Flashcards in Animal Responses Deck (63)
Define the term “central nervous system”.
Consists of the brain and spinal cord.
Define the term “peripheral nervous system”.
Consists of all the neurones that connect the CNS to the rest of the body. These are the sensory neurones which carry nerve impulses from the receptors to the CNS, and the motor neurones which carry nerve impulses away from the CNS to the effector.
Define the term “somatic nervous system”.
Under conscious control, used when you voluntarily decide to do something i.e. moving a muscle in your arm.
Define the term “autonomic nervous system”.
Under subconscious control and happening all the time. It is involuntary - there is no decision making. I.e. heart beat, digesting food. Carries nerve impulses to glands and smooth muscle.
Define the term “sympathetic nervous system”.
A division of the autonomic nervous system. Initiates flight or fight response i.e. increased heart rate. Has noreadrenaline as a neurotransmitter.
Define the term “parasympathetic nervous system”.
A division of the autonomic nervous system. Initiates rest responses (Peace = Parasympathetic). Includes decreases in heart rating or breathing after exercise.
State 5 differences between the autonomic nervous system and the somatic nervous system.
1) Somatic is voluntary and autonomic is involuntary.
2) Autonomic controls things that are happening constantly, somatic is only sometimes.
3) Neurones in somatic nervous system are mostly myelinated, mostly unmyelinated in autonomic.
4) Somatic carries the impulse to skeletal muscles, autonomic carries the impulse to smooth, cardiac and glands.
5) In somatic, one neurone to connect CNS with effector. Autonomic, it is two neurones.
Define the term “antagonistic system” in relation to the sympathetic and parasympathetic nervous systems, and outline how they co-ordinate responses.
The parasympathetic and sympathetic nervous system have an antagonistic (opposing) effects on the organs they control.
The action of one system opposes the action of the other. Under normal conditions impulses are passing along the neurones of both systems at a relatively low rate. Changes to conditions lead to an altered balance between the two systems which leads to an appropriate response.
Draw a table to compare the structure and function of the sympathetic and parasympathetic nervous systems.
- PNS is most active in sleep and relaxation.
- SNS Is most active in times of stress.
- SNS neurones of a pathway are linked at a ganglion just outside the spinal (long post-gangleonic neurones and short pre-gangleonic neurones).
- PNS neurones of a pathway are linked at a ganglion within the target tissue (long pre-gangleonic neurones and short post-gangleonic neurones).
- SNS uses noreadrenaline as a neurotransmitter and PNS uses acetylcholine.
Label a diagram of the human brain showing the location of the cerebrum, cerebellum, medulla oblongata, hypothalamus and pituitary gland.
- Main top bit is the cerebrum.
- Skull surrounds the brain.
- The corpus callosum is located just underneath the cerebrum.
- Pituitary gland comes off the hypothalamus, and they are both under the corpus callosum.
- Hypothalamus comes off the medulla oblongata.
- The cerebullum is leafy structure which is connected to the spinal cord.
Describe the structure of the cerebrum.
- Highly convoluted which increases its surface area considerably and therefore its capacity for complex activity.
- Its split into left and right halves known as cerebral hemispheres. Each hemisphere controls one half of the body and has discrete areas which perform specific functions.
- The outer layer of the cerebral hemispheres is known as the cerebral cortex.
- It has six areas; the frontal lobe, parietal lobe, occipital lobe, the temporal lobe, medulla oblongata and cerebellum.
Describe the role of sensory areas, association areas and motor areas of the cerebral cortex.
1) Sensory areas - receives information from receptor cells located in the sense organs. The size of the sensory area allocated is in proportion to the number of receptors cells present in the body part.
2) Association areas - Info passed on from sensory areas to be analysed and acted upon
3) Motor areas - Impulses come into motor areas where motor neurones send out impulses e.g. to move skeletal muscles. Size of motor area in proportion to the number of the motor endings present.
Describe the role of the cerebellum in coordinated muscular movement.
Controls unconscious functions such as muscular movement, posture, balance and non-voluntary movement. It does not initiate movement but co-ordinates. Cerebellum receives information from the organs of balance in the ears and information about the tone of muscles and tendons. Then relays this information to motor areas.
