Homeostasis (chapter 7-8)

Question 1

7.1 Define Homeostasis

Answer 1

The physiological state of the body in which internal physical and chemical conditions are kept within a range that is suitable for life processes. For example – body temperature is 37˚C, blood pH 7.4 etc

Question 2

7.1 Define Dynatic Equilibrium

Answer 2

A condition that remains stable within fluctuating limits

Question 3

7.1 Negative feedback vs Positive feedback + Examples

Answer 3

+Process by which a small effect is amplified i.e. childbirth
-Process by which a mechanism is activated to restore conditions to their original state i.e. testosterone production

Question 4

7.2 Define Homeotherm + Example

Answer 4

Organism that maintains a stable body temperature regardless of the temperature of the external environment; eg. Humans and birds.

Question 5

7.2 Define Poikilotherm + Example

Answer 5

Organism whos body temperature varies with, and often matches, the temperature of the external environment; eg. Reptiles, amphibians.

Question 6

7.2 Define Endotherm

Answer 6

Organism that maintains its body temperature by internal mechanisms

Question 7

7.2 Define Ectotherm

Answer 7

Organism that maintains its body temperature by absorbing thermal energy from the environment

Question 8

7.2 Explain the body’s response to heat

Answer 8

Hypothalamus sends signals to sweat glands to initiate sweating, evaporation on skin causes cooling, blood vessels dilate and blood loses heat to skin to cool internal organs

Question 9

7.2 Explain the body’s response to cold

Answer 9

Hypothalamus sends signals to organs and tissues to increase body temp. Blood vessels constrict to prevent loss of heat to skin. Hair follicle muslces contract to cause goosebumps that trap warm air near skin. Shivering increases metabolism. Brown fat converts chemical energy to heat and is used when prolonged eposure to cold causes hormonal responses

Question 10

7.3 Define Deamination + Where it occurs

Answer 10

Removal of an amino group from an organic compound. Occurs in
liver

Question 11

7.3 Name 3 Products of Nitrogenous Waste + When they are released

Answer 11

Ammonia (released during deamination)
Uric acid (released during breakdown of nucleic acids)
Urea (formed by 2 ammonia and carbon dioxide as a way to remove ammonia from the body)

Question 12

7.4 Explain the Pathway of the Human Urinary System (parts + functions)

Answer 12

Kidney produces urine, ureter transports urine, bladder stores urine, urethera exports urine

Question 13

7.5 Explain the Pathway of the Formation of Urine (parts + functions)

Answer 13

Kidneys -> nephrons -> bowmans capsule -> glomerulous (filtration) -> proximal convoluted tubule (salts reabsorbed) -> descending loop on henle (water reabsorbed) -> ascending loop of henle (solutes reabsorbed) -> distil convoluted tubule (solutes reabsorbed, secretion) -> collecting duct -> ureter

Question 14

7.6 Name + Explain 3 functions of kidneys

Answer 14

Water Balance - ADH makes the walls of the distal tubule and collecting ducts more permeable to H2O

Blood PSI - Aldosterone increases N+ and H2O absorption, lowering psi. This triggers Renin to produce Angiotensin to constrict the blood vessels.

pH Balance - Bicarbonate-carbon dioxide buffer system, excess H+ are absorbed by bicarbonate ions.

Question 15

7.7 (Kidney Disease) Explain Diabetes Mellitus

Answer 15

Low insulin, high blood sugar, reverse osmotic psi, excess sugar in nephron causes water to stay in the nephron and gets lost in urine.

Question 16

7.7 (Kidney Disease) Explain Diabetes Insipidus

Answer 16

No ADH producing cells, no regulation of water reabsorption, lots of urine (and water) released

Question 17

7.7 (Kidney Disease) Explain Bright’s

Answer 17

Inflamed nephrons, permeability of nephron affected, large molecules can enter the nephron (no mechanism designed to reabsorb), proteins stuck in nephron cause water to flow into the nephron and increases urine output

Question 18

7.7 (Kidney Disease) Explain Kidney Stones

Answer 18

Caused by the precipitation of mineral solutes from the blood. The sharp-sided stones can lodge in the renal pelvis or move into the narrow ureter.

Question 19

7.7 (Kidney Disease) Explain Kidney Transplant + Body’s reaction

Answer 19

A new kidney and ureter are placed into the lower abdomen and surgically attached, the old kidney is only removed if it is infected, and a catheter is inserted to drain urine for the first few days. The immune system will usually attack the new kidney and this is they only downside.

Question 20

8.1 Define Hormones

Answer 20

Chemical messengers produced by cells in one part of the body (i.e ovaries) that effect cells of another part of the body (i.e breasts).

Question 21

8.1 Steroid vs Protein hormones (structure, receptor location, hydro-,example)

Answer 21

Steroid vs Protein
4 carbon rings cholesterol / 2-300 amino acid proteins
Nuclear membrane / Cell membrane
Hydrophobic / Hydrophilic
Sex hormones / Growth hormones

Question 22

8.1 Hypothalamus and pituitary function

Answer 22

The brain monitors bodys internal environment and regulates pituitary gland. Together they control many processes that maintain homeostasis. Hypothalamus secretes releasing factors into the pituitary gland.

