NERVOUS SYSTEM

The parts of the nervous system:

The parts of the central nervous system:

Peripheral nervous system:

The human nervous system is composed of two main parts; namely, the central nervous system (CNS) and the peripheral nervous system (PNS). The central nervous system is comprised of the snail cord and the brain, while the peripheral nervous system is composed of nervous tissue connecting the central nervous system to the other parts of the body. The peripheral nervous system is responsible for relaying information and feedback to the central nervous system. The PNS is comprised of the autonomic nervous system and the somatic nervous system, each of which have different functions.

Involuntary arc:

A reflex is a response to a perturbing stimulus that acts to return the body to homeostasis. This may be subconscious as in the regulation of blood sugar by the pancreatic hormones, may be somewhat noticeable as in shivering in response to a drop in body temperature; or may be quite obvious as in stepping on a nail and immediately withdrawing your foot.

A reflex arc refers to the neural pathway that a nerve impulse follows. The reflex arc typically consists of five components (3):

1. The receptor at the end of a sensory neuron reacts to a stimulus.

2. The sensory (afferent) neuron conducts nerve impulses along an afferent pathway towards the central nervous system (CNS).

3. The integration center consists of one or more synapses in the CNS.

4. A motor (efferent) neuron conducts a nerve impulse along an efferent pathway from the integration center to an effector.

5. An effector responds to the efferent impulses by contracting (if the effector is a muscle fiber) or secreting a product (if the effector is a gland).

Más sobre los reflejos

voluntary arc:

Deseases:

Parkinson

Alzheimer

Diabetes

ENDOCRINE SYSTEM

Your endocrine system is made of many glands and organs. They have different functions, and work together to keep you healthy. These are the glands of your endocrine system:

Adrenal glands - influence the way your body uses energy, they also release a hormone called adrenaline when you are under stress

Hypothalamus - part of your brain that controls hormone production by releasing different chemicals to the pituitary gland

Ovaries - produce estrogen and progesterone in women, and also release egg cells

Pancreas - releases the insulin your body needs to metabolize sugar; problems with the pancreas can lead to diabetes

Parathyroid - located behind the thyroid gland, they are essential for proper bone development

Pineal gland - connects the endocrine system with the nervous system; produces several important hormones, including melatonin, important to sleep/wake cycles and sexual development

Pituitary gland – likely the most important gland in your body, it is crucial to growth, mental development and reproduction; influences or controls the rest of your endocrine system

Testes - produce the hormone testosterone; in men, testosterone maintains sperm production and bone mass

Thymus - crucial to normal immune function in childhood; once a child reaches puberty, its tissue is replaced by fat

Thyroid gland – located in the front of your neck, it releases hormones that control your metabolism and govern the way your body uses energy

Mas información sobre el sistema endocrino aquí

Endocrine system information and 3D anatomy

HUMAN REPRODUCTION

Reproductive organs:

male:

Información sobre: Male reproductive organs

Female:

Información sobre: Female reproductive organs

Sex cells:

Sex hormones:

Female

Estrogens are present in significant amounts in both men and women. They are present in significantly higher amounts in women after menarche (onset of menstrual periods at puberty) until menopause (cessation of menstrual periods after completion of reproductive age).

The primary function:

The primary function of estrogens is development of female secondary sexual characteristics. These includes breasts, endometrium, regulation of the menstrual cycle etc.

Secundary function:

Estrogen is responsible for development of the female body and the secondary sexual characters. It helps decelerate height increase in females during puberty, accelerates burning of body fat and reduces muscle bulk. It also stimulates growth of the inner lining of the uterus (endometrium) during the menstrual cycle, increases uterine growth, improves lubrication of the vagina, and thickens the vaginal wall while increasing blood vessels to the skin.

Click here for more information about estrogens

Male

Male sex hormones are called androgens. The main androgen is testosterone. Testosterone is secreted mainly by the testes.

Male Primary Sex Characteristic:

Enlargement of the testes (and with it the production of spermatozoa)

Male Secondary Sex Characteristics:

increased body hair growth (and sometimes the opposite, baldness, too)
larynx enlargement and thickening of the vocal folds to lower voice pitch
thickening of the skin
increased muscular growth and change in body shape
thickening and strengthening of the bones

Click here for more information about androgen

Para saber más: sex hormones link

Female cycle:

Fertilization:

Videos:

Enlace a fecundación y desarrollo embrionario

desarrollo embrionario:

Placenta:

Steps of Birth:

The first stage of labor (dilation) begins when the cervix is 3 cm dilated. The cervix is pulled upward during contractions. Full dilation occurs when the cervix is wide enough to allow passage of the baby's head, about 10 cm for a full-term infant.

The duration of labor varies widely, but the active phase averages some 20 hours for women giving birth to their first child and 8 hours for women who have previously given birth.

The second stage (expulsion) begins when the cervix is fully dilated, ending when the baby is born. Fetal movement through the birth canal is assisted by the additional maternal efforts of "bearing down" or pushing. The fetal head is seen to 'crown' as the labia part, and the baby is born.

The period from just after the fetus is expelled until just after the placenta is expelled is called the third stage of labor (placenta expulsion), which lasts, on average, 10–12 minutes.

Source: Boundless. “Stages of Labor.” Boundless Anatomy and Physiology. Boundless, 14 Nov. 2014. Retrieved 25 May. 2015 from https://www.boundless.com/physiology/textbooks/boundless-anatomy-and-physiology-textbook/human-development-and-pregnancy-28/birth-parturition-266/stages-of-labor-1303-9021/