RAP Flashcards
1
Q
Stimulus
A
A change in the controlled condition, which is detected by stimulus receptor.
2
Q
Cell
A
The basic structural and functional unit of an organism.
3
Q
How is an organism formed
A
Groups of cells will combine to form tissues, tissue combine to form organs, organs combine to form organ systems.
4
Q
Cytosol
A
Cytosol is the fluid part of the cytoplasm which is gel substance which surrounds the organelles and cellular structures.
5
Q
Bone remodeling
A
The ongoing replacement of old bone tissue with new bone tissue
6
Q
Appositional growth
A
Growth that makes the bone diameter thicker
7
Q
Bone resorption
A
When osteoclasts break down extra cellular matrix in the bone and release stored minerals into the blood
8
Q
Calcification
A
When bone tissue becomes harder because of added calcium
9
Q
Nucleus
A
The center of the cell, it’s function is to store and protect genetic material.
10
Q
Rough endoplasmic reticulum
A
An organelle found in eukaryotic cells with ribosomes attached to the surface, the proteins produced by ribosomes on surface are transported to other organelles within the cell, inserted into the plasma membrane or expand through the exocytosis.
11
Q
Golgi complex
A
Near the rough endoplasmic reticulum, modifies, sorts and packages proteins produced by the rough endoplasmic reticulum into transport vesicles.
12
Q
Mitochondria
A
The powerhouse of the cell. A double membrane bound organelle that produces ATP found in high concentration in cells that need a lot of energy.
13
Q
Active cell transport vs passive cell transport
A
Active cell transport needs energy (ATP) to move molecules across a cell membrane, this normally happens against their concentration gradient. Passive cell transport does not need energy, substances will move along their gradient downstream naturally.
14
Q
ATP
A
Adenosine triphosphate is the main energy carrier in cells. Consists of three phosphate groups. Energy used for muscle contraction, nerve impulse propagation, biochemical synthesis.
15
Q
Connective tissue
A
A tissue that supports and protects and gives structure to other organs in the body. Also used as transport system.
16
Q
Marfan’s syndrome
A
A problem within the connective tissue that can be dangerous to those who have it. It affects the proteins in the connective tissues and the development in connective tissue which causes problems.
17
Q
Epithelial tissue
A
Covers the body’s surface and lines the body cavities, covers internal and external surfaces. Protects, discharges and absorps .
18
Q
Muscle tissue
A
Tissue surrouding the muscles. Generates force to allow for movement
19
Q
Nervous tissue
A
Located in brain, spinal cord and nerves throughout the body. Function is to coordinate and control electrical signals for communication.
20
Q
What does connective tissue do?
A
Connects or separates other types of tissue for example blood transports nutrients and waste, and this is a connective tissue and cartilage, which reduces friction and provides structure.
21
Q
What is homeostasis?
A
How to body maintains equilibrium through changes and have active mechanisms which help maintain a relatively stable internal environment. Makes sure that the internal environment in the body is consistent.
22
Q
What are the different functions for homeostasis?
A
Stimulus, sensor, control, effector
23
Q
Stimulus
A
Monitors the change in a controlled condition which sends input to the control centre through afferent pathway.
24
Q
Afferent pathway
A
Carries the input to the control centre
25
Control centre
Evaluates the input and generates a response to send to the effector through the efferent pathway.
26
Efferent pathway
Carries output from control centre towards the effector.
27
Effector
Produces an output to maintain homeostasis.
28
Feedback loops
Processes that control how our body reacts to an action and changes and adjusts to these processes. Made up of the receptor, control centre and effector.
29
Positive vs negative feedback loops
Positive increases the change or the output. Negative occurs to return the body to the optimal condition so that the body will continue to function smoothly.
30
Disruption of homeostasis
This is when the body fails to respond to changes from the external environment. This could be caused by genetic mutations, infections or injury, lifestyle changes and environmental factors.
31
Anterior
Front or towards the front of the body
32
Posterior
Back or facing the back of the body
33
Superior
Above or towards the head of the body
34
Inferior
Below or towards the bottom of the body
35
Proximal
Closer to the heart/point of origin
36
Distal
Further from the heart/point of origin
37
Medial
Towards the middle of the body
38
Lateral
Away from the middle of the body
39
Superficial
Closer to the surface of the body
40
Deep
Further away from the surface of the body
41
Prone
Lying face down
42
Supine
Lying face up
43
Long bone
Greater in length than width, there to support the weight of your body in conjunction with skeletal muscle.
44
Flat bone
Quite thin usually. Made up of two parallel layers of compact bone which encloses a layer of spongey bone. Provide protection for your organs and tissues that are underneath them and a large surface area for attachment of muscle.
