Biochemistry - Human Systems Flashcards
1
Q
Macromolecules:
A
Large, complex, organic molecules. Macromolecules are classified as polymers because they are long chains of similar chemical subunits, called monomers.
2
Q
Polymers:
A
Long chains of similar chemical subunits.
3
Q
Monomers:
A
Similar chemical subunits.
4
Q
What are the three main classes of macromolecules that make up living things?
A
Carbohydrates, lipids, and proteins.
5
Q
What do the three main macromolecules store?
A
All of these macromolecules store chemical potential energy, with lipids containing 2.25 times more energy per unit than carbohydrates and proteins.
6
Q
Carbohydrates:
A
Macromolecules made up of carbon, hydrogen and oxygen atoms. Carbohydrates are the primary energy source in living things.
7
Q
Monosaccharides:
A
The simplest carbohydrates, consisting of a single sugar subunit. Examples include glucose, galactose and fructose, which are all isomers of C6H12O6.
8
Q
Things that end in “ose” are ______.
A
sugars
9
Q
Disaccharides:
A
Simple carbohydrates composed of two monosaccharide subunits. Examples include maltose (grain sugar), lactose (milk sugar) and sucrose (table sugar).
10
Q
Glucose + glucose =
A
Maltose.
11
Q
Monosaccharide + monosaccharide =
A
Disaccharide.
12
Q
Glucose + galactose =
A
Lactose.
13
Q
Glucose + fructose =
A
Sucrose.
14
Q
Polysaccharides:
A
Complex carbohydrates composed of many monosaccharide subunits. Examples include starch, glycogen and cellulose.
15
Q
Starch:
A
A polysaccharide that is used to store energy in plants. It also aids in creating glucose in humans.
16
Q
Glycogen:
A
A polysaccharide that is used to store energy in animals.
17
Q
Cellulose:
A
A polysaccharide that makes up the cell walls of plant cells.
18
Q
Lipids:
A
Macromolecules made up of carbon, hydrogen and oxygen atoms. Lipids function in long-term energy storage, insulation and form critical components of hormones and cell membranes. Lipids are non-polar molecules, with the exception of phospholipids. There are many different types of lipids, such as phospholipids, steroids, waxes and triglycerides (fats and oils).
19
Q
Lipids are ________ molecules, with the exception of phospholipids.
A
nonpolar
20
Q
Triglyceride:
A
Fats and oils. A triglyceride is composed of a glycerol molecule and three fatty acids.
21
Q
Saturated Fatty Acids:
A
Saturated fatty acids contain only single bonds between carbon atoms. Triglycerides with saturated fatty acids are called fats and are solid at room temperature.
22
Q
Unsaturated Fatty Acids:
A
Unsaturated fatty acids contain one or more double bonds between carbon atoms. Triglycerides with unsaturated fatty acids are called oils and are liquid at room temperature.
23
Q
Proteins:
A
Proteins are macromolecules made up of carbon, hydrogen, oxygen and nitrogen atoms. One or more polypeptides fold into a unique three-dimensional shape, forming a protein. This shape is important in the proper functioning of the protein. The type of protein is determined by the order and number of amino acids present. Proteins are involved in a variety of functions in the human body including cellular transport, blood clotting, immunity, enzyme catalysis and muscle action.
24
Q
Polypeptide:
A
A polypeptide is a chain of amino acid subunits joined together by peptide bonds.
25
If a molecule has protein what is it likely?
A protein.
26
Dehydrolysis:
Polymers of organic compounds are formed by the process of dehydration synthesis, also called dehydrolysis. In this process, monomers are joined together and one water molecule is produced for each new bond that is formed.
27
Hydrolysis:
Polymers of organic compounds are broken down by the process of hydrolysis, also called condensation. In this process, water is used to break polymers down into monomers. Hydrolysis reactions are sped up, or catalyzed, by enzymes.
28
Enzyme:
A protein catalyst that speeds up chemical reactions by lowering the activation energy of the reaction.
29
Activation energy:
The energy required to initiate a chemical reaction.
30
Enzymes (are/are not) consumed by the chemical reaction and can be used again.
are not
31
The ___________ _____ is used to explain the action of enzymes.
induced-fit model
32
Explain the induced-fit model.
