multicellular organisms Flashcards
what are stems cells?
stem cells are unspecialised animal cells which can divide to self renew or divide into different types of specialised cells
essential for growth and repair
what are the two sources of stem cells?
embryonic stem cells are obtained from very early stage embryos
tissue stem cells are found in the body throughout life
how are new cells produced?
mitosis/ cell division. provides new cells for growth and repair of damaged cells
what are replicated chromosomes called?
chromatids
stages of mitosis:
chromosomes become visible and replicate
identical copies now shorten and thicken into chromatids
Chromatids line up along the equator and the spindle fibres attach
spindle fibres shorten pulling the chromatids to opposite poles
nuclear membrane forms around each set of chromosomes
cytoplasm divides and the cells spits into two identical daughter cells containing the same amount of chromosomes, same chromosome compliment
what is the function of a tail on a sperm cell?
allows movement to swim to the egg
what does the nervous system consist of?
central nervous system and other nerves
what is the CNS composed of?
the brain and spinal cord
what does the cerebrum do?
controls memory and emotions
what does the cerebellum do?
controls balance and movement
what does the medulla do?
controls heart rate and breathing rate
what does the sensory neuron do?
passes information from sensory receptors to the CNS. Receptors are located in the sense organs.
what is the function of the inter neuron?
located in the CNS, they process information coming from sensory neurons and pass on information to motor neurons
what is the function of the motor neuron?
passes information from the CNS to the effectors. Effectors could be muscles or glands that enable a response
what is an effector?
An effector is part of the body that produces the response.
either rapid responses in muscles or slow responses in glands
what are synapses?
electrical impulses carry messages along neurons. Neurons are separated by gaps called synapses
what happens at the synapse?
chemicals are released which transfer these messages between neurons
what are reflex actions?
reflex occur to protect the body from harm. The circuit of the neurons that act to produce a reflex are called a reflex arc
explain the neural pathway.
hand touches a hot plate and the high temperature stimulates a pain receptor in the skin
An electrical impulse is transmitted from the sensory receptor along the sensory neuron
the electrical impulses reach the end of the sensory neuron. Chemical messengers are released across the synapse and trigger an electrical impulse in the inter neuron
the electrical impulse travels to the end of the inter neuron. chemical messengers are released across the synapse and trigger an electrical impulse in the motor neuron
the electrical impulse is transmitted along the motor neuron. it reaches the end of the motor neuron and chemicals are released across the synapse to the muscle.
this causes the muscle to contract and the hand pulls away from the hot object
what are hormones?
chemical messengers which travel through the bloodstream.
where are hormones released?
endocrine glands
explain how hormones travel
hormones are released from an organ in the endocrine system
hormones travel through bloodstream
target tissue has a complimentary receptor for a specific hormone
explain blood glucose control.
after a meal, blood glucose increases, the pancreas then detects this change and releases glucagon, the liver then converts glucose into glucagon. when it’s time to eat again the blood glucose decreases
nervous control
type of message:
speed:
length:
type of transmission:
body system:
electrical
rapid
short
neurons
nervous
