Chapter 1-6 Flashcards
1
Q
Define Homeostasis
A
Maintenance of stable internal environment regardless of outside changes
2
Q
Name 5 components of Control Mechanism
A
- Stimulus - change in external environment
- Receptor - senses the change and sends a message via afferent pathway (sensory neuron) to the control centre
- Control Centre - analyses and decides on response and sends msg to effector via efference pathway (motor neuron)
- Effector - the muscle or gland that responds to the command from the control centre
- Response - the action carried out by the effector
3
Q
Describe Negative Feedback and give an example
A
Response that reduces or shuts off the original stimulus. If stimulus is decreased then response is increased.
EG. regulation of blood volume
1. Receptor senses a decrease on blood volume
- Control Centre in hypothalumus detects the loss of blood and sends a msg to the pituitary gland to release ADH hormone
- ADH causes kidneys (effector) to return more water to the blood
- Response is increased blood volume
- Return to normal volume sensed by receptors.
- Control centre stops stimulation of pituitary gland.
- Pituitary gland stops release of ADH.
4
Q
Describe positive feedback and give an example
A
Response increases or exaggerates original stimulus. If there is an increase in stimulus, response is increased.
This type of feedback is otherwise normal self limiting (childbirth) or can result in an abnormal disease condition (heart failure)
EG. Childbirth:
stretching of cervix -> oxytocin -> contraction of uterus -> more oxytocin -> more contractions -> more oxytocin, etc… then once baby is born the cycle will end
5
Q
Describe a positive feed back that ends heart failure
A
EG. Heartfailure
plaque build up in vessels -> decreased diameter of vessels -> inflammation of vessels -> more plaque build up -> increased restriction of flow -> increased blood pressure -> stress on heart -> heart failuretion
6
Q
What is the function of the plasma membrane and what is it made of?
A
- Plasma membrane separates intercellular fluid from extracellular fluid and plays a major part in cellular activity
- Constantly changing fluid mosaic
7
Q
What is the fluid mosaic made up of?
A
- 75% phosophlipid bilayer
- 5% glycolipids
- 20% cholesterol
8
Q
What is the phospholipid bilayer made up of?
A
- phosphate heads that are polar (hydrophilic)
2. fatty acid tails that are non polar (hydrophobic)
9
Q
What are the glycolipids and where are they located?
A
- Glycolipids are lipids with attached sugar groups
2. They are attached to the outer surface of the membrane.
10
Q
What is the function of cholesterol in the membrane?
A
stabilizes the membrane, regulates fluidity
11
Q
List the 6 functions of the membrane protein
A
TRAEIC
- Transport (ATP - Active Transport)
- Receptors - sites for chemical messengers to bind on (eg. hormones)
- Attachment - cytoskeleton and extracellular matrix
- Enzymes - catalysts (speed up reactions)
- Intercellular joining - anchor cells to each other
- Cell to cell recognition - identify cells, self or foreign (eg. WBC’s can tell whether to attach or not)
12
Q
Name the 3 membrane proteins, location and function
A
- Integral - located firmly into the membrane and transport proteins, enzymes or receptors
- Peripheral - loosely attached to integral proteins either inside or outside the membrane. They act as enzymes, motor proteins, cell-to-cell links, support on intracellular surface
- Glycoprotein - proteins with sugar groups attached. They function in cell identification and form part of the glycocalyx (sugar coating)
13
Q
Name two special structures of the cell membrane
A
- Glycocalyx - sugar coating on cells, composed of glycolipids and glycoproteins and plays a part on cell recognition
- Microvilli - outfoldings on the apical cell membrane, increase surface area (eg. digestive tract)
14
Q
Name the 3 membrane junctions
A
- Tight junction
- Desmosome
- Gap junction
15
Q
What is the function of the tight junction and where in the body where it might be useful?
A
Prevents fluids and molecules from moving between cells.
These would be useful in the stomach
16
Q
What is the function of the desmosome?
A
They act like rivets that anchor cells together. They resist tension and resist cells from being separated.
17
Q
What is the function of the gap junction?
A
Permit quick spread of ions between cells.
18
Q
What are the 3 functions of the plasma membrane?