45
Short bone
Cube shaped and equal in length and width. Made of spongey bone tissue apart from the surface where there is a thin layer of compact tissue. When short bones are together they are able to provide stability and some movement.
46
Irregular bones
Have an irregular shape so they don't fit into any of the other categories, this shape helps them protect internal organs or tissues.
47
Sesamoid bones
Bones that develop in tendons where there is a lot of friction, tension and physical stress. They protect tendons from excessive wear and can change the direction of the pool of the tendon and improves mechanical advantage of the joint.
48
Articular cartilage
A thin, smooth, white tissue that covers the ends of bones in joints and allows bone to glide over each other without too much friction.
49
Diaphysis
The bone's body or shaft, the longer cylinder-ish shape in the middle of the bone holding it together.
50
Endosteum
The thin membrane that lines the inner surface of the bone, which has a single layer of bone forming cells and a small amount of connective tissue.
51
Distal epiphysis & proximal epiphysis
Every bone has an epiphysis that connects the two epiphysis, which are proximal and distal depending on close they are to the heart
52
Medullary cavity
The hollow, cylinder shaped space inside the diaphysis
52
Epiphyseal line
A line on the long bones that shows where the growth plate was. It happens when the bone stops growing.
53
Periosteum
The layer of tough connective tissue that surrounds the entirety of the bone except for the articular cartilage. It's made up of an outer fibrous layer, and an inner osteogenic layer which a protective tissue uses to cover bones. It also protects the bone, nourish bone tissue and an attachment sight for ligaments.
54
Function of the skeletal system
The skeletal system is a support system for the body, especially soft organs, and it is the attachment point for the tendons of most skeletal muscle. It protects the organs, allows for movement as skeletal muscles attach to bones and create movement at the joint, mineral homeostasis, which stores and releases minerals, blood cell production, as it produces red blood cells, white blood cells and platelets and triglyceride storage, which is where we find yellow bone marrow.
55
What is blood cell production?
The process of how the body makes blood cells, which happens mainly in bone marrow. It produces red blood cells, white blood cells and platelets, which are small cell fragments that help your blood to clot and stop bleeding when you get a cut.
56
What is bone tissue made of?
Made up of extracellular matrix and bone cells.
57
Extracellular matrix
15% water, 30% collagen fibres, 55% crystalized mineral salts. It surrounds and protects cells in tissues, it can provide structural support and strength to tissues, it helps anchor cells in place, provides scaffold for tissue organisation and influences cell behaviour. It can help with repair and regeneration as well as it can heal tissue wounds.
58
Osteoprogenitor bones
Found in the inner portion of the periosteum, and is a type of stem cell found in the bone. They play an important role in formation and maintenance of bone tissue. Only cells to undergo cell division, so they transform into osteoblasts.
59
Osteoblasts
An immature bone cell and a bone building cell. They produce and discharge collagen fibers and other components needed to build the extracellular matrix of bones
60
Osteoid
The unmineralized, organic portion of bone matrix that forms before the bone matures.
61
Osteocyte
The mature bone cells that sit within the lacunae and function to maintain bone metabolism through exchanging nutrients and waste in the blood. Osteocytes communicate with one another through their long processes through antenna and Tummel's called cuniculi.
62
Osteoclast
Big cells that are formed from a lot of white blood cells joining up. They're found in the endosteum and the side of a cell facing the bone's surface. They are responsible for resorption of bone tissue. Their process is important for bone remodeling, growth and repair.
63
Compact bone
In compact bones there is not much space between the the bone cells and extracellular matrix. It's strong and provides protection, support and resists the stresses provided by the weight of gravity.
64
Spongey bone
In the interior of a bone and protected by a layer of compact bone. It's made up of lamellae which is arranged in an irregular thin pattern. It has osteocytes and canaliculi which connects the osteocytes.
65
Osteon
A compact cylinder of concentric lamellae which makes up compact bone
66
Concentric lamellae
Circular rings of calcified extracellular matrix that forms osteons
67
Central canal
A small tunnel running through osteon houses vessels and nerves
68
Lacunae
Small, hollow space between lamellae where osteocytes are
69
Canaliculi
thin channels that contain processes of osteocytes, connects lacunae.
70
Perforating canal
Connects vessels and nervous of periosteum and central canals.
71
What is a spongey bone made up of?
osteon, osteocyte, perforating canal, central canal, trabeculae
72
How is bone tissue formed?
It is formed before birth and is continually changed and remodeled throughout our lifespan. It's formed through intramembranous or enchorial ossification.
