BIOL460 Exam 4

adrenal glands

a pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress

adrenal cortex

outer section of each adrenal gland; secretes cortisol, aldosterone, and sex hormones

ACTH

adrenocorticotropic hormone

What does ACTH do?

stimulates adrenal cortex to release cortisol

What are corticoids?

the steroid hormones produced by the adrenal cortex

What are the three regions of the adrenal cortex?

zona glomerulosa, zona fasciculata, zona reticularis

zona glomerulosa

mineralocorticoids (aldosterone)

What do mineralocorticoids do?

regulates electrolyte concentration in the blood

What does aldosterone do?

increases reabsorption of sodium, increases secretion of potassium, increases water retention

Where does aldosterone go?

kidneys

kidney filtrate

urine

How does aldosterone affect blood pressure?

increases blood pressure

How does aldosterone affect blood volume?

increases blood volume

What is hyperkalemia?

high K+ in the blood; used as a form of euthanasia

What does hyperkalemia cause?

cells depolarise, no APs are generated, and the heart and diaphragm stop working resulting in death

renin angiotensin aldosterone mechanism

This term refers to the mechanism involved in renal control of blood pressure. The kidneys respond to decreased blood pressure or blood flow by forming renin, which converts angiotensinogen into angiotensin I, which is finally converted to angiotensin II. Angiotensin II constricts arterioles and triggers aldosterone release.

renin

hormone secreted by the kidney; it raises blood pressure by influencing vasoconstriction (narrowing of blood vessels)

angiotensin

a peptide hormone that constricts blood vessels (vasoconstrictor), causes the retention of sodium and water, and produces thirst and a salt appetite

zona fasciculata

glucocorticoids (cortisol), metabolism of glucose; restricts entry of glucose into the cell, causes lipolysis and gluconeogensis; immune suppression leading to inflammatory problems

What is lipolysis?

the process of breaking down triglyceride to its basic units to be used for energy

gluconeogenessis

makes glucose from novel sources (AAs)

What triggers the zona fasciculata?

ACTH

Which region of the adrenal cortex synthesises glucocorticoids?

zona fasciculata

zona reticularis

produces sex steroids (prehormones), also referred to as weak androgens that produce other sex steroids

What does the zona reticularis secrete?

androgens

Cushing's Syndrome

hypersecretion of corticosteroids; too much ACTH, tumour on adrenal cortex

symptoms of Cushing's Syndrome

hyperglycemia, hypertension, muscle weakness, puffy appearance, moon-shaped face

Addison's Disease

hyposecretion of corticosteroids; fatal if left untreated, oral medication fixes it

symptoms of Addison's Disease

hypoglycemia, generalised weakness due to electrolyte imbalances, rapid weight loss

adrenal medulla

secretes epinephrine and norepinephrine (adrenergic receptors); stimulates lipolysis and provides energy in an emergency

adrenal medulla B2 receptors

on a liver cell follow the adenylate cyclase/cAMP pathway resulting in glycogenesis (breakdown of glycogen into glucose in the blood)

adrenal medulla A1 receptors

A1 receptors on a liver cell stimulate glycogenesis via the phospholipase C/Ca2+ mechanism

What kind of stress is the adrenal medulla associated with?

immediate/short-term stress

What kind of stress is the adrenal cortex associated with?

long term stress

What happens in animals that are stressed for long periods of time?

they have higher ACTH/corticosteroid concentrations that. suppress their immune system, making them get sick more often; atrophy of lymph glands and tissues; cancer is more likely

What is the thyroid gland composed of?

thyroid follicles

What is in thyroid follicles?

colloid suspension (protein-rich fluid) secreted by. cuboidal cells

parafollicular cells

between follicles, secrete calcitonin

calcitonin

decreases blood calcium levels and inhibits osteoclasts that dissolve bone; kidneys excrete more Ca2+

T3 and T4

thyroid hormones

What does the thyroid stimulating hormone (TSH) release?

T3 and T4

T4 is also known as

thyroxine

T3 is also known as

triiodothyronine

Which thyroid hormone is more active?

T3; it is 3-4x more potent than T4

What do follicles cells remove?

iodide; enzymes combine iodine with tyrosine residues of thyroglobulin

thyroglobulin

secreted by follicle cells; binds with iodine to produce T4 and T3

What binds to thyroglobulin?

