Topic 7 - Animal Coordination, Control and Homeostasis

this one was mad to say the least

endocrine system

made up of endocrine glands that produce and release hormones into the blood stream

endocrine vs nervous system: way of transmission

endocrine is via hormones

nervous is via neurones

endocrine vs nervous system: speed of transmission

nervous is very rapid

endocrine is much slower

endocrine vs nervous system: response

endocrine is slow

nervous is rapid

endocrine vs nervous system: area of response

nervous is more localised

endocrine is widespread

endocrine vs nervous system: passage of transmission

nervous - via neurones

endocrine - via bloodstream

endocrine vs nervous system: length of time of response

endocrine - much longer

nervous - much shorter

gland

a group of cells that produces and releases one or more substances(known as secretion)

pituitary gland

a ‘master gland‘

makes hormones such as FSH and LH

thyroid gland

produces thyroxine

guys thyroidmax

pancreas

produces insulin which maintains blood glucose levels

adrenal glands

produces adrenaline

testes(males)

produces testosterone

don’t touch the receipts

ovaries(females)

produce oestrogen

hormone

a chemical substance produced by a gland

What do hormones generally do?

Transmit info from one part of the organism to another and brings about a change by providing a signal that triggers a response

What does negative feedback do?

ensures that in any controlled system changes are reversed and returned back to the set, optimal narrow level

What does thyroxine do?

Stimulates the basal metabolic rate(BMR) - the speed at which chemical reactions occur in the body when it is at rest

What happens if thyroxine level is normal/too high?

TRH(thyroxine releasing hormone) is inhibited in the hypothalamus

TSH(thyroxine stimulating hormone) is inhibited in the pituitary gland

so less thyroxine is released from the thyroid gland

What happens if thyroxine level is below normal levels?

TRH is released in the hypothalamus

This increases the release of TSH from the pituitary gland

TSH stimulates the thyroid to release more thyroxine

What is hyperthyroidism?

A condition caused by an overactive thyroid gland secreting too much BMR into the bloodstream which causes a BMR increase and protein synthesis increase

hypothalamus

a small portion of the brain which is responsible for homeostasis of hunger temperature and hormones

What is hypothyroidism?

Caused by an underactive thyroid gland

As such the gland secretes less thyroxine

causes a BMR and protein synthesis decrease

Symptoms of hyperthyroidism

weight loss

heat sensitivity

abnormally fast HR

Symptoms of hypothyroidism

Weight gain

cold sensitivity

tiredness

in extreme cases can lead to heart and nerve problems and death

When is adrenaline normally produced?

In situations where the body may be in danger

What do the effects of adrenaline aim to do?

Prepare it for movement#

i.e. fight or flight

Adrenaline effects on the body

Increased HR

Increased breathing rate

Increased BP

Diverting blood flow to muscles

Dilation of pupils

Increased blood glucose conc.

Effect of adrenaline(and why) on HR/BP and BR

Increased to allow for more O2 for more respiration for more energy and more Co2 to be taken away from muscle cells more quickly

Effect of adrenaline(and why) on blood glucose concentration

increased for more respiration

Effect of adrenaline(and why) on directing of blood flow

diverted towards muscles and away from non essential body parts by narrowing their blood vessel diameters to ensure respiration reactants are as available as possible

Effect of adrenaline(and why) on lumen of vessels

increased

to allow for more bp

increased resp.

Effect of adrenaline(and why) on pupil

becomes dilated

allows as much light as possible to reach retina so more info can be sent to the brain

stages of the menstrual cycle

menstruation

lining thickens

ovulation

lining maintained

When does ovulation occur within the menstrual cycles stage

around the middle

about day 14

How often does ovulation/menstrual cycle repeat?

every 28 days

What are the 4 hormones of the menstrual cycle?

FSH

LH

oestrogen

progesteron

What does FSH(Follicle Stimulating Hormone) do?

causes the maturation of follicles in the ovary

What does LH(Luteinising Hormone) do?

Causes the ovulation/release and development of the corpus luteum

What is the corpus luteum?

An empty egg follicle

What does progesterone do?

maintains uterus lining

What does oestrogen do?

develops secondary sexual characteristics in females

repairs the uterus lining

Where are progesterone and oestrogen produced?

ovary

Where are FSH and LH produced?

pituitary gland

What happens first in the menstrual cycle(hormones)?

Pituitary gland produces FSH which matures the follicle in ovary

What happens to oestrogen due to the effects of FSH?

It is stimulated.

What happens after oestrogen is stimulated?

Repairs the uterus lining

inhibits the production of FSH

What happens to oestrogen when it reaches a high enough amount?

Stimulates the release of LH which causes ovulation around the 14 day mark.

What happens after ovulation?

The follicle becomes a corpus luteum.

LH stimulates the production of progesterone

What does progesterone do to FSH production?

inhibits it

What does progesterone do to LH production?

inhibits it

What happens if the egg is not fertilised?

Corpus luteum breaks down

progesterone levels drop

menstruation/period occurs

What happens if the egg is fertilised?

the corpus luteum continues to produce progesterone

as such the uterus lining is maintained

FSH levels are inhibited to prevent further follicle production

What happens when the placenta develops?

It starts secreting progesterone.

Continues to do so throughout the pregnancy to maintain lining

What happens to oestrogen levels from day 1 to 14?