A reactant molecule, called the substrate, binds to the active site of an enzyme forming an enzyme-substrate complex. Each enzyme has a unique three-dimensional shape that allows it to bind to specific substrate molecules. The binding of the substrate to the active site alters the shape of the active site, improving the fit between the substrate and the active site. By orienting substrate molecules correctly and providing an optimal chemical environment, enzymes allow the reaction to proceed with lower activation energy. The enzyme then releases the products and is free to catalyze another reaction.
33
Anabolic vs catabolic reactions:
```
Anabolic = Putting together.
Catabolic = Taking apart
```
34
Enzymes have an optimal ___________ _____ in which they function.
temperature range
35
Increasing temperature increases reaction rates because...
the molecules are moving faster.
36
What happens if the temperature continues to increase in reactions past the optimal temperature?
The reaction rate will start to decrease because high temperatures will cause the enzyme to denature.
37
What happens when an enzyme denatures?
It loses its shape and the substrate will not be able to bind to the active site.
38
Enzymes have an optimal __ _____ in which they function.
pH range
39
What happens if there's a change of pH for enzymes?
An increase in H + (aq) or OH -(aq) can disrupt the chemical bonds that are responsible for the enzyme folding into its unique three-dimensional shape. This results in the enzyme denaturing and losing its function.
40
What is the optimal pH level for enzymes in our body?
7.
41
What is the optimal temperature for enzymes in our body?
37 degrees Celcius.
42
What happens in an enzyme reaction if there is a change in substrate concentration?
Increasing substrate concentration results in increased reaction rate until all of the enzyme molecules are being used, at which point the reaction rate levels off.
43
Competitive Inhibitors:
Molecules that bind to the active site of an enzyme, preventing substrate molecules from binding to the active site.
44
What is maltose made of?
Glucose + Glucose
45
What is lactose made of?
Glucose + Galactose
46
What is sucrose made of?
Glucose + Fructose
47
Allosteric inhibition:
In allosteric inhibition, non-competitive inhibitors bind to a regulatory site, called an allosteric site, on an enzyme. This causes the active site to change shape, preventing the substrate from binding to the active site. Often the non-competitive inhibitor is the product of the metabolic pathway, so as the product accumulates, it provides feedback inhibition, slowing the initial reaction rate.
48
Ingestion:
Taking in food.
49
Digestion:
The physical and chemical breakdown of macromolecules.
50
Absorption:
The transport of digested substances from the bloodstream.
51
Egestion:
Removal of food waste from the digestive tract.
52
Digestive tract:
The digestive tract consists of all of the digestive organs through which food passes. Includes the mouth, the pharynx, the esophagus, the stomach, sphincters, the small intestine and the large intestine.
53
Accessory organs:
Accessory organs of the digestive system support the digestion of macromolecules but do not form part of the digestive tract. Includes the salivary glands, liver, gallbladder and pancreas.
54
The mouth/oral cavity:
The mouth, or oral cavity, forms the beginning of the digestive tract.
55
Teeth:
Break food into smaller pieces.
56
Salivary glands:
Release saliva, which contains mucus and enzymes.
57
Tongue:
Moves food around the mouth, forming it into a small ball called a bolus, and aids in swallowing.
58
The pharynx/throat:
The pharynx, or the throat, is a passageway that carries food from the mouth to the esophagus. The pharynx is a common passageway for both the digestive and respiratory systems.
59
Esophagus:
The esophagus carries food from the pharynx to the stomach. Food enters the esophagus through the upper esophageal sphincter (UES).
60
Sphincters:
Muscles that control an opening through contraction (close) and relaxation (open).
61
The bolus moves through the esophagus through ___________.
peristalsis
62
Peristalsis:
Involves a series of contractions and relaxations of smooth muscles that move contents through the digestive tract.
63
Lower esophageal sphincter (LES):
Controls the passage of food into the stomach.
64
Stomach:
The stomach is a muscular, J-shaped organ with many folds in the interior called rugae that allow it to expand. The stomach temporarily stores food, is involved in some digestion and pushes food through the pyloric sphincter into the small intestine using peristalsis.
65
The small intestine is a long, narrow tube with three main sections.
1. duodenum 2. jejunum 3. ileum
66
The small intestine is much ______ than the large intestine, but it is _______ in diameter.
longer, smaller
67
What is the primary site of digestion and absorption of nutrients?