Question 23

8.2 Explain Glucose Regulation + Hormones and what cells they are released by

Answer 23

Insulin - helps High Blood Sugar (produced by beta cells, released when blood sugar increases, causes cells of muscles, liver, and other organs to become permeable to glucose, In the liver glucose is converted into glycogen, the storage form of glucose)

Glucagon - helps Low Blood Sugar (produced by alpha cells, released when blood sugar decreases. Goes to the liver and forces glycogen to become glucose)

Question 24

8.2 What are the 3 types of diabetes + differences

Answer 24

Type 1 - Juvenile (insulin dependant) 10%
Early degeneration of beta cells. Some, but not enough insulin.
Type 2 - Adult (non-insulin dependant) 90%
Decreased insulin production or ineffective use of insulin produced.
Gestational 2%-10%
Temporary condition during pregnancy that increases the risk of diabetes in both mom and baby.

Question 25

8.4 2 Adrenal glands + Use + Hormones produced

Answer 25

Adrenal Medulla Short term stress - Epinephrine (adrenaline) and Norepinephrine (noradrenaline)

Adrenal Cortex Long term stress - Glucocorticoids: associated with blood glucose levels (cortisol), Mineralocorticoids (Aldosterone), Sex hormones

Question 26

8.3 Thyroid gland + Hormones produced

Answer 26

A two-lobed gland at the base of the neck that regulates the rate of glucose oxidation and lowers calcium in the blood.

produces thyroxine and triiodothyronine, and calcitonin

Question 27

8.3 Parathyroid glands + Hormones produced

Answer 27

four pea-sized glands in the thyroid gland that increase calcium in the blood.

produces parathyroid hormone

Question 28

8.3 (Thyroid Disorder) Explain goiter thyroidism

Answer 28

Low iodine in the diet lowers thyroid production and secretion of thyroxine drops. This causes more TSH to be produced and the thyroid is stimulated more; thyroid cells continue to develop resulting in an enlarged thyroid.

Question 29

8.3 (Thyroid Disorder) Explain hyperthyroidism

Answer 29

Overproduction of thyroxine by the thyroid gland, the fast oxidation of nutrients causes weight loss, elevated body temperature, and nervous behaviour. The most common cause of hyperthyroidism is an inherited disorder known as Graves’ disease, or thyrotoxicosis.

Question 30

8.3 (Thyroid Disorder) Explain hypothyroidism -

Answer 30

Underproduction of thyroxine causes slowed body movements

Question 31

8.3 (Growth Disorder) Explain gigantism

Answer 31

high GH secretion during childhood, bone size ^^

Question 32

8.3 (Growth Disorder) Explain dwarfism

Answer 32

low GH secretion during childhood, inhibit development of bones

Question 33

8.3 (Growth Disorder) Explain acromegaly

Answer 33

if GH production occurs after cartilaginous growth plates have fused, long bones cannot increase in length; however, width of forehead, fingers, and toes increase.

Question 34

8.4 Reaction to stress, explain Hans Selye’s General Adaptation Syndrome

Answer 34

Alarm (body mounts fight or flight response)

Resistance (Body attempts to deal with stress. If stress stops the body normalizes. If not the body adapts at a cost)

Exhaustion (The body’s resources are depleted, body function is impaired, sometimes death)

Question 35

8.5 Explain 2 Male Reproductive Hormone System Cycles + Initiation

Answer 35

At puberty, the hypothalmus secretes gonadotropic releasing hormone (GnRH) which causes the anterior pituitary to release FSH and LH.

LH stimulates interstitial cells -> increases testosterone -> increases sperm production -> inhibits anterior pituitary and hypothalmus -> inhibits LH release

FSH stimulates seminiferous tubules -> produces sperm -> sperm producing cells release inhibin -> inhibits anterior pituitary and hypothalmus -> inhibits FSH release

Question 36

8.5 Female Reproductive System (Ovarian cycle)

Answer 36

Flow Phase - day 1
Low progesterone causes GnRH released by hypothalamus -> GnRH stimulates the pituitary to release FSH -> FSH stimulates the ovaries to release estrogen and mature egg -> estrogen stimulates uterus to thicken the lining

Follicular Phase - day 6
High estrogen levels -> inhibit FSH -> stimulates LH

Ovulation - day 14
LH stimulates ovulation (release of egg)

Luteal Phase - day 28
The released egg travels to oviduct -> Follicle that egg is released from becomes corpus luteum -> produces progesterone ->
1. if fertilization occurs progesterone remains high (stops cycle) ->
inhibits LH and FSH
2. If fertilization doesnt occur, egg released will pass out uterus lining and estrogen/progesterone will stop production

Question 37

Endocrine Glands vs Exocrine Glands

Answer 37

exocrine glands secrete substances into a ductal system to an epithelial surface (sweat)

endocrine glands secrete products directly into the bloodstream