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Biology OCR A Level > Animal Responses > Flashcards

Animal Responses Flashcards

1
Q

What does the cerebrum control?

A

Voluntary actions (e.g thinking, memory and speech)

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2
Q

What does the cerebellum control?

A

Involuntary movements and balance

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3
Q

What does the hypothalamus do?

A

It is an endocrine gland that controls osmoregulation and thermoregulation

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4
Q

What is the hypothalamus connected to?
What type of gland is it?
What do its two separate parts do? (Anterior and Posterior)

A

Pituitary Gland: (Endocrine)

  • Anterior Pituitary Gland: Produces and Releases Hormones e.g FSH
  • Posterior Pituitary Gland: Stores and Releases Hormones from the Hypothalamus (e.g ADH)
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5
Q

What does the medulla oblongata do?

A

Regulates functions of ANS (Heart rate and Breathing rate)
Controls cardiac and smooth muscles

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6
Q

What is a reflex action?
Name three properties…

A

Involuntary response to a stimulus

  • Fast
  • Happen without conscious thought
  • Minimise damage to organism
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7
Q

Explain the knee jerk reflex.

A

Stimulus- Patellar Tendon Stretches
Sensory Receptor- Stretch receptors detect this
CNS- Spinal cord: Sensory neuron -> Motor neuron
Effector - Leg muscles
Response- Leg kicks

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8
Q

Why is the knee jerk reflex fast?

A
  • Doesn’t involve the brain
  • Only involves one synapse
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9
Q

Explain the blinking reflex.

A

Stimulus- An object hits the cornea
Sensory Receptor- Cornea receptors detect/ Free nerve endings detect
CNS- Brain Stem: Sensory Neuron -> Relay Neuron -> Motor Neuron
Effector- Eyelid Muscles
Response- Eyelids close

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10
Q

The parasympathetic system … . The sympathetic system prepares the body for … . We say they are … .

A
  • Conserves energy
  • Activity
  • Antagonistic
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11
Q

Name some features of the somatic nervous system.

A
  • The motor neurons contact effectors that are under voluntary control (mostly skeletal)
  • Conduction of action potentials is usually rapid, so most neurons are myelinated
  • Conscious voluntary actions
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11
Q

Name some features of the autonomic nervous system.

A
  • Controls unconscious activities: Heart Rate, Smooth muscle in digestive system and airways, Glands
  • Most neurons unmyelinated as responses do not need to be rapid
  • At least two motor neurons in the pathway between CNS and effector. These two neurons connect at swellings like ganglia.
  • Without conscious thought
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11
Q

What is a ganglion?

A

A cluster of neurone cell bodies outside the CNS.

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11
Q

Why might an increase in heart rate be useful in the sympathetic response?

A
  • Increased O2 transport to muscles for respiration
  • Increased CO2 removal
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11
Q

What is the effect of the sympathetic stimulation on the digestive system.

A
  • Blood diverted away
  • Stops peristalsis
  • Salivary glands stop working
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11
Q

What does the corpus callosum do?

A

Connects the two cerebral hemispheres

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12
Q

What is the cerebral cortex?

A

The outer layer of the cerebrum. It has become highly folded to increase SA.

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13
Q

What are some adaptations of reflexes?

A
  • Localised to the part of the body where the point of response occurs
  • Few synapses
  • Some signals are still sent to the brain for its comprehensive decision making process if deemed necessary
  • Simple mechanism so does not have to be learnt (effective from birth so is an innate response)
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14
Q

What is a dorsal root ganglion?

A

A swelling in the spinal cord that contains sensory neuron cell bodies

15
Q

Which factors will the body respond to by altering heart rate?

How are they monitored?

How are they communicated to the SAN?

How does heart rate change?

A

Increase in movement:
Stretch mediated receptors
Accelerans Nerve (Sympathetic NS)
Increase

Blood pH
Chemoreceptors in medulla oblongata
Accelerans Nerve
(Sympathetic NS)
Increase

Blood Pressure
Baroreceptors
Vagus Nerve
(Parasympathetic NS)
Decrease

16
Q

What are the three main types of muscle?

A
  • Skeletal
  • Cardiac
  • Involuntary
17
Q

Skeletal Muscles:

Structure:

Control:

Contraction Speed:

Length of Contraction:

A

Structure:
- Striated
- Tube shaped
- Multinucleated

Control:
- Somatic

Contraction Speed:
- Fast but tires easily

Length of Contraction:
- Short

18
Q

Cardiac Muscles:

Structure:

Control:

Contraction Speed:

Length of Contraction:

A

Structure:
- Striated
- Branched
- Uninucleated

Control:
- Parasympathetic (Myogenic)

Contraction Speed:
- Intermediate, continuously contracts, does not tire easily

Length of Contraction:
- Intermediate

19
Q

Involuntary Muscles:

Structure:

Control:

Contraction Speed:

Length of Contraction:

A

Structure:
- Non Striated
- Uni Nucleated
- Spindle Shaped

Control:
- Parasympathetic

Contraction Speed:
- Slow, Does not tire easily

Length of Contraction:
- Slow, can be contracted for a long time

20
Q

What is the H zone?

A

Myosin only zone

21
Q

What is the I band?

A

Actin only

22
Q

What is the A band?

A

Actin and myosin overlap

23
Q

Outline the stress response via ACTH.

