Search Results

Vascular tissues in a corn stem and a buttercup root

By: HWC, Views: 2239

Vascular tissues in a corn stem and a buttercup root. The cells that make up each tissue. Xylem conducts water and dissolved ions. It also helps mechanically support a plant. The cells, called vessel members and tracheids, are dead at maturity. Their lignified walls interconnect and serve as p...

Hormonal regulation of pregnancy - weeks 17 through 38

By: HWC, Views: 7996

• Estrogens increase uterine blood flow, maintaining the endometrium during pregnancy. • High levels of estrogen and progesterone inhibit the synthesis of milk. Progesterone inhibits myometrial contractions of the uterus to prevent premature birth. • Relaxin inhibits myometrial contract...

Bone cells and tissues - tissue composition and cells

By: HWC, Views: 8576

Bone tissue consists of bone cells secreting bone matrix. • The extracellular bone matrix is a connective tissue that is hard, yet flexible. • Collagen fibers provide flexibility. • Inorganic mineral salts (primarily calcium phosphate, or hydroxyapatite) provide hardness. • Togethe...

Type of Cell Junctions - Desmosome, Hemidesmosomes and Gap Junctions

By: HWC, Views: 8087

Cell Junctions: Cell junctions are found in some multi-cellular organisms. They exist of complexes and are found between cells and between cells and other structures. The junctions provide a way for cells to connect and exchange signals. What are tight junctions, desmosomes, and gap junctions...

Component of feedback systems & Communication and regulation of body systems

By: HWC, Views: 7862

• Primary responsibility for communication and regulation in the body is shared by the nervous and endocrine systems. • The two systems work alone or together in specialized physiological processes called feedback systems to maintain homeostasis. • Feedback systems - or loops - are ...

Optic Nerve and Optic Disk Animation (Part 2 of 2)

By: Administrator, Views: 10736

The optic disc or optic nerve head is the point of exit for ganglion cell axons leaving the eye. Because there are no rods or cones overlying the optic disc, it corresponds to a small blind spot in each eye. The ganglion cell axons form the optic nerve after they leave the eye. The optic disc ...

Primary and secondary response to infection

By: HWC, Views: 7486

• Pathogens enter the body by penetrating the non-specific barriers in the skin and mucus membranes. • Pathogens first encounter macrophages and natural killer cells that carry out phagocytosis and cytolysis respectively. • A pathogen's first encounter with the immune system can promo...

Acid-base imbalances - metabolic acidosis and alkalosis

By: HWC, Views: 7813

• Metabolic acidosis typically results from very low HCO3- ion blood concentrations. • Metabolic alkalosis typically results from very high HCO3- ion blood concentrations.

Definition of heart rate

By: HWC, Views: 7874

• Heart rate is determined by the rate of depolarizations of the sinoatrial (SA) node. • Cardiac output is directly proportional to heart rate, the greater the heart rate the greater the cardiac output. • Changes in heart rate are associated with exercise, stress or injury. Nervous ...