1
Q
The Nervous System
Emergent Properties?
A
Those that exist when the sum of all the parts creates features that don’t exit within the individual components.
2
Q
The Nervous System
Hormones?
A
- Chemicals produced in one location then carried in fluid (bloodstream) to other locations in the body to communicate instructions/information.
- produce slower but long-lasting changes in organisms
- made of amino acid chains, larger proteins & steroid lipids.
3
Q
The Nervous System
Central Nervous System vs Peripheral System?
A
Nervouse System is divided into central and peripheral nervous systems.
Central – consists of the brain and spinal cord, involved in information processing and conscious thought.
Peripheral – the nerves that deliver messages between brain and body.
4
Q
The Nervous System
Cerebrum?
A
- Largest outermost part of the brain, divided into two hemispheres and four lobes.
- four lobes control conscious experiences (sensation, movement, problem solving, memory & emotion.
5
Q
The Nervous System
Spinal Cord?
A
- A cylindrical bundle of nerves connecting all of the peripheral nerves of the body to the brain.
- An information transmission system that sends and delivers messages
- Has the ability to control some reflex reactions to intense stimuli
6
Q
The Nervous System
Brainstem?
A
- The bottom of the brain, connects the spinal cord with rest of brain.
- responsible for autonomic nervous system (controls vital organs)
- It’s activities are necessary for life, but outside of our conscious awareness.
7
Q
The Nervous System
Cerebellum?
Located under the cerebrum.
A
- Cerebellum recieves these sepearte messages and works to coordinate them, so we retain balance/smooth movement.
- Does this because the cerebrum is heavily localized (each part controlling a seperate process), the commands coming it aren’t coordinated and would lead to uncoordinated movement.
8
Q
The Nervous System
Levels of Organisaiton in Plants and Animals
A
- Cells, which then cluster into specialized tissues.
- Many types of tissues make up an organ.
- Functionally related organs make up organ systems.
- Highest level of organisation is the whole organism, which relies on coordination of all the organ systems.
9
Q
The Nervous System
Endocrine vs Nervous System Coordination.
A
Both systems involved in communication and coordination between body systems.
Nervous System - uses electrical impulses for fast, short-lived signals.
Endorcrine – uses hormones (chemical messenges) to send slower and longer lasting messages, by targeting cells through the bloodstream.
10
Q
The Nervous System
Role of Cerebrum
A
Summarized into understanding the function of each of the four lobes that together regulate our conscious senseations, movements and thoughts.
Frontal lobe - problem solving & voluntary movement.
Occipital lobe – vision
Parietal lobe – touch and pain sensation
Temporal lobe – houses emotion and memory
11
Q
The Nervous System
Role of Cerebellum
A
- Coordinates voluntary movement, so our limbs move in unison, creating fluid movement.
- Faciliates balance, keeps us upright/posture.
12
Q
The Nervous System
Role of Brainstem
A
- Controls out vital functions like breathing, heart rate, blood pressure as well as relaying information between the brain and spinal cord (conntected to the nerves of the body).
- Brainstem includes medulla (oblongata) that monitors carbon dioixde levels to adjust breathing rate accordingly.
13
Q
The Nervous System
Importance of the Autonomic Nervous System
A
- The part of the peripheral nervous system that communicates with and controls involunatry vital organs to adjust our breathing, heart rate & digestion as needed.
- includes a sympathetic nervous system (increases alertness for action)
- includes a parasympathic nervous system (relaxes our body for rest)
14
Q
Neurons and Pain
Sensory Neurons?
A
- Neurons (nerve cells) that carry impulses/messages from the receptor cells of the body to the spinal cord.
- Have distinct shape with a soma at the end near the axon terminals.
15
Q
Neurons and Pain
Receptor Cells?
A
- Detect environmental stimuli.
- A specialized/modifited neuron capable of starting an action potential that travels through sensory neurons to the brain.
16
Q
Neurons and Pain
Motor Neurons?
A
- Recieve messages from the brain – specifically from motor cortex & then transfer them through connected motor nuerons to the terminal motor neuron which connects with msucle fibres at the neuromuscular junction.
17
Q
Neurons and Pain
Motor Cortex?