73
What is bone remodeling?
This is how old bone is replaced with new bone tissue, which involves a balance of bone resorption and the removal of minerals and collagen fibers from the bone by osteoclasts and bone deposition, which is the addition of minerals and collagen fibers to bone by osteoblasts.
74
Intramembranous ossification
The conversion of mesenchyme into bone, which happens in flat bones through...
Development of ossification center, where mesenchyme differentiates into osteoblasts and osteoblasts secrete osteoid until they are surrounded.
Then calcification occurs Osteocytes extend processes into cuniculi. Hydroxyapatite crystals deposit into the extracellular matrix which causes calcification.
Then the trabeculae is formed as the extracellular matrix develops into trabeculae from spongey bone.
Then the periosteum develops. Mesenchyme at the periphery of bone develops into the periosteum, compact bone replaces the surface layer of spongey bone.
This is just how bones are created, but they are changed and remodeled a lot as the person grows up.
75
Endochondral ossification
The replacement of hyaline cartilage with bone. First there is the development of cartilage model, mesenchyme develops into chondroblasts and these secrete cartilage extracellular matrix where perichondrium forms.
The cartilage model grows, chondrocytes undergo cell division and hypertrophy. Extracellular matrix beings to calcify, lacunae forms from death of chondrocytes.
The primary ossification centre develops, then the medullary cavity develops from osteoclasts breaking down spongey bone and forming medullary cavity. The compact bone replaces the spongey bone surrounding the cavity.
Then there is development of secondary ossification centre where blood vessels in epiphysis stimulate secondary ossification. Spongey bone remains and no medullary cavity. Then articular cartilage and epiphyseal plate form as hyaline cartilage covering epiphysis becomes articular cartilage, hyaline cartilage at the metaphysis remains being epiphyseal growth plate.
76
What are the two zones of cartilage?
There is a layer of cartilage in long bones to allow growth in length with four zones:
Zone of resting cartilage, zone of proliferating cartilage, zone of hypertrophic cartilage and zone of calcified cartilage.
77
Zone of resting cartilage
The zone closest to the epiphysis, made up of small, scattered chondrocytes or cartilage cells, the cells in this zone are not part of bone growth but another plate. This zone is mostly just for inactive bones and it is used as a reserve of cartilage cells which can be used to proliferate and contribute to bone growth if it's needed.
78
Zone of proliferating cartilage
Larger cartilage cells arranged in a shape like a stack of coins, they go through intestinal growth (which happens rapidly in fetal development but goes into adulthood). They are dividing and multiplying and this is needed for bone growth and lengthening. The chondrocytes are arranged in stacks or columns and as they divide, they go up to the next zone.
79
Zone of my hypertrophy
The chondrocytes pushed up from the proliferating cartilage zone increase in size. They start to discharge other extracellular matrix components. The chondrocytes that are bigger than before die and their space is filled with bone tissue.
80
Zone of calcified cartilage
Final stage, closest to the diaphyseal shaft of the bone. Only a few cells thick and made up of mostly dead chondrocytes as the extracellular matrix has been calcified. The cartilage matrix becomes mineralized which means that calcium salts are deposited in the cartilage, which gives the bone it's structure and strength. Basically, bones become harder because minerals, mainly calcium are being added to make the bone become stronger.
81
Bone deposition
The addition of minerals and collagen fibers to the bone by osteoblasts.
82
Bone absorption
The destruction of the bone tissue in the extracellular matrix, where it breaks down and releases minerals into the bloodstream, which is a process that helps bones become stronger.
83
Remodel rate for compact and spongey bones
Rate for compact bones is about 4% per year. For spongey bones, 20% per year. In total, 5% per year.
84
Bone metabolism
Bone growth in children and bone remodeling in adults
85
Factors that influence bone remodeling
Minerals, vitamins (A,C,D) , hormones (growth, sex), mechanical stress.
86
Open/compound fracture
When the broken ends of the bone are sticking out through the skin.
87
Comminated fracture
The bone is crushed into multiple pieces at the sight of the fracture. In smaller bone fractures, it will lie between the two larger pieces of bone.
88
Greenstick fracture
a partial fracture where one side is broken while the other side is just bent, these only happen in children when the bone is not fully calcified.
89
Impacted fracture
Where one end of the fractured bone is forcefully driven into the interior of another. This would be common from a fall from a height.
90
Epiphyseal plate fracture
A fracture that involves the epiphyseal plate of someone still growing, and it could mean the bone will be shorter than normal when they're an adult. This is because the damage can affect the ability of chondrocyte or cartilage cells to undergo cell division and can cause permanent closure of the epiphyseal plate.
