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Hormonal regulation of pregnancy - week 1

By: HWC, Views: 6982

• During pregnancy, hormones play a significant role in triggering changes in the mother and fetus. • Ormones : • Maintain the lining of the uterus and prevent menstruation. Prepare the mammary glands for lactation. • Increase flexibility of the pubic symphysis. • Affect the mot...

The Pressure Flow Model in a Plant

By: HWC, Views: 6024

The vascular system of plants has two transport tissues, called xylem and phloem. Xylem transports water and minerals, while phloem transports a variety of dissolved substances, including sugars and amino acids, throughout the plant. Water in the xylem always moves up, in the direction from th...

Bone cells and tissues - tissue composition and cells

By: HWC, Views: 7437

Bone tissue consists of bone cells secreting bone matrix. • The extracellular bone matrix is a connective tissue that is hard, yet flexible. • Collagen fibers provide flexibility. • Inorganic mineral salts (primarily calcium phosphate, or hydroxyapatite) provide hardness. • Togethe...

A Human Karyotype Preparation Animation

By: HWC, Views: 3853

Blood is collected from the person being analyzed. The blood is added to a growth medium that also contains a chemical that stimulates mitosis. The cells are allowed to grow in this medium for two or three days at body temperature. Colchicine is added to arrest cell division at metaphase. T...

Types of antimicrobial substances (interferons & complement protein)

By: HWC, Views: 6732

• Found in blood and interstitial fluids. • Discourage microbial growth. • Include interferon and complement proteins. • Produced and released by virus-infected lymphocytes. • Enter new cells and inhibit viral replication. • Act against a large variety of viruses (non-speci...

Muscle cell structures - actin, myosin and titin filaments

By: HWC, Views: 6784

Once the muscle cell has been excited it will contract. • A muscle action potential will trigger the release Of Ca2+ ions into the sarcoplasm. • The Ca2+ ions bind to the regulatory proteins and trigger contraction. • Within skeletal muscle cells are structures that provide the ability...

Interspecific Competition Relationship - Competitive & Niche Differentiation

By: HWC, Views: 6323

In an environment with limited resources, any organisms that utilize the same resources will be in competition with each other. For example, let's look at two competing species of paramecium, a single-celled organism that feeds on bacteria. If we raise each of these species in isolation, both...

Protein Structure - Primary, Secondary, Tertiary and Quaternary

By: HWC, Views: 6651

A protein's first order structure, or primary structure, begins with the amino acid sequence of the polypeptide chain. The 20 different amino acids can be arranged in an infinite number of sequences. For example, the hormone insulin, which regulates the uptake of glucose from the blood into ce...

Secretin (inhibiting gastric acid secretion), Cholecystokinin (fat digestion) & Cholecystokinin

By: HWC, Views: 6407

• As chyme approaches the small intestine, secretin also targets acid-producing parietal cells in the gastric mucosa. • Increased secretin inhibits gastric add secretion. • With less gastric acid produced, the chyme going into the intestine is less acidic. • The hormone CCK also reg...