concentration inside the membrane than outside whereas the opposite is true for sodium (Na+), calcium (Ca2+), and chloride (Cl-) ions (Fig. 1.9-1). The bulk solutions on either side of the membrane are electrically...
Receptors and Second Messengers
Tutorials/exercises - 11 pages - Biology
Neuropeptide receptors have undergone the same process of discovery and characterization that receptors for other neurotransmitters have enjoyed. The process begins with the pharmacological characterization of the receptor's physicochemical binding properties by assessing the affinity of...
Neuropeptides: Biology and Regulation
Tutorials/exercises - 7 pages - Biology
The past several decades have witnessed a veritable explosion of knowledge about the central nervous system (CNS), and in no area has this been as impressive as in peptide neurobiology. Numerous peptide neurotransmitter candidates have been identified and characterized, their CNS distributions...
Physiology of Pregnancy
Tutorials/exercises - 4 pages - Medical studies
Endometrium/decidua is the anatomical site of blastocyst apposition, implantation, and placental development. The endometrium is the mucosal lining of the uterine cavity and the decidua is the highly modified and specialized endometrium of pregnancy. From an evolutionary perspective, the human...
Gas Chromatography
Case study - 4 pages - Physics
Chromatography is a technique used to separate and analyze chemicals. It was initially discovered in the early 1900's by chemist Mikhail Tsvett who was researching chlorophyll to separate plant pigments.1 The components undergoing separation are divided into two phases, a stationary phase, and a...
Pinus strobus - Eastern White Pine
Presentation - 26 pages - Biology
Common: Eastern White Pine Scientific: Pinus strobus Derivation of name: Latin name for pine from Greek "pitus" / incense-bearing or a gum-yielding tree (pitchy) or [sic] Greek "strobus" (cone) [1] Also known as: white pine, northern white pine, northern pine, ship-mast pine, soft pine, pin...
Mites
Tutorials/exercises - 4 pages - Biology
Mites make up the largest group in the class Arachnida. Most are small arthropods, and many are barely visible. Mites have two body regions, a small cephalothorax and a larger, unsegmented abdomen. The cephalothorax and abdomen are broadly joined, giving most mites an oblong to globular...
Lice
Tutorials/exercises - 2 pages - Biology
Lice are small wingless insects that are ectoparasites of mammals. They are mostly host specific, and two species are human parasites: Pthirus pubis (pubic louse) and Pediculus humanus, with two varieties, P. h. capitis (head louse) and P. h. corporis (body louse). They are obligatory parasites,...
Bees, Wasps and Ants
Thesis - 4 pages - Biology
By far the most important venomous insects are members of the order Hymenoptera, including bees, wasps, and ants. They vary in size from minute to large (up to 60 mm in body length). The abdomen and thorax are connected by a slender pedicle that may be quite long in certain wasps and ants. Bees...
Venomous Species and Venoms
Tutorials/exercises - 2 pages - Biology
Insects of the order Lepidoptera typically cause human envenomation, but effects generally are less serious than with hymenopterans. Injury usually follows contact with caterpillars, occurring less frequently with the cocoon or adult stage. The larval lepidopteran (caterpillar) is usually free...
Diptera: Two-winged flies
Tutorials/exercises - 5 pages - Biology
Insects of the order Diptera are characterized by one pair of wings. The second pair is usually modified to form a pair of drumsticklike structures known as halteres. A typical life cycle consists of eggs, limbless larvae, pupae, and winged adults, but numerous variations exist. Mouthparts are...
Wasting Away
Essay - 2 pages - Medical studies
Over the centuries, numerous scientists have devoted their lives to curing the ailments that have plagued mankind. While some diseases (such as polio) have been heroically defeated, others still kill millions of people every year. HIV/AIDS, Ebola, and Influenza, are just some of the many diseases...
Human Pregnancy
Essay - 2 pages - Medical studies
Healthier mothers and babies ranks as one of the 10 great public health achievements in the United States between 1900 and 1999. At the beginning of the century, almost 1 in every 100 women giving birth in this country died of pregnancy-related complications, and nearly 1 of 10 infants died...
Perspectives on Obstetrics
Essay - 3 pages - Medical studies
Medical writers have recently turned to the opening line of Charles Dickens's A Tale of Two Cities to describe these prevailing times in medicine and obstetrics as "the best of times. . . the worst of times. . ." (Grumbach, 1999; Morrison, 2000). Why are these times at once the best and worst...
Scorpion Envenomation
Tutorials/exercises - 2 pages - Biology
Scorpion envenomation can result in distinct clinical syndromes. Most scorpion species' stings cause only local pain and inflammation that respond well to minimal supportive therapy and wound care. These scorpions pose no significant management issues and, with few exceptions, are not...
North American Venomous Reptile Bites
Tutorials/exercises - 2 pages - Biology
North America is unique in that it is home not only to venomous snakes, but also to the world's only known venomous lizards. Fortunately, bites by venomous reptiles in North America are relatively uncommon, although precise statistics are not available. The only systematic attempt to evaluate...
North American Arthropod Envenomation and Parasitism
Tutorials/exercises - 2 pages - Biology
The phylum Arthropoda contains about four fifths of the known animals of the world, and insects are the largest group of arthropods. Insects are an important part of the biota of all terrestrial and freshwater environments that support life; only in marine environments are they relatively...
Neuropsychiatric Aspects of Aging
Tutorials/exercises - 3 pages - Medical studies
The process of aging produces important physiologic changes in the central nervous system, including neuroanatomic, neurotransmitter, and neurophysiologic changes. These processes result in age-related symptoms and manifestations for many older persons. These physiologic changes develop at...