91
1st phase of fracture repair
Reactive phase: Formation of fracture hematoma. The blood vessels will be torn and massive amounts of blood will be at the sight of the wound. Nearby bone cells will die and swelling and immflation will occur in response to dead bone cells.
92
2nd phase of fracture repair
Reparative stage with a fibrocartilaginous callus. Blood vessels will grow into the fracture heamatoma and continue to clean up the dead bone cells. The fibrocartilaginous callus is a repair tissue made up of collagen fibers and cartilage that bridges the two broken ends of the bone.
93
3rd phase of fracture repair
Bony callus formation. In this one, osteoprogenitor cells transform into osteoblasts to produce spongey bone trabeculae which creates a bony callous
94
4th phase of bone remodeling
Bone remodeling phase: Dead fractions of the original bone will gradually be resorbed by the osteoclast, compact bone will replace spongey bone at the outside of the fracture and bone remodeling will occur to turn the bone into it's original shape.
95
What is a joint
A point of contact between either two bones, bone and cartilage or bone and teeth. Joints provide flexibility and movement in various parts of the skeleton. They're supported by ligaments, tendons and other connective tissues.
96
Fibrous joint
A joint where two bones are connected by dense connective tissue which is made up of collagen fibre. These joints don't have a joint cavity, and do not allow for much movement.
97
Synarthrosis
Immovable joint
98
Amphiarthrosis
A slightly moveable joint
99
Diarthrosis
A freely movable joint
100
Types of fibrous joints
1. Sutures - a joint made up of thin irregular tissue. These only occur between bones of the skull and they have irregular edges that give them added strength.
2. Syndesmoses: Greater distance between articulating surfaces to the bones and more dense connective tissue surrounding the joint. Connective tissue is arranged as a bundle and this limits the amount of movement in the joint
3. Gomphoses: Peg and socket joints, for instance teeth into the jawbone. These are immovable.
101
Cartilaginous joint
Has no synovial cavity and allows little to no movement, the articulating bones are connected by hyaline cartilage or fibre cartilage.
102
2 types of cartilaginous joints
Synchondrosis - cartilage connecting material to hyaline cartilage, these are normally immovable, or unable to be moved.
Symphyses - Connected by fibrocartilage, which is a stronger type of cartilage. These allow for some movement and provide strength and shock absorption.
103
Interosseous
A large sheet of dense irregular connective tissue which binds long bones next to each other and allows for very small amounts of movement.
104
Fibrous membrane
Made up of dense, irregular tissue that attaches into the periosteum, the fibrous membrane is flexible and strong which allows for a lot of movement.
105
Hyaline cartilage and it's purpose
A dense connective tissue with a smooth, glossy appearance. Made up of a dense network of collagen fibres. It provides flexibility and support, a smooth surface for joint movement, shock absorption, bone growth and forming the embryonic skeleton.
106
Synovial membrane
Special tissue that lines the inner surface of synovial joints. It produces synovial fluid, which provides nutrients to cartilage and removes waste, the fluid acts as a shock absorber, protects from joint from infection and inflammation and provides support and stability.
107
Synovial fluid
A liquid found in the cavities of synovial joints. It's important for lubrication of the joint surface, supplying nutrients and removing waste, shock absorption, waste removal and immune function.
108
Bursa
A fluid filled sac that acts like a cushion between bones and soft tissues. They reduce friction, help with structure and helping with movement.
109
Ball and socket joints
Consists of a small like surface for one joint and a fitting cup for another, which move around three axis. They allow for...
Flexion and extension (where a joint gets smaller and then longer)
Abduction and adduction (moving something away from the centre of body)
Rotation (spin around)
110
Plane joints
Type of synovial joint. These have articulating surfaces that are flat or slightly curved and they allow for back to front or side to side and rotation.
111
Synovial joint
A joint in the body that allows for a wide range of motion and have a synovial cavity which is filled with synovial fluid. Made up of two or bones connected by joint capsule made up of outer fibrous layer and inner synovial membrane that secretes synovial fluid. 6 different types
112
Hinge joint
When the convent of one surface of one joint fits into the convex surface of another joint. Produces an angular opening and closing motion like a huge door. In most movements, one joint remains fixed while another moves around it on an axis. They only permit flexion and extension.
113
Pivot joints
Have a rounded or pointed surface and another bone has a ring and this allows for rotation around it's axis.
114
Condyloid joints
Where there is a convex oval shaped projection of one bone that fits into an oval shaped pression of another. It allows movement around two axis and allows flexion and extension of one axis.