The small intestine.
68
Substances are moved through the small intestine by ___________ ______.
peristaltic action
69
The inner walls of the small intestine contain finger-like projections, called _____.
villi
70
Villi:
Increase surface area for the absorption of nutrients.
71
Within each villus, there is a lymphatic vessel, called a _______, and a capillary network where nutrients are ________ into the lymphatic system and the circulatory system.
lacteal, absorbed
72
Villi are covered with microscopic hair-like structures, called __________.
microvilli
73
Microvilli:
Further increase surface area.
74
The large intestine is a long tube that is _______ than the small intestine, but ______ in diameter.
shorter, larger
75
The large intestine contains the _____ and the ______.
colon, rectum
76
Waste is concentrated in the _____ and stored in the ______ until it can be eliminated.
colon, rectum
77
Substances are moved through the large intestine by ___________ ______.
peristaltic action
78
The liver:
The liver is an accessory organ that aids in digestion.
79
The liver produces ____ which consists of ____ ________ and ____ _____.
bile, bile pigments, bile salts
80
Bile pigments:
Contain waste products from the breakdown of red blood cells that will be eliminated in feces.
81
Bile salts:
Bile salt splay a critical role in the digestion of lipids.
82
The gallbladder:
The gallbladder is an accessory organ that temporarily stores bile produced in the liver.
83
The bile in the ___________ is released into the ________ of the small intestine when it is needed for digestion of ______.
gallbladder, duodenum, lipids
84
Ducts from the liver and gallbladder connect to the _____ _________.
small intestine
85
The pancreas:
The pancreas is an accessory organ that produces and secretes a variety of digestive enzymes into the duodenum of the small intestine.
86
A duct from the pancreas connects to the _____ _________.
small intestine
87
Digestion involves...
both the physical and chemical breakdown of macromolecules.
88
Physical digestion:
Also called mechanical digestion, involves breaking food down into smaller pieces to increase the surface area available for chemical digestion by enzymes.
89
Chemical digestion:
Chemical digestion involves the hydrolysis of macromolecules using enzymes.
90
Physical digestion begins in the _____.
mouth
91
Salivary Glands:
In the mouth. Release saliva to moisten and lubricate food.
92
What does chewing do?
Breaks food into smaller pieces to increase surface area for enzyme action and to make it easier to swallow.
93
Chemical digestion of starch, a carbohydrate, begins in the _____.
mouth
94
Salivary amylase:
Breaks down some starch into disaccharides in the mouth.
95
What is the optimal pH of the mouth?
7
96
When food is present, the cells lining the stomach secrete _______ _____ composed of hydrochloric acid, water, alkaline mucus, salts and enzymes.
gastric juice
97
The hydrochloric acids in the stomach juice keep the pH of the stomach between _ and _, which kills most bacteria ingested with food and activates the enzymes secreted.
1, 3
98
What is the role of mucus in the stomach?
The mucus protects the cells of the stomach from hydrochloric acid and enzymes.
99
What does peristaltic action do in the stomach? What does it create?
It breaks it into smaller pieces and mixes it with gastric juices. This creates chyme.
100
Chemical digestion of proteins begins in the _______.
stomach
101
Pepsinogen:
The inactive form of the enzyme pepsin, secreted by stomach lining cells. It prevents protein digestion of stomach cells.
102
What is pepsinogen activated by?
Hydrochloric acid.
103
What is the optimal pH of pepsin?
2
104
Pepsin:
Catalyzes hydrolysis reactions that break proteins into shorter polypeptides.
105
What is absorbed by the stomach?
Some water, salts and alcohol go to the bloodstream. Some lipid-soluble medications are absorbed into the lymphatic system.
106
What process is involved in the digestion of the small intestine?
Segmentation
107
Segmentation:
Segmentation separates chyme then forces it back together, mixing the chyme with secretions from the cells lining the small intestine and allowing for digestion and absorption of nutrients.
108
____ is released from the gall bladder into the small intestine, contributing to the physical digestion of lipids.
Bile
109
Lipids are insoluble in water, but _______ are water-soluble.
lipases
110
____ _____ in bile emulsify lipids so that lipases can act on the lipids.
Bile salts
111
The ________ secretes various carbohydrases, proteases, lipases and bicarbonate ions into the duodenum of the small intestine.
pancreas
112
Bicarbonate Ions:
Bicarbonate ions in the small intestine neutralize the acidic chyme, bringing the pH up to about 8, which is the optimal pH of enzymes in the small intestine.
