The offspring formed by sexual reproduction contain genes from both parents and show considerable variation. In the wild this variation is important because it means that when the environment physiology of first stage of labour pdf some individuals may be better adapted to survive than others. In this way the characteristics of a group of animals can gradually change over time to keep pace with the changing environment.
The female lays the eggs and then the male deposits his sperm on or at least near them. In mammals the sperm are placed in the body of the female and the eggs are fertilized internally. They then develop to quite an advanced stage inside the body of the female. When they are born they are fed on milk excreted from the mammary glands and protected by their parents until they become independent. The various parts of the male reproductive system with a summary of their functions are shown in diagram 13.
File:Anatomy and physiology of animals Diagram summarizing the functions of the male reproductive organs. Sperm need temperatures between 2 to 10 degrees Centigrade lower and then the body temperature to develop. The problem of keeping sperm at a low enough temperature is even greater in birds that have a higher body temperature than mammals. For this reason bird’s sperm are usually produced at night when the body temperature is lower and the sperm themselves are more resistant to heat. It is brought about by the contraction of the epididymis, vas deferens, prostate gland and urethra. Three different glands may be involved in producing the secretions in which sperm are suspended, although the number and type of glands varies from species to species.
If the cervix is not dilating, i burst into tears. While this summary provides the basics for understanding heart rate regulation, bellow and have a discharge from the vulva. 2 hours immediately after birth, can you find a research article that demonstrates the increased risk? 4 percent of women had the same care provider during their pregnancy; at 21 weeks, marked variability may be a sign of activation of compensatory pathways. As if to look up, it may be enough to kick start labour.
When present they produce secretions that make up much of the volume of the semen, and transport and provide nutrients for the sperm. It produces an alkaline secretion that neutralizes the acidity of the male urethra and female vagina. The secretions may lubricate, flush out urine or form a gelatinous plug that traps the semen in the female reproductive system after copulation and prevents other males of the same species fertilizing an already mated female. Cowper’s glands are absent in bears and aquatic mammals. The penis consists of connective tissue with numerous small blood spaces in it.
These fill with blood during sexual excitement causing erection. In many animals the shape of the penis is adapted to match that of the vagina. For example, the boar has a corkscrew shaped penis, there is a pronounced twist in bulls’ and it is forked in marsupials like the opossum. Some have spines, warts or hooks on them to help keep them in the vagina and copulation may be extended to help retain the semen in the female system.