115
Saddle joints
Articular surface of one joint is saddle shaped and the other bone is curved so it will fit into it like the saddle in a horse. This allows for flexion and extension, abduction and adduction and circumduction.
116
What are the sensory and motor functions of the nervous system?
Sensory: Receptors detect stimuli and transmit sensory information into the brain and spinal cord.
Motor function: Effectors are stimulated to carry out the determined response
117
How can this help us do certain actions?
Senses, or neurons, will detect if something is wrong and they will send signals using electrical impulses and chemicals. They will interpret this with environmental factors, which will lead to a reaction.
118
What is the central nervous system?
Made up of the brain and spinal cord, and the spinal cord is attached to the brain. It processes different kinds of sensory information, and is the source of our thoughts, emotions and mental processes. It is also the main source that stimulates muscles to contract or activate.
119
What is the peripheral nervous system?
This is made up of all the tissue outside of the central nervous system. It's use is to allow the body to communicate with the brain and spinal cord through both sensory and motor neurons, which allows you to react with the rest of the environment.
120
Describe the sub-functions of the peripheral nervous system
The peripheral nervous system is divided into three parts, the somatic nervous system, autonomous nervous system and enteric nervous system. After this, they all are divided into sensory and motor, and then the autonomous nervous has two extra parts, the sympathetic and parasympathetic nervous systems.
121
Somatic vs automatic, vs enteric
The somatic nervous system is made up of sensory neurons which convey information to the central nervous system. The motor neurons transmit information from central nervous system to our skeletal muscles (the muscles of the body which attach to the bone and can be voluntarily moved).
The autonomic nervous system has sensory receptors that convey information to the central nervous system from the autonomic sensory receptors. The motor neurons transmit information to our smooth muscle, cardiac muscle and our glands, which are all under voluntary control. This one also is divided into sympathetic and parasympathetic.
The enteric nervous system is mostly responsible for the functioning of the gastrointestinal system, and can operate independently with the central nervous system, and also communicates with it. It can control digestion, and discharge of digestive enzymes.
122
Sensory vs motor somatic nervous system
The sensory motor system is responsible for transmitting sensory information from the body to the central nervous system and can include stimuli such as touch, pain, temperature and proprioception. This is processed through the central nervous system which allows the body to react to certain stimulus.
Motor nervous system is responsible for carrying out responses based off information it receives from the sensory system. The motor neurons send signals from the central nervous system to skeletal muscles, which lets us perform voluntary movements.
123
Sensory vs motor autonomous nervous system
The sensory system collects information from the environment and sends it to the central nervous system, this includes sensory neurons that can detect various stimuli such as touch, temperature, pain and body proprioception, this is processed by the central nervous system which helps the body understand what's happening around it.
The motor system is responsible for taking information from the the central nervous system and translating it into actions, and consists of motor neurons that carry signals from the central nervous system to skeletal muscles, which allows for voluntary movement. Basically, sensory system collects information for the central nervous system and the motor systems sends signals from the CNS to muscles for movement.
124
Sensory vs motor in the enteric nervous system
The sensory neurons are responsible for transmitting sensory information from the body's sensory receptors to the central nervous system, such as light, sound, temperature, pressure and pain. They will receive this information and convert it into electrical signals and send the signals to the brain and spinal cord for processing.
The motor neurons carry signals away from the central nervous system to the muscles and glands, which are responsible for initiating and controlling voluntary and involuntary movements, and when the central nervous system processes information it sends signals through motor neurons to specific muscles, which cause them to contract and produce movement.
125
Sympathetic vs parasympathetic nervous system
Effectors will receive support from both of these divisions and they will have opposite effects.
The sympathetic nervous system is responsible for fight or flight response and prepares your body for reacting to dangerous situation. When it's activated, heart rate will increase, slows digestion, release adrenaline and prepares the body for a rapid action, as well as mobilizing energy and resources which handle emergencies.
The parasympathetic nervous system is responsible for "rest and digest", which helps conserve energy and helps the body relax, slows heart rate, stimulates digestion, promotes relaxation which allows the body to recover and restore energy.
126
Nervous tissue
Made up of neurons and neuroglia, it is a special type of tissue that makes up the nervous system. It connects all of the regions of the body to the brain and spinal cord. Neurons provide most of the unique functions of the nervous system. It is needed for processing and transmitting information, coordinating bodily functions and responding to stimuli.
127
Neuron (nervous tissue)
Functional units for the nervous system that are responsible for transmitting electrical signals throughout the body. They have three main parts: the cell body, dendrites (which receive signals from other neurons) and the axon (which sends signals to other neurons or muscles).