113
All the enzymes from the pancreas are secreted in an inactive form and are activated by enzymes secreted by cells lining the _____ _________.
small intestine
114
The cells lining the small intestine, called _____ ______ _____, release mucus, water and more enzymes.
brush border cells
115
Pancreatic amylase:
A carbohydrase secreted from the pancreas into the small intestine. Pancreatic amylase catalyzes hydrolysis reactions that break remaining undigested starch into disaccharides.
116
The small intestine breaks the _______________ released from the brush border cells into _______________.
disaccharidases, monosaccharides
117
What happens to monosaccharide monomers in the small intestine?
They are absorbed through active transport into the cells of the intestinal villi. Then they defuse into the bloodstream through capillary networks.
118
Trypsin and chymotrypsin:
Proteases secreted from the pancreas into the small intestine. Trypsin and chymotrypsin catalyze hydrolysis reactions that break polypeptides down into short peptide chains.
119
Peptidases
Secreted from the pancreas and brush border cells. Complete the breakdown of peptides into individual amino acids.
120
What happens to broken-down amino acid peptide monomers?
They are absorbed through active transport into the villi, then diffused to the bloodstream via capillary networks, then carried to the liver and eventually transported to body cells for protein synthesis.
121
Chemical digestion of lipids occurs in the _____ _________.
small intestine
122
Lipase:
Secreted from the pancreas into the small intestine. Catalyzes hydrolysis reactions that break lipids down into glycerol and fatty acids.
123
Glycerol and fatty acid monomers are absorbed passively into...
the cells of the intestinal villi.
124
Once inside the cells of the villi, glycerol and fatty acids are reassembled into _____________ and covered with a protein coat to make them ______________. The coated triglycerides then diffuse into the _____ _______ in the _____ and are carried to the circulatory system.
triglycerides, water-soluble, lymph vessels, villi
125
Once in the circulatory system, the protein coating on lipids is removed and ______ lining the blood vessels break the triglycerides back down into glycerol and fatty acids molecules. Glycerol and fatty acid molecules are then transported through the ___________ to various cells of the body.
lipase, bloodstream
126
What is the role of the large intestine?
Undigested material enters the large intestine where waste is concentrated for elimination.
127
Mucus in the large intestine:
The cells lining the colon produce mucus to aid in the movement of substances through the large intestine.
128
What is absorbed in the colon?
Water, salts vitamins and small organic molecules produced by bacterial cells are absorbed into the cells of the colon.
129
Dietary fibre:
Indigestible by humans and forms the bulk of the feces. For example, cellulose.
130
What are the two components of breathing?
Inhalation and exhalation.
131
Inhalation:
Taking in air, a mixture of gases that includes oxygen
132
Exhalation:
Expelling air, a mixture of gases that includes waste gases
133
External respiration:
Gas exchange between the air in the lungs and the blood in the capillaries.
134
Internal respiration:
Gas exchange between the blood and the body cells.
135
Cellular respiration:
The use of oxygen to metabolize glucose and produce ATP energy and waste gases: carbon dioxide and water vapour
136
Respiratory system:
Consists of all the organs, structures and tissues that work together to exchange matter and energy with the atmosphere.
137
Nostrils:
Nostrils form the entrance to the nasal passages at the beginning of the respiratory tract.
138
What is the purpose of mucus and hair in nostrils?
Mucous and tiny hairs lining the nasal cavity filter air by trapping foreign particles.
139
Air is warmed and moistened in the _____ ______.
nasal cavity
140
The air moves from the nasal cavity or from the oral cavity to the _______.
pharynx
141
The pharynx:
The pharynx is located at the back of the oral cavity and below the nasal cavity, just above the entrances to the esophagus and trachea.
142
The epiglottis:
The epiglottis is a flap of elastic cartilage at the entrance to the larynx. During breathing, the epiglottis is open allowing air to pass. During swallowing, the epiglottis lowers to allow food or drink into the entrance of the esophagus and seals off the trachea restricting access to the lungs.
