Flashcards in 6.5-6 Deck (68)
What 2 parts does the nervous system consist of?
The central nervous system and peripheral nerves
What are the different parts of the central nervous system?
Brain and spinal cord
What are the 2 branches off the peripheral nervous system?
Motor neurones and sensory neurones
What are the two branches off motor neurones?
The automatic nervous system and the somatic nervous system
What are the different parts of the automatic nervous system?
Sympathetic nervous system and parasympathetic nervous system
What nerves do the automatic nervous system include?
Nerves from internal receptors and nerves attached to smooth muscle
What nerves do the somatic nervous system include?
Motor neurones attached to the skeletal muscles and sensory neurones attached to the receptor sense organs
What do dendrites do?
Receive electrical impulses from other neurones
What is the myelin sheath?
A layer of schwann cells wrapped around the axon for insulation
What happens in the node of ranvier?
It is where the nerves pass through
What does a Schwann cell do?
It insulates the axon, making nerve impulses faster
What is the order of movement of a nerve impulse in a reaction?
Stimuli- receptor- sensory nerve- relay nerve- motor neuron- effector- response
What is resting potential?
When there is an electrical potential across a cell membrane when not conducting an impulse. ( -70mV)
What is action potential?
The localised depolarisation and then repolarisation if electrical potential between the inside and outside of a neurones as the impulse moves along it
What happens at resting potential in a neurone?
Na+ and K+ ion channels are closed
What happens at depolarisation in a neurone?
Na+ voltage channels opens, sodium flooding into the cytosol causing the voltage to rise
What happens at the rising phase of action potential?
More sodium channels open once the voltage reaches -55mV and Na+ floods into neurones
What happens at the falling phase of action potential?
Na+ channels close and K+ channels open and rush outside to reverse concentrations- this begins to reduce the voltage
What happens at hyperpolarisation?
The sodium channels open and the sodium returns to the outside of the neurone, making the inside overall negative, reducing the voltage. Then potassium channels and potassium returns to the inside of the neurone at resting potential
Why must ion pumps used to create action potential use active transport?
As they are moving ions against the concentration gradient
What voltage is action potential?
What is a synapse?
The junction between 2 neurones
What is the synaptic cleft?
The fluid filled space between the axon terminal and end of a dendrite. It is the location of communication between neurones and glands or muscles
What are the stages as a chemical signal crosses a synapse?
1. Nerve impulses pass electrical or chemical signals to their target cells
2. When an action potential reaches the end of a neurone, the Ca+ ion channels open to allow Ca+ to flow in, which causes exocytosis of a neurotransmitter.
3. Neurotransmitter diffuses across the synaptic cleft and then binds to a post-synaptic receptor.
4.The post synaptic membrane becomes polarised, causing the Na+ ion channels to open.
5.An action potential is created in the post synaptic neurone. The post synaptic membrane then becomes depolarised.
6.The K+ ion channels open to cause hyper polarisation of the post-synaptic membrane
7. An enzyme binds to the neurotransmitter to hydrolyse it and prevent future function.
How do neonicotinoid pesticides work and what are the consequences of them?
Artificially made pesticides that block the post- synaptic membrane used for breaking down acetylcholine and fit into the binding site of the post- synaptic neurotransmitter receptor so acetylcholine can’t bind. It prevents action potential in the post synaptic neurone and leads to paralysis and death of bees, reducing pollination and biodiversity of plants
What is the endocrine system?
The hormone system, that consists of glands that release hormones to our cells.
How to hormones travel?
They circulate through the bloodstream from glands
Where is homeostasis maintained?
What is homeostasis?
The maintenance of a constant internal environment
What does the hypothalamus do?
It sends signals to the pituitary gland in the form of hormones, which then sends hormones into the bloodstream to the target gland
How does the body lower temperature?
- decreased metabolism
- skin arterioles increase in diameter
- relaxed skeletal muscles
How does the body rise temperature?
- vasoconstriction to lower blood flow to the skin to decrease heat loss
- increases metabolism
What does the oviduct do?
It collects eggs at ovulation, provides a site for fertilisation and then moves the embryo to the uterus
What does the uterus do?
Provides for the embryo
What does the ovary do?
Produces eggs, oestrogen and progesterone
What does the vulva do?
Protects internal parts of the reproductive system
What does the cervix do?
Protects foetus during pregnancy and dilates to form birth canal
What does the vagina do?
Simulates penis to cause ejaculation
What does the sperm duct do?
Transfers sperm during ejaculation
What do the seminal vesicle and prostate gland do?
Secrets fluid containing alkali, protein and microbes to make semen from sperm
What does the epididymis do?
Stores sperm until ejaculation
What does the scrotum do?
Holds testes at lower than core body temperature
What does the testis do?
Produces sperm and testosterone
What does the uretha do?
Transfers semen during ejaculation and urine during urination
What is a gonad?
Genderless embryo in the first 8 weeks of pregnancy
How does an embryo become male?
Testosterone is developed after 8 weeks which masks the maternal oestrogen and progesterone and forms SRY gene, which codes TDF which makes testes
How are female genes produces?
Maternal oestrogen and progesterone cause female reproductive organs to develop, so gonads develop into ovaries without SRY gene
When and where is FSH released?
Days 5-13 from the pituitary gland
What does FSH do?
Stimulates the maturation of a follicle in the ovary. Also stimulates secretion of oestrogen
When and where is LH produced?
Day 14 for ovulation in the pituitary gland
What does LH do?
It causes ovulation and the development of the corpus luteum, which produces progesterone and reduces oestrogen
When and where is oestrogen produced?
Released during days 5-13 in the ovaries
What does oestrogen do?
It stimulates release of LH and caused the repair of the uterus
When and where is progesterone produced?
On days 14-20 in the ovaries, released from the corpus luteum
What does progesterone do?
It causes the wall of the uterus to thicken and it increases bloody supply, ready for the implantation of a fertilised ovum. It inhibits the production of FSH so that no more follicles will mature in the ovaries, as well as reducing oxygen concentration. It inhibits LH and activity of the corpus luteum.
What is the corpus luteum?
The remnants of the follicle after ovulation has occurred
What happens in the follicular phase?
- FSH from pituitary gland leads to growth of ovarian follicles
- oestrogen is produced from the follicle, inhibiting FSH
- oestrogen thickens uterus wall
What happens in ovulation?
- oestrogen stimulates secretion of LH
- LH causes the follicle to rupture and release the egg
What happens in the luteal phase?
- ruptured follicle develops into corpus luteum
- corpus luteum secretes progesterone
- progesterone and oestrogen thickens uterus lining in preparation for pregnancy
What happens in menstruation?
- pregnancy- embryo implants in uterus and corpus luteum is sustained
- no pregnancy- corpus luteum degenerates- oestrogen and progesterone drop and the uterus wall breaks down
- uterus wall is eliminated as menstrual blood
What do sensory neurons do?
Carry from receptors to central nervous system
What do relay neurons do?
Carry from sensory neuron to motor neuron
What do motor neurons do?
How is blood glucose regulated?
There are reserves of glucose in cells as glycogen. If there is excess glucose detected in pancreas, islets of langerhaus release beta cells which stimulate insulin to control uptake of glucose to body cells. If glucose levels low, alpha cells secrete glucagon which coverts glucagon to glucose and reduces the rate of respiration.
What hormone controls temperature and how?
Thyroxin- stimulates oxygen consumption and increases basal metabolic rate of organs
What hormone controls appetite?
How does leptin work?
It is regulated by the hypothalamus and is secreted by adipose tissue. If one overeats, fat cells fill with lipids- as they fill up, more leptin is secreted to suppress hunger