Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology🧬 > Responding to Changes in the Environment > Flashcards

Responding to Changes in the Environment Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Outline the reflex arc

A

Stimulus (change in environment)
Receptor
Sensory neuron
Relay neuron
Coordinator (CNS)
Motor Neuron
Effector
Response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is Taxis?

A

A response to stimulus that is determined by the direction of the stimulus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the taxis when you move towards stimulus, and away?

A

Towards= positive taxis
Away= negative taxis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is Kinesis?

A

Responding to a stimulus where an organism doesn’t specifically move towards or away from the stimulus.

e.g changes direction or speed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is Tropism?

A

Plant responses to stimuli, negative and positive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Name some types of tropism

A

Phototropism- light
Gravitropism- Gravity
water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are auxins?

A

Hormone for growth in plants, moves away from light and grows in tips and in roots they slow growth and sink to the lower sides.
(meristems)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Name ways in which plants can grow

A

-Cell division (mitosis)
-Cell elongation
-Cell differentiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the other name for auxins?

A

IAA (indoleacetic acid)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe phototropism

A
  1. Light is detected by photoreceptors, sets off chain reactions to re-distribute IAA to shaded side of stem.
  2. IAA causes cells to elongate by loosening the cell wall.
  3. Shaded side has higher conc of IAA, more mitosis, stretches more, shoot bends towards light.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe gravitropism

A
  1. Cells in root tip produce IAA which is initially transported evenly along the root.
  2. Gravity causes IAA conc to build on the lower side of the root.
  3. IAA inhibits growth in root cells, causing less elongation in the cells lower side, resulting in the root bending downwards.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does the myelin sheath do?

A

-Composed of hundreds of layers of Schwann cells
-Insulates axon, reduces metabolic cost
-Allows action potential to jump the nodes of ranvier, makes it quicker, Saltatory Conduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

3 adjectives to describe the reflex arc

A

Rapid
Automatic
Protective

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the structure of the nervous system

A

Nervous system

Central NS:
-Spinal cord
-Brain

Peripheral NS:
-Sensory NS
-Motor NS, splits off to:

-Voluntary NS
-Autonomic NS, splits off to:

-Sympathetic NS
-Parasympathetic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Explain receptors

A

-Specific
-When not stimulated, in resting state
-During resting state, difference in charge on inside and outside of cell (created by ion pumps and channels) so there is a potential difference across the membrane (resting state).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe receptors and how they can pass an action potential

A
  1. Receptor is stimulated, membrane becomes more permeable allowing movement of ions and changing the potential difference.
  2. This is called generator potential, the bigger the stimulus, more movement of ions, higher the generator potential.
  3. If generator potential reaches threshold an action potential is passed along the neuron.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is a Pacinian Corpuscle?

A

They respond to changes in mechanical pressure.

It is a specific to a single type of stimulus and produces a generator potential by acting as a transducer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a transducer?

A

Convert energy by stimulus into nerve impulses.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Name some structures in a pacinian corpuscle

A

-Neuron
-Neuron ending
-Blood capillary
-Capsule
-Lamellae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Where are Pacinian Corpuscles found?

A

-Deep in the skin and most abundant in fingertips, they are pressure receptors
-Occur in ligaments and tendons where they help us to know which joints are changing direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What feature does a Pacinian Corpuscle have in the plasma membrane that allows ot to detect pressure?

A

Stretch mediated sodium channel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Explain how the Pacinian Corpuscles detect a stimulus

A
  • In a normal resting state the stretch mediated sodium channels are narrow, so sodium ions cannot pass along.
    -When pressure is applied it deforms the membrane and becomes stretched, widening the sodium channels
    -Sodium ions diffuse into neuron
    -This changes potential, producing a generator potential causing action potential (if threshold is met).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How do photoreceptors detect light?

A
  1. Light enters eye through pupil, and the amount of light that enters is controlled by the iris.
  2. Light rays are focused by the lens onto the retina which lines the inside of the eye. The retina contains photoreceptor cells which detect light.
  3. The fovea is an area of the retina where there are lots of photoreceptors.
  4. Action potentials from the photoreceptor cells are carried from the retina to the brain by the optic nerve, a bundle of neurons. (where the optic nerve leaves the eye is called the blind spot).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How do Rod cells produce impulses?

A

Rod cells allow vision in dim light due to the presence of a pigment called rhodopsin, which is found in the membrane bound vesicles.

When rhodopsin absorbs light it splits into its constituent parts, opsin and retinal- this is called bleaching. Low light intensity is sufficient to cause this breakdown.

The presence of opsin causes a change in the permeability of the rod cell to sodium, which initiates a generator potential. rhodopsin can reform in the absence of further light simulation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How do cone cells produce impulses?