Describe the structure, location and role of the pituitary gland.
- Found at the base of the hypothalamus.
- Controls most of the glands in the body.
- Divided into the anterior pituitary and the posterior pituitary.
- Anterior pituitary produces 6 hormones, including one which is involved in reproduction and growth.
- Posterior pituitary stores and releases hormones produced by the hypothalamus, such as ADH.
Describe the roles of medulla oblongata.
- Contains many important regulatory centres of the autonomic nervous system.
- These control reflex activities such as ventilation, heart rate and peristalsis.
Describe the roles of the hypothalamus.
- Main controlling region of the autonomic nervous system.
- Has two centres, one for the sympathetic and the parasympathetic.
- Controls patterns of behaviour such as feeding, sleeping and aggression.
- Monitoring the composition of blood plasma, such as concentration of water and blood glucose therefore it has a very rich blood supply.
- Producing hormones because it is an endocrine gland.
Define the term “reflex action”.
Involuntary response to a sensory stimulus.
Define the term “reflex arc".
The pathway of neurones involved in the reflex action.
Define the term “stimulus".
A detectable change in the internal or external environment.
Define the term “receptor”.
Extrinsic glycoproteins that binds to chemical, triggering a response by the cell.
Define the term “effector”.
Muscle or gland which carries out body's response to a stimulus.
Define the term “response”.
The way a body reacts to a stimulus.
Draw, label and annotate a diagram to show the arrangement of neurones in the “withdrawal of the hand from a heat stimulus” reflex arc and the actions that occur in the stimulus-response pathway.
1) Stimulus heat from candle flame.
2) Thermoreceptor in skin detects heat.
3) Sensory neurone passes nerve impulse to spinal cord.
4) Relay neurone passes impulses across the spinal cord.
5) Motor neurone passes impulses to the muscle.
6) Effector contracts.
7) Response hand is moved quickly away from flame.
Describe the characteristics of reflex actions and the survival value of them.
- Reflexes avoid the body being harmed or reduce the severity of any damage.
- Involuntary responses, the decision-making regions of the brain are not involved, therefore the brain is able to deal with more complex responses. It prevents the brain from being overloaded.
- Reflexes do not have to be learnt, they are present from birth to death and therefore provide immediate protection.
- Extremely fast, the reflex arc is very short. It normally only involves one or two synapses, which are the slowest part of nervous transmission.
Draw, label and annotate a diagram to show the arrangement of neurones in the “knee jerk” reflex arc and the actions that occur in the stimulus-response pathway.
1) Stimulus is when the leg tapped just below the knee cap, it stretched the patellar tendon.
2) Stimulus initiates a reflex arc which causes the extensor muscle on top of the thigh to contract. At the same time, a relay neurone inhibits the motor neurone of the flexor muscle, causing it to relax.
3) This contraction co-ordinated with the relaxation of the antagonistic flexor hamstring muscle causes leg to kick.
Explain the “survival value” of the knee jerk reflex.
- Helps maintain posture and balance.
- Lack of the reflex will indicate nervous problems and the multiple oscillation of the leg may be a sign of a cerebellar disease.
Draw, label and annotate a diagram to show the arrangement of neurones in the “corneal blinking” reflex arc and the actions that occur in the stimulus-response pathway.
1) Stimulus can be corneal irritation like a foreign body entering the eye, a loud sound more 40-60 dB or as a results of a very bright light. Reflex occurs in the brain, not spinal cord, so it is a cranial reflex.
2) Impulse triggered by stimulus and travels along the sensory neurone.
3) The impulse then passes through a relay neurone in the lower brain stem.
4) Impulses are then sent along branches of the motor neurone to initiate a motor response to close the eyelids.
5) The reflex initiated a consensual response - this means that both eyes are closed at the same time.
Describe other stimuli that can trigger the blinking reflex and describe the response that occurs.
1) Bright light = optical reflex. Causes iris to contract, limiting amount of light that can enter the eye, protecting retina from damage.
2) Foreign body enters eye/ loud sound = corneal reflex.
Explain the “survival value” of the blinking reflex.
- Presence of reflex indicates that lower brain stem is functioning.
- Presence or absence of reflex is used to determine wether a patient is brain dead.
- Protects retina from damage.