martes, 17 de mayo de 2011

Skeleton vocabulary

I'm sure some of you were missing the post about the vocabulary:

  • Bone marrow Soft connective tissue found inside many bones; site of blood cell formation.

  • Cartilage Smooth covering found at the end of bones; made of tough collagen protein fibers; creates smooth surfaces for the easy movement of bones against each other.

  • Compact bone The dense, hard outer layer of a bone.

  • Joint Point at which two or more bones meet.

  • Ligaments Fibrous tissue that connects bones to other bones; made of tough collagen fibers.

  • Movable joint Most mobile type of joint; the most common type of joint in the body.

  • Skeletal system Body system that is made up of bones, cartilage, and ligaments.

  • Skeleton Sturdy scaffolding of bones and cartilage that is found inside vertebrates.

  • Spongy bone Lighter and less dense than compact bone; found toward the center of the bone.

  • Sprain A ligament injury; usually caused by the sudden overstretching of a joint which causes tearing.

martes, 10 de mayo de 2011

Joints and How they move

A joint is a point at which two or more bones meet. There are three types of joints in the body:
Fixed joints is a joint between two bones that doesnt move . Many of the joints in your skull are fixed joints. The skull plates don't move together or against each other, but they are connected or fused
Partly movable joints allow only a little movement..Your backbone has partly movable joints between the vertebrae. They are connected to each other by pads of cartilageand ligaments. They can only move a small amount
Movable joints allow movement and provide mechanical support for the body. Movable joints are the most common type of joint in your body. Your fingers, toes, hips, elbows, and knees all have movable joints. The surfaces of bones at movable joints are covered with a smooth layer of cartilage. The space between the bones in a movable joint is filled with a liquid called synovial fluid. The fluid lubricates and cushions the bones when they move at the joint. Ligaments help provide their stability and muscles contract to produce movement.
The knee joint is the largest joint in the body, consisting of 4 bones- the femur (thigh bone), the tibia (shin bone), fibula (outer shin bone) and patella (kneecap)- and an extensive network of ligaments and muscles..
There is a joint capsule that is a thick ligamentous structure that surrounds the entire knee. Inside this capsule is a specialized membrane known as the synovial membrane which provides nourishment to all the surrounding structures. The capsule itself is strengthened by the surrounding ligaments.
The stability of the knee owes greatly to the presence of its ligaments. Each has a particular function in helping to maintain optimal knee stability in a variety of different positions. There are two Collateral Ligaments ( inner and outer side) and two Cruciate ligaments.
Each knee joint has two crescent-shaped cartilage menisci. These lie on the medial (inner) and lateral (outer) edges of the upper surface of the tibia bone. They are essential components, acting as shock absorbers for the knee as well as allowing for correct weight distribution between the tibia and the femur.

Singing and dancing with the skeleton.

I have found several skeleton songs with lyrics that can help to learn all the bone names.
I'll begin with this funny cartoons:

It is easy, isn't it?
The two next one are from animaniac cartoons. the first one is the original
This second one is like a karaoke:
Finally "The Bone Dance" of Miley Cirus (Hanna Montana) that maybe some of you have already seen in TV:

In this second one you can read the lyrics


Do you know this word? I don’t think so. Serendipity is when one finds something that one was not expecting to find. You can learn more about this concept in wikipedia.
But Why this title of a post in this blog?
The reason is very simple this mornig I was teaching about pollination and how important is for all living being and this evening I have found in the digital edition of The Guardian this wonderful video of Louie Swarzberg about pollination.
I think that It’s worth and I encourage you to watch it. It is subtitled and the images are really amazing.
"Always take time to smell the flowers and let it fill you with beauty and rediscover this sense of wonder”
(You can begin in 3:20 if you don’t want to listen to the presentation.)

What did you think of that amazing aerial barrel-roll that the hummingbird did at 3:52? Did you see it flying upside down? And did you see the baby bat clinging to mama at 5:55?

domingo, 8 de mayo de 2011

Appendicular Skeleton

Appendicular Skeleton The appendicular skeleton consists of the bones of>the upper and lower extremities.
The upper extremity consists of the bones of the shoulder (pectorla girdle), the arm, the forearm, the wrist, and the hand.