128
Neuroglia
Also known as glial cells, which are there to support and protect neurons. They do not transmit electrical signals but play important parts in maintaining homeostasis, providing structural support and protecting neurons. Basically protect neurons.
129
Anatomy of a neuron
Neurons are made up of three parts. A cell body (soma) which contains the nucleus, dendrites, are extensions around a cell body that are receptor sites that receive signals from other neurons. And the axon, which sends signals to to other neurons or muscles.
130
What is an action potential?
A rapid and temporary change in the electrical charge across a membrane of a neuron. It is the most important way that neurons are able to communicate and transmit signals with one another within the nervous system.
131
What is the process of an action potential?
First, it starts at resting potential, which is normally around -70 millivolts, this is when the inside of the neuron is negatively charged compared to the outside.
Then it goes through depolarization, when a neuron receives a stimulus that is enough to make it reach a threshold level. Then the voltage-gated sodium channels open and sodium ions rush into the neuron, causing the inside to become more positively charged.
Peak is when the membrane potential rapidly rises and can reach around 30mV. At this point, sodium channels close and potassium channels open.
Repolarization is when potassium ions flow out of the membrane, causing the membrane potential to become more negative again.
Then hyperpolarization: where the membrane can become more negative than the resting potential due to the flow of potassium ions.
Then the neuron will return to it's resting potential, and will get ready to fire another action potential if it's stimulated again.
132
Astrocytes
These are in the central nervous system. They are blue star shaped cells and the largest and most numerous of all of the neuroglia. They provide structural support for the neurons, forming part of the blood-brain barrier. In an embryo, they secrete chemicals that appear, regulate the growth migration and inter connection of neurons in the brain.
133
Blood-brain barrier
A barrier that keeps potentially harmful substances in the blood and away from the brain tissue.
134
Oligodendrocytes
Also in the central nervous system, their main function is to give support and insulation by making a protective covering called the myelin sheath around the their axons which makes it easier for it to have rapid communication between the neurons.
135
Microglia
Found in the central nervous system, these are small green cells with thin processes that have spines coming out of them. They're function is to remove cellular debris, microbes and damaged nervous tissue and this provides immune protection as well.
136
Ependymal cells
Found in the central nervous system that lines the ventricles in the brain, the central canal and the spinal cord. They are important for maintaining homeostasis of the central nervous system by producing and circulating cerebrospinal fluid and acting as a barrier.
137
Myelin sheath
A protective covering that surrounds the axons of neurons in the nervous system. It's made up mostly of lipids (fats) and proteins. It is essential for efficient and rapid transmission of electrical signals in the nervous system, which supports communication between neurons.
138
Schwann cells
Part of the peripheral nervous system, this is a type of glial cell found in the peripheral nervous system that plays an important role in supporting and insulating nerve fibers. They are also responsible for forming the myelin sheath around the peripheral nerve axons. It makes sure that there is efficient communication between the nervous system and the rest of the body.
139
Satellite cells
Also found in the peripheral nervous system, and these are flat cells that surround the bodies of neurons in the peripheral nervous system. They provide structural support and exchange of materials (nutrients and waste) between the cell body of a neuron and the surrounding interstitial fluid.
140
How do neurons communicate with one another?
Through a process called synaptic transmission. After an action potential, the neurons will synapse (which consists of the presynaptic neuron and postsynaptic neuron). Then the neurotransmitter is released at the synaptic terminal of the presynaptic neuron which triggers the release of chemical messengers called neurotransmitters. The neurotransmitter then binds to specific receptors on the membrane of the postsynaptic neuron. Then after this, the signal will have to terminate.
141
What is an ion
An ion is an atom that has a positive or negative charge, and ions are located both within and outside of cells. They are needed for nerve impulse transmission, muscle contraction and maintaining the balance of fluids in cells.
142
What is resting membrane potential?
The difference in the electrical charge across a membrane.
143
Leak channel
Will randomly alternate between open and closed positions, which let ions specific to the channel slowly leak into or out of the cell. Normally in neurons there are high numbers of potassium leak channels and small amounts of sodium leak channels.
144
Ligand-gated channels
Open and close in response to ligand or chemical. There is a wide variety of ligands which include neurotransmitters, hormones and particular ions. These can all be the stimulus for opening and closing the ligand gated channels, and make up part of the chemical synapse.
145
Mechanically gated channels
Opens and closes in response to mechanical stimulations, for example, vibrations, touch or pressure on the skin or stretching of the tissue. Mechanical force distorts channel from it's resting position and opening the gate of the channel. It is found in auditory receptors that monitor stretching of internal organs and touch and pressure receptors in the skin.
