Module 3 Flashcards
What are the four types of tissues?
Epithelial, connective, muscle and nervous tissues
What is the function of connective tissue?
It binds the cells and organs of the body together and functions in the protection, support, and integration of all parts of the body.
What are the three major types of muscle tissue?
Skeletal (voluntary) muscle, smooth muscle and cardiac muscle.
Describe the muscle tissue.
Muscle tissue is excitable, responding to stimulating and contracting to provide movement.
Describe the nervous tissue.
Nervous tissue is excitable, allowing the propagation of electrochemical signals in the form of nerve impulses that communicate between different regions in the body.
What are the three germ layers from which all the tissues eventually form? Differentiate between the three.
Ectoderm -outer
Mesoderm - middle
Endoderm - inner
Where is the nervous tissue, and muscle tissue derived from?
Nervous tissue - ectoderm
Muscle tissue - mesoderm
What is a tissue membrane?
A tissue membrane is a thin layer or sheet of cells that covers the outside of the body, the organs, internal passageways that lead to the exterior of the body and the lining of the movable joint cavities.
What are the two parts of a long bone?
Diaphysis and epiphysis
What is diaphysis?
The tubular shaft that runs between the proximal and distal ends of the bone.
What is the hollow region in the diaphysis called? What is it filled with?
Medullar cavity; with yellow marrow
The walls of the diaphysis are composed of what?
dense and hard compact bone
What is the epiphysis? What is it filled with?
The wider section at each end of the bone. It is filled with spongy bone.
What fills the spaces in the spongy bone?
Red marrow
Where does each epiphysis meet the diaphysis?
At the metaphysis
What is metaphysis?
The narrow area that contains the epiphyseal plate (growth plate), a layer of hyaline (transparent) cartilage in a growing bone.
What happens when the bone stops growing in early adulthood (approximately 18-21 years)?
The cartilage is replaced by osseous tissue and the epiphyseal plate becomes an epiphyseal line.
What is the delicate membranous lining that a medullary cavity has? What takes place in this?
Endosteum, this is where bone growth, repair and remodelling occur.
What is the outer surface of the bone covered with? What does it contain?
A fibrous membrane called the periosteum, which contains blood vessels, nerves, and lymphatic vessels that nourish the compact bone.
The periosteum covers the entire outer surface except for what? What is it covered with?
Except where the epiphyses meet other bones to form joints. In this region, the epiphyses are covered with articular cartilage.
What is the articular cartilage?
A thin layer of cartilage that reduces frictions and acts a shock absorber.
What is the diploe?
a layer of spongy bone lined on either side by a layer of compact bone that flat bones consist of.
What is the function of the two layers of compact bone and the interior sponge?
They work together to protect the internal organs.
What happens to the outer layer of a cranial bone if it fractures?
The brain is still protected by the intact inner layer (like spongy bone).
What are the three general classes of bone markings?
Articulations, projections, and holes.
What is an articulation?
This is where two bone surfaces come together.
What is a projection?
An area of a bone that projects above the surface of the bone; these are the attachment points for tendons and ligaments.
What is a hole (bone marking)?
An opening or groove in the bone that allows blood vessels and nerves to enter the bone.
What is the function of hydroxyapatite crystals and collagen fibres?
The hydroxyapatite crystals give bones their hardness and strength, while the collagen fibres give them the flexibility so that they are not brittle.
What ae the four types of cells found within bone tissue?
Osteoblasts, osteoclasts, osteocytes and osteogenic cells.
Which of the two types of bone tissue is denser and stronger?
Compact bone
Where can you find compact bone?
It can be found under the periosteum and in the diaphyses of long bones, where it provides support nd protection.
What is the microscopic unit of compact bone called?
Osteon or Haversian system
What is lamellae?
Concentric rings of calcified matric that each osteon is composed of.
What is the central canal or Haversian canal?
Center of each osteon which contains blood vessels, nerves, and lymphatic vessels.
Where do the vessels and nerves branch off through at right angles to extend to the periosteum and endosteum?
Perforating canal, aka Volkmann’s canals.
What is the spongy bone also known as?
Cancellous bone
What is the similarities and differences between compact bone and spongy bone?
Like compact bone, spongy bone contains osteocytes housed in lacunae but they are not arranged in concentric circles.
Where are the lacunae and osteocytes found in a spongy bone?
In a lattice-like network of matrix spikes called trabeculae.
What is the function of the trabecula?
It forms along lines of stress to provide strength to the bone.
What is the purpose of the spaces of the trabeculated network?
Provide balance to the dense and heavy compact bone by making bones lighter so that muscles cam move them more easily.
Where do the spongy bone and medullary cavity receive nourishment from?
From arteries that pass through the compact bone.
Where do the arteries enter?
Through the nutrient foramen, small opening in the diaphysis.
What are the osteocytes in spongy bone nourished by?
By blood vessels of the periosteum that penetrate spongy bone and blood that circulates in the marrow cavities.