A
- selectively permeable - only lets certain molecules through
- controls movement of materials in and out
- maintains homeostasis
19
Q
Name the 2 types of membrane transport and describe
A
- Passive process - no ATP required, substance moves down its concentration gradient
- Active process - ATP energy required, proteins required, substances move against concentration gradient
20
Q
Name 3 characteristics that determine whether or not a substance can passively penetrate a membrane
A
- its solubility
Lipid soluble - substance can diffuse through the bilayerWater soluble - must use channels or carriers - its size - large molecules cannot get through
- suitable carrier proteins - carriers are specific, can only bind to certain molecules
21
Q
Name 4 types of passive procceses
A
- Filtration
- Simple Diffusion
- Facilitated Diffusion
- Osmosis
22
Q
Describe Filtration
A
Materials are carried along with fluid from an area of high fluid pressure to an area of low fluid pressure
23
Q
Describe Simple Diffusion
A
Diffuse directly through the phospholipid bilayer following a concentration gradient. Kinetic energy causes them to move - random movement
24
Q
Describe Facilitated Diffusion
A
- Uses carriers or channel proteins
2. substances can only move with a concentration gradient from high to low.
25
Describe Osmosis
Diffusion of water across a selectively permeable membrane.
26
Describe carrier proteins
Integral proteins transport specific polar molecules. Binding of substrate causes shape change in carrier.
27
Describe channel proteins
aqueous channels formed that selectively transport ions or water
28
Name two types of channel proteins
1. Leakage - always open
| 2. Gated - controlled by chemical or electrical signals
29
Name the two ways water diffuses through the plasma membrane during osmosis
1. through the lipid bilayer - wiggling between phospholipids
2. through protein channels calls aquaporins
30
What does water respond to when it diffuses?
It responds to concentration gradients from higher water concentration to areas of lower water concentration
31
What happens when osmosis occurs?
1. Water enters or leaves a cell
32
What is tonicity?
Terms used to describe concentration solutes in two different solutions
33
What are isotonic solutions?
Two solutions with the same solute concentrations
34
What are hypertonic solutions?
A solution having a greater solute concentration than some other solution
35
What are hypotonic solutions?
A solution with a lower solute concentration than some other solution
36
What is the effect of an isotonic solution on a red blood cell?
no change - osmosis happens equally in both directions
37
What is the effect of a hypertonic solution on a red blood cell?
Cell will shrink (crenated)
38
What is the effect of a hypotonic solution on a red blood cell?
Cell will swell (lyses).
39
Name 2 types of active processes
1. Active transport pumps
| 2. Vesicular transport
40
Name 3 characteristics of Active Transport
1. requires carrier proteins
2. moves solute against a concentration gradient
3. requires ATP energy
41
Name 3 types of active transport
1. Primary transport
2. Secondary transport
3. Cotransport
42
Describe primary active transport
Energy comes directly from hydrolysis of ATP. Causes shape change on transport protein so that ions are pumped across the membrane. (eg. sodium/potassium pump)
43
Describe secondary active transport
Depends on ion gradient created by primary active transport.
44
Describe cotransport
Always transports more than one substance at a time.
45
Name the two systems used by contransport
a. Symport system - two substances transported in the same direction
b. Antiport system - two substances transported in opposite direction
46
Describe vesicular transport
transports large molecules, macromolecules and fluids across plasma membrane..requires ATP.
47
Name 3 types vesicular transport
1. Exocytosis - transport out of cell
2. Endocytosis - transport into cell
3. Transcytosis - transport into, across, and then out of cell
48
Name 3 types of endocytosis
1. Phagocytosis - solid materials are engulfed and brought into interior of cell, carried out by some types of white blood cells
2. Pinocytosis - liquids and solutes brought into cell by infolding of plasma membrane
3. RME - specific endo and trans cytosis. Main mechanism for the movement of most macromolecules.
49
What type of molecules help cells stick together?
Cell adhesion molecules (CAMs)
50
Name 3 things that CAMs do.
1. anchor cells to extracellular matrix or to each other
2. assist in movement of cells past one another
3. CAMs of blood vessel lining attract white blood cells to injured or infected areas
51
What is the cytoplasm?
The cytoplasm is the cell contents outside the nucleus and is the major site of most activities carried out by the cell.
52
What is the fluid part of the cytoplasm called?
The cytosol.
53
What parts of the cell carry out specific activities for the cell as a whole?