146
Voltage gated channel
This will open in response to a change in voltage or a change in the membrane potential and will open when the membrane potential hits a particular change in voltage that's called threshold. Voltage gated ion channels are particularly important for generation and propagation of action potentials in all of the neurons. We have specific sodium, potassium and calcium voltage gated ion channels for each of these regions.
147
Voltage gated sodium channel
A type of ion channel to opens in response to change in the membrane potential of a cell, which are responsible for the generation and propagation of action potentials in neurons and muscle cells. They have three different states, open (ions will move through the channel down the concentration or electrical gradient), inactivated (what state it becomes after being opened) and closed (where the gate is closed so ions can't move through the channel).
148
Sodium-potassium pump
Important for the maintaining electrochemical gradient. It uses ATP to move sodium and potassium ions against their concentration gradients. It opens up to the cytoplasm and three sodium ions will bind to the pump, which causes the breakdown of ATP, phosphorylation then causes the protein to change it's conformation, expelling sodium to the outside. Two potassium ions then bind to the protein which causes the release of phosphate groups, which then restores the protein's original conformation. The potassium is then released into the cytosol and sodium can bind again, letting the cycle repeat.
149
Graded potentials
A change in membrane potentials that change and vary in size. This change can either be depolarizing (making the inside of the cell more positive) or hyperpolarizing (making it more negative). These can occur in response to stimuli, such as a neurotransmitter, binding to the receptor, these stimuli cause ion channels to open.
150
Summation
Graded potentials only produce a small and short change in the membrane potential, so in order to become stronger, they will summate, or add together, with other graded potentials. If two depolarizing graded potentials summate, then there will be bigger depolarized graded potential and same with hyperpolarized. And if two equal but opposite graded potentials interact, then they will cancel each other out.
151
Depolarization
When a series of graded potentials summate, at threshold the voltage gated sodium channels will open and sodium moves into the neuron. If the summation of these graded potentials doesn't reach threshold, then the sodium channels stay shut and the action potential doesn't occur.
152
Repolarization
Happens when voltage gated sodium channels become inactivated and sodium can no longer move into the cell. As well as this, voltage gated potassium channels will open and due to potential and electrical gradients, potassium will start to move out of the cell
153
Hyperpolarization
When the voltage gated sodium channels are closed but the voltage gated potassium channels are still open so because there are positively charged potassium ions continuing to exit the cell, the membrane potential drops below resting potential.
154
Propagation
The way that electrical signals or action potentials travel along neurons. This is crucial for communication between different parts of the body.
155
Continuous vs saltatory propagation
Continuous propagation is when a method that involves the way that action potentials travel along unmyelinated axons going through depolarization and repolarization consistently. This type of propagation is slower because every segment of the atom has to go through this depolarization and repolarization.
Saltatory propagation happens in myelinated axons, where the action potential goes from one node of Ranvier to another. This is a much quicker process, and because of myelin, the depolarization does not have to happen in every single section and instead it can jump between sections.
156
What is a synapse?
This is the junction between either two neurons or between a neuron and another type of cell. It is the structure in the nervous system that lets the cells communicate with one another.
Pre-synaptic cell means the neuron before the synapse, and this neuron carries the information of the action potential to the synapse.
Post-synaptic neuron is the receiving cell that comes after the synapse and receives the action potential.
157
Electrical synapse
Action potentials conduct directly between the plasma membranes, and direct electrical connections between neurons through the gap junctions, which allows for faster communication.
158
Chemical synapse
The pre-synaptic and post-synaptic cells are separated by the synaptic cleft. Nerve impulses cannot conduct directly across this synaptic cleft so a different form of communication must occur. This means that the neurotransmitter is the way which it communicates with another neuron or target cell.
159
What is a post-synaptic potential
Changes in the membrane potential of a postsynaptic neuron that happen as a result of the neurotransmitter binding receptors on it's membrane which can either be excitory or inhibitory.
160
What are the protective coverings for the brain?
The bones of the skull and the meninges.
161
What are the meninges and their layers?
Three protective connective tissue coverings that circle around the brain and the spinal cord. They have three layers: the dura mater, arachnoid mater and pia mater.
162
Dura mater
The most superficial (outer) layer. Made up of dense, irregular connective tissue and encloses dural venous sinuses which drain blood from the brain.
163
Arachnoid mater
Looks like a spiderweb, the middle layer made up of loosely arranged collagen and elastic fibers. This layer serves as a protective barrier and assists in the role of circulation of cerebrospinal fluid. It also helps to supply blood to the brain.