A
- The back of the frontal lobe, which sends commands via action potentials to specific muscles in the body.
- Highly localized (each section of it controls a specific part of the body)
18
Q
Neurons and Pain
Internuerons?
A
- Connect a sensory & motor nueron, only found in the central nervous system.
- Contain many dendrites to recieve messages efficiently.
19
Q
Neurons and Pain
Effectors?
Effector muslces/organs
A
- Recieves the neurotransmitter message and acts upon the command from the neuron.
- In somantic nervous system, this is a skeletal muscle (e.g., bicep)
- In the autonomic system, other organs can be effectors responding to signals.
20
Q
Neurons and Pain
Nerve?
A
- Clusters of individual neurons (nerve cells) with connective tissue and blood supply near them.
- Contain sensory & motor neurons in one place.
21
Q
Neurons and Pain
Pain Reflex Arc?
A
- An involuntary response that relies on only three neurons.
- A specific receptor (nocireceptor) is a pain receptor that sends an action potential all the way from the recepetor to the spinal cord.
- Connects with an interneuron in the spinal cord which sends a motor command back from the spinal cord to the receptor site for a muscle reflex action to move away from the source of pain. (bicep pulling hand away from flame, say.)
22
Q
Neurons and Pain
Types of Receptors (Don’t need to memorize all)
A
- Photoreceptors
* In retina, vision - Chemoreceptors
* Tongue for taste - Thermoreceptors
* Skin for temperature - Mechanoreceptors
* Ear for sound - Osmoreceptors.
* Arteries and brain for water balance. - Baroreceptors
* Arteries for carbon dioxide levels
23
Q
Neurons and Pain
Role of Acetylcholine
A
- The speific neurotransmitter that’s released from the final motor neuron into the neuromuscular junction of the muscle fibres (Main neurotransmitter for voluntary movement.)
- Stimulates the release of calcium, opening up the actin binding sites to allow for muscle contraction.
24
Q
Neurons and Pain
Myelinated vs Unmyelinated Neurons
A
- Myelinated - have schwann cells wrapped around their axons which leave gaps between the myelin called nodes of Ranvier.
- When action potentials travel down myelinated axon, they can skip from one node to the other, making transmission quicker.
- Unmyelinated - don’t contain shwann cells, thus have no nodes. Are often shorter nuerons involved in less rapid transmisison.
25
# Neurons and Pain
Pain Arc Response
An adaptation to allow us to quickly react to danger is the pain reflex arc, whereby there's a receptor directly at the end of a nerve.
1. Touching something painful initiates an action potential that travels up to the spinal cord.
2. The interneuron directly connects to a motor neuron that sends the command to move the hand from the pain.
3. Message will go to brain, so you can process the sensation.
26
# The Endocrine System
What are Circadian rhytms?
* Any pattern of behaviour/physiology based on a 24hr cycle.
* E.g., sleep-wake cycle (regulated by daylight), temperature and blood pressure (daily cycle, supportive of sleep)
* Activity during the daytime --> dinurnal (survival advantage for our poor night vision)
27
# The Endocrine System
Pineal Gland?
A key gland (in the endocrine system) located behind the hypothalamus and thalamus and **secretes the hormone melatonin** that regulates human's sleep-wake cycle so we sleep when it's dark .
28
# The Endocrine System
Adrenal Glands?
* Another gland in the endocrine system located one on top of each kidney,
* **release stress hormones (cortisol and adrenaline) in response to actual/perceived danger**.
* Adrenaline controls short term stress reactions to get to safety.
* Cortisol controls long term stress responses (e.g., adjusting blood sugar)
*Note there's other hormones released, which include noradrenaline and some sex hormones.*
29
# The Endocrine System
Hypothalamus?
* The area of the brain that acts as a **link between the endocrine and nervous system**.
* Contains receptors that allow it to regulate our autonomic nervous system that manages vital functions.
* Has nuerons and galndular cells, allowing it to produce hormones as well as regulate the release of hormones form pituitary glands.
30
# The Endocrine System
Pituitary Gland?
| Contains both....
* Located below the hypothalamus, made up of two lobes (the **anterior** and **posterior** pituitary each of which secrete different hormones).