MIT and DIT

MIT

monoiodotyrosine

DIT

diiodotyrosine

MIT + DIT =

T3

DIT + DIT =

T4

How do T3 and T4 travel through the blood?

with carrier protein called thyroid-binding globulin

How do follicle cells take in T3 and T4?

endocytosis

genomic action

steroid hormone influence on gene expression

three parts of genomic action

1. protein synthesis
2. maturation of nervous system
3/ increase in basal metabolic rate (BMR)

hyperthyroidism

excessive activity of the thyroid gland

symptoms of hyperthyroidism

hot, awake more (less sleep), manic, increased heart rate, quick reflexes, frequent bowel movements, lose weight and eat more

hypothyroidism

underactivity of the thyroid gland

symptoms of hypothyroidism

cold, tired (more sleep), depressed, lowered heart rate, slow reflexes, constipation, weight gain and eat less

goiter

enlarged thyroid gland

endemic/iodine deficiency will lead to

hypothyroid symptoms

What happens if you don't have enough iodine in your diet?

not enough T3 and T4 is produced, therefore there is no negative feedback loop to regulate TRH, AP/AH, and TSH levels and the thyroid grows in size

WIS

wonderful iodine state = SC; foods grown here and milk produced here were high in iodine

Grave's Disease or thyrotoxicosis

most common type of hyperthyroidism characterised by weight loss, tachycardia, palpitations, heat intolerance, excessive perspiration, nervousness, irritability, exophthalmos

What does the immune system do with Grave's Disease?

makes antibodies that bind to the cells of the thyroid gland and mark the pathogen for destruction; they have TSH-like effects and increase the amount of T3 and T4

Cretinism

a congenital (present from birth) form of hypothyroidism resulting in severe physical and mental disabilities as the CNS is not fully developed; treatable if caught early

parathyroid glands

four small yellowish masses embedded in the back of the thyroid

PTH

parathyroid hormone

What does PTH do?

increases blood calcium levels; kidneys excrete less Ca2+ in the urine and reabsorb it from the filtrate; osteoclasts that dissolve bone for Ca2+ increase in activity

pancreas

a spongy, airy organ that regulates the level of sugar in the blood

exocrine function of pancreas

produce pancreatic juice, digestive enzymes; pancreatic duct empties into the small intestine

endocrine function of pancreas

secretion of insulin and glucagon by pancreatic islet cells

Islets of Langerhans

areas of pancreatic cells that produce insulin and glucagon

alpha cells of pancreas

secrete glucagon

glucagon

increases blood glucose levels by stimulating liver to break down glycogen into glucose (glycogenolysis), and via lipolysis and gluconeogenesis

insulin

decreases blood glucose levels by promoting glucose entry into cells via GLUT4 (in adipose cells) and the formation of storage molecules; causes lipogenesis and glycogenogenesis

somatostatin

inhibits the activity of the alimentary canal

alimentary canal

digestive tube that extends from the mouth to the anus

beta cells of pancreas

secrete insulin

delta cells of pancreas

secrete somatostatin

glycogenolysis

breakdown of glycogen to glucose that occurs in the liver

lipolysis

breakdown of lipids for energy

gluconeogenesis

the making of glucose from a noncarbohydrate source such as amino acids or glycerol

lipogenesis

making lipids using glucose

glycogenogenesis

formation of glycogen

pineal gland

found in the epithalamus (posterior segment of diencephalon); looks like a pine cone and is sensitive to light

What do early reptiles and amphibians have?

a third pineal eye, which is a thin scale that was lost entirely in humans

What does the pineal gland produce?

melatonin (similar to serotonin)

melatonin

synthesised from tryptophan and entertains/resets circadian rhythms and photoperiodism; inhibits the production and release of FSH, LH, and gametes (anti-gonadotropic)

photoperiodism

the response of an organism to seasonal changes in day length; important in rodents, caribou, moose, etc.

When do animals in South Carolina have offspring?

in the spring and summer

How do deciduous trees respond to a change in day length?

by shedding leaves

gonads

produce gametes and sex hormones (estrogen and testosterone); ovaries and testes

male gonads

testes

testes

have seminiferous tubules lined with germinal epithelium that produce sperm via meioisis (spermatogenesis)

Leydig cells

cells that produce testosterone; in testes

testosterone

male sex hormone that maintains the integrity of genital. organs and aids in the development of male secondary sex characteristics; dictates body fat distribution, muscle and bone size, and beard(s)

female gonads

ovaries

estradiol-17-beta

principle estrogen made by ovaries, after puberty and until menopause

ovary

contains follicles with the mother's mRNAs and proteins (genome) and stem cells that form the egg/ovum via meiosis