A&P2 Exam 1 Lecture Review

Endocrine and Blood

First step of cAMP pump

First messenger binds to receptor

Second step of cAMP pump

Receptor activates a G protein

Third step of cAMP pump

The G protein activates effector enzyme adenlyate cyclase

Fourth step of cAMP pump

ATP is converted into cAMP

Fifth step of cAMP

cAMP activates a protein kinase, which phosphorylates other proteins

What enzyme degrades cAMP?

Phosphodiesterase

When does signal amplification occur in the cAMP pathway?

Step three: when one receptor activates adenylate cyclase

DAG and IP3

DAG: activates kinase

IP3: causes Ca2+ from intracellular storage

How does the same target hormone produce different effects in different tissues?

Different receptors, a different number of receptors, and specific tissue signaling produces different responses

Humoral stimuli

The changing levels of nutrients and ions in the blood affects this. For example, low Ca2+ levels stimulate parathyroid release of the hormones, and Ca2+ is released.

Neural stimuli

Nerve fibers are what stimulate hormone release. For example, the adrenal medulla stimulates catecholamine release (e.g. you see Brandon and feel a rush to your legs, shaky, like you’re going to puke, and heart out of your chest)

Hormonal stimuli

Hormonal release stimulates other endocrine release; for example, the hypothalamic-pituitary-target organ loop

Up-regulation

Up-regulation means cells ADD receptors because levels are low

Down-regulation

Cells REMOVE receptors because of high levels of the hormone

Permissiveness

One hormone needs another to exert effects

Synergism

More than one hormone creates effects at target cell (like glucagon and epinephrine at liver)

Antagonism

Insulin and glucagon

Posterior pituitary

Contains pituicytes, makes up the HYPOTHALAMIC-HYPOPHYSEAL tract connected through axons. Paraventricular and supraoptic tract. Runs through the infundibulum.

Anterior pituitary

Adenohypophysis; primary and secondary capillary plexus,

Posterior hormones

Oxytocin and ADH

ADH and oxytocin

ADH = reduces urine output

Oxytocin = paraventricular, from touch or infant

Diabetes Insipidus vs SIADH

DI = there is a deficit in ADH and INTENSE thirst due to very high urine output.

SIADH = main thing is HYPERsecretion. Headache, disorientation; fluid levels need to be restricted

Anterior pituitary hormones

– 1. Growth hormone (GH) – 2. Thyroid-stimulating hormone (TSH) (tropic) – 3. Adrenocorticotropic hormone (ACTH) (tropic) – 4. Follicle-stimulating hormone (FSH) (tropic) – 5. Luteinizing hormone (LH) (tropic) – 6. Prolactin (PRL)

DIRECT effects of growth hormone

• decreases glucose uptake

• increases blood glucose uptake and fatty acid use

• Increases fatty acid and amino acid uptake

INDIRECT actions of growth hormone

• Stimulation of IGFs

• Growth of bone and collagen matricces

Hypersecretion of GH in children/adults

Gigantism/acromegaly

Thyroid hormone synthesis

A seven step process.

Relationship between PTH and calcitonin

Calcitonin is the antagonist to PTH. CalcitonIN = reabsorption of calcium

PTH = raises blood calcium

Target organs of PTH

Bones, kidneys, small intestine

What are the effects and physical characteristics of cortisol in the body?

Cortisol raises blood glucose levels, and increases vasoconstriction. Very high levels lower bone and cartilage growth, don’t allow for proper inflammation, lower immunity, and throw off normal function.

What is the role of aldosterone?

Aldosterone increases Na+ reabsorption, and increase K+ secretion.

Renin-Angiotensin-Aldosterone System

Low blood volume means that the kidney secretes renin, which produces angiotensin, and then raises aldosterone from the ADRENAL CORTEX, from the zona glomerulosa, which releases

What is the purpose of acinar cells?

They produce fluid with enzymes for digestion

Polyuria, polydipsia, polyphagia

Urinating, thirst, hunger; ketoacidosis is toxicity from excess ketone bodies, leading to loss of electrolytes and a drop in blood pH.

Type 1

This is the autoimmune destruction of beta cells, which produce glucagon.

Little to no insulin production.

Treatment includes insulin, monitoring.

Type 2

A combination of resistance and deficiency result in Type 2. Insulin is produced, but essentially, the body becomes desensitized to it. Lifestyle modifications are necessary.

Pineal gland

The pineal gland is located in the epithalamus above the third ventricle. It secretes melatonin, which is responsible for circadian rhythms

What key functions are carried out by the secondary endocrine organs?

Heart: ANP is secreted in response to high blood pressure

Kidneys: EPO and calcitriol. EPO is secreted in response to hypoxia.

Adipose tissue: secretes leptin

GI tract: the stomach secretes gastrin and ghrelin; the GI tract CCK and GIP

Skeleton: secrete osteocalcin. Osteocalcin improves how we use glucose and reduces the storage of fat.

Age and environment

• PTH remains more or less steady with age

• TH declines with age

• GH declines with age