Nerves and Hormones (B1) Flashcards
How does the nervous system allow us to coordinate movement?
very voluntary movement that a person performs is under the direct control of the nervous system as the nervous system sends the messages to the particular body parts to move. If the movement has been repeated numerous times (walking for most of us…) the movement will be very efficient.
What is a reflex arc?
The nerve pathway involved in a reflex action, including at its simplest a sensory nerve and a motor nerve with a synapse between.
What are reflexes for?
A reflex is an involuntary or automatic action that your body does in response to something — without you even having to think about it. You don’t decide to kick your leg, it just kicks. There are many types of reflexes and every healthy person has them.
What is the difference between hormonal and nervous control?
The biggest difference between the two is that the nervous system uses electrical impulses to send signals through neurons, whereas the hormonal system uses chemical messengers transported into blood plasma to target cells. … This means that communication is faster when using the nervous system.
What is homeostasis? 3 examples.
The tendency towards a relatively stable equilibrium between interdependent elements, especially as maintained by physiological processes.
Two examples of things that the body keeps the same are:
body temperature at 37°C
the amount of water inside our body
How do synapses work?
This triggers the nerve-ending of a neuron to release chemical messengers called neurotransmitters. These chemicals diffuse across the synapse (the gap) and bind with receptor molecules on the membrane of the next neuron.
How do hormones control the menstrual cycle?
Follicle stimulating hormone, FSH:
The hormone FSH is secreted by the pituitary gland. FSH makes two things happen:
it causes an egg to mature in an ovary
it stimulates the ovaries to release the hormone oestrogen.
Oestrogen:
The hormone oestrogen is secreted by the ovaries. Oestrogen makes two things happen:
it stops FSH being produced - so that only one egg matures in a cycle
it stimulates the pituitary gland to release luteinizing hormone (LH), which triggers ovulation (the release of the mature egg from the ovary).
This diagram shows how the level of oestrogen changes during the menstrual cycle.
How can hormones control fertility?
Menstrual cycle:
The menstrual cycle in women is a recurring process in which the lining of the uterus is prepared for pregnancy. If pregnancy does not happen, the lining is shed at menstruation.
Several hormones control this cycle:
Oestrogen, which causes the repair of the uterus wall
progesterone, which maintains the uterus wall
Both hormones are secreted by the ovaries. The image below shows how the levels of oestrogen and progesterone change during the menstrual cycle. If a woman becomes pregnant, the level of progesterone remains high.
What are the main stages involved in IVF treatment?
Step one: suppressing the natural menstrual cycle
Step two: boosting the egg supply
Step three: checking progress
Step four: collecting the eggs
Step five: fertilising the eggs
Step six: embryo transfer
How do plant hormones work?
Plants produce hormones and respond to external stimuli, growing towards sources of water and light, which they need to survive. A tropism is a growth in response to a stimulus and an auxin is a plant hormone produced in the stem tips and roots, which controls the direction of growth.
What are the commercial uses of plant hormones?
The selective weedkiller contains growth hormone that causes the weeds to grow too quickly. The weedkiller is absorbed in larger quantities by the weeds than the beneficial plants.
Rooting powder makes stem cuttings quickly develop roots. Rooting powder contains growth hormones.
Some hormones slow the ripening of fruits and others speed it up. These hormones and their inhibitors are useful for delaying ripening during transport or when fruit is displayed in shops.
Dormancy stops seeds germinating until conditions are ideal for growth. Hormones can be used to remove the dormancy of a seed so it can germinate at all times of year.
