female sexs cells

Female sex cells

The ovaries produce secondary oocytes -the female sex cells. During fetal development stem cells, called oogonia, go through mitosis. Some of these cells develop into 46-chromosome primary oocytes. At the onset of female puberty tens of thousands of primary oocytes each form part of a primordial follicle in the ovaries. Between menarche and menopause, each […]

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involuntary reflexes

Involuntary reflexes

Somatic reflexes are automatic responses to stimuli that allow for fast reactions, before messages reach the brain. These reflex actions occur in a series of steps known as the reflex arc. First a sensory receptor detects a stimulus and a signal travels through afferent neurons towards the spinal cord. When the signal passes through the […]

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cardiac aupt

Cardiac output

With each contraction of the ventricles blood is pumped out of the heart. Stroke volume is the amount of blood a ventricle pumps out in one contraction. Cardiac output is the volume of blood that each ventricle ejects every minute. To find the cardiac output volume, multiply the number of heart beats in one minute […]

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heart conduction

Heart conduction

The heart’s conduction system regulates the electrical impulses that make the heart beat. An impulse begins in a bundle of nerve tissue called the sinoatrial (or SA) node. The impulse makes the atria contract, and blood empties into the ventricles. Next, the impulse travels to the atrioventricular (or AV) node. It passes through the Bundle […]

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urine creation ii

Urine creation I

Each kidney includes over a million blood-filtering units called nephrons. Blood enters the nephron through a capillary bed called a glomerulus. It is surrounded by a cup-like structure, the glomerular capsule, which is the beginning of the duct called the renal tubule. As blood flows through the glomerulus, blood pressure forces it against a specialized […]

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urina creation

Urine creation II

Glomerular filtration produces a plasma-like filtrate containing waste, but also water and other substances the body needs. As the filtrate passes out of the glomerular capsule and through the renal tubule, substances like water, essential ions, glucose, amino acids, and proteins are reabsorbed into the body through cells along the tube wall. At the same […]

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funtion the skip

Function of the skin

The skin, nails, and hair of the integumentary system provide a barrier between the environment and tissues and organs within the body. The skin is the largest organ in the body. It absorbs nutrients, regulates internal body temperature, and eliminates waste. The epidermis is the outermost layer of skin that provides a barrier between the […]

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singth

Sight

The process of seeing begins when light waves enter the front of the eye. Brightness and distinct colors are first interpreted by structures in the back of the eye, and then sent as stimulus signals that the brain interprets as vision. On the exterior of the eye is an area, called the cornea, that includes […]

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long bone formacion

Long bone formation

During embryonic development cells called chondroblasts begin secreting cartilage that develops in the shape of the skeleton’s long bones. The blue-ish, transparent, avascular tissue formed is called hyaline cartilage. As the cartilage grows, the chondroblasts in the interior calcify and die. Blood vessels penetrate the structure, and deliver osteoblasts. These cells lay down bone material. […]

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