Rise to peak just before day 14, the peak is just before the egg is released

What happens to progesterone levels from day 1 to 14 and after?

Stays low from day 1 to 14, and rises after it

natural forms of contraception

abstinence from sex

rhythm method

What is the rhythm method and why is it unreliable?

Avoids sexual intercourse during the fertile period of the menstrual cycle when ovulation occurs

worked out by measuring body temp and cervical mucus quality

unreliable as it can be inaccurate

chemical forms of contraception

contraceptive pill

IUD

How it works: pill

The hormones prevent ovulation - no egg is available to be fertilised

the hormone is often progesterone or a mix of it and oestrogen

Advantages of pill

high success rate

works automatically

Disadvantages of pill

prescription needed/GP visit

doesn’t prevent STI transmission

How it works: IUD(Intrauterine copper coil)

releases hormones that thicken cervix mucus making it difficult for sperm to swim into the uterus

also acts as a barrier method

often used with spermicide

Advantages of IUD

high success rate

works automatically

Disadvantages of IUD

prescription needed/GP visit

doesn’t prevent STI spread

Physical contraception methods

condom

diaphragm/cap

How it works: condom

letex sheath over penis

prevents sperm entering the vagina

Adv. of condom

cheap

easy to use

prevents STI spread

readily available

Dis. of condom

frequently used incorrectly

How it works: diaphragm/cap

stops sperm from entering cervix

worn by a woman

Advantages of diaphragm/cap

cheap

more readily available

Disadvantages of diaphragm/cap

doesn’t prevent STI transmission

lower success rate

infertility

when a couple can’t get pregnant despite having unprotected sex

Reasons for Infertility

thyroid problems

premature ovarian failure

surgery scarring

sperm side effects

poor quality of semen

testicular damage

low test levels - less sperm produced

What is the usual reason why some females may not produce enough egg/not on a regular basis?

As a result of the pituitary gland not producing sufficient FSH to stimulate egg maturation

What does clomifene do?

It causes more of the hormones FSH and LH to be released, which obviously stimulate more egg follicle maturations as well as more corpus luteum development

downsides of clomifene therapy

several eggs can be released which increases the chance of multiple births(twins, triplets, etc)

can be expensive

doesn’t have a particularly high success rate

Process of IVF

A drug is taken to suppress natural FSH and LH production(to ensure the woman has full control over her menstrual cycle)

A larger than normal dose of FSH is given to the mother every day for several days

A larger than normal LH dose is given to a woman.

The matured eggs of her is collected and fertilised by the father’s sperm in the lab

The mother is given progesterone

The sperm develop into embryos.

At this stage, one/two embryos are inserted into the mother’s uterus

Issues with IVF

high risk of multiple births, which increases the risk of stillbirth/miscarriage

low success rate(around 30%)

there is a concern about who handles the embryos and if they’re even used in research(an embryo is considered by some as a life)

genetic testing is controversial as it could be misused in choosing offspring characteristics

homeostasis

the maintenance of a constant internal environment

What does insulin do?

Stimulates cells to take in glucose from the bloodstream(particularly liver and muscle cells)

What happens to excess glucose in muscle and liver cells?

turned into glycogen, a polymer of glucose, for storage

What cells secrete glucagon?

alpha cells in the pancreas

What cells secrete insulin?

beta cells in the pancreas

How does negative feedback respond to high blood glucose?

Beta cells in the pancreas detect the high blood glucose levels

These cells then secrete insulin.

Insulin causes the uptake of glucose by body cells, as well as the conversion of excess glucose to glycogen in muscle and liver cells

leading to less blood sugar levels

How does negative feedback respond to low blood glucose?

alpha cells in the pancreas detect the low levels

they secrete the hormone glucagon

this breaks down glycogen into glucose

resulting in increased blood sugar levels

glucagon vs glycogen

glycogen is a monosaccharide and the storage molecule of glucose

glucagon is the hormone that breaks down glycogen into glucose

What happens in type 1 diabetes?

the immune system destroys beta cells in the pancreas leaving the body unable to produce insulin

What happens in type 2 diabetes?

People with this still make insulin but it cannot be effectively used by the body cells. This is known as insulin resistance

How do people get type 1 diabetes?

genetically

How do people get type 2 diabetes?

poor diet such as sugar overconsumption

lack of exercise

poor lifestyle factors such as smoking

It CAN be reversible however

How to treat type 1 diabetes?

insulin injections

The timing of these depend on:

when you eat

level and timing of exercise and activity

Blood sugar monitoring is necessary

How to treat type 2 diabetes?

diet management(low carb)

regular exercise

reduce poor lifestyle factors

For severe type 2 diabetes, medicine can be given that reduces the amount of glucose in the blood and increases organ insulin sensitivity

Where and how is body temperature detected and controlled?

thermoreceptors in the hypothalamus

What happens if body temp is below 37?

shivering

hair stands upright

hands standing upright

reduction of blood flow near skin(vasoconstriction)

What happens if body temp is above 37?

sweating

increased blood flow near skin(vasodilation)

How does shivering work to increase body temp?

There is increased skeletal muscle contraction

This leads to increased respiration and more heat released

How does hairs standing up work to increase body temp?

traps air around the skin which is an excellent insulator

How do hands standing upright increase body temp?

Act as an insulating layer

reduces heat loss by radiation

How does sweating work to decrease body temp?

sweat evaporates

leading to decreased body heat