The organelles
54
Define nucleus
Control centre of the cell. Is the site for genetic material - DNA.
55
When the cell is not dividing what is the genetic material in a threadlike form called?
Chromatin
56
When the cell is dividing the chromatin coils and condenses to form what?
Chromosomes
57
What function does the nucleoli play?
Nucleoli is the assembly sites for ribosomes.
58
What is the double layered membrane that surrounds the nucleus called?
Nuclear envelope
59
Define smooth ER
Site of lipid synthesis
60
Define Mitochondrion
Powerhouse of the cell, produces ATP energy
61
Define Lysosome
Digest worn out cell organelles and foreign substances that enter the cell
62
Define Centrioles
Direct the formation of the mitotic spindle during cell division
63
Define Microvilli
Fingerlike projections that greatly increase the surface area of the cell
64
Define microfilaments
Anchor the organelles and moving them within the cell
65
Define microtubule
Give cell shap and form. Move materials within the cytoplasm of cell.
66
Define intermediate filaments
Resist mechanical forces acting on cells
67
Peroxisome
Detoxify alcohol, hydrogen peroxide and other harmful chemicals.
68
Golgi Apparatus
Packages proteins or other substances that will be exported by the cell.
69
Ribosomes
Made of RNA and protein. Sites of protein synthesis...they are free floating or attached to a the rough ER.
70
Rough ER
Studded with ribosomes associated with protein synthesis. Ribosomes making these proteins will be secreted.
71
Name the 6 steps in mitosis.
1. Interphase
2. Early prophase
3. Late prophase
4. Metaphase
5. Anaphase
6. Telephase (cytokinesis)
72
What is the difference between mitosis and cytokinesis?
Mitosis - nuclear division
Cytokinesis - division of the cytoplasm
73
What happens during interphase?
Period from cell formation to cell division. Nuclear material called chromatin.
74
Name for 4 phases of interphase
1. G1 - (gap 1) vigorous growth and metabolism
2. G0 - gap phase in cells that permanently cease dividing
3. S(synthetic) - DNA replication
4. G2 - gap 2 - preparation for division
75
What is the importance of cell division?
Necessary for growth and cell repair.
76
What is the difference between mitosis and meiosis?
1. Mitosis - daughter cells are diploid (have 46 chromosomes)
2. Meoisis - occurs only in germ cells and results are haploid cells (23 chromosomes)
77
What are the largest molecules in the body?
Nucleic acids
78
What two major molecules are included in nucleic acids?
1. Deoxyribonucleic acid (DNA)
| 2. Ribonucleic acid (RNA)
79
What are the structural units of nucleic acids called?
Nucleotides
80
What are the 3 components nucleotides consist of?
1. nitrogen-containing base
2. pentose sugar
3. phosphate group
81
What are the major cell sites for DNA and RNA?
1. DNA - the nucleus
| 2. RNA - cytoplasm
82
What is the major function of DNA vs RNA?
1. DNA - genetic material, directs protein synthesis, replicates itself before cell division
2. RNA - carries out the genetic instructions for protein synthesis
83
What are the sugars in DNA vs RNA?
1. DNA - deoxyribose
| 2. RNA - ribose
84
What are the bases in DNA vs RNA?
1. DNA - adenine, guanine, cytosine and thymine
| 2. RNA - adenine, guanine, cytosine and uracil
85
What are the base pairings in DNA?
A always bonds to T
| G always bonds to C
86
What is the difference in structure between DNA and RNA?
1. DNA is a double strand coiled into a double helix
| 2. RNA - single strand, straight or folded
87
Describe what happens in prophase
Chromatin coil together in pairs to make chromosomes (double stranded structures).
Chromosomes are connected by button like structures called centromeres.
The centrioles separate and the microtubules make a system called the mitotic spindle.
Nuclear envelope and nucleolus disaappear.
88
Describe what happens in metaphase
Chromosomes line up with the equator of the spindle
89
Describe what happens anaphase
The centromeres split and the chromosomes (chromotids) seperate from one another and move slowly to opposite ends of the cell with their "arms" dangling behind them.
90
Describe what happens in telophase
Chromosomes uncoil and resume the chromatin form, spindles breaks down and disappears, nuclear envelope forms around each chromatin mass and nucleoli appear.
