SB7: Animal Coordination, Control and Homeostasis

What does the hormonal system do?

endocrine system has glands which secrete hormones as chemical messengers to cause long term change in body

What is a target organ

A target organ is a specific organ or tissue in the body that is affected by a particular hormone that has specific receptors to produce a response.

What hormone does the adrenal gland secrete and what is it used for?

* on kidneys
* secretes adrenaline for flight or fight response when “scared”


* increases heart rate
* increases blood pressure
* increases blood flow to muscles
* increases blood glucose levels by stimulating conversion from glycogen to glucose

What hormone do the testes gland secrete and what is it used for?

* testosterone-controls puberty
* producing gametes (sperm)

What does oestrogen for? What gland is it produced in?

oestrogen- effects menstrual cycle and puberty

* holds gametes

What is the pituitary gland?

“MASTER GLAND”-tells other glands what to do

What is the thyroid gland?

* neck
* secretes thyroxine


* regulate metabolic rate
* growth and development

What are the differences between the nervous system and the endocrine system?

* endocrine system = hormones
* nervous systems = electrical impulses
* the nervous system is faster than the endocrine system
* endocrine system has long term effects

What hormone do pancreas secrete and what is it used for?

secretes

What is puberty

adolescents develops secondary sexual characteristics like facial hair triggered by reproductive hormones (testosterone and estrogen)

What are the 4 stages of the menstrual cycle?

28 days!

Where are eggs kept?

From an ovary

What happens to an egg after ovulation if fertilised?

If this egg is fertilised and embeds itself in the thickened lining of the uterus, the lining is maintained and the woman becomes pregnant.

What happens to an egg after ovulation if not fertilised?

If the egg has not been fertilised, the corpus luteum dies and progesterone levels drop. This causes menstruation, where the uterus lining breaks down - this is known as having a period.

What happens to the uterus lining when an egg is fertilised

When an egg is fertilized, it implants into the thickened uterus lining, then the lining is maintained by progesterone to prevent it from shedding. This allows the fertilized egg to continue developing into an embryo and eventually a fetus.

What is this a graph of?

Thickness of the uterus lining

What is the first stage of the menstrual cycle (DAY 1-DAY 4)?

This is menstruation. Usually when bleeding occurs and uterus lining breaks down.

What is the secondstage of the menstrual cycle (DAY 4-14)?

This is when the lining builds up again. Uterus lining becomes a “thick spongy layer”. This prepares the uterus for a fertilised egg in stage 3.

What is the third stage of the menstrual cycle? (day 14)

This is ovulation. This happens in one single day and an egg is released from the ovaries.

What is the fourth stage of the menstrual cycle? (day 15-28)

This involves maintaining the uterus lining. If no egg is fertilised, the uterus lining will break down within the cycle that repeats. If the egg is fertilised, the egg will implant into the uterus lining. The cycle won’t start again if it is fertilised.

What is the dark blue line?

Oestrogen- stimulates the uterus lining to grow. The line rises in stage 2 as the uterus develops and falls when the lining grows

What is the light blue line?

Progestorne- increases in stage 4 and maintains lining of uterus. If lining breaks down progestorne decreases

What is the orange line?

FSH-Produced in the pituitary gland. FSH makes egg mature in ovaries

What is the pink line?

LH-Produced in the pituitary gland. LH causes the egg to be released

How are FSH and Oestrogen related?

* when FSH causes a follicle to mature the levels of FSH increases causing an increase in oestrogen to build up the lining fo the uterus.
* When oestrogen increases it will inhibit FSH

What is the FSH and oestrogen relationship an example of?

Negative feedback

What does increases oestrogen trigger?

* oestrogen increasing causes a spike in LH
* LH increase results in ovulation
* this causes an increase in progesterone

What relationship does progesterone have with FSH and LH

When progesterone increases it will inhibit FSH and LH.

What is contraception?

A method to prevent pregnancy

* hormonal methods
* barrier method

What does the combined oral contraceptive pill do?

Releasing Oestrogen- This inhibits FSH. FSH is required to stimulate egg development so eggs won't mature or be released.

Releasing Progesterone- This inhibits LH and FSH. So an egg cannot be released and ovulation is stopped.

Progesterone also releases a thick mucus preventing sperm from fertilizing the egg

What are other hormonal methods?

* contraceptive patch
* contraceptive implant-most permanent
* contraceptive injection
* IUD-placed in the uterus and releases progesterone (plastic) or prevents sperm fertilising eggs (copper)

Define the purpose of a non homronal contraceptive methods

Prevent sperm from meeting egg. Acts as a physical barrier

Why are non-hormonal contraceptives important?

The physical barrier can be used to prevent STI/STD.

What are other non-hormonal contraceptives methods?

* diaghram
* femdom
* sterilization

What pills are administered to increase fertility?

FSH hormone in pill

LH hormone in pill

IVF (In-vitro fertilisation)

* Women are given FSH and LH to mature eggs and increase ovulation
* Eggs are collected from women’s ovaries and then fertilised by sperm from a man.
* They will then develop ot embryos
* Then inserted into mothers uterus
* external to the human body

Homeostasis

the regulation of conditions within the body to maintain a stable internal environment to respond to external and internal changes.

