Directed Objectives: Final Exam Flashcards
Osteoblast Pg. 167
Bone forming cells, have an extensive endoplasmic reticulum and numerous ribsomes.
- Produce collagen and proteoglyans, which are packed into vesicles by the Golgi apparatus and releases from the cell by exocytosis.
- Ossification: The formation of new bone by osteoblasts. Occurs by appositional growth on the surface of previously existing material, either bone or cartilage.
- Also release matrix vesicles, which contain high concentrations of Ca2+ and PO3-/4
- Elongated cell extensions from osteoblasts connect to the cell extensions of other osteoblasts through gap junctions.
- Bone matrix produced by the osteoblasts covers older bone surface and surrounds the osteoblast cell bodies and extensions. The result is a new layer of bone.
Osteoclasts Pg. 168
Bone destroying cells. Large, multinucleated cell.
- Perform reabsorption, or breakdown, of bone that mobilizes crucial Ca2+ and phosphate ions for use in many metabolic processes.
- Mature osteoclasts carry out bone reabsorption through a multi-step process.
- Integrins: Form attachment structures via interactions with cell-surface proteins.
Calcitonin (What Does It Do) Pg. 187
- One of three hormones that helps to maintain calcium homeostasis.
- Secreted from the thyroid gland when blood Ca2+ levels are too high.
- Inhibits osteoclast activity by binding to receptors on the osteoclasts.
Simplified Version: Hormone released from parafollicular cells that acts on tissues to cause a decrease in blood levels of calcium ions.
Parathyroid Hormone (PTH) (What does it do?) Pg. 186
- One of three hormones that helps to maintain calcium homeostasis.
- The major regulator of blood Ca2+ levels.
- Secreted from the parathyroid glands when blood Ca2+ levels are low, stimulates an increase in the number of osteoclasts, which break down bone and elevate blood Ca2+ levels.
- Stimulates osteoblasts to release enzymes that break down the layer of unmineralized organic bone matrix covering bone, thereby making the mineralized bone matrix available to osteoclasts.
Simplified Version: Peptide hormone produced by the parathyroid gland; increases bone breakdown and calcium levels.
What Are The Functions of Bone Pg. 166
- Body support:
- Rigid, strong bone is well suited for bearing weight and the major supporting tissue of the body.
- Cartilage provides a firm yet flexible support within certain structures. Ex. Nose, External Ear, Thoracic Cage, and Trachea.
- Ligaments strong bands of fibrous connective tissue that hold bones together. - Organ Production:
- Bone is hard and protects the organs it surrounds.
- Example: The skull encloses and protects the brain, and the vertebrae surround the spinal cord. The ribcage protects the heart, lungs, and other organs of the thorax. - Body Movement:
- Skeletal muscles attach to bones by tendons, which are strong bands of connective tissue.
- Contraction of the skeletal muscles move the bones, producing body movements. Joints, which are formed where two or more bones come together, allow movement between bones.
- Smooth cartilage covers the ends of bones within some joints, allowing the bones to move freely. Ligaments allow some movement between bones but prevent excessive movements. (Ligaments: connect bone to bone) - Mineral Storage:
- Some minerals in the blood are stored in bone. If blood cells of the minerals decrease, the minerals are released from bone into the blood.
- The principal minerals stored are calcium and phosphorus, two mineral essential for many psychological processes. Adipose tissue is also stored within bone cavities, If needed, the lipids are releases into the blood and used by other tissues as a source of energy. - Blood Cell Production:
- Many bones contain cavities filled with red bone marrow, which gives rise to blood cells and platelets.
Components of Bone Matrix Pg. 167
The intercellular substance of the bone tissue; comprised of organic (collagen and proteoglycans) and inorganic substances (mainly hydroxyapatite). Gives bone tensile strength and weight bearing strength
- Normally about 35% organic and 65% inorganic material.
- The collagen and mineral components are responsible for the major functional characteristic of bone.
- Can be compared to reinforced concrete.
- The collagen fibers lend flexible strength to the matrix, like concrete, the mineral components give the weight-bearing strength.