What happens as the blood passes through the marrow cavities?
It is collected by veins which then pass out of the bone through the foramina.
What are the functions of the nerves?
They sense pain and regulate blood supplies and bone growth
Bone is a replacement tissue, what does this mean?
It uses a model tissue on which to lay down its mineral matrix.
For skeletal development, what is the most common template?
Cartilage
During fetal development, what is the purpose of a framework?
It is laid down that determines where bones will form.
Cartilage is avascular, what does this mean?
It has no blood vessels supplying the nutrients and removing metabolic wastes.
Where does bone form throughout fetal development and into childhood growth and development?
On the cartilaginous matrix.
By the time a fetus is born, what happens to most of the cartilage?
They have been replaced with bone.
What happens during intramembranous ossification?
Compact and spongy bone develops directly from sheets of mesenchymal (undifferentiated) connective tissue.
What bones are formed via intramembranous ossification?
The flat bones of the face, most of the cranial bones, and the clavicles.
What is osteoid?
Uncalcified matrix, which calcifies (hardens) within a few days as mineral salts are deposited on it, thereby entrapping the osteoblasts within.
What happens to the osteoblasts once they are entrapped?
They become osteocytes
What happens to the osteoid secreted aroung the capillaries?
They result in a trabecular matrix
What happens to the osteoblasts on the surface of the spongy bone?
They become the periosteum
What does the periosteum do during intramembranous ossification?
It creates a protective layer of compact bone superficial to the trabecular bone.
What happens after trabecular bone crowds nearly blood vessels?
They eventually condense into red marrow.
When and where does intramembranous ossification begin?
In utero during fetal development.
What are the last bones to ossify via intramembranous ossification?
Flat bones of the face.
What happens in endochondral ossification?
Bone develops by replacing hyaline cartilage.
True or False. Cartilage becomes bone. Explain.
False, cartilage does not become bone. Cartilage serves as a template to be completely replaced by new bone.
What bones are formed via endochondral ossification?
Bones at the base of the skull and long bones.
What are chondrocytes?
Cartilage cells
What is the perichondrium?
The membrane that covers the cartilage during endochondral ossification in long bones.
What happens to the chondrocytes in the center of the cartilaginous model as more matric is produced?
They grow in size
What happens as the matrix calcifies in long bones?
Nutrients can no longer reach the chondrocytes which results in their death and the disintegration of the surrounding cartilage.
What happens when the blood vessels invade the resulting spaces during endochondral ossification?
They enlarge the cavities and also carry the osteogenic cells with them, many of which become osteoblasts. These enlarged spaces eventually combine to become the medullary cavity.
As the cartilage grows, what happens?
Capillaries penetrate it which initiates the transformation of the perichondrium into the bone-producing periosteum.
What is the primary ossification center?
A region deep in the periosteal collar where ossifctaion begins.
What increases the bone’s length at the same time bone is replacing cartilage in the diaphyses?
Chondrocytes and cartilage that continue to grow at the ends of the bone (the future epiphyses)
What happens by the time the fetal skeleton is fully formed?
Cartilage only remains at the joint surface as the articular cartilage and between the diaphysis and epiphysis as the epiphyseal plate.
After birth, matrix mineralization, death of chondrocytes, invasion of blood vessels from the periosteum and seeding with osteogenic cells that become osteoblasts occurs in the epiphyseal region and each of these centers of activity is referred to as a?
Secondary ossification center
What is the epiphyseal plate?
Area of growth in a long bone.
What happens on the epiphyseal side and the diaphyseal side on the epiphyseal plate?
epiphyseal side - cartilage is formed
diaphyseal side - cartilage is ossified
When the cartilage is ossified on the diaphyseal side, what happens to the diaphysis?
It grows in length
What are the four zones of cells and activity that an epiphyseal plate is composed of?
Reserve zone, proliferative zone, maturation and hypertrophy, and calcified matrix
What is appositional growth?
bone growth in diameter
What is modelling?
A process during bone’s growth; Erosion of old bone along the medullary cavity and the deposition of new bone beneath the periosteum
What is bone remodelling?
Resorption of old or damaged bone takes place on the same surface where osteoblasts lay new bone to replace that which is resorbed.
What is hypocalcemia?
A condition characterized by abnormally low levels of calcium.
Why is adequate calcium is important?
Without this, blood has difficulty coagulating, the heart may skip beats or stop beating altogether, muscles may have difficulty contracting, nerves may have difficulty functioning, and bones may become brittle.
What is hypercalcemia?
A condition characterized by abnormally high levels of calcium
What happens when one has hypercalcemia?
The nervous system is underactive which results in lethargy, sluggish reflexes, constipation and loss of apetite confusion and in severe cases, coma.
What is the purpose of the bones?
They act as a storage site for calcium
Where does the body deposit and release calcium?
The body deposits calcium in the bones when blood levels get too high and it releases calcium when blood levels drop too low.
What is the normal calcium level?
10 mg/dL