A

Cone cells are sensitive to high light intensities due to a presence of the pigment iodopsin.

In bright light, iodopsin is broken down into constituent parts generating an action potential in the ganglion cell.

There are 5 different types of cone cell, each containing different forms of iodopsin. each form of iodopsin absorbs different wave lengths of light- green, blue, red.

The colour seen depends on the relative degree of stimulation of the 3 different types of cone cell.

25
Q

What is the structure of rod cells and what do they detect?

A

Multiple rod cells share a bipolar cell that is connected to ganglion cells.

Black and white

26
Q

What is the structure of cone cells and what do they detect?

A

Each cells is connected to its own nerve (ganglion or bipolar)
Most found in fovea.

Colour

27
Q

Briefly explain the autonomic nervous system

A

-Subconscious control of muscle and glands.
Splits into:

Sympathetic-responds to stressful situations by speeding up activity of the heart, stimulates effectors

Parasympathetic- conserves energy during resting condition, inhibits effectors, slows down activity

28
Q

What is the respiratory centre?

A

Controls rate and depth of breathing

29
Q

What is the cardiovascular centre?

A

Controls heart rate

30
Q

What does myogenic mean with regards to the heart?

A

If we were to cut nerves leading to the heart:

-Would continue to beat at a slow regular pace
-However, heart rate can no longer be matched to the needs of the body.

31
Q

How is heart rate controlled?

A
  1. The sinoatrial node (SAN) initiates and sends out regular waves of electrical activity to atrial walls, causing right and left atria to contract at the same time.
  2. A band of non-conducting collagen prevents waves being passed from atria to ventricle, so the electrical wave is transferred to the the atrioventricular node (AVN) from the SAN.
  3. The AVN then passes on the action potential onto the Bundle of His, where there is a slight delay so atria has emptied before ventricles contract.
  4. Bundle of His conducts the cation potential between ventricles and the apex, where it then splits into Purkyne tissue in both ventricle walls.
  5. The purkyne tissue carries the action potential into muscular walls of the right and left ventricles causing them to contract simultaneously from the bottom up.
32
Q

Where does the cardiovascular centre receive info from?

A

Chemoreceptors in…
-aorta
-carotid artery

Pressure receptors in…
-aorta
-vena cava

33
Q

What 2 nerves connect the cardiovascular centre to the sinoatrial node?

A

Sympathetic and parasympathetic nerves.

34
Q

What do the sympathetic nerves do?

A

-Increase impulses to sino-atrial node
-Speeds up heart rate, and increase force of ventricular contraction.

35
Q

What do the parasympathetic nerves do?

A

-Decrease impulses to sino-atrial node
-Slows down heart rate , an force of ventricular contraction is not affected.

36
Q

What do chemoreceptors do when there is low blood oxygen, high CO2, and low pH?

A

Detect chemical changes, the medulla sends impulses along sympathetic neurons. Noradrenalin binds to receptors on the SAN and heart rate increases.

37
Q

What do chemoreceptors do when there is high blood oxygen, low CO2, high pH?

A

Detect chemical changes, medulla sends impulses along parasympathetic neurons. Acetylcholine binds to receptors on the SAN and heart rate decreases.

38
Q

What do baroreceptors do?

A

Detect blood pressure

Use the same method as chemoreceptors by releasing either noradrenalin (low) or acetylcholine (high).

39
Q

Explain the functions of Acetylcholine

A

In a cholinergic synapse, the release of acetylcholine stimulates the post-synaptic neuron to fire an action potential by opening sodium channels, allowing sodium ions to diffuse into a cell, depolarising the cell, causing an action potential.

In the heart, acetylcholine acts as an inhibitory neurotransmitter by causing potassium ions to diffuse out of the cell, resulting in cell becoming hyperpolarised and less likely to fire an action potential.

40
Q

Define a nerve impulse

A

Self-propagating wave of electrical disturbance that travels along the axon membrane.

Temporary, exists in 2 states, a resting or action potential.

41
Q

Why are nerves electrochemical?

A

An impulse travels through a neuron due to a difference in chemicals (ions) from inside and outside the neuron causing an electrochemical imbalance that forms an electrical impulse (uses neurotransmitters)

42
Q

Explain how a resting potential is achieved

A
  1. 3 sodium ions are pumped out and 2 potassium ions are pumped into axon membrane via a sodium-potassium pump, using active transport (ATP) creating an electrochemical gradient and potential difference.
  2. Potassium ion leakage channels are open so K+ ions move out more easily than Na+ ions, as their channels are closed and there 10 times less of them. Membrane is 100 times more permeable to potassium ions.
  3. There is more positive charge outside than in , and the imbalance in voltage creates a potential difference.
    Usually a -65mv to -70mv difference.
43
Q

Outline the characteristics of resting potential

A

-Charge across the axon membrane
-Caused by unequal distribution of ions
-Outside is more positive, inside is negative
-Said to be polarised, now ready to send impulse.