* Pituitary glands release a variety of hormones that largely work together to maintain homeostasis by adjusting metabolic rate, reproduction and water balance.
31
# The Endocrine System
Anti-Diuretic Hormone?
| (ADH or Vasopressin)
* A hormone produced by the hypothalamus and **stored in the posterior pituitary**
* secreted from posterior pituitary when **osmoreceptors detect high solute concentration in blood**.
* this secretion **causes kidneys to reabsorb water back into the bloodstream.**
* Allows osmolarity to return to normal in blood (isontonic)
32
# (ADH or Vasopressin)
Osmoreceptors?
* Specialized receptor neurons in the hypothalamus.
* As blood passes through, they detect water content of the blood.
* The receptor cells adjust in size according to the tonicity of the blood --> adjusting the speed of action potentials.
* If osmoreceptors shrink (size wise), it increases firing rate causing vasopression to be released from the pituitary.
33
# The Endocrine System
Role of Melatonin (hormone)
1. Sun inhibits the production of the hormone melatonin by the pineal gland.
2. This faciliates wakefulness during the day.
3. When daylight ends, SCN (Suprachiasmatic nucleus) detects the dark and enables the pineal gland to secrete melatonin.
4. Melatonin stimulates the feeling of tiredness to ecnourage sleep during dark hours.
34
# The Endocrine System
Anterior vs Posterior Pituitary Glands
| (Both comprise the pituitary gland & secrete seperate hormones)
**Posterior Gland**: Doesn't MAKE hormones, but stores and secretes two homrones made by the hypothalamus (oxytocin and ADH).
**Anterior Gland**: Secretes hormones directly into the bloodstream and secretes a larger range of hormones.
35
# The Endocrine System
Hypothalamus, Pituitary and Water Balance
* Hypothalamus and & *posterior* pituitary together regulate osmolarity (solute balance) of the blood using the hormone ADH.
1. Osmoreceptors in the hypothalamus detect high solutes in the blood, they shirnk and trigger posterior pituitary to release ADH into bloodstream.
2. ADH travels to the kidney and tells it to reabsorb water out of the urine to stay in the blood, decreasing solute conc.
3. If hydrated --> ADH not released, and we remove large amounts of water into urine.
36
# Feedback Control of Vital Functions
Feedback Control?
When outcomes of a function influence its continuation, allowing for regulation (often to a set point) and adaption to changing conditions.
* includes positive and negative feedback processes
* Example - negative feedback, allowing for small adjustments to maintain homeostasis.
37
# Feedback Control of Vital Functions
Baroreceptors?
* Specialized receptor neurons that **monitor blood pressure** by detecting pressure changes in arterial walls.
* Located **INSIDE** the heart (one on each aortic arch then at the base of the carotid arteries as well.)
* Send messages to medulla, decreasing heart rate, forcing a contraction when blood pressure is elevated.
38
# Feedback Control of Vital Functions
Chemoreceptors?
* Specialized receptor nuerons able to detect changes in blood pH, oxygen and carbon dioixde.
* Found in similar location to baroreceptors (aorta and carotid arteries) but sit on the **OUTSIDE** of the vessels. Also found in medulla.
* If there's a change in pH, O2 or CO2, nuerons alert the medulla --> changes can adjust both respiratory and heart rate.
39
# Feedback Control of Vital Functions
Stroke Volume?
* The volume of **blood pumped out of the heart's left** ventricle during each systolic cardiac contraction.
* A way that the functioning of the heart is regulated, is with changes to stroke volume.
40
# Feedback Control of Vital Functions
Medulla?
* **Part of the brainstem that controls the vital functions** of breathing, heart rate and blood pressure.
* Loctaed between the spinal cord and rest of the brain.
* **Recieves messages from baroreceptors and chemoreceptros** to make adjustments in ventiliation rate & heart funciton to best meet our bodies O2 needs.
41
# Feedback Control of Vital Functions
Respiratory Centres?
Clusters of cells that recieve messages from chemoreceptors and send commands to the diaphragm & intercostal muscles to adjust breathing rate.
* When at rest, they send action potentials at a slow consistent pace to maintain our resting resp. rate.
