6.5-6 Flashcards Preview

Biology COPY > 6.5-6 > Flashcards

Flashcards in 6.5-6 Deck (68)
Loading flashcards...

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?

The hypothalamus


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
- sweating
- lethargy
- 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
- goosebumps


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?

Stimulate effectors


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


What are circadian rhythms?

24 hour human behaviour cycles controlled by melatonin from the pineal gland