143
Air from the pharynx travels past the epiglottis and enters the ______ at the top of the trachea.
larynx
144
The larynx:
Made of different types of cartilage and muscle. Also known as the voice box, the larynx has two vocal folds that control the pitch and volume of sound vibrations by changing the tension. Thick cartilage, called the Adam’s apple, protects the larynx.
145
The trachea:
The trachea, or windpipe, carries air from the larynx to the bronchi. Tiny hairs called cilia and mucous-producing cells line the trachea to filter any foreign matter. The walls of the trachea contain many strong, flexible C-shaped rings of cartilage that keep the tube open at all times. The walls also contain muscle and connective tissue.
146
The bronchi:
The trachea branches into two primary bronchi: the left and right bronchus. Each bronchus leads to a lung. The walls of both bronchi have cartilage bands for support in addition to smooth muscle.
147
An infection in the bronchi is called __________.
bronchitis
148
Bronchioles
The air passes through the left or right bronchus and branches into many smaller passageways called bronchioles. The walls of bronchioles do not have cartilage rings and contain muscle. The diameter of a bronchiole is 1 mm or less! The nervous and endocrine systems control the diameter of the bronchioles based on stimuli.
149
An infection in the bronchioles is called _____________.
bronchiolitis
150
The air moves from the bronchioles into tiny sacs called _______.
alveoli
151
Each alveolus is wrapped in a _________ _______.
capillary network
152
Gas exchange in the alveoli:
Gas exchange between the air and blood occurs across the membranes and is driven by concentration gradients.
153
Describe the structure of alveoli when breathing:
Alveoli collapse and inflate during breathing. Lipoprotein film lining the alveoli prevents the alveoli walls from sticking together.
154
The rate of gas exchange in the alveoli is increased by:
Very thin alveolar walls, very small alveolar diameter of ~0.1μm, about 150 million alveoli per lung, the bulbous shape, which increases the surface area.
155
The diaphragm:
The diaphragm is a thick, dome-shaped, horizontal muscle that separates the chest, or thoracic, and abdominal cavities. As the diaphragm contracts and relaxes, the volume and pressure of the chest cavity change, which causes breathing.
156
The diaphragm motion causes breathing by changing the volume of the ________ ______. When the diaphragm contracts and pulls down, the volume of the thoracic cavity _________, which causes a ________ in air pressure inside, and air rushes into the lungs. When the diaphragm relaxes and returns to its dome shape, the volume of the thoracic cavity _________, which causes an ________ in air pressure inside, and air rushes ___ of the lungs.
thoracic cavity, increases, decrease, decreases, increase, out
157
The change in thoracic cavity volume, and breathing, is also helped by muscles in between the ribs called ___________ _______.
intercostal muscles
158
When intercostal muscles contract, the rib cage moves up and out. This _________ the volume and _________ the air pressure of the thoracic cavity, allowing air to rush ____ the lungs.
increases, decreases, into
159
When intercostal muscles relax, the rib cage moves down and in. This _________ the volume and _________ the air pressure of the thoracic cavity, causing air to rush ___ of the lungs.
decreases, increases, out
160
The pleural membranes:
The pleural membranes are thin membranes that cover the outside of the lungs and the inside of the chest cavity. The adhesion of the pleural membranes to each other causes the lung volume to change with the chest cavity volume. Friction between the membranes is reduced by a small amount of pleural fluid.
161
Breathing depends on differences in ___ ________ between the atmosphere and the lungs.
air pressure
162
Gases move from areas of ____ pressure to areas of ___ pressure.
high, low
163
The pressure of a gas is __________ ____________ to the volume of the gas.
inversely proportional
164
Manipulation of the volume of the thoracic cavity impacts...
the direction of airflow.
165
Inhalation:
Inhalation occurs when air rushes from an area of higher pressure in the atmosphere to an area of lower pressure in the body’s thoracic cavity.
