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Phases of the Female Reproductive Cycle - Hormonal regulation

By: HWC, Views: 7108

FSH, LH and estrogen • FSH travels through the bloodstream from the anterior pituitary to the ovaries. • FSH promotes follicular growth. Increased follicular growth promotes estrogen production. • Small increases in blood estrogen levels inhibit the release of FSH and LH into the bl...

Hormonal regulation of pregnancy - weeks 17 through 38

By: HWC, Views: 6916

• Estrogens increase uterine blood flow, maintaining the endometrium during pregnancy. • High levels of estrogen and progesterone inhibit the synthesis of milk. Progesterone inhibits myometrial contractions of the uterus to prevent premature birth. • Relaxin inhibits myometrial contract...

The Lac Operon in E. Coli

By: Administrator, Views: 10700

The lac operon (lactose operon) is an operon required for the transport and metabolism of lactose in Escherichia coli and many other enteric bacteria. Although glucose is the preferred carbon source for most bacteria, the lac operon allows for the effective digestion of lactose when glucose is no...

Lactation and Breast Feeding

By: HWC, Views: 7491

Regulation of lactation - breast preparation • Pregnancy hormones trigger breast changes to prepare for feeding the new baby. • The amount of the hormone prolactin, essential to the initiation of lactation, increases steadily throughout pregnancy. • However, high levels of both estroge...

Brain Anatomy Animation (Part 2 of 2)

By: Administrator, Views: 10903

Its nervous tissue consists of millions of nerve cells and fibers. It is the largest mass of nervous tissue in the body. The brain is enclosed by three membranes known collectively as the meninges: dura mater arachnoid pia mater The major structures are the: cerebrum cerebellum dienc...

Role of the respiratory system - effect of altered ventilation rates

By: HWC, Views: 6537

• Dissociation of the chemical substances in the body fluids can result in the production of free hydrogen ions. • The pH scale is used to measure the concentration of hydrogen ions in solution. • Normal blood pH values vary around 7.4. • When hydrogen ion concentration increases, t...

Metabolic Rate, Heat and Thermoregulation - response to heat and cold stresses

By: HWC, Views: 6872

• A neuron group in the anterior portion of the hypothalamus controls heat balance. • Neurons in the preoptic region of the hypothalamus integrate signals that come from thermoreceptors. • The temperature control center in the preoptic region propagates control signals to two other part...

Structures that affect circulation - arterioles and vasomotor responses and venous return

By: HWC, Views: 6742

■ Small arteries and arterioles determine SVR. • Blood pressure drops significantly as blood passes through arterioles. • Decreasing arteriole radius and decreased wall elasticity are the main reasons for increased SVR. ■ Small changes in arteriole radius can cause large changes in ...

Spermatogenesis Animation

By: Administrator, Views: 9930

Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubules. These cells are called spermatogonial stem cells. T...