91
Describe what happens in cytokinesis
Cell divides. Daughter cells grow and carry out the normal spectrum processes until its their turn to divide.
92
What are undifferentiated cells that can develop into any needed kind of cell?
Stem cells
93
What is the normal way for cells to die called?
Apoptosis
94
What happens during apoptosis?
hydrolytic enzymes are activated inside cell
digest contents of cell
cell shrinks, releases chemical signal which triggers phagocytosis
95
What is increased rate of cell division called?
Hyperplasia
96
What is shrinkage or loss of tissue called?
Atrophy
97
What is the tail on a chromosome (protects DNA) called?
Telomere
98
What does the telomere do?
determines the number of times a cell can divide
tail gets shorter with each division
at minimum length cell can no longer divide
plays a big role in aging with the body
99
Name 4 major types of tissues
1. Nervous - internal communication
2. Muscle - movement
3. Epithelial - covering and lining
4. Connective - supporting
100
What is the study of tissue called?
Histology
101
What is a photograph taken through a microscope called?
Photomicrograph
102
What colours are normally used for staining and for which parts?
1. Nuclei - stained blue or purple
| 2. Cytoplasm - stained pink
103
Name two types of epithelial tissues
1. Covering and lining epithelia - eg. goblet cells, serous membranes
2. Glandular epithelia - eg. goblet cells, gastric glands
104
Name 5 characteristics of epithelium
1. Polarity
2. Closely packed cells
3. Supported by reticular lamina (connective tissue)
4. Avascular but innervated
5. High rate of regeneration
105
Name the two types of covering and lining epithelia
1. Simple - one layer of cells
| 2. Stratified - two or more layers of cells
106
Name the three shapes of the simple & stratified cells and describe their shape
1. Squamous - flat cells
2. Cuboidal - cube shaped
3. Columnar - taller than they are wide
107
Describe simple sqaumous and its location and function
1. one layer of flat cells
2. located in airsac of lungs, cavities and vessels
3. function: diffusion, filtration and lubrication
108
Describe the two types of surfaces in epithelial tissue
1. Apical - top surface
| 2. Basal - bottom surface (basal lamina attached to the reticular lamina create the basement of the membrane)
109
Describe simple cuboidal and its location and function
1. single layer cubed cells
2. location: kidney tubules and ducts of glands
3. function: secretion and absorption
110
Describe simple columnar and its location and function
1. single layer of tall skinny cells with microvilli
2. location: digestive tract, large bronchi, unterine tubes, stomach and colon
3. function: propels mucous and moves material through, secretion and absorption
111
Describe pseudostratified columnar and its location and function
1. single layer but varied cell heights look stratified with cilia
2. location: large ducts of glands, trachea and upper respiratory tract
3. function: capture debris and move debris up and out
112
Describe stratified squamous and its location and function
1. several layers of cells, surface cells are flat and basal cells are cubed or long
2. location: esophagus, mouth, vagina, skin
3. function: protection, resists wear and tear
113
Describe stratified cuboidal and its location and function
1. rare - two layers
2. location: ducts of sweat glands and mammary glands
3. function: secretion
114
Described stratified columnar and its location and function
1. rare
| 2. location: transition area between two other types of epithelia
115
Described transitional and its location and function
1. 3-6 layers, apical cells vary, basal cells are cubed or columnar - change shape depending on distension
2. location: ureters, urinary bladder
3. function: stretch or shrink to adjust to volume of urine
116
Name two types of glandular epithelia and describe
1. Endocrine glands - secrete directly into the blood via exocytosis and travel directly to the target organ which has the appropriate membrane receptors
2. Exocrine glands - secret into a tube and onto the body surface - eg. mucous, sweat, oil and salivary glands
117
Name the two types of exocrine glands and describe
1. Unicellular - only important cell is the goblet cell
| 2. Multicellular - composed of duct and secretory units
118
Name the two duct types found in exocrine glands
1. Simple - duct does not branch
| 2. Compound - many branches
119
Name the three secretory units found in exocrine glands
1. Tubular - tube shaped
2. Alveolar - sac shaped
3. tubuloalveolar - both types
120
Name 6 exocrine glands and location
1. simple tubular - intestine glands
2. simple branched tubular - stomach glands
3. compound tubular - duodenal glands (small intestine)
4. simple branched alveolar - sebaceious (oil) glands
5. compound branched alveolar - mammary glands
6. compound tubuloalveolar - salivary glands
121
Name the 2 modes of secretion and describe
1. Merocrine - secreted by exocytosis, long lived (eg. pancreas, sweat and salivary glands)
2. Holocrine - product accumulates and releases by the rupture of apical cells. Cells die and are placed by mitosis of basal cells. (eg. oil glands)
122
Name 4 classes of connective tissue
1. connective tissue proper (loose and dense)
2. cartiliage
3. bone
4. blood
123
Name 5 major functions of tissue
(BSPIT)
```
Binding
Support
Protect
Insulation
Transport
```
124
Name 3 characteristics of connective tissue
1. messenchyme common tissue of origin
2. varying degrees of vascularity / blood supply
3. cells are scattered in a nonliving matrix
125
Describe two elements of the matrix
1. fills space between cells
| 2. acts as a filter materials can diffuse through
126
Name the 3 substances the matrix is composed of and their function
1. interstitial fluid, function: reservoir
2. CAMs - function: "glue"
3. proteoglycans - function: store water
127
Name and describe 3 fibers embedded in the matrix
1. collagen - thick white fibers (function: resist stretching)
2. elastic - thin yellow fibers (function: recoil like elastic)
3. reticular - thin collagen fibers (function: form internal skeleton of some organs)
128
Name and describe the two types cells that are associated with connective tissue
1. blasts - immature, mitotically active (eg. osteoblasts in bone)
2. blast cells that develop into mature cells that maintain the matrix but can revert to blasts to repair tissue (ie. osteocytes in bone or chondrocytes in cartiliage)
129
Name the two types of cells involved in defense
White Blood Cells
| Macrophages
130
Name the cells involved in fat storage
Adipose Cells
131
Name the embryonic tissue
Mesenchyme
132
Name the 3 loose connective tissues
1. Aerolar
2. Adipose
3. Reticular
133
Name the 3 dense connective tissues
1. dense regular
2. dense irregular
3. dense elastic
134
Name the 3 cartilage tissues
1. hyaline
2. elastic
3. fibrocartilage
135
Describe areolar and its location and function
1. location: packages organs, around capillaries
| 2. binds tissues together, protects organs and defense
136
Describe adipose and its location and function
1. location: under skin, around kidneys and eyeballs, abdomen and breasts
2. function: energy storage, insulation, shock absorber
137
Describe reticular tissue and its location and function
1. location: lymphoid organs (lymph nodes, bone marrow, spleen)
2. function: supporting framework
138
Describe dense regular tissue and its location and function
1. location: tendons and ligaments
| 2. function: resist stretching - rope like structures
139
Describe dense irregular tissue and its location and function
1. location: joint capsules and dermis of the skin
| 2. function: able to with stand tension exerted in many directions and provides structural strength
140
Describe dense elastic and its location and function
1. location: walls of large arteries and lymph vessels
| 2. function: allows recoil of tissue following stretching
141
Describe hyaline cartilage and its location and function
1. location: joint cavities, nose, trachea
| 2. resists compression
142
Describe elastic cartilage and its location and function
1. location: external ear and epiglottis
| 2. function: maintains the shape but is flexible
143
Describe fibrocartilage
1. location: intervertebral discs, pubic symphsis
| 2. function: strengh with the ability to absorb compressive shock
144
Name 3 types of epithelial membranes
1. cutaneous
2. mucous
3. serous
145
Describe where the cutaneous membrane is located and what its function is
1. location: covers the outside of the body, stratified keratinized
2. function: protects against abrasion, tearing & penetration
146
Describe where the mucous membrane is located and what its function is
1. location: line body cavities
| 2. function: secretion, absorption
147
What is a goblet cells function?
To secrete mucous.
148
Describe where the serous membrane is located and what is function is
1. location: line ventral cavities (parietal serosae) and cover internal organs (visceral serosae)
2. function: no friction
149
Name the 5 steps in tissue repair
RHSPI
```
Redness
Heat
Swell
Pain
Immobilization
```
150
Describe the 4 steps in the imflammatory response
1. inflammatory chemicals are released by damaged cells and chemicals trigger pain
2. capillaries become "leaky" - exudate leaks out of capillaries into injured area - causes swelling and pain that immobilizes area
3. the exudate contains WBC's that attack invaders
4. clotting occurs and a scab forms
151
Describe the 4 steps in organization and restore blood supply
1. clot replaced by granulation tissue
2. epithelium regenerates
3. fibroblasts produce collagen fibers
4. debris phagocytized
152
Describe 3 steps in regenration and fibrosis
1. scab detaches
2. fibrous tissue matures
3. results in fully regerated epithelium with underlying scar tissue.
153
Name 3 skeletal cartliages and confirm if they contain blood vessels or nerves
No blood vessels or nerves
1. Hyaline
2. Elastic
3. Fibrocartiliage
154
Define appositional cartilage growth
chrondroblasts in the surrounding membrane secrete new matrix against external face of existing cartilage
155
Define interstitial cartilage growth
chondrocytes inside the cartilage divide and secrete new matrix expanding cartilage from within
156
Name the 2 main groups of bones and what they represent
1. Axial - skull, backbone and ribcage
| 2. Appendicular - all the rest; girdles and appendages
157
Name the 4 classification shapes
1. long bones - longer than they are wide
2. short bones - cube shaped - wrist, ankle bones
3. flat bones - thin, flat, slightly curved - skull
4. irregular bones - complicated shapes - vertebrae
158
Name the 6 functions of the bones
SPMSBT
1. Support - for body and soft organs
2. Protection - for brain, spinal cord and vital organs
3. Movement - form levers for muscle action
4. Storage - minerals (calcium and phosphorus)
5. Blood cell formation - (hematopoiesis) in red marrow
6. Triglyceride - (fat) energy stored in yellow marrow
159
What are bone markings?
Bulges, depressions and holes in the bone - any irregularity in surface
160
What function do the bone markings serve?
Sites of attachment for muscles, ligaments and tendons. Conduits for blood vessels and nerves
161
Name the two bone textures
1. compact - dense outer layer made up of osteons
| 2. spongy - inner core; honeycomb of trabeculae
162
What is the shaft of a long bone called?
Diaphysis
163
What cavity contains yellow marrow in adults?
Medullary cavity
164
What are either ends of a long bone called?
Proximal and distal epiphyses
165
What is the remnant of growth plate called?
Epiphyseal line
166
What type of hyaline cartilage protects bone ends - on joint surfaces?
Articular cartilage
167
Name the two membranes of bones and where they are located
1. periosteum - connective tissue that encloses outside of bone
2. endosteum - connective tissue membrane on inside of bone
168
What 3 cells are located in the periosteum?
1. osteoblasts - bone forming cells
2. osteoclasts - bone destroying cells
3. osteogenic cells - stem cells
169
What 2 cells are located in the endosteum?
1. osteoblasts
| 2. osteoclasts
170
What is the nutrient foramen?
openings in the periosteum where blood vessels, lymph vessels and nerves can enter bone
171
What type of fiber attach periosteum to bone?
Sharpey's fibers
172
Describe the structure of short, irregular and flat bones
like a sandwich:
1. compact bone covered with periosteum on both surfaces
2. spongy bone covered with endosteum in the centre
3. red bone marrow between trabeculae
173
What is another name for spongy bone?
Diploe
174
Where is the location of red marrow (hematopoietic tissue) in adults?
1. trabecular cavities of heads of femur and humerus
| 2. trabecular cavities of flat bones
175
Where is the location of red marrow in infants?
1. medullary cavities of long bones
| 2. in all spaces of spongy bones
176
Name the 4 cells associates with bones and their function
1. osteogenic - location: periosteum and endosteum
function: stem cells that give rise to osteoblasts
2. osteoblasts: function: bone forming cells, produce matrix
3. osteocytes: location - mature bone cells trapped inside cavities in the bone called lacunae
function: maintain health of bone
4. osteoclasts: macrophages (WBCs) that breakdown bone by secreting enzymes
177
What is the osteon structural unit called?
Haversian system
178
What are weight bearing, column like matrix tubes called?
Lamellae
179
Which canal contains blood vessels and nerves
Central (Haversian) canal
180
What are the small cavities that contain osteocytes?
Lacunae
181
What are the hair like canals that connect lacunae to each other and central canal?
Canaliculi
182
What connects blood vessels and nerves of the periosteum and central canal?
Perforating (Volkmann's) canals
183
What encloses the whole bone and resists twisting forces?
Circumferential lamellae
184
Describe 2 characteristics of spongy bone
1. contain irregularly arranged lamellae, osteocytes, and canaliculi
2. capillaries in endosteum supply nutrients
185
What is the organic bone matrix secreted by osteoblasts?
Osteoid
186
What percentage of bone mass is the osteoid and what does it contain?
1. 35% of bone mass
| 2. contains: proteoglycans, glycoproteins and collagen fibers
187
What is the function of osteoid?
1. provide tensile strength and flexibility
| 2. resists stretching and twisting
188
What is the inorganic material in the bone?
hydroxyapatites (mineral salts)
189
What is the percentage of hydroxyapatites in the bone?
65%
190
What is the function of hydroxyapatite?
provides hardness and resistance to compression
191
What is bone tissue formation called?
Osteogeneisis (ossification)
192
Name the 3 basic steps of ossification and when they occur.
1. bone formation - begins in the 2nd month of development
2. postnatal bone growth - until early adulthood
3. bone remodelling and repair - lifelong
193
Name the two types of ossification
1. intramembranous ossification
| 2. endochondral ossification
194
What types of bones does intramembranous ossification form?
flat bones (eg cranial)
195
What type of cartilage forms the flat bones?
fibrous cartilage
196
Describe the process of intramembranous ossification (4 steps)
1. ossification centre develops in fibrous connect tissue membrane
2. osteoid is secreted and calcifies
3. woven bone (spongy bone) and periosteum form
4. lamellar bone replaces woven bone and red marrow develops
197
What types of bones does endochondral ossification form?
Most of the rest of the skeleton
198
What type of cartilage forms bones produced by endochondral cartiliage?
Hyaline cartiliage. Cartilage is broken down and replaced by bone.
199
Describe the 5 steps in the endochondral ossification process
1. ossification centre forms bone collar
2. cartilage in centre if diaphysis calcifies and then develops cavities
3. spongy bone begins to form in cavities
4. diaphysis elongates, medullary cavity forms, secondary ossification developes at ephiphyses
5. epiphyses ossify, hyaline cartilage remains only at epiphyseal plates & articular cartilage
200
Name the 2 types of postnatal bone growth and describe
1. interstitial growth - increase in length (occurs at articular cartilage and epiphyseal plates)
2. appositional growth - increase in thickness and remodeling of all bones by osteoblasts and osteoclasts on bone surfaces
201
Name the 4 functional zones of the epiphyseal plates
1. proliferation - growth
2. hypertrophic - increase size
3. calcification - converted to bone
4. ossification - osteogenic
202
What stimulates epiphyseal plate activity?
growth hormone
203
What modulates activity of growth hormone?
thyroid hormone
204
What hormones promote adolescent growth spurts and end growth inducing epiphyseal closure?
testosteron and estrogens
205
In an adult no further bone growth occurs except remodelling of bones due to ..... (name two)
1. response to stress
| 2. variations to blood
206
What are the instances bone remodelling occurs? (name 4 of them)
1. mechanical stress
2. damage
3. hormonal changes
4. variations in blood calcium levels
207
What happens when a bone is injured or requires added strength?
Bone deposit
208
What occurs when there is a reduction in mechanical stress?
Bone resorption
209
If a bone deposit is required, what must a diet be rich in?
protein, calcium and phosphorus, vitamins C, D and A
210
What do osteoclasts secrete?
1. lysosomal enzymes that digest organic matrix
| 2. acids - convert calcium salts into soluble forms
211
What happens to the matrix after its been digested by the osteoclast?
its transcytosed across osteoclast, enters instertitial fluid and then blood
212
What controls continual remodelling?
hormonal mechanisms - negative feedback loops
213
Name 5 things blood calcium is necessary for.
1. transmission of nerve impulses
2. muscle contraction
3. blood coagulation
4. secretion by glands and nerve cells
5. cell division
214
Describe the negative feedback scenario with PTH (parathyroid hormone)
1. decreased blood calcium
2. parathyroids release PTH
3. PTH stimulates osteoclasts to degrade bone matrix
4. calcium released into blood
5. increase in blood calcium