42
# Feedback Control of Vital Functions
Peristalsis?
| Peristaltic reflex
* **A series of smooth muscle contractions** that occur along the digestive canal that moves food through.
* An **involuntary muscle reflex, follows a wave-like motion that slowly propels food** to the next site along the tube.
43
# Feedback Control of Vital Functions
Enteric Nervous System?
* A complex network of nuerons within the gastrointestinal tract (from oesophagus to rectum) that controls various digestive functions **independent** of the central nervous system.
* Most digestive processes are thus not actually regulated by the brain, but by this seperate set of nuerons.
44
# Feedback Control of Vital Functions
Alimentary Canal?
| (Gastrointestinal/ Digestive Tract)
* A continuous tube that extends form the mouth to the anus wherein food travels.
* Inclues the oesophagus, stomach, small and large inestines, mouth, rectum and anus.
* Does not include liver, gallballer and pancreas.
45
# Feedback Control of Vital Functions
Baroreceptors vs Chemoreceptors
* **Similar**
* Both located in major arteries coming off the heart (aorta and carotid arteries)
* Both send messages to the medulla to help monitor vital functions.
* **Different**
* Baroreceptors are inside the vessel monitoring the pressure exerted on the wall (a physical change.)
* Chemoreceptors sit outside the vessel and monitor chemical properties of blood - pH, O2 and CO2 levels.
46
# Feedback Control of Vital Functions
Strenuous Exercise and Ventilation Rate
* Strenuous exercise requires high amounts of O2, which is consumed in cellular respiration and carbon dioxide is produced.
* Chemoreceptors in the medulla monitor the pH of blood passing through the brain, which should remain between 7.35 and 7.45.
* The additional CO2 generated during execise lowers the pH of the blood (acidifies).
* This lower pH is detected, and then action potentials are fired through to the motor nuerons that control the diaphragm & intercostal muscles to increase ventilation rate.
47
# Feedback Control of Vital Functions
Voluntary vs Involuntary Digestion Movement
* **Voluntary**: Choose when to chew and swallow food, and egest feces.
* **Involuntary**: All processes between those two (swallowing and egesting) events are under involuntary control, done by smooth muslce which moves food through the esophagas and intesntines by peristalsis.
* Additional involuntary persitalic churning of food in the stomach.
48
# Feedback Control of Vital Functions
Excitatory vs Inhibitory Neurotransmitters
| (Refer to Diagram)
*Peristalsis relies of the action of both excitatory & inhibitory neurotransmitters.*
**Excitatory**: Fire action potentials that promote movement - act behind the food 'bolus' as it travels through.
**Inhibitory**: Stop action potentials and promote the relaxation, which fire ahead of the bolus, allowing the relaxing tissue to accept the bolus in that further along position.
49
# Plant Hormones
Tropism?
* **A growth response towards or away from an external stimulus**.
* Can be seen in other non-motile organisms but are most in plants.
* In absence of locomotion tropisms are a beneficial adaptation that allow organisms to better position themselves for obtaining resources.
50
# Plant Hormones
Phototropism?
* **A positive tropism (towards a stimulus)** specifically towards sunlight.
* **The growth of the stem of a plant towards the light source**.
* An adaptation that increases the exposure to sunlight for the leaves of a plant to maximise their rate of photosynthesis.
* Caused by the **elongation of the cells on the shaded side of the plant, caused by the hormone auxin**.
51
# Plant Hormones
Phytohormones?
* **Hormones produced by plants;** they are singnalling molecules that **control the growth and development** of flows & seeds and allow for plants to **respond to external stimuli**.
* Plants lack a nervous system/ true endorine system, so these hormones help in coordination and development of plants.
52
# Plant Hormones
Auxin Efflux Carriers?
* Membrane proteins that **enables auxin to exit the cell.**
* Auxin is produced by growing regions of plants and faciliates growth by the elongation of cells.
* It enters cells easily by diffusion but **requires Auxin Efflux carriers to exit**.
* By distributing Auxin efflux carriers more on one side of the plant than others, auxin concentrations can differ --> some cells will elongate more than others.
53
# Plant Hormones
Apoplast & Process of cell elongation?
* Apoplast: **Includes the cell walls and interceullular spaces between the cell walls**. (Any area of adjoining plant cells outside the cell membranes).
* The process of cell elongation requires the lengthening of the cell walls.
* This is done by auxin, causing the synthesis of H-ion pumps in the cell membrane.
* These pumps use ATP and pump hydrogen ions into the apoloplast.
54
# Plant Hormones
Expansin?
A protein already in the cell wall but previously (before H-ions) inactive.
* After hydrogen ions accumulate in the cell wall/apoplast area, they activate expansin.
* Once activated, it loosen the hydrogen bonds that cross-link cellulose fibres to move past one another.
* When water is absorbed and there is a rise in turgor pressure, the fibres stretch out and cause the cell wall the lengthen.
55
# Plant Hormones
Positive vs Negative Tropic Responses
**Positive**: towards an external stimulus. Tropic responses to gravity (geotropism) are positive for roots. Stems show positive phototropism.
**Negative**: away from an external stimulus. Tropic responses to gravity by stems is negative. Roots show negative phototropism.
56
# Plant Hormones
Function of Plant Hormones: Auxin
* Auxin is a phyohormone that is produced in growing regions of the plant **(tips of shoots)**.
* It is then transported from shoots through to roots.
* It is transported in **phloem** with sap.
* Auxin functions to **elongate existing cells by acidifying the cell walls** to allow for stretching of cellulose fibres.
57
# Plant Hormones
Function of Plant Hormones: Cytokinin
Cytokinin is another phytohormone that regulates plant growth, however differs from auxin.
* It is often produced in the **roots** and then transported in **xylem** to the shoorts.
* It promotes growth by **stimulating mitosis for cell proliferatoin**.
Both Auxin and Cytokinin interact to make new cells & elongate existing cells towards stimuli.
58
# Plant Hormones
Function of Plant Hormones: Ethylene
A plant hormone released as a gas by ripened fruits.
* This functions as a positive feedback loop, as when ripe fruits produce the gas, adjacent fruits are also stimulated to ripen and release ethylene.
* Fruits thus ripen at the same time --> beneficial as it makes it more likely for the dispersal of more seeds by herbivores.
59
# Plant Hormones
Functions of Plant Hormones: Gibberellin
A phytohormone which controls a wide range of plant development, but is specifically crucial for seed germination.
* Also impacts flowering & dormancy.
60
# Plant Hormones
Maintenance of Auxin Conc. Gradients
* Auxin conc. can be accumulated in one area of the plant using the placement of auxin efflux carriers.
* These transport auxin into some cells --> production of efflux carriers in cells exposed to light in order to transport auxin to the shaded side.
* Cells on the shaded side elongate more, causing the stem to bend towards the light source.
61
# Plant Hormones
Auxin and Cell Elongation
* Auxin faciliates cell elongation by creating H-ion pumps in cell membrane.
* This allows for H-protons to be actively pumped into the cell wall (apoplast), this acidity activates the protein expansin.
* Activated expansin breaks H-bonds in cellulose, then when enough water enters the cells and turgor pressure accumulates, the pressure stretches the cellulose, expanding the cell wall.
62
# Plant Hormones
Auxin vs Cytokinin for Plant Growth
**Auxin**: produced in the shoot tips and transported down to the roots in the phloem.
**Cytokinin**: produced in the roots and transported to the stem in the yxlem.
* In the tips of the stems AND roots, the two hormones are synergetic (stimulate one another to encourage growth).
* In the branches/lateral growth of roots & branches, they are antagonists --> auxin inhibits lateral growth of shoots but stimulates root expansion.
Biology
flashcards
Decks in class (41)
# Cards
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B4.141
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B4. 23
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C4.138
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C4.230
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A4. 137
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A4. 225
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D4.134
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D4.224
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D4.353
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A1.1.254
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B1.121
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B1.18
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B.1.223
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A2.123
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A2.229
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A2.313
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B3.142
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B3.252
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B3.329
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C3.162
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C3.239
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D3.178
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D3.252
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D3.336
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A3.131
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A3.223
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C2.131
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C2.239
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B2.132
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B2.219
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B2.331
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D2.134
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D2.244
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D2.320
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C1.132
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C1.229
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C1.333
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D1.131
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D1.230
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D1.328
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(Continued) D1.322