166
In inhalation, contracting muscles result in a _________ _____.
shortened state
167
When the diaphragm contracts, it flattens and pulls downward. This _________ the volume of the thoracic cavity.
increases
168
When the intercostal muscles contract, they pull the ribs up and out. This _________ the volume of the rib cage.
increases
169
The diaphragm and intercostal muscles contract at the same time, both __________ the volume of the thoracic cavity and the air inside.
expanding
170
The adhesion of the lungs to the pleural membranes causes the lungs to ______ when the thoracic cavity expands.
expand
171
When the volume of the thoracic cavity and air increases, the pressure of the air in the lungs _________.
decreases
172
Air moves from ______ air pressure in the atmosphere to _____ air pressure in the lungs, causing inhalation.
higher, lower
173
Exhalation occurs when air rushes from an area of ______ pressure in the lungs within the body’s thoracic cavity to an area of _____ pressure in the atmosphere.
higher, lower
174
Relaxation of muscles results in a ___________ _____.
lengthened state
175
The diaphragm relaxes upwards into its round shape, ________ the volume of the thoracic cavity.
reducing
176
The intercostal muscles relax and lengthen, moving the rib cage downward and inward, ________ the volume.
reducing
177
The adhesion of the lungs to the pleural membranes causes the lungs to ________ when the thoracic cavity becomes smaller.
contract
178
As the volume of the thoracic cavity and the air inside decreases, the air pressure _________.
increases
179
The air moves from an area of higher pressure in the lungs to an area of _____ pressure in the atmosphere, causing exhalation.
lower
180
______, a requirement for cellular respiration, must reach each body cell.
Oxygen
181
______ ________ and _____ ______, the waste gases, must be removed from each cell to the atmosphere.
Carbon dioxide, water vapour
182
Gas exchange between the air in the alveoli and the blood occurs...
across the membranes and is driven by concentration gradients.
183
Oxygen diffuses from higher concentration inside the ________ to lower concentration in the blood in the _________.
alveolus, capillary
184
Carbon dioxide diffuses from higher concentration in the blood in the _________ to lower concentration inside the ________.
capillary, alveolus
185
In gas exchange water moves by _______ across the membranes.
osmosis
186
Ciliary dysfunction:
Immotile cilia of the respiratory tract and middle ear.
187
Chronic bronchitis:
Long term inflammation of the bronchi .
188
Emphysema:
Weakened, damaged alveoli.
189
Hemoglobin:
A protein in red blood cells, used to transport oxygen and carbon dioxide.
190
Hemoglobin contains iron, which binds to ______ molecules.
oxygen
191
Oxygenated blood appears brighter than deoxygenated blood due to...
the colour change that results when oxygen is bound to iron.
192
When oxygen binds to hemoglobin, it forms _____________.
oxyhemoglobin
193
When oxygen binds to hemoglobin, it maintains...
the concentration gradient for more oxygen to continue to diffuse into the red blood cells.
194
The red blood cells carrying oxygen travel through _____ _______ to the body cells.
blood vessels
195
Gas exchange through capillaries and cell membranes involves:
Oxygen diffuses from higher oxygen concentration in the oxygenated blood to lower oxygen concentration in the body’s cells. Carbon dioxide diffuses from higher carbon dioxide concentration in the body’s cells to lower carbon dioxide concentration in the blood.
196
About 5-7% of oxygen dissolves directly into the _____ ______.
blood plasma
197
About 10% of oxygen binds to __________ in red blood cells to form ___________________.
hemoglobin, carbaminohemoglobin
198
The bond that forms carbaminohemoglobin, is reversible, and the carbon dioxide can ______ when the blood reaches the lungs.
detach
199
About 85% of oxygen becomes part of the ___________ ______ ______. Explain this process:
bicarbonate buffer system, At the body capillaries, carbon dioxide diffuses into the red blood cells where an enzyme converts it to carbonic acid. Carbonic acid immediately dissociates into hydrogen ions and bicarbonate ions, and this reaction maintains the concentration gradient for more carbon dioxide to continue to diffuse into the red blood cells. The free hydrogen ions bind to hemoglobin, releasing oxygen in the process.
200
Carbon dioxide can be absorbed into the blood (with/without) a large change in pH.
without
201
Explain the reverse process bicarbonate buffer system:
At the lung capillaries, the reverse chemical reaction occurs, where the hydrogen ion is released from hemoglobin and reacts with bicarbonate to produce carbonic acid. An enzyme converts the carbonic acid back to carbon dioxide, which diffuses into the alveoli and is exhaled.
202
The waste products of cellular respiration released during exhalation:
Carbon dioxide, water, and thermal energy.
