5.5 Plant and animal responses Flashcards by Faye Mason

What are the two divisions of the nervous systems?

Central nervous system (CNS) and peripheral nervous system (PNS)

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What two parts are the CNS divided into?

The brain and the spinal cord

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What type of neurones found in the PNS?

Motor and sensory neurones

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The peripheral motor system is divided further into two systems, what are they called?

The somatic and autonomic nervous systems

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The autonomic system is divided into two systems what are they called?

Sympathetic and parasympathetic

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What is the role of the PNS?

To ensure rapid communications between the sensory receptors, the CNS and effectors.

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What is the role of the somatic nervous system?

Conduct action potentials to the effectors that are under voluntary control, for example skeletal muscle.
Rapid due to myelination

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What is the role of the autonomic nervous system?

Conduct action potentials to the effectors that are under involuntary control, includes glands, cardiac muscle, does not require rapid control.
Controls majority of the homeostatic mechanisms.

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How many neurones connect the CNS to effector in the somatic nervous system?

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How many neurones connect the CNS to effector in the autonomic nervous system?

2, connected at ends called ganglia

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What is the role of the sympathetic system?

Prepares the body for activity

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What is the role of the parasympathetic system?

Conserves energy

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What is an antagonistic mechanism

The action of one system counteracts the other.

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What are some differences between the sympathetic and parasympathetic system?

-Many nerves in sympathetic system leads to separate effectors
-Few nerves in parasympathetic system leads to different effectors
-Sympathetic is most active at times of stress, where as parasympathetic system is most active during sleep or relaxation

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What are some effects of the sympathetic system?

-Increases heart rate,
-Dilates pupils
-Increases ventilation rate
-Reduces digestive activity
-Orgasm

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What are some effects of the parasympathetic system?

-Decreases heart rate
-Constricts pupils
-Reduces ventilation rate
-Increases digestive activity
-Sexual arousal

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What part of the brain controls. active thought and memory?

Cerebrum

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What is the role of the Cerebrum in the brain?

Controls active thought, memory and speech.

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What is the role of the Cerebellum in the brain?

Coordinates movement and balance

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What is the role of the Hypothalamus and Pituitary complex in the brain?

Organises homeostatic responses and control various physiological processes

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What is the role of the Medulla Oblongata in the brain?

Coordinates many of the automatic responses, such as cardiac control and respiratory centre

What is the name of the tracts of neurones that connect the two hemispheres in the brain?

The corpus callosum

What is the thin layer of nerve cell bodies on the outermost layer of the cerebrum called?

The cerebral cortex

How does the hypothalamus control homeostatic functions?

-Temperature regulation and osmoregulation through osmoreceptors

What are the two lobes that the pituitary gland consists of?

The posterior lobe and the anterior lobe

Describe the role of the posterior lobe in the pituitary gland.

Stores and releases ADH which is made in the hypothalamus

Describe the role of the anterior lobe in the pituitary gland.

Produces own hormones, which are released in the blood in response to releasing factors produced by hypothalamus

What is a reflex?

An involuntary response to changes in the environment

How are reflexes important for survival?

Reduce the risk of harm

What does a typical reflex pathway look like?

Sensory neurone - relay neurone - motor neurone

What are some examples of a reflex action?

The blinking reflex and the knee jerk reflex

What is the events in a reflex arc?

-Stimuli detected by receptor, -Impulses sent to coordinator (CNS) -CNS sends impulses to the effector, which carries out response.

What response does the blinking reflex give?

-The temporary closing of eyelids to protect eyes from damage

Describe the nervous pathway for the blinking reflex.

-Passes through the brain, but is a direct pathway but does not require thought. -Because the receptor and effector in the same place (eye) it is called a reflex arc.

What is it called when a reflex causes impulses through the brain?

Cranial reflex

What are some stimuli that cause the blinking reflex?

-A foreign object touching eye (corneal reflex) -Sudden bright light (Optical reflex) -Loud sounds -Sudden movements towards eye

Where is the sensory neurone in the corneal reflex?

In the cornea

Where does the sensory neurone in the corneal reflex travel to?

The Pons (the brainstem connecting with spinal cord)

Describe the corneal reflex arc.

-Sensory neurone to relay neurone, passes action potential to motor neurone -Motor neurone passes back to facial muscles causing eyelids to blink

How long does the corneal reflex usually take?

0.1 seconds

What is the Pons involvement in the corneal reflex?

-Myelinated neurones in pons carry action potential to sensory region of cerebral cortex. -Cerebral cortex can prevent a corneal reflex by sending inhibitory action potentials that are more rapid than the non-myelinated relay in the pons. This reaches the motor neurone before the other action potential does, preventing a response.

What is the optical reflex

-Protects light-sensitive cells of retina from damage -Stimulus detected from retina, mediated by the optical centre in cerebral cortex

Is the optical reflex faster or slower than the corneal reflex?

slightly slower.

Is the knee jerk reflex passed through the spine or brain?

Spine

What does the knee jerk reflex help to achieve?

-Coordinated movements, -Balance

What is the muscle at the front of the thigh called?

Quadriceps

What is the tendon called that helps to connect the quadriceps to the lower leg?

Patella tendon

How does the knee jerk reflex happen?

By tapping the patellar tendon: -Quadriceps stretch, -Stretch receptors (Muscle spindles) detect the length of muscle while stretched. -If stretch unexpected, reflex action causes contraction of the same muscle, straightening the leg

Describe the nervous pathway of the knee jerk reflex.

Only 2 neurones, Sensory and motor.

How does lack of a relay neurone prevent an inhibitory action potential?

-The cerebellum sends out inhibitory action potentials down a myelinated neurone in order to get to the motor neurone faster than the original which should go down the non-myelinated relay neurone. -As there is no relay neurone the original action potential gets to the motor neurone quicker as there is less synapses to cross. -This means the knee-jerk reaction is an immediate response that cannot be inhibited

How can the knee jerk reflex be diagnostically helpful?

If there is multiple kicks, shows symptoms of cerebellar disease If there is a lack of kicks, could mean there is nervous problems