Automatic control systems (Loop of negative feedback)

Comprised of receptors, coordination centres and effectors (muscles that contract or glands for hormones). Since these may be in different parts of the body electrical impulses can be used to transport signals between them(quick). Endocrine system releases chemicals into bloodstream (slow but longterm)

Negative Feedback

Whenever the level of something is too high, negative feedback will “inhibit” the production of this so it will be higher. (It does the opposite of whatever the change is)

Blood glucose concentration

* sugar within blood
* important so that glucose can always be used by cells for respiration
* if it is too high it can damage tissues

glycogen

Long term storage glucose

glucagon

Secreted by the pancreas when glucose levels are too low to convert glycogen to glucose

insulin

Secreted by the pancreas when glucose levels are too high to convert glucose to glycogen.

How does the body combat a spike in glucose levels?

1. Pancreas detect increased glucose
2. Secrete insulin in response and this binds to receptors on the cells (in liver).
3. The insulin causes the cells to take up the glucose and convert this to glycogen.
4. Glucose levels will decrease

How does the body combat a decresae in glucose levels?

1. Pancreas detect decreased glucose
2. Secretes glucagon and this binds to receptors in liver cells
3. The insulin would take the glycogen and convert it back to glucose
4. This increases glucose concentration in the blood so more cells have glucose for respiration

What problem does diabetes cause?

People with diabetes won’t be able to regulate their blood glucose levels as the pancreas produce low levels or no insulin.

Type 1 Diabetes

* occurs early in life
* Pancreas stops producing insulin or low levels of insulin
* This means blood glucose can become extremely high

\
MAIN SOLUTION: inject glucose into abdomen based on exercise done and amount of carbohydrates eaten

Type 2 Diabetes

* occurs to older people with unhealthy diets
* cells grow resistant to insulin
* No longer respond to insulin so cells dont take in glucose from bloodstream
* this means insulin as a treatment wont help

\
MAIN SOLUTION: healthy low sugar diet and regular excercise

Thermoregulation

Regulation of the internal body temperature (achieves homeostasis)

37 degrees

Why does the body need to be kept at 37 degrees?

this is the optimum temperature for our body’s enzymes to function and react

BELOW THIS TEMP: react much slower

ABOVE THIS TEMP: may denature and no longer collide successfully

What does hypothalymus do?

“body thermostat”

* paired with effectors in skin to detect change


* the brain can detect wether we are too warm or cold overall
* signals are sent out to reverse whatever the external condition is

TOO WARM UP

1. vasoconstriction
2. shivering

Vasoconstriction

* constrict blood vessels near surface of skin
* this causes less blood to flow near surface and less heat energy is lost towards the surroundings

What do erector muscles do to warm up body?

* contract erector muscles to make hairs stand up
* this creates an insulating layer of air so less heat energy is lost

How does shivering warm up the body?

* muscles contract automatically
* muscle contraction requires lots of energy from respiration
* results in lots of heat energy being released as waste to warm body

Vasodilation

* widens blood vessels near surface of skin
* this causes more blood to flow near surface and more heat energy is lost towards the surroundings

How does sweating cool body?

When sweat evaporates heat energy is taken with our body so that heat is lost and we are left cooler

What happens to erector muscles to cool down body?

The hair erector muscles in the skin **contract**, causing hairs to **stand on end.** This forms an insulating layer over the skin's surface by trapping air between the hairs and stops heat from being lost by **radiation**

Define Urea

excess amino acids that are no longer needed by the body are converted to fats and carbohydrates

How are some ions and water molecules lost?

sweating-ions and water

respiration-water

Why is water regulation important?

Cells can gain or lose water based on osmosis.

How does thyroxine control the metabolic rate?

LOW LEVELS OF THYROXINE:

* this stimulates production of TRH in the hypothalymus
* TRH causes the release of TSH from the pituitary gland
* TSH acts on thyroid to produce thyroxine

\
Normal levels of thyroxine will inhibit the production of TSH. This is negative feedback as limiting production of TSH makes level of thyroxines fall.

What is clomifene therapy?

Artificial hormones are used when the female is not producing enough eggs, or they are not producing them on regular basis. This is usually as a result of the pituitary gland not producing sufficient FSH to cause egg maturation. This clomifene drug produces more FSH and LH

What is the importance of homeostasis? (thermoregulation and osmoregulation)

THERMOREGULATION: if the body gets to above 37 degrees, this will cause enzymes to be less effective as they denature

OSMOREGULATION: if too much water enters cells they will burst as they swell. if blood is too concentrated then the cells will shrink.

BMI equation

BMI = mass (kg) (height (m))2

Explain how thermoregulation takes place, with reference to the function of the skin (the role of the dermis)

**Sweat glands** in the dermis release more sweat onto the surface of the epidermis. The sweat evaporates, transferring heat energy from the skin to the environment

Explain how thermoregulation takes place, with reference to the function of the skin (the role of the hypothalymus)

This has receptors that receive impulses from EPIDERMIS + DERMIS skin receptors that provide information about the external temperature.If the hypothalamus detects temperature change, a response occurs.

What is the purpose of the kidneys?

To filter the blood and remove all waste products, the main one is urea.

The kidney also regulates the level of useful substances (ions)

What do tubules in the nephrone do?

when blood passes through kidneys tubules absorb all smaller particles.

Describe the structure of the urinary system?

Regions of the kidney:

**Cortex** - the outermost region

**Medulla** - the inner section of the kidney

**Renal pelvis** - the tube linking the kidney to the ureter

* Nephrons start in the **cortex** of the kidney, loop down into the **medulla** and back up to the cortex


* The contents of the nephrons drain into the **renal pelvis** and the **urine collects** there 

What is absorbed in filtration and what is not?

absorbed: water, glucose, amino acids, urea

not absorbed: cells and proteins

What occurs in selective reabsorption?

Glucose is always reabsorbed, some water is reabsorbed and no urea is absorbed back into the bloodstream