- If all the mineral is removed from a long bone, collagen becomes the primary constituent and the bone is overly flexible. On the other hand, if the collagen is removed from the bone, the mineral component becomes the primary constituent and the bone is very brittle.
Osteogenic Cells Pg. 169
Immature bone cells capable of mitosis that give rise to osteoblasts.
- Osteochondral progenitor cells are stem cells that can become osteoblasts or chondroblasts.
- Located in the endosteum, the inner surface of the periosteum, and within harversian canals.
- From these locations, they are a potential source of new osteoblasts or chondroblasts.
- Osteoblasts are derived from osteochondral progenitor cells, and osteocytes are derived from osteoblasts. Whether or not osteocytes freed from their surrounding bone matrix by reabsorption can revert to become active osteoblasts is a debated issue. As discussed in the previous section, osteoclasts are not derived from osteochondral progenitor cells but from stem cells in red bone marrow.
Osteocytes Pg. 168
Osteocytes: Mature bone cell surround by bone matrix.
- Retain their connections to neighboring osteocytes through cell extensions.
- Become relatively inactive, compared with most osteoblasts, but it is possible for them to produce the components needed to maintain the bone matrix.
- Lacunae: The spaces without the matrix but occupied by the osteocyte cell bodies.
- Canaliculi: The space occupied by the osteocyte cell extensions.
- In a sense, the cells and their extensions form a “mold” around which the matrix is formed.
Where Articular Cartilage Would Be Found? What Type of Cartilage Is It? Pg. 172
Location: Within joints, the end of the bone bone.
Type: Hyaline Cartilage
Part: Yellow Marrow
Description: Fat stored within the medullary cavity or in the spaces of the spongy bone.
Ampiarthrosis Pg. 242
A slightly moveable joint.
Joints can be classified according to it’s degree of motion.
Diarthrosis Pg. 242
Freely moveable joints
Joints can be classified according to it’s degree of motion.
Synarthrosis Pg. 242
Nonmovable joints.
Joints can be classified according to it’s degree of motion.
Positive Feedback Systems (What Are They, When Do They Happen, What Makes Them Stop) Pg. 11
Positive Feedback Systems:
-The body changes from a normal point and amplifies it.
When do they happen?
-Mechanisms occur when a response to the original stimulus results in the deviation from the set point becoming even greater.
What makes them stop?
-Positive Feedback Systems stop when the action is completed.
For example, birth is an example of a normal positive feedback mechanism. Near the end of pregnancy, the baby’s larger size stretched the uterus. This stretching, especially around the opening of the uterus, stimulates contractions of the urine muscles. The uterine contractions push the baby against the opening of the uterus and stretch it further. This stimulates additional contractions, which result in additional stretching. This positive-feedback sequence ends when the baby is delivered from the uterus and the stretching stimulus is eliminated.
The Ability to Sense Changes In The Environment is _______________. Pg. 6
Responsiveness
- An organism’s ability to sense changes in its external and internal environment and adjust to those changes is Responsiveness.
- Responses include actions such as moving toward food or water and moving away from danger or environmental conditions.
- Organisms can also make adjustments that maintain their internal environment. For example, if the external environment causes the body temperature to rise, sweat glands produce sweat, which can lower body temperature down to the normal range.
Homeostasis Pg. 9
The existence and maintenance of a relatively constant environment within the body.
- To achieve homeostasis, the body must actively regulate conditions that are constantly changing.
- As our bodies undergo their everyday processes, we are continuously exposed to new conditions. These conditions are called variables because their values can change.
For example, a small amount of fluid surrounds each body cell; for cells to function normally, the volume, temperature, and chemical content of this fluid must be maintained within a narrow range.
- Homeostatic mechanisms, such as sweating or shivering, normally maintain body temperature near an ideal normal value, set point. *These mechanisms are not able to maintain body temperature precisely at the set point.
- Body temperatures increases and decreases slightly around the set point to a produce a normal range.
- The organ systems help keep the body’s internal environment relatively constant.