164
Pia mater
The innermost layer of delicate, thin membrane that's close to the surface of the brain and spinal cord. This layer helps contain and circulate the cerebrospinal fluid which protects the central nervous system. It also helps prevent infections.
165
Astrocyte end feet
The special extensions of astrocytes, which are a type of glial cell in the central nervous system. They are important for nutrient support, they transport nutrients from the blood to neurons and remove waste from the neuronal environment. They also help the blood-brain barrier to function, ion homeostasis and clinical relevance.
166
Circle of Willis
A circular arrangement of interconnected arteries that are the base of the brain and work to provide a back up route for arteries to make sure that there is a continuous supply of blood to the brain. The circle in the middle is made up as the meeting point for several different arteries that can provide new paths for blood to flow through if there is a blockage.
167
Cerebrospinal fluid
A clear, colourless liquid that protects the brain and spinal cord from physical injury so it can continue circulating through the brain and spinal cord and the space between the pia and arachnoid mater. This acts as protective cushioning to the brain and spinal cord which prevents injury. It also helps with buoyancy which reduces the effective weight of the brain which lets it maintain it's shape and position in the skull. It also helps with nutrient transport go to the brain and removes waste products. It also helps with maintain homeostasis maintaining the chemical stability for the central nervous system.
168
Lateral ventricles
One in each hemisphere of the brain and can produce cerebrospinal fluid and circulation for the cerebrospinal fluid
169
Brain stem
An important part of the central nervous system, it is located at the base of the brain, and connects the brain to the spinal cord and is important for the way that the body functions automatically that are needed for survival. It contains the midbrain, pons and medulla oblongata.
170
Medulla oblongata
An enlargement of the spinal cord involved in controlling vital reflexes such as heartbeat, breathing, blood vessel diameter and non-vital such as swallowing, vomiting and hiccupping.
171
Pons
Broad bands of myelinated axons that function as a bridge between the medulla oblongata and the cerebral peduncles.
172
Cerebellum
Located at the back of the head beneath the cerebrum that controls voluntary movements, maintains posture, balance and motor learning. Divided into two hemispheres.
173
Midbrain
Above the pons and below the cerebrum, it relays messages from higher to lower brain parts and helps coordinate head and eye movements.
174
Diencephalon
Part of the brain located between the cerebrum and the brain stem. Plays an important role in functions such as sensory and motor signal processing and regulating many autonomic functions. Consists of thalamus, hypothalamus, epithalamus and subthalamus.
175
Thalamus
Located in diencephalon, acts as a relay station for sensory and motor signals, playing an important role in processing information from the senses and motor pathways to the cerebral cortex so they can be further processed.
176
Hypothalamus
A small part of the brain located below the thalamus in the diencephalon, and plays an important role in maintaining homeostasis and regulating autonomic functions in the body, including autonomic nervous system control and behavior responses.
177
Epithalamus
Located above the thalamus and consists of the pineal gland and some other structures. The epithalamus produces melatonin which is responsible for controlling sleep-wake cycles and rhythms for the body's internal clock. It also regulates the circadian rhythms, which increases in response to darkness and decreases in response to light, influences sleep patterns and seasonal biological changes, connects with other brain regions, which can include the limbic system and it's also involved in emotion and memory. It also has other structures.
178
Cerebrum
The largest part of the brain, and has the highest centers of the nervous system. Divided into right and left parts.
179
Frontal lobe
Located in front part of cerebral cortex. Responsible for executive functions (planning, decision making, organizing thoughts), motor control, personality and social behavior, language production and attention and concentration.
180
Parietal lobe
Located near the center of cerebral cortex, plays a role in processing sensory information and using it for various functions. Also used for spatial awareness, integration of information, language processing and attention and perception.
181
Occipital lobe
Located at the back of the cerebral cortex and responsible for processing visual information, also visual perception, visual memory, integration with other lobes and visual field processing.
182
Temporal lobe
Located on the sides of the cerebral cortex and plays an important role in functions such as auditory processing, language comprehension, memory function, emotional responses and visual recognition.
183
Pyramids: made up of corticospinal tract
Found in brainstem, medulla oblongata. Corticospinal tract is a pathway that carries motor signals from the brain to the spinal cord, at medulla oblongata, most of the fibers in the corticospinal tract cross over to the opposite side of the body known as the pyramid decussation, which means that the left side of the brain controls the right side and vice versa. The pyramids look like two bulges of the ventral surface of the medulla and each pyramid consists a large amount of descending axons. The function is the transmit motor commands from the brain to the spinal cord.
184