A
  1. Stimulation of neurosecretory cells. Adrenocorticotrophic hormone released by pituitary gland. ACTH attaches to receptors surface membrane of cells in adrenal cortex. Cascade of reactions result in secretion of cortisol. Cortisol causes an increase in bp, blood sugar levels and suppression of the immune system.
24
Q

What does adrenaline do to smooth muscle in bronchioles?

A

Relax. Bronchioles dilate and allow more oxygen to reach blood.

25
Q

What does adrenaline do to the SAN?

A

Increases rate of firing impulses. Increased heart rate circulates blood more quickly.

26
Q

What does adrenaline do to the liver cell?

A

Increases glycogenolysis so that more glucose is available for respiration.

27
Q

What does adrenaline do to the erector muscle in skin?

A

Contraction of muscle. Causes hair to be raised so animal looks larger/more aggressive.

28
Q

Suggest how the Moro reflex helps to prevent harm to a newborn baby.

A

Allows baby to hold on to something. Crying draws attention to the baby.

29
Q

What are the negative effects of prolonged stress response?

A

Cortisol:

Prolonged high blood pressure can lead to cardiovascular problems.

Prolonged high blood sugar can lead to diabetes/ insulin resistance.

Prolonged immune system suppression can lead to susceptibility to diseases and infections.

30
Q

What is the blinking reflex useful for?

A

It is an involuntary response where the eyes shut rapidly. It can prevent damage to the eyes.

31
Q

Why is glucose required for the contraction of skeletal muscle?

A
  • Glucose is used as a respiratory substrate to produce ATP
  • ATP needed for breaking cross bridges between myosin and actin
  • Hydrolysed to reset myosin head from its lower energy conformation to a higher energy conformation
  • ATP for active transport of Ca2+ ions back into sarcoplasmic reticulum
32
Q

Explain what happens during muscle contraction.

A

An action potential arrives at the presynaptic bulb of the motor neurone. The voltage gates Ca2+ channels open, Ca2+ enters the neurone and causes the vesicles containing neurotransmitter to fuse with the membrane. The neurotransmitter diffuses across the synapse (exocytosis). The ACh binds to its receptors on the sarcolemma and opens Na+ channels. The Na+ ions enter the sarcolemma and it becomes depolarised. The wave of depolarisation goes down the inverted t tubules to the sarcoplasmic reticulum. This causes Ca2+ to be released into the sarcoplasm. The Ca2+ binds to troponin and causes a conformational change which moves th tropomyosin revealing the myosin binding sites on the actin molecules. The myosin heads bind to the actin molecules. The myosin heads bind to the actin molecule and forms a cross bridge. The myosin head tilts and ADP is released (power stroke.) This causes the sarcomere to shorten. ATP binds to the myosin head and is hydrolysed. This breaks the cross bridge and the myosin head returns to its original position ready to bind again.

33
Q

Explain the stress response (adrenaline).

A

Adrenaline binds to adrenaline receptors embedded in the cell surface membrane. A G-protein attached to the adrenaline receptor activates adenylyl cyclase. Adenylyl cyclase activates enzymes via phosphorylation. A cascade of enzyme controlled reactions stimulates an increase in glycogenolysis. This means glucose is more readily available in the bloodstream for respiration.

34
Q

What is the purpose of creatine phosphate?

A

In active muscles, creatine phosphate releases ADP and Pi as well as energy.

In resting muscles, creatine turns ATP into ADP and creatine phosphate.

35
Q

What is the differences between the sympathetic and parasympathetic autonomic nervous systems?

A

Sympathetic:
Origin of Nerve Pathways: Spinal Cord
CNS Links with: Autonomic Ganglia
Form synapses with: Cardiac + Smooth Muscle
Neurotransmitter: Noradrenaline
Effect on Heart: Increased force and contraction
Effect on Eyes: Pupil Dilation
Ciliary Muscles Relax (Long Distance)
Effect on Digestive System: Stops Peristalsis, Glucose released by liver, blood diverted away, salivary glands inhibited
Effect on Skin: Sweat glands stimulated (cool body down when it starts to overheat due to stress), erector muscles stimulated, vasoconstriction
Excretory System: Inhibits urination + defecation

Parasympathetic:
Origin of Nerve Pathways: Brain (vagus nerve) and Spinal Cord
CNS Links with: Mostly Vagus Nerve
Forms synapses with: Cardiac + Smooth Muscle
Neurotransmitter: Acetylcholine
Effect on Heart: Decreased force and contraction
Effect on Eyes: Pupils constrict, Ciliary Muscles Contract (Short Distance)
Effect on Digestive System: Peristalsis stimulation, increased glycogen production, glandular secretion
Effect on Skin: No Effect
Excretory System: Urination + Defecation sphincter muscles relax

36
Q

What happens to the … during contraction?

  • Sarcomere
  • A Band
  • I Band
  • H-Zone
  • Z-Line
A

Shorten
Stay the Same
Shorten
Shorten
Stay the Same

37
Q

What if there was no ATP in muscle contraction?

A
  • The myosin head would not be able to move back into its higher conformation position from its lower conformation position
  • Myosin head and actin cross bridges would not be able to be broken
  • Ca2+ ions would not be able to be actively transported back into the sarcoplasmic reticulum
38
Q

Actin forms the…

A

Thin protein filaments in myofibrils in muscle fibre

39
Q

Myosin forms the…

A

Thick protein filaments in myofibrils in muscle fibre

40
Q

What is a sarcomere?

A

The distance between two adjacent Z lines on a myofibril

41
Q
A

Biology OCR A Level (18 decks)

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