  • Clavicle.The clavicle (commonly called the collar bone) The clavicle and the scapula forms the pectoral girdle
  • Scapula.The scapula is a triangular bone that lies in the upper part of the back
  • Humerus.—The humerus is the longest bone of the upper extremity and is often called the arm bone It articulates with the pectoral girdle to form the shoulder joint, and with the bones of the forearm to form the elbow
  • Radius and Ulna.—When the arm is in the anatomical position with the palm turned forward, the radius is on the lateral (thumb) side and the ulna is on the medial (little finger) side of the forearm
  • Carpal.There are eight carpal bones, arranged in two rows, forming the wrist. Metacarpal.The metacarpal bones are in the palm
  • Phalanges.The small bones of the fingers are called phalanges, and each one of these bones is called a phalanx. Each finger has three phalanges, except the thumb (which has two)
LOWER EXTREMITY.—The lower extremity includes the bones of the hip (pelvic girdle), thigh, leg, ankle, and foot
  • Pelvic bones.— Commonly known as the hip, is a large, irregularly shaped bone composed of three parts: the ilium, ischium, and pubis
  • Femur.The femur, or thigh bone, is the longest bone in the body (fig. 1-24).
  • Patella.The patella is a small oval-shaped bone overlying the knee joint. It is enclosed within the tendon of the quadriceps muscle of the thigh.
  • Tibia.The tibia, or shin bone, is the larger of the two leg bones and lies at the medial side.
  • Fibula.The fibula, the smaller of the two leg bones, is located on the lateral side of the leg, parallel to the tibia.
  • Tarsus.—The tarsus, or ankle, is formed by seven tarsal bones
  • Metatarsus.—The sole and instep of the foot is called the metatarsus and is made up of five metatarsal bones
  • The phalanges are the bones of the toes and are similar in number, structure, and arrangement to the bones of the fingers

Axial Skeleton

The human skeleton can be divided into two main parts; the first part is the axial skeleton and second part is the appendicular skeleton.
Axial Skeleton:
The axial skeleton consists of the skull, thevertebral column, and the thorax.

SKULL.— The skull is the bony structure in the head. It supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible

Cranial Bones.—The cranium is formed by eight major bones, most of which are in pairs.
The frontal bone forms the forehead and the nasal cavity.
The parietal bones form the roof of the skull.The temporal bones help form the sides and base of the skull and also house the auditory and hearing organs.
The occipital bone forms part of the base and back of the skull, and contains a large hole called the foramen magnum
The sphenoid bone is situated on the base of the skull
The ethmoid bone is located in front of the sphenoid
Facial Bones.— : 13 immovable bones and a movable lower jawbone
The maxillary bones form the upper jaw, the anterior roof of the mouth, the floors of the orbits, and the sides and floor of the nasal cavity
The lower jawbone is called the mandible

The vertebral column consists of 24 movable or true vertebrae; the sacrum; and the coccyx or tail bone. The bodies of the vertebrae are separated from each other by intervertebral discs

The spinal column is divided into five regions in the following order:
Cervical (neck), seven vertebrae
Thoracic (chest) twelve vertebrae that articulate with the ribs
Lumbar five lumbar vertebrae located in the small of the back, these vertebrae are the larger and stronger segments of the vertebral column
Sacrum is the triangular bone immediately below the lumbar vertebrae. It is composed of five fused vertebrae The sacrum is connected on each side with the hip bone and with the coccyx to form the posterior wall of the pelvis.
Coccyx is the tailbone. It have four fused vertebrae
The skeleton of the thorax includes 12 ribs on each side articulates posteriorly with the thoracic vertebrae and the sternum in the front upper half of the chest wall.
ribs 1 to 7 are connected to the sternum' by their costal cartilages and are called true ribs
ribs 8 to 10 are termed false ribs. They join the costal cartilage immediately means of their costal cartilages.
ribs 11 and 12, which are free, are known as floating ribs.

Structure of Bones

Bones are rigid organs that are made up of two main types of bone tissue:
Compact bone makes up the dense outer layer of bones.
Spongy bone is lighter and less dense than compact bone, and is found toward the center of the bone. The tough, shiny, white membrane that covers all surfaces of bones is called the periosteum
Many bones also contain in their innermost part a soft connective tissue called bone marrow. There are two types of bone marrow: red marrow and yellow marrow. Red marrow makes blood cells. Yellow marrow consists of fat cells although it will have a different role to that of normal fat cells
The bones of newborn babies contain only red marrow. As children get older, thei red marrow is replaced by yellow marrow. In adults, red marrow is found mostly in the bones of the skull, the ribs, and pelvic bones.

Classification of bones
There are four main types of bones in the human body. They can be long, short, flat, or irregular. Identifying a bone as long, short, flat, or irregular is based on the shape of the bone not the size of the bone.
Long bone are longer than wide . They consist of a long shaft (diaphysis) with two bulky ends or extremities(epiphyses). The structure of a long bone is shown in Figure. They are primarily compact bone but may have a large amount of spongy bone at the ends or extremities. Long bones include femur, tibia, and fibula of the leg, the humerus, radius, and ulna of the arm and the phalanges of the fingers and toes.
Short bones are roughly cube shaped with vertical and horizontal dimensions approximately equal. They consist primarily of spongy bone, which is covered by a thin layer of compact bone. Short bones include the bones of the wrist and ankle.
Flat bones are thin, flattened, and usually curved. Most of the bones of the cranium are flat bones.
Irregular bones are not in any of the above three categories. They are primarily spongy bone that is covered with a thin layer of compact bone. The vertebrae and some of the bones in the skull are irregular bones.
In this video you can watch the different types of bones:


Humans are vertebrates, which are animals that have a backbone. The sturdy scaffolding of bones and cartilage that is found inside vertebrates is called a skeleton. The adult human skeleton has about 206 bones, some of which are named in Figure.
The skeletal system is made up of bones, cartilage, and ligaments.
Bones are not only the hard mineral part as the remains that you might see in a museum. Living bones are full of life. They contain nerves, blood vessels and many different types of tissues
Cartilage is found at the end of bones and is made of tough protein fibers called collagen. Cartilage creates smooth surfaces for the movement of bones that are next to each other, like the bones of the knee.
Ligaments are made of tough protein fibers and connect bones to each other.
Functions of Bones
Your skeletal system gives shape and form to your body, but it is also important in other homeostatic functions. The main functions of the skeletal system are:
  • Support The skeleton supports the body against the pull of gravity. The large bones of the lower limbs support the trunk when standing.
  • Protection The skeleton provides a framework that supports and protects the soft organs of the body. For example, the skull surrounds the brain to protect it from injury. The bones of the rib cage help protect the heart and lungs.
  • Movement Bones work together with muscles as simple mechanical lever systems to move the body.
  • Making Blood Cells Blood cells are made mostly inside certain types of bones.
  • Storage Bones store calcium. They contain more calcium than any other organ does. Calcium is released by the bones when blood levels of calcium drop too low. The mineral phosphorus is also stored in bones.
As in other units in this link Kidshealth you can read and listen information about this subject, and finally a video with a reviw of all about skeleton.

Hormonal Regulation

Hormones are important to homeostatic regulation because they regulate many cell activities. We are going to see two different regulation:
  • Homeostatic feedback control mechanisms
  • Hormone antagonists.
Feedback control mechanism is a signaling system in which a product or effect of the system controls an earlier part of the system, either by shutting the process down (Negative feedback) or speeding it up (positive feed back). Most feedback mechanisms of the body are negative, only a few are positive.
Negative Feedback:
Negative feedback is a reaction in which the system responds in such a way as to reverse the direction of change. Since this tends to keep things constant, it allows for a process to return from a state of imbalance back to a homeostatic equilibrium. The thermostat is a good example to understand the negative feedback:
An example of negative feedback in the body is the control of blood-glucose concentrations by insulin. A higher amount of glucose in the blood signals the pancreas to release insulin into the blood. Then, the blood glucose concentration decreases and this lower concentration causes a decrease in the secretion of insulin by the pancreas.
Another example of negative feedback is the Regulation of pituitary glands and tropic hormans as you can see in the figure:
Positive Feedback
Positive feedback is a reaction in which the system responds in such a way as to speed up the direction of change. Positive feedback mechanisms are not as common as negative one.
Hormone antagonists
Many hormones work with hormone antagonists to control the concentrations of substances in the body. The hormones have opposite actions on the body and so are called antagonistic.
Insulin and glucagon make up an antagonistic hormone pair. The action of insulin is opposite that of glucagon. When your blood glucose concentration rises sharply after you eat food that contains simple carbohydrates, the increase in blood glucose level stimulates the pancreas to release insulin into blood. In response to signals by insulin most body cells take up glucose, which removes it from the blood, and the blood glucose concentration returns to the set point.
Later, when your blood glucose concentration has dropped below the set point, the decrease in glusose stimulates the pancreas to release glucagon. Glucagon causes the release of glucose from liver cells, which increases your blood-glucose concentration. This antagonistic relationship between the two hormones helps to maintain the narrow range of blood glucose concentration.

jueves, 5 de mayo de 2011

Adrenal glands

Adrenal Glands
An adrenal gland is located above each of the kidneys, as shown in Figure. Each adrenal gland is separated into two structures, the adrenal medulla, which is the center of the gland, and the adrenal cortex, which is the outer layer. The medulla and the cortex work as two separate endocrine glands.
Adrenal medulla
It is the core of the adrenal gland, and is surrounded by the adrenal cortex. Secretion of hormones from the medulla is controlled by the sympathetic nervous system. It produce the hormones adrenaline (epinephrine) mainly.This hormone is part of the fight-or-flight response initiated by the sympathetic nervous system. It plays central role in short-term response to stress, increases heart rate and supply of blood with oxygen and glucose to the brain and muscles, while suppressing other non-emergency bodily processes, such as digestion.

Adrenal cortex
Is is the site of steroid hormone synthesis. In contrast to the medulla that is controlled directly by the nervous system, the cortex is regulated by hormones secreted by the pituitary gland. In adrenal cortex are produced:
Cortisol, often called the "stress hormone" as it is involved in the response to stress, and is involved in restoring homeostasis after a stressful event. Cortisol increases blood pressure, blood sugar levels and has an immunosuppressive action.
Aldosterone regulates balance of salt and water in the body. It stimulate sodium reabsorption in the kidneys. This increases blood volume and, therefore, increases blood pressure

The ovaries of females and the testes of males are the gamete producing organs, or gonads. Ovaries in females are homologous to testes in males. In addition to producing gametes, an exocrine action, the gonads are endocrine glands that produce steroid sex hormones. Sex hormones secretion is controled by the gonadotropines produced in pituitary gland.
The sex hormones produced in testes are called androgens. The main androgen produced by the testes is testosterone. Testosterone is responsible for development of the male sex organs and secondary sex characteristics of males such as facial hair and deepening of the voice .
In females the ovaries produce two hormones: estrogen and progesterone. Estrogen causes the release of an egg from the ovaries and progesterone prepares the uterus for a possible implantation by a fertilized egg. Both hormans take part in control the menstrual cycle.
The placenta is an endocrine gland of pregnancy because it secretes estrogens and progesterone which are important for maintaining a pregnancy.

Other Endocrine Glands I

Thyroid Glands
The thyroid is one of the largest endocrine glands in the body. This butterfly-shaped gland is found in the neck, wrapped around the trachea, as shown in Figure. The thyroid is controlled by the pituitary.
The main thyroid hormone is thyroxine (T4). It controls the pace of all of the processes in the body. This pace is related to your metabolism. If there is too much thyroid hormone, every function of the body tends to speed up. As thyroxine controls how quickly the body burns calories, the thyroid gland regulates the body temperature by secreting more or less hormones.
The element iodine is very important for making thyroxine. If a person’s diet does not have enough iodine, their thyroid cannot work properly and the person develops an iodine deficiency disease called goiter. The addition of small amounts of iodine to table salt, has helped reduce the occurrence of iodine-deficiency in developed countries
As a result, problems with the under secretion (Hypothyroidism) or over secretion (Hyperthyroidism) of thyroid hormones affect many body systems.
The pancreas is both an exocrine gland as it secretes pancreatic juice containing digestive enzymes, and an endocrine gland as it produces several important hormones. It is located just below and behind the stomach, as shown in Figure. The endocrine cells of the pancreas are grouped together in areas called islets of Langerhans, shown in Figure. The islets produce the hormones insulin and glucagon. Insulin and glucagon are both involved in controlling blood glucose levels. Insulin causes excess blood glucose to be taken up by liver and muscle cells, where it is stored as glycogen, a polysaccharide. Glucagon stimulates liver cells to break down stores of glycogen into glucose which is then released into the blood.

  • Insulin reduces blood glucose concentration

  • Glucagon raises blood glucose concentration

Hypothalamus and pituitary gland

The hypothalamus is a portion of the brain located in its lower central part. The hypothalamus is the primary link between the endocrine and nervous systems. Nerve cells in the hypothalamus control the pituitary gland by producing chemicals that either stimulate or suppress hormone secretions from the pituitary.
Pituitary Gland
The pituitary gland is about the size of a pea and is attached the hypothalamus by a thin stalk at the base of the brain, shown in Figure. The pituitary gland is considered the most important part of the endocrine system. It's often called the "master gland" because it makes hormones that control several other endocrine glands called tropic hormones. The pituitary hormones regulate homeostasis.
Both of the lobes are under the control of the hypothalamus so the production and secretion of pituitary hormones can be influenced by factors such as emotions and seasonal changes.
The pituitary gland consists of two components:

The anterior pituitary (front lobe), makes many important hormones:
Among the hormones it produces are:

  • Growth hormone, which stimulates the growth of bone and other body tissues and plays a role in the body's handling of nutrients and minerals

  • Prolactin, which activates milk production in women who are breastfeeding

  • Thyrotropin, which stimulates the thyroid gland to produce thyroid hormones

  • Corticotropin, which stimulates the adrenal gland to produce certain hormones

  • Gonadotropin, which stimulates the gonades (ovaries or testes)
Most of these hormones are released under the influence of chemicals from the hypothalamus.
The posterior pituitary (rear lobe), releases two hormones:

  • oxytocin which triggers the contractions of the uterus that occur during the labour and delivery process.

  • antidiuretic hormone (ADH) which helps control body water balance through its effect on the kidneys and urine output.
Oxytocin creates a positive feedback loop. During the labor and delivery process, when the cervix dilates the uterus contracts. Uterine contractions stimulate the release of oxytocin from the posterior pituitary, which in turn increases uterine contractions. This positive feedback loop continues until the baby is born.
Eventually this video will help you to learn the endocrine functions ( you don't need to pay attention to how hyphotlamus stimulates the pituitary gland):

lunes, 2 de mayo de 2011

The endocrine system

The endocrine system and the nervous system work closely together to help us respond to our environment. This is a system of organs ( endocrine glands) that releases chemical message molecules, called hormones, into the blood. Unlike the nervous system whose action helps the body react immediately to change, the endocrine system controls changes that happen to the body over a long period of time; from minutes, hours, to years of change. The endocrine system is important in controlling metabolism, growth and development, reproduction, and salt, water and nutrient balance of blood and other tissues
Organs of the Endocrine System
The endocrine system is made up of many glands that are located in different areas of the body. Hormones are made and secreted by cells in endocrine glands. Endocrine glands are ductless organs that secrete hormones directly into the blood or the fluid surrounding a cell rather than through a duct. The major glands of the endocrine system are shown in Figure. Many other organs, such as the stomach, heart, and kidneys secrete hormones and are considered to be part of the endocrine system.
  • Hypothalamus
  • Pituitary gland
  • Thyroid
  • Adrenal glands
  • Pancreas
  • Ovary (female)
  • Testicles (male)

You can take a look to a video about endocrine system to learm the vocabulary.
The body produces many different hormones, but each hormone is very specific for its target cells. A target cell is the cell on which a hormone has an effect. Target cells are affected by hormones because they have receptor proteins that are specific to the hormone. Hormones will travel through the bloodstream until they find a target cell with the specific receptors to which they can bind. When a hormone binds to a receptor, it causes a change within the cell.
The effects of hormones vary widely, and certain hormones, called tropic hormones (or tropins), regulate the production and release of other hormones. Many of the responses to hormones regulate the metabolic activity of an organ or tissue.