44
Q

Outline the characteristics of a leakage channel

A

-Ungated
-Open all the time
-A lot more K+ than Na+ channels

45
Q

Outline the characteristics of voltage gated channels

A

-Open when a specific voltage is applied
-Charge causes a conformational change
-Specific to the ion they allow to cross

46
Q

Describe how an action potential happens

A
  1. Depolarisation: voltage gated Na+ channels open at around -30mv depending on the neuron, for 0.5 milliseconds and the sodium ions rush in, so inside is more positive than outside, uneven distribution of charges.
  2. Repolarisation: Sodium channels close, then potassium ion channels open for 0.5 milliseconds where K+ ions rush out, so charge across membrane is brought back to resting potential.
  3. Hyperpolarisation: Usually there is an overshoot so that it becomes more of a potential difference (-80mv). Leakage channels correct the resting potential to -70mv.
47
Q

Describe the process of synaptic transmission across a cholinergic synapse (a fucking long process :)

A
  1. Incoming action potential causes depolarisation in the synaptic knob. Causes calcium channels to open, calcium ions flood the knob.
  2. Calcium ion cause synaptic vesicles to fuse with the pre-synaptic membrane which release neurotransmitters into the cleft.
  3. Neurotransmitter, acetylcholine, diffuses across the cleft and bind to the receptor site on the sodium ion channels, on the post-synaptic membranes, sodium channels open.
  4. Depolarisation inside the postsynaptic neuron must be above threshold value. If threshold is met, a new action potential ion sent along the axon of the postsynaptic neuron.
  5. Acetylcholinesterase is a hydrolytic enzyme that beaks down acetylcholine into acetyl and choline. Sodium channels close, and the 2 parts diffuse back to the presynaptic neuron.
  6. Acetylcholine is remade (see another flashcard)
48
Q

What happens to sodium channels when a neurotransmitter binds to it?

A

They are normally closed on the postsynaptic neuron, but when a neurotransmitter binds there is a conformational change, opening the channel allowing Na+ ions to flood, causing depolarisation in the postsynaptic neuron.

49
Q

What happens if Acetylcholine is not broken down?

A

Could allow it to continuously generate new action potentials.

50
Q

How is Acetylcholine remade? (step 6)

A
  • ATP released by mitochondria is used to recombine acetyl and choline.
  • This is stored in the synaptic vesicle for future use.
    -More acetylcholine can be made at the smooth endoplasmic reticulum
    -Sodium channels close in the absence of acetylcholine at receptor sites, synapse is now ready to be used again.
51
Q

What effects the speed of an impulse?

A

-If axon has a myelin sheath
-Axon diameter
-Temperature
-Summation

52
Q

Discuss speed and axon diameter

A

The greater the diameter, the faster the impulse.

Smaller diameters mean a large SA:V ratio, so larger amount of ions can leak out, more difficult for action potential.

53
Q

What is Saltatory Conduction?

A

When the axon is myelinated, impulse travels quicker as it can jump between nodes of ranvier.

54
Q

Discuss speed and temperature (impulse)

A

Higher temp, faster speed as it effects diffusion of ions.

55
Q

Discuss threshold value and speed

A

Stimulants must be greater than the threshold value to generate an action potential, so only if a sufficient number of sodium channels ate open. all or nothing principle.

56
Q

Discuss speed and summation

A

Allows rapid build up of neurotransmitter in synapse, resulting in action potential in postsynaptic cell. low frequency action potentials can result in insufficient amount of neurotransmitter released.

2 types:
-Temporal
-Spatial

57
Q

What is Temporal summation?

A

Takes place when a presynaptic cell undergoes a series of action potentials in quick succession. a large amount of neurotransmitter is released into the synapse, causing an action potential in the postsynaptic cell.

58
Q

What is Spatial summation?

A

When a number of presynaptic cells have s synapse with one postsynaptic cell. If all of the presynaptic cells are stimulated a large amount of neurotransmitter is released into the synapse causing an action potential in the postsynaptic cell.

59
Q

What 3 ways can you inhibit the stimulus?

A
  1. Anything that prevents respiration (no ATP)
  2. Substances that block or close ion channels will inhibit action potential.
  3. an influx of negatively charged ions as it reduces chance of meeting threshold.

Biology🧬 (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions