5.1.5 Animal responses Flashcards
What are the two main divisions of the nervous system?
central nervous system
peripheral nervous system
What structures make up the central nervous system (CNS)?
the brain & spinal chord
relaye neurones and many synapses
What is the structure and function of the peripheral nervous system?
Made up of the nerves that connect the CNS to the rest of the body.
What are the two subdivisions of the peripheral nervous system (PNS)?
Somatic nervous system
Autonomic nervous system
What does the somatic nervous system control?
Voluntary actions, e.g. running
What does the autonomic nervous system control?
Unconscious activities, e.g. heart rate & digestion
What are the two subdivisions of the autonomic nervous system?
Sympathetic nervous system
Parasympathetic nervous system
What is a ganglion?
A structure containing a number of nerve cell bodies
Describe the Sympathetic nervous system.
-‘Fight or flight’ response
-Neurotransmitter is noradrenaline
-Short preganglionic neurones but long post ganglionic neurones
-Increases breathing rate, diameter of airways & blood flow to skeletal muscles
-Dilates pupils & glycogenolysis
-Reduces peristalsis
Describe the Parasympathetic nervous system.
-‘Rest and digest’
-Neurotransmitter is acetylcholine
-Long preganglionic neurones but short postganglionic neurones
-Decrease breathing rate, diameter of airways & blood flow to skeletal muscles
-Constricts pupils & glycogenesis
-Increases peristalsis
Explain the role of the cerebrum
Controls voluntary actions
Vision, language, thinking & memory
What is the role of the cerebellum?
Muscle coordination, movement & balance
What is the role of the Medulla Oblongata?
Controls unconscious actions
heart rate and breathing rate
What are the main functions of the Hypothalamus?
Thermoregulation
Osmoregulation
Regulates digestive activity
Controlling endocrine functions
What is the role of the Pituitary gland?
Produces a range of hormones
Control the activity of other glands
Where is ADH secreted from?
Posterior pituitary gland
What is a reflex?
A rapid, unconscious response to a stimulus that helps protect the body from harm.
What are two examples of reflex actions?
The blinking reflex and the knee-jerk reflex.
When does the blinking reflex occur?
The cornea is stimulated and the eyelid closes to prevent anything from entering the eye.
What is the purpose of the knee-jerk reflex?
Maintain balance and posture by straightening the leg if the quadriceps muscle suddenly stretches
Describe the pathway of the knee-jerk reflex.
- Stretch receptors in the quadriceps muscle detect muscle is being stretched
- A nerve impulse is passes along a sensory neurone, which then directly communicates with a motor neurone (no relay neurone)
- The motor neurone carries the nerve impulse to the quadriceps muscle causing it to contract.
What two systems control the fight or flight response?
The endocrine (hormonal) system and the nervous system.
What hormone does the anterior pituitary gland release and what is its function?
ACTH
Stimulates the adrenal cortex to release steroid hormones, e.g. cortisol
How does the sympathetic system contribute to ‘fight or flight’?
Stimulates the adrenal medulla to release adrenaline
What are the effects of adrenaline and steriod hormones (e.g. cortisol)?
-Increased heart rate (pump blood around body faster)
-Muscles around bronchioles relax (breathing is deeper)
-Increased glycogenolysis (more glucose availble for respiration)
-Erector pili muscles contract (make animal look bigger)
-Muscle in the arterioles supllying the skin and gut constrict
-Muscle in the arterioles supplying lungs and skeletal muscles dilate
Where is the cardiovascular control centre located?
Medulla Oblongata
What are the two types of receptors involved in controlling heart rate?
-Baroreceptors (pressure receptors)
-Chemoreceptors (chemical receptors).
Where are baroreceptors and chemoreceptors located?
In the aortic and carotid bodies
What do baroreceptors detect?
Changes in blood pressure.
What do chemoreceptors detect?
Oxygen & Carbon dioxide concentration
pH of the blood
How does the cardiovascular control center respond to high/low blood pressure or oxygen levels?
High: activates the parasympathetic NS, secretes acetylcholine & decreases frequency of waves of excitation from SAN
Low: activates the Sympathetic NS, secretes noradrenaline & increases frequency of waves of excitation from SAN.
Describe the pathway of the response to high blood pressure.
- Baroreceptors detect high blood pressure
- Impulses are sent to the medulla oblongata, which sends impulses along the Vagus nerve.
- This actvates the parasympathetic NS and secretes acetylcholine, which binds to receptors on the SAN
- The frequency of the waves of excitations from the SAN is reduced
- Heart rate slows to return to normal bp
Describe the pathway of low blood pressure.
- Baroreceptors detect low blood pressure
- Impulses are sent to the medulla oblongata, which send impulses along the Accelerator nerve
- This activate the sympathetic nervous system, causing the secretion of noradrenaline that binds to receptors on the SAN
- Increases the frequency of waves of excitation from the SAN
- Heart rate speeds up to increase blood pressure to normal.
Describe the pathway of response to high blood O₂/CO₂ or high blood pH
- Chemoreceptors detect chemical changes in the blood
- Impulses are sent to the medulla oblongata, which send impulses along the Vagus nerve.
- This activates the parasympathetic NS & secretes acetylcholine, which binds to receptors on the SAN.
4.Decrease frequency of waves of excitation from SAN - Heart rate increases to return chemical levels to normal.
What is the purpose of the Student’s t-test?
To determine whether the means of two sets of data are significantly different.
What is the null hypothesis in a t-test?
That there is no significant difference between the means of the two groups.
When should you reject the null hypothesis?
The t value is greater than the critical value
The difference between the means is statistically different
What does a probability of 0.05 (5%) mean in a t-test?
There is a less than 5% chance that the difference between the two means is due to chance.