203
Tidal Volume:
Normal breath in, normal breath out.
204
Expiratory reserve:
After a normal breath out.
205
Inspiratory capacity:
After a normal breath in. Includes the tidal volume.
206
Vital capacity:
Full in, full out.
207
The motor system:
Converts chemical potential energy into the kinetic energy of muscle contractions.
208
There are three main types of muscle tissue:
Cardiac muscle, smooth muscle, and skeletal muscle
209
Where is cardiac muscle found?
In the walls of the heart.
210
Cardiac muscles contract and relax automatically, so they are said to be under ___________ _______.
involuntary control
211
Describe the structure of cardiac muscle:
Cardiac muscle cells are tubular and branched. Cardiac muscle cells are striated - they have visible light and dark bands called striations.
212
What is the main function of cardiac muscle?
The main function of cardiac muscle is to move blood through and out of the heart.
213
Where is smooth muscle found?
Smooth muscle is found in the blood vessels and walls of internal organs.
214
Is smooth muscle contraction and relaxation automated or mechanical?
Smooth muscles contract and relax automatically, so they are said to be under involuntary control.
215
Describe the structure of smooth muscle cells:
Smooth muscle cells are non-striated.
216
What are the main functions of smooth muscle?
Peristalsis in the digestive system. Peristalsis in the excretory system. Regulation of involuntary sphincters. Vasoconstriction and vasodilation of blood vessels. Controlling the amount of light that enters the eyes by changing the size of the iris.
217
Where is skeletal muscle found?
Skeletal muscle is usually found attached to the bones of the skeleton, but it is also found along the outside of veins and lymphatic vessels.
218
Is skeletal muscle movement mechanical or automatic?
Skeletal muscles attached to the skeleton are under voluntary control.
219
Describe the structure of skeletal muscle:
Skeletal muscle cells are tubular, striated and multinucleated.
220
What are the main functions of skeletal muscles?
Locomotion of the body. Producing breathing movements. Moving blood through veins and lymph through lymphatic vessels. Support to allow the body to maintain posture. Regulation of voluntary sphincters. Maintaining body temperature.
221
What do skeletal muscles consume and generate?
Skeletal muscles consume ATP and generate thermal energy when they contract.
222
How are skeletal muscles arranged?
Skeletal muscles are arranged in antagonistic pairs. One muscle must relax as the other muscle contracts to produce movement of the skeleton. For example, when the bicep contracts, the tricep relaxes to flex the arm.
223
What is a muscle composed of?
A muscle is composed of many bundles of muscle fibres and associated nerves and blood vessels.
224
What is a single muscle cell called?
A single muscle cell is called a muscle fibre.
225
The sarcolemma:
The sarcolemma is the cell membrane of a muscle fibre.
226
The sarcoplasm:
The sarcoplasm is the cytoplasm of a muscle fibre.
227
Myofibrils:
Muscle cells contain thousands of myofibrils that run the entire length of the cell.
228
What is a myofibril made of?
A myofibril is composed of two types of protein myofilaments, actin and myosin.
229
Actin vs myosin:
Actin is the thin filament and myosin is the thick filament.
230
Sarcomeres:
Actin and myosin filaments are arranged into sarcomeres, the functional contractile unit of a muscle fibre.
231
The arrangement of actin and myosin into sarcomeres produces...
the visible striations of skeletal muscle cells.
232
The Z line:
The Z line is the junction between two sarcomeres.
233
The M line:
The M line is the centre of the myosin filament.
234
The sliding filament theory:
The sliding filament theory is used to describe skeletal muscle contractions. In this model, the myosin filaments pull the actin filaments inward, towards the M line. Since the actin molecules are attached to the Z lines, the Z lines are pulled inward. Since the myofibrils are attached to the sarcolemma of the muscle fibre, these contractions cause the entire muscle cell to contract.
235
Explain the contraction of a sarcomere:
1. The active site on actin is exposed as Ca2+ (calcium) binds to troponin. 2. The myosin head forms a cross-bridge with actin. 3. During the power stroke, the myosin head bends and ADP and phosphate are released. 4. A new molecule of ATP attaches to the myosin head, causing the cross-bridge to detach. 5. ATP hydrolyzes to ADP and phosphate, which returns the myosin to the "cocked" position.