Example: For example, the digestive, respiratory, cardiovascular and urinary systems work together, so that each cell in the body receives adequate oxygen and nutrients and waste products do not accumulate to a toxic level. If body fluids deviate from homeostasis, body cells do not function normally and can even die. Disease disrupts homeostasis and sometimes results in death. Modern medicine attempts to understand disturbances in homeostasis and works to reestablish a normal range.
Levels of Structural Organization Pg. 4 and 5
Six Levels of Organization:
- Chemical Level (Atoms):
- Involves interactions between atoms, which are tiny building blocks of matter.
- Atoms combine to form molecules.
- Function of a molecule is related to their structure.
- For example, collagen molecules are ropelike protein fibers that give skin structural strength and flexibility. With old age, the structure of collagen changes, and the skin becomes fragile and more easily torn. - Cell:
- The basic structural and functional units of plants and animals.
- Molecules combine to form organelles, which are the small structures inside cells.
- For example, the nucleus is an organelle that contains the cell’s heredity information, and mitochondria are organelles that manufacture adenosine triphosphate (ATP), a molecule cells use for energy, - Tissue:
- Composed of a group of similar cells and the materials surrounding them.
- The characteristics of the cells and surrounding materials determine the functions of the tissue.
- The body is made up of four basic tissue types: epithelial, connective, muscle, and nervous. - Organ:
- Composed of two or more tissue types that perform one or more common functions.
- The urinary bladder, heart, stomach, and lung are examples of organs. - Organ Systems:
- A group of organs that together perform a common function or set of functions and are therefore viewed as a unit.
- For example, the urinary system consists of the kidneys, ureter, urinary bladder, and urethra. The kidneys produce urine, which the ureters transport to the urinary bladder, which it is stored until being eliminated from the body through the urethra. - Organism:
- Any living thing considered as a whole – whether composed of one cell such as a bacterium, or of trillions of cells, such as a human.
- The human organism is a network of organ systems, all mutually dependent on one another.
* The simplest to the most complex:* - Atom
- Molecule
- Cell
- Tissue
- Organ
- Organ System
- Organism
Astrocytes
- Support neuronal activity
- Remove ions and neurotransmitters that accumulate in extracellular space
- Provide neurons with energy
- Mediate brain development by secreting growth factors, guiding neuronal migration, and enhancing formation of synapses.
Astrocyte means a star-shaped cell. More specifically, these are non-neuronal cells of the nervous system that help to support the neurons (nerve cells).
Responsible for ensuring that water gets to its citizens in an appropriate manner through the pipes. Well, the central nervous system has pipes of its own, blood vessels, and the astrocytes help regulate the flow of blood through these vessels.
Schwann Cells
A glial cell that wraps around the nerve fiber in the peripheral nervous system, and spirally wraps around an axon to form the myelin sheaths of peripheral axons.
Oligodendrocytes
Oligodendrocytes are the myelinating cells of the central nervous system (CNS).They are characterized by having dark round, oval and sometimes irregularly shaped nuclei, in which chromatin is clumped both beneath the nuclear envelope and throughout the nucleoplasm. Oligodendrocytes are most abundant in white matter, but they also occur in gray matter, sometimes as satellites to neurons.Oligodendrocytes are types of cells that make up the supportive or glial tissue of the brain.
Ependymal Cells
Ependymal cell, type of neuronal support cell (neuroglia) that forms the epithelial lining of the ventricles (cavities) in the brain and the central canal of the spinal cord. Ependymal cells also give rise to the epithelial layer that surrounds the choroid plexus, a network of blood vessels located in the walls of the lateral ventricles (the two largest ventricles, which occur as a pair in the cerebral hemispheres).
Ependymal cells and their epithelial derivatives of the choroid plexus have several important functions. In the ventricles ependymal cells possess tiny hairlike structures called cilia on their surfaces facing the open space of the cavities they line. The cilia beat in a coordinated pattern to influence the direction of flow of cerebrospinal fluid (CSF), bringing nutrients and other substances to neurons and filtering out molecules that may be